Physica Medica: European Journal of Medical Physics RSS feed: Articles in Press. Physica Medica is the official journal of the Associazione Italiana di Fisica Medica , the European Federation of Organisations for Medical Physics and the Irish Association of Physicists in Medicine . Physica Medica, European Journal of Medical Physics, publishing with Elsevier from 2007, provides an international forum for research and reviews on the following main topics: Medical Imaging Radiation Therapy Radiation Protection Measuring Systems and Signal Processing Education and training in Medical Physics Professional issues in Medical Physics Contributions on other topics related to Applications of Physics to Biology and Medicine and in particular related to new emerging fields such as Molecular Imaging, Hadrontherapy, System biology, Nanoparticles and Nanotechnologies, etc. are strongly encouraged. http://www.physicamedicaonline.com//inpress?rss=yesElsevier Inc.en © 2012 Associazione Italiana di Fisica Medica. Published by Elsevier Inc. All rights reserved. Physica Medica: European Journal of Medical Physics1120-17972012-05-21 © 2012 Associazione Italiana di Fisica Medica. Published by Elsevier Inc. All rights reserved. healthpermissions@elsevier.comhttp://www.physicamedicaonline.com/article/PIIS1120179712000373/abstract?rss=yesAbstract: Boron Neutron Capture Therapy (BNCT) is a binary radiotherapy method developed to treat patients with certain malignant tumours. To date, over 300 treatments have been carried out at the Finnish BNCT facility in various on-going and past clinical trials. In this technical review, we discuss our research work in the field of medical physics to form the groundwork for the Finnish BNCT patient treatments, as well as the possibilities to further develop and optimize the method in the future. Accordingly, the following aspects are described: neutron sources, beam dosimetry, treatment planning, boron imaging and determination, and finally the possibilities to detect the efficacy and effects of BNCT on patients.Boron neutron capture therapy (BNCT) in Finland: Technological and physical prospects after 20 years of experiences - Corrected ProofSauli Savolainen, Mika Kortesniemi, Marjut Timonen, Vappu Reijonen, Linda Kuusela, Jouni Uusi-Simola, Eero Salli, Hanna Koivunoro, Tiina Seppälä, Nadja Lönnroth, Petteri Välimäki, Heini Hyvönen, Petri Kotiluoto, Tom Serén, Antti Kuronen, Sami Heikkinen, Antti Kosunen, Iiro Auterinen10.1016/j.ejmp.2012.04.008Physica Medica: European Journal of Medical Physics (2012)2012-05-21Physica Medica: European Journal of Medical Physics2012-05-21REVIEW PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179712000312/abstract?rss=yesAbstract: Monte Carlo simulations and TLD dosimetry have been performed to determine the dose distributions along the central axis of the 12 mm COMS eye plaques loaded with IRA1-103Pd seeds. Several simulations and measurements have been employed to investigate the effect of Silastic insert and air in front of the eye on dosimetry results along the central axis of the plaque and at some critical ocular structures. Measurements were performed using TLD-GR200A circular chip dosimeters in a PMMA eye phantom. The central axis TLD chips locations were arranged in one central column of eye phantom, in 3 mm intervals. The off-axis TLD chips locations were arranged in three off-axis columns around the central axis column. Version 5 of the MCNP code was also used to evaluate the dose distribution around the plaque. The presence of the Silastic insert results in dose reduction of 14% at 5 mm; also about 7% dose reduction appears at the interface point, due to the air presence and lack of the scattering condition. The overall dosimetric parameters for the COMS eye plaque loaded with new palladium seeds are similar to a commercial widely used seed such as Theragenics200. As the dose calculations under TG-43 assumptions do not consider the effect of the plaque backing and Silastic insert for accurate dosimetry, it's suggested to apply the effect of the eye plaque materials and air on dosimetry results along the central axis of the plaque and at some critical ocular structures.Experimental measurements and Monte Carlo calculations for 103Pd dosimetry of the 12 mm COMS eye plaque - Corrected ProofPooneh Saidi, Mahdi Sadeghi, Claudio Tenreiro10.1016/j.ejmp.2012.04.002Physica Medica: European Journal of Medical Physics (2012)2012-05-16Physica Medica: European Journal of Medical Physics2012-05-16ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179712000208/abstract?rss=yesAs is commonly known, radiological protection of paediatric and pregnant patients exposed to medical diagnostic and therapeutic radiation has always received special attention. This is because children, embryos and foetuses have higher radiation sensitivities, and they exhibit an increased likelihood of developing radiation-induced cancer over their lives compared with people who are exposed to radiation as adults . Considering the potential risk of stochastic effects (i.e., incurring cancer or heritable effects) in children, the IAEA (International Atomic Energy Agency) and the ICRP (International Commission on Radiological Protection) have paid particular attention to medical radiation exposure in children.The impact of early life exposure to diagnostic and therapeutic radiation on childhood cancer risk - Corrected ProofYong Jian Ju, Li Qing Du, Jia Cao, Yan Wang, Xu Dong Miao, Hong Wang, Feng Hua Chen, Fei Yue Fan, Gao Ren Wang, Qiang Liu10.1016/j.ejmp.2012.02.002Physica Medica: European Journal of Medical Physics (2012)2012-05-14Physica Medica: European Journal of Medical Physics2012-05-14LETTER TO THE EDITORhttp://www.physicamedicaonline.com/article/PIIS1120179712000300/abstract?rss=yesAbstract: Purpose: To adapt the multi-parametric fit method to reconstruct brachytherapy needles inserted with free hand technique for treatment of surface malignancies.Methods: An alternative reconstruction method for brachytherapy (BT) needles is presented. The method is based on the digitized tip and end coordinates on pairs of posterior-anterior and posterior-oblique reconstruction images obtained with a non-isocentric C-arm. The needles tip and end coordinates are computed with the multi-parametric fit method that also incorporates the determination of the magnification factors of the reconstruction images. We tested the reconstruction accuracy with radio-opaque markers inserted into known positions. The range of C-arm angles that resulted in an accurate reconstruction was also investigated. We applied the method in treatments of the vulvar cancer using 3 to 5 pieces of BT needles located in a distance of approximately 1 cm.Results: The phantom test showed largest difference between the reconstructed and expected distance between the simulated needles ±1.3 mm. In vulvar insertions, the reconstructed position of the BT needles obtained with different image pairs agreed within 3 mm.Conclusion: The reconstruction accuracy of the multi-parametric fit method in with proper imaging is suitable for the clinical use.Multi-parametric fit method in reconstruction of brachytherapy needles - Corrected ProofJeno Palvolgyi10.1016/j.ejmp.2012.04.001Physica Medica: European Journal of Medical Physics (2012)2012-05-14Physica Medica: European Journal of Medical Physics2012-05-14TECHNICAL NOTEhttp://www.physicamedicaonline.com/article/PIIS1120179712000348/abstract?rss=yesAbstract: The purposes of this study were to perform tests for the ArcCHECK QA system, and to evaluate the suitability of this system for IMRT and VMAT verification. The device was tested for short term reproducibility, dose linearity, dose rate dependence, dose per pulse dependence, field size dependence, out of field dependence and directional dependence. Eight simple plans that each used four beams of different field sizes as well as IMRT and VMAT plans for various organs of 10 patients were measured by ArcCHECK. The phantom data was then compared with ion chamber measurements and planned results. The ArcCHECK diodes performed well for all tests except directional dependence, which varies from a minimum of −4.9% (seen only when the beam is incident on the diode at 180°) to a maximum of 9.1% (approximately at 105°). For simple plan verification, the absolute dose pass rates of γ index (3%/3 mm) were almost identical. They had an average pass rate of 94.6% ± 1.3% when the field size was ≤20 cm in the X direction (right to left direction), but the pass rate fell rapidly when the field size was >20 cm in the X direction. For all patient-specific IMRT and VMAT QA, the pass rates exceeded 95% and 93%, respectively, and high reproducibility of these results has been observed from week to week. The comparative measurements show that the ArcCHECK QA system is completely suitable for clinical IMRT and VMAT verification.Evaluation of the ArcCHECK QA system for IMRT and VMAT verification - Corrected ProofGuangjun Li, Yingjie Zhang, Xiaoqin Jiang, Sen Bai, Guang Peng, Kui Wu, Qingfeng Jiang10.1016/j.ejmp.2012.04.005Physica Medica: European Journal of Medical Physics (2012)2012-05-14Physica Medica: European Journal of Medical Physics2012-05-14ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179712000336/abstract?rss=yesAbstract: Purpose: The aim of this study is to report results of measurements of dose to the skin in vivo with radiochromic EBT films in treatments with helical tomotherapy.Methods and materials: In vivo measurements were performed by applying pieces of radiochromic films to the skin or to the inner side of thermoplastic mask before the treatment. The sites of treatment included scalp, brain, head and neck, cranio-spinal axis and lower limbs. Skin dosimetry was performed in a patient who experienced grade 3–4 acute side effects to the skin shortly after the first treatment sessions. For each patient we measured the setup errors using the daily MVCT acquired for image guidance of the treatment. EBT films were read with a flatbed Epson Expression scanner and images were processed with an in-house written routine.Results: A total of 96 measurements of dose to the skin performed on 14 patients. The mean difference and standard error of the mean difference between measured and TPS-calculated dose was −9.2% ± 2.6% for all treatments, −6.6% ± 2.6% for head and neck treatments. These differences were statistically significant at the 0.05 significance level (t-Student test). Planned dose and dose range in the region of measurements were not correlated with dose discrepancy.Conclusions: Radiochromic EBT films are suitable detectors for surface dose measurements in tomotherapy treatments. Results show that TPS overestimates dose to the skin measured with EBT radiochromic films. In vivo skin measurements with EBT films are a useful tool for quality assurance of tomotherapy treatments, as the treatment planning system may not give accurate dose values at the surface.Dose to the skin in helical tomotherapy: Results of in vivo measurements with radiochromic films - Corrected ProofMichele Avanzo, Annalisa Drigo, Stefano Ren Kaiser, Antonella Roggio, Giovanna Sartor, Paola Chiovati, Giovanni Franchin, Maurizio Mascarin, Elvira Capra10.1016/j.ejmp.2012.04.004Physica Medica: European Journal of Medical Physics (2012)2012-05-10Physica Medica: European Journal of Medical Physics2012-05-10ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179712000324/abstract?rss=yesAbstract: The aim of the current study was to compare the film method against the method based on a new CT slice detector in assessing geometric efficiency (GE) of x-ray beams utilized by a multi-detector CT (MDCT) scanner. Measurements of GE were performed using radiographic films and a solid state CT slice detector for all beam qualities, collimations and focal spot sizes available on an MDCT scanner. Repeatability of GE measurements was assessed. The radiographic film and the solid state detector methods were compared to each other in regard to efficacy in measuring free-in-air GE. The values of GE determined using the radiographic film method were found to range between 48.5% and 90.6%. Differences between values obtained with the radiographic film method and corresponding values obtained with the solid state detector were less than 10% exceeding 5% for only one case. Both methods show that wide beams have higher GE values compared to thin ones. The use of large instead of small focal spot was found to deteriorate GE values by up to 23.1%. Beam quality did not seem to influence GE of the various collimations. When thin beam collimations are employed, a considerable amount of the radiation is wasted for non-imaging purposes. Both film and solid state probe methods are capable of measuring GE of thin as well as wide collimations. The solid state detector is the easiest to use, however its usefulness is reduced by the fact that it cannot measure dose profiles of beam collimations available for step-and-shoot mode of operation.Comparison of methods for assessing geometric efficiency on multi-detector CT scanners - Corrected ProofTheocharis Berris, Kostas Perisinakis, Antonios E. Papadakis, John Damilakis10.1016/j.ejmp.2012.04.003Physica Medica: European Journal of Medical Physics (2012)2012-05-07Physica Medica: European Journal of Medical Physics2012-05-07TECHNICAL NOTEhttp://www.physicamedicaonline.com/article/PIIS1120179712000270/abstract?rss=yesAbstract: Beam hardening filters have long been employed in X-ray Computed Tomography (CT) to preferentially absorb soft and low-energy X-rays having no or little contribution to image formation, thus allowing the reduction of patient dose and beam hardening artefacts. In this work, we studied the influence of additional copper (Cu) and aluminium (Al) flat filters on patient dose and image quality and seek an optimum filter thickness for the GE LightSpeed VCT 64-slice CT scanner using experimental phantom measurements. Different thicknesses of Cu and Al filters (0.5–1.6mm Cu, 0.5–4mm Al) were installed on the scanner’s collimator. A planar phantom consisting of 13 slabs of Cu having different thicknesses was designed and scanned to assess the impact of beam filtration on contrast in the intensity domain (CT detector’s output). To assess image contrast and image noise, a cylindrical phantom consisting of a polyethylene cylinder having 16 holes filled with different concentrations of K2HPO4 solution mimicking different tissue types was used. The GE performance and the standard head CT dose index (CTDI) phantoms were also used to assess image resolution characterized by the modulation transfer function (MTF) and patient dose defined by the weighted CTDI. A 100mm pencil ionization chamber was used for CTDI measurement. Finally, an optimum filter thickness was determined from an objective figure of merit (FOM) metric. The results show that the contrast is somewhat compromised with filter thickness in both the planar and cylindrical phantoms. The contrast of the K2HPO4 solutions in the cylindrical phantom was degraded by up to 10% for a 0.68mm Cu filter and 6% for a 4.14mm Al filter. It was shown that additional filters increase image noise which impaired the detectability of low density K2HPO4 solutions. It was found that with a 0.48mm Cu filter the 50% MTF value is shifted by about 0.77lp/cm compared to the case where the filter is not used. An added Cu filter with approximately 0.5mm thickness accounts for 50% reduction in radiation-absorbed dose as measured by the weighted CTDI. The FOM results indicate that with an additional filter of 0.5mm Cu or minimum 4mm Al, a good compromise between image quality and patient dose is achieved for CT images acquired at tube voltages of 120 and 140kVp. The results seem to indicate that an optimum filter for high kVp acquisitions, routinely used in cardiovascular imaging, should be 0.5mm copper or 4mm aluminium minimum.Experimental assessment of the influence of beam hardening filters on image quality and patient dose in volumetric 64-slice X-ray CT scanners - Corrected ProofMohammad Reza Ay, Abolfazl Mehranian, Asghar Maleki, Hossien Ghadiri, Pardis Ghafarian, Habib Zaidi10.1016/j.ejmp.2012.03.005Physica Medica: European Journal of Medical Physics (2012)2012-04-27Physica Medica: European Journal of Medical Physics2012-04-27ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179712000282/abstract?rss=yesAbstract: Continuing professional development (CPD) and continuing professional education (CPE) are seen as being necessary for medical physicists to ensure that they are up-to-date with current clinical practice. CPD is more than just continuing professional education, but can include research publication, working group contribution, thesis examination and many other activities. A systematic way of assessing and recording such activities that a medical physicist undertakes is used in a number of countries. This can be used for certification and licensing renewal purposes. Such systems are used in 27 countries, but they should be implemented in all countries where clinical medical physicists are employed.A survey of the CPD systems that are currently operated around the world is presented. In general they are quite similar although there are a few countries that have CPD systems that differ significantly from the others in many respects. Generally they ensure that medical physicists are kept up-to-date, although there are some that clearly will fail to achieve that.An analysis of what is required to construct a useful medical physics CPD system is made. Finally, the need for medical physicist professional organizations to cooperate and share in the production and distribution of CPD and CPE materials is emphasized.Continuing professional development systems for medical physicists: A global survey and analysis - Corrected ProofW.Howell Round10.1016/j.ejmp.2012.03.006Physica Medica: European Journal of Medical Physics (2012)2012-04-23Physica Medica: European Journal of Medical Physics2012-04-23ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179712000294/abstract?rss=yesAbstract: Background and purpose: Tomotherapy treatment planning depends on parameters that are not used conventionally such as: field width (FW), pitch factor (PF) and modulation factor (MF). The aim of this study is to analyze the relationship between these parameters and their influence on the quality of treatment plans and beam-on time.Material and methods: Ten prostate cancer patients were included in the study. For each patient, two cases of irradiation were considered depending on the target volume: PTV1 included the prostate gland, seminal vesicles, pelvic lymph nodes and a 1 cm margin, whereas PTV2 included only the prostate gland with a 1 cm margin. For each patient and each case of irradiation (PTV1 and PTV2) 8 treatment plans were created – all consisted of a different combination of planning parameters (FW = 1.05, 2.5, 5 cm; PF = 0.107, 0.215, 0.43; MF = 1.5, 2.5, 3.5). Default values used in this study were FW = 2.5 cm, PF = 0.215 and MF = 2.5. Hence, for plans with different FWs, parameters of PF and MF were 0.215 and 2.5, respectively; for different PFs, FW and MF were 2.5 and 2.5, respectively; finally for different MFs, FW and PF were 2.5 and 0.215, respectively. The reference plan was optimized for FW = 1.05 cm, PF = 0.107 and MF = 3.5, which was assumed to result in the best dose distribution and the longest treatment time. As a result, 160 plans were created. Each plan was analyzed for dose distribution and execution time.Results and conclusion: : Treatment plans with FW of 5 cm resulted in the shortest execution time compromising the dose distribution. Moreover, the dose fall off in the longitudinal direction was not sharp. FW of 1.05 cm and PF of 0.107 were not recommended for routine prostate plans due to long execution time, which was 3 times longer than for plans with FW = 5 cm. There was no substantial decrease of irradiation time when PF was increased from 0.215 to 0.43 for both cases (PTV1 and PTV2); however, the dose distribution was slightly compromised. Finally, decreasing MF from 2.5 to 1.5 was useless because it did not change the beam-on time; however, it did remarkably decrease the dose distribution. Nevertheless, increasing MF up to 3.5 could be considered. The lowest EUD for the rectum and intestines, could be observed for PF = 0.107. For the other plans the differences were rather small (the EUD was almost the same). By reducing PF from 0.43 to 0.107 or FW from 5 to 1.05 the EUD for bladder (in PTV1 case) decreased by 3.13% and 2.60%. When PTV2 was a target volume, the EUD for bladder decreased by 4.54% and 3.43% when FW was changed from 5 to 1.05 and MF from 1.5 to 3.5, respectively. For optimal balance between beam-on time and dose distribution in OARs for routine patients, the authors would suggest to use: FW = 2.5, PF = 0.215 and MF = 2.5.Optimization of treatment planning parameters used in tomotherapy for prostate cancer patients - Corrected ProofM. Skórska, T. Piotrowski10.1016/j.ejmp.2012.03.007Physica Medica: European Journal of Medical Physics (2012)2012-04-23Physica Medica: European Journal of Medical Physics2012-04-23ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179712000233/abstract?rss=yesAbstract: Purpose: To track the saline during infusion with a 15 G needle into healthy pig livers at high and low infusion rates for 300 s.Methods: In each experiment, the needle was inserted into a single lobe of the liver to a depth of at least 2 cm following its longer axis. Two sets of experiments were defined: 1) low infusion rate of 0.1 mL/min (n = 6) and 2) high infusion rate of 1 mL/min (n = 6). Cine CT scans were carried out and three transverse planes were defined around the infusion point (IP), which corresponds with needle tip. Two assessments were performed: 1) a dynamic plane study focused on the time progress of the saline distribution on a single plane, which provided the Mean Percentage of Grayscale Intensity (MPGI); and 2) a volumetric study focused on the three dimensional distribution of the saline around IP at the end of the experiment, which provided the High Intensity Volume Ratio (HIVR).Results: The saline solution was conspicuous around the IP and shortly after heterogeneously inside the vessels. At the high infusion rate, the saline became conspicuous not only much sooner (evident at 20 s) but farther away (mean value of MPGI over 2%, up to 17 mm from the IP) and at a much higher intensity (mean value of MPGI over 10% up to 4 mm from the IP). The lower the radial distance to the IP, the greater the difference in HIVR between both groups.Conclusions: The high infusion rate leads to a faster, wider and a more marked presence of saline than the low rate. The rapid drainage into the hepatic veins may explain the heterogeneous distribution.CT mapping of saline distribution after infusion of saline into the liver in an ex vivo animal model. How much tissue is actually infused in an image-guided procedure? - Corrected ProofFernando Burdío, Enrique Berjano, Olga Millan, Luis Grande, Ignasi Poves, Claudio Silva, Maria Dolors de la Fuente, Sergi Mojal10.1016/j.ejmp.2012.03.001Physica Medica: European Journal of Medical Physics (2012)2012-04-05Physica Medica: European Journal of Medical Physics2012-04-05ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179712000257/abstract?rss=yesAbstract: Organ and tumour motion has a significant impact on the planning and delivery of radiotherapy treatment. At present imaging modality such as four-dimensional computer tomography (4DCT) cannot be used to measure the variability of motion between different respiratory cycles. To create reliable motion models, one needs to acquire volumetric data sets of the lungs with sufficient sampling of the breathing cycle. In this paper we investigate the use of highly parallel MRI to acquire such data. A 32 channel coil in conjunction with a balanced SSFP sequence and a SENSE factor of 6 were used to acquire volumetric data sets in five healthy volunteers. The acquisition was repeated for seven series of different breathing patterns. The data acquired was of sufficient spatial resolution (5 × 5 × 5 mm3) and image quality to carry out automated non-rigid registration. The acquisition rate (c.a. 2 volumes per second) allowed for a meaningful sampling of the different respiratory curves that were automatically obtained from the skin surface motion. This acquisition technique should provide images of high enough quality to create statistical respiratory models.Patient-specific respiratory models using dynamic 3D MRI: Preliminary volunteer results - Corrected ProofM.E. Miquel, J.M. Blackall, S. Uribe, D.J. Hawkes, T. Schaeffter10.1016/j.ejmp.2012.03.003Physica Medica: European Journal of Medical Physics (2012)2012-04-05Physica Medica: European Journal of Medical Physics2012-04-05TECHNICAL NOTEhttp://www.physicamedicaonline.com/article/PIIS1120179712000269/abstract?rss=yesAbstract: Background and purpose: For conformal radiotherapy, it is feasible to achieve high accuracy in contouring the outline of the target volume in treatment planning process. In contouring process, target volume is occasionally defined by means of either surgical clips or skin marker during patient anatomical data acquisition. Treatment planning systems are predicting invalid radiation dose distributions by using surgical clips and skin marker within the patient. Purpose of this study is the production of new skin marker which affects less dose distributions of electron beam.Materials and methods: The influences of lead and commercial markers on dose calculations in a 3D treatment planning systems were investigated in terms of electron beam energy and dose profile depth. Dose deviation with commercial marker was observed to smaller than lead marker. However this dose deviation was still at big value. In order to reduce of this value, barium sulfate suspension and ultrasound gel were mixed with different volumetric ratio. With the purpose of acception the most suitable marker for radiation therapy, obtained new suspensions were investigated in terms of visibility and dose deviation.Results: B:G/1:10 marker was determined to cause optimum visibility and the lowest dose deviation on dose calculations in terms of electron beam energy and dose profile depth.Conclusions: Appropriate marker, mixture of substances such as barium sulfate suspension and ultrasound gel can be produced. This marker is both ease of usage and practical and economical. Each clinic can prepare marker which is peculiar to suspension with different concentration of substance for specific visibility. But, it should be taken into account resultant dose deviation to beam calculation depending on barium sulfate concentration.Concentration modulated skin marker for radiotherapy treatment planning process - Corrected ProofYıldıray Özgüven, Birsen Yücel, Betül Özyürek, Gülderen Karakuş, Yücel Özgüven10.1016/j.ejmp.2012.03.004Physica Medica: European Journal of Medical Physics (2012)2012-04-04Physica Medica: European Journal of Medical Physics2012-04-04ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179712000245/abstract?rss=yesAbstract: High-energy proton microscopy provides unique capabilities in penetrating radiography including the combination of high spatial resolution and field-of-view, dynamic range of density for measurements, and reconstructing density variations to less than 1% inside volumes and in situ environments. We have recently proposed to exploit this novel proton radiography technique for image-guided stereotactic particle radiosurgery. Results of a first test for imaging biological and tissue-equivalent targets with high-energy (800 MeV) proton microscopy are presented here. Although we used a proton microscope setup at ITEP (Moscow, Russia) optimized for fast dynamic experiments in material research, we could reach a spatial resolution of 150 μm with approximately 1010 protons per image. The potential of obtaining high-resolution online imaging of the target using a therapeutic proton beam in the GeV energy region suggests that high-energy proton microscopy may be used for image-guided proton radiosurgery.First biological images with high-energy proton microscopy - Corrected ProofD. Varentsov, A. Bogdanov, V.S. Demidov, A.A. Golubev, A. Kantsyrev, P.M. Lang, D.N. Nikolaev, N. Markov, F. Natale, L. Shestov, P. Simoniello, G.N. Smirnov, M. Durante10.1016/j.ejmp.2012.03.002Physica Medica: European Journal of Medical Physics (2012)2012-04-03Physica Medica: European Journal of Medical Physics2012-04-03TECHNICAL NOTEhttp://www.physicamedicaonline.com/article/PIIS1120179712000063/abstract?rss=yesAbstract: Purpose: To compare two angiography systems of different image capture technology, one with flat detector (FD) and one with image intensifier (II), in terms of entrance surface air kerma (ESAK) rate, detector dose (DD) rate and image quality (IQ), in interventional cardiology procedures concerning both adult and pediatric patients.Materials and methods: In order to determine ESAK and DD rates, a digital dosimeter and polymethylmethacrylate (PMMA) plates were used. For the evaluation of IQ, two contrast objects (the Leeds TOR 18FG and a 5 mm-thick Aluminum plate) were used and two figures of merit were defined in fluoroscopy and cine acquisition modes. Measurements of ESAK, DD rates and IQ were made for various fields of view, pulse and frame acquisition rates.Results: For the particular setup used in this study was noted that ESAK values in the II system were generally larger than the respective values in the FD system (on average 70% for fluoro mode, 5 times for cine mode). When halving the fluoroscopy pulse rate, reduction in ESAK was not proportional, in fluoroscopy mode. Image quality evaluations indicated that II performs better in terms of low contrast sensitivity (LCS) and signal-to-noise ratio (SNR) than the FD system which performs better regarding high contrast resolution (HCR). However, when considering image quality in relation to ESAK the FD system performs better than the II system (with the exception of low thicknesses and zooms for high pulse rates in the fluoroscopy mode).Conclusions: The FD system, generally, provides a better image quality–dose relation than the II system although II unit provides better LCS and SNR. This means that with the right adjustments to both systems, FD unit is able to provide same image quality with lower dose. However, newer technology does not automatically imply better image quality and further investigation is necessary for deriving safe conclusions for units which utilize different capture technology.Comparative performance evaluation of a flat detector and an image intensifier angiographic system both used for interventional cardiology procedures in adult and pediatric patients - Corrected ProofSofia D. Kordolaimi, Aikaterini-Lampro N. Salvara, Ioannis Antonakos, Ioannis A. Tsalafoutas, Elias Broutzos, Efstathios P. Efstathopoulos10.1016/j.ejmp.2012.02.001Physica Medica: European Journal of Medical Physics (2012)2012-03-07Physica Medica: European Journal of Medical Physics2012-03-07ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179712000051/abstract?rss=yesAbstract: Objectives: To verify the dosimetric accuracy of treatment plans in high dose rate (HDR) brachytherapy by using Gafchromic EBT2 film and to demonstrate the adequacy of dose calculations of a commercial treatment planning system (TPS) in a heterogeneous medium.Methods: Absorbed doses at chosen points in anatomically different tissue equivalent phantoms were measured using Gafchromic EBT2 film. In one case, tandem ovoid brachytherapy was performed in a homogeneous cervix phantom, whereas in the other, organ heterogeneities were introduced in a phantom to replicate the upper thorax for esophageal brachytherapy treatment. A commercially available TPS was used to perform treatment planning in each case and the EBT2 films were irradiated with the HDR Ir-192 brachytherapy source.Results: Film measurements in the cervix phantom were found to agree with the TPS calculated values within 3% in the clinically relevant volume. In the thorax phantom, the presence of surrounding heterogeneities was not seen to affect the dose distribution in the volume being treated, whereas, a little dose perturbation was observed at the lung surface. Doses to the spinal cord and to the sternum bone were overestimated and underestimated by 14.6% and 16.5% respectively by the TPS relative to the film measurements. At the trachea wall facing the esophagus, a dose reduction of 10% was noticed in the measurements.Conclusions: The dose calculation accuracy of the TPS was confirmed in homogeneous medium, whereas, it was proved inadequate to produce correct dosimetric results in conditions of tissue heterogeneity.Dosimetric verification of a high dose rate brachytherapy treatment planning system in homogeneous and heterogeneous media - Corrected ProofS.C. Uniyal, S.D. Sharma, U.C. Naithani10.1016/j.ejmp.2012.01.004Physica Medica: European Journal of Medical Physics (2012)2012-02-20Physica Medica: European Journal of Medical Physics2012-02-20ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179712000038/abstract?rss=yesAbstract: Intensity Modulated Radiation Therapy (IMRT) is a complex treatment modality that requires pre-treatment patient-specific quality control (QC) in order to assess a correct treatment delivery. The aim of this work is to investigate pre-treatment patient-specific per-field QCs performed with an on-board EPID at the gantry angle of 0° and at the treatment ones, and to asses if measurements executed at 0° are able to guarantee a correct treatment.Ten patients with prostate cancer were evaluated. Two “verification” plans were created for each patient in order to calculate the dose at the EPID surface: one with all fields positioned at 0° and one with all fields at the actual treatment angles.EPID’s mechanical shifts due to gravity effects were always taken into account and corrected.0 and no-0 plans were compared using a gamma-index method (3%, 3 mm). The gamma index was found dependent on gantry angles but the difference between 0 and no-0 samples was small (−0.3% mean value) and the criteria of acceptability of the gamma method was always satisfied for every field delivered at angles different from 0.Therefore patient-specific pre-treatment QCs should be done at treatments angles, but, if periodical quality assurance is performed on dynamic MLC for different gantry angles, this requirement was shown not strictly mandatory and pre-treatment IMRTQC can be reasonably executed at 0° angles too.Gantry angle dependence in IMRT pre-treatment patient-specific quality controls - Corrected ProofAngelo Filippo Monti, Chiara Berlusconi, Stefania Gelosa10.1016/j.ejmp.2012.01.002Physica Medica: European Journal of Medical Physics (2012)2012-01-27Physica Medica: European Journal of Medical Physics2012-01-27TECHNICAL NOTEShttp://www.physicamedicaonline.com/article/PIIS1120179712000026/abstract?rss=yesAbstract: The beam quality correction factor and the perturbation factor pQ, commonly considered in dosimetry with ionization chambers, were calculated for the NE2571 and the Standard Imaging A19 and A12S chambers, using the Monte Carlo simulation code PENELOPE. For the NE2571 chamber, the values of obtained are in very good agreement with those found in previous works by Wulff et al. and Muir and Rogers with the code EGSnrc and also with the experimental results summarized in the NCS code of practice. For pQ, a difference of ∼0.4% has been found between our results and those obtained with EGSnrc for 60Co and this difference increases slightly with values. These factors have been calculated also for the A19 and A12S chambers of Standard Imaging. The values of show reasonable agreement with those recently calculated by Muir and Rogers and the measurements of McEwen.Calculation of beam quality correction factors for various thimble ionization chambers using the Monte Carlo code PENELOPE - Corrected ProofFabián Erazo, Antonio M. Lallena10.1016/j.ejmp.2012.01.001Physica Medica: European Journal of Medical Physics (2012)2012-01-25Physica Medica: European Journal of Medical Physics2012-01-25ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS112017971100161X/abstract?rss=yesAbstract: Background and purpose: High dose rate (HDR) brachytherapy is a clinically used procedure in prostate cancer treatment. The purpose of this study was to present the influence of using different optimization algorithms in 3D-CBRT planning on the treatment plan quality.Materials and methods: Treatment plans were calculated for 15 patients – three plans for each patient using: geometrical optimization (GO), inverse optimization (IO) and blind inverse optimization (BIO). For each patient, PTV and OAR volumes, number of needles and geometry of the implant were set equal. Differences between dose distributions were tracked using: D90, V100, V200, Dmax (for prostate); D10, Dmax (for urethra); D10, V100, Dmax (for rectum).Results: The analysis of mean values of D90 and V100 in the prostate showed that inverse algorithms gave the best results (mean D90 was 12.1% for BIO and 9.3% for IO better than for GO, mean V100 was 8.2% for BIO and 6.3% for IO better than for GO). From a clinical point of view, GO diminished the doses in the PTV and urethra in all analyzed parameters. The lowest mean doses in the rectum were achieved for plans optimized with IO and BIO (mean D10: 61.2% for GO, 58.1% for IO, 58.0% for BIO; mean Dmax: 92.8% for GO, 85.1% for IO, 83.6% for BIO).Conclusions: Application of the blind inverse optimization (BIO) algorithm led to clinically best dose parameters for PTV and the rectum. Use of geometrical optimization (GO) led to smaller doses in the urethra, which was however associated with a certain dose decrease also in PTV.Evaluation of clinical benefits achievable by using different optimization algorithms during real-time prostate brachytherapy - Corrected ProofMarta Adamczyk, Grzegorz Zwierzchowski, Julian Malicki, Janusz Skowronek10.1016/j.ejmp.2011.12.005Physica Medica: European Journal of Medical Physics (2012)2012-01-06Physica Medica: European Journal of Medical Physics2012-01-06ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179711001608/abstract?rss=yesAbstract: This paper characterizes and evaluates the potential of three commercial CT iterative reconstruction methods (ASIR™, VEO™ and iDose4 (™)) for dose reduction and image quality improvement. We measured CT number accuracy, standard deviation (SD), noise power spectrum (NPS) and modulation transfer function (MTF) metrics on Catphan phantom images while five human observers performed four-alternative forced-choice (4AFC) experiments to assess the detectability of low- and high-contrast objects embedded in two pediatric phantoms. Results show that 40% and 100% ASIR as well as iDose4 levels 3 and 6 do not affect CT number and strongly decrease image noise with relative SD constant in a large range of dose. However, while ASIR produces a shift of the NPS curve apex, less change is observed with iDose4 with respect to FBP methods. With second-generation iterative reconstruction VEO, physical metrics are even further improved: SD decreased to 70.4% at 0.5 mGy and spatial resolution improved to 37% (MTF50%). 4AFC experiments show that few improvements in detection task performance are obtained with ASIR and iDose4, whereas VEO makes excellent detections possible even at an ultra-low-dose (0.3 mGy), leading to a potential dose reduction of a factor 3 to 7 (67%–86%). In spite of its longer reconstruction time and the fact that clinical studies are still required to complete these results, VEO clearly confirms the tremendous potential of iterative reconstructions for dose reduction in CT and appears to be an important tool for patient follow-up, especially for pediatric patients where cumulative lifetime dose still remains high.Iterative reconstruction methods in two different MDCT scanners: Physical metrics and 4-alternative forced-choice detectability experiments – A phantom approach - Corrected ProofFrédéric A. Miéville, François Gudinchet, Francis Brunelle, François O. Bochud, Francis R. Verdun10.1016/j.ejmp.2011.12.004Physica Medica: European Journal of Medical Physics (2012)2012-01-04Physica Medica: European Journal of Medical Physics2012-01-04ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179711001426/abstract?rss=yesAbstract: The purpose of this study was to develop and assess the performance of a tumor tracking method designed for application in radiation therapy. This motion compensation strategy is currently applied clinically only in conventional photon radiotherapy but not in particle therapy, as greater accuracy in dose delivery is required.We proposed a tracking method that exploits artificial neural networks to estimate the internal tumor trajectory as a function of external surrogate signals. The developed algorithm was tested by means of a retrospective clinical data analysis in 20 patients, who were treated with state of the art infra-red motion tracking for photon radiotherapy, which is used as a benchmark. Integration into a hardware platform for motion tracking in particle therapy was performed and then tested on a moving phantom, specifically developed for this purpose.Clinical data show that a median tracking error reduction up to 0.7 mm can be achieved with respect to state of the art technologies. The phantom study demonstrates that a real-time tumor position estimation is feasible when the external signals are acquired at 60 Hz.The results of this work show that neural networks can be considered a valuable tool for the implementation of high accuracy real-time tumor tracking methodologies.Real-time tumor tracking with an artificial neural networks-based method: A feasibility study - Corrected ProofMatteo Seregni, Andrea Pella, Marco Riboldi, Roberto Orecchia, Pietro Cerveri, Guido Baroni10.1016/j.ejmp.2011.11.005Physica Medica: European Journal of Medical Physics (2012)2012-01-03Physica Medica: European Journal of Medical Physics2012-01-03http://www.physicamedicaonline.com/article/PIIS1120179711001591/abstract?rss=yesAbstract: The aim of this study was to design a cylindrical stepwedge phantom and an appropriate treatment procedure, based on which parameters of tomotherapy machine and generated beam of radiation will be defined. The accuracy of parameter determination, which can be defined with the aid of the measurement system, was also evaluated.The cylindrical phantom that we developed and manufactured (stepwedge phantom) consists of four cylinders with different diameters made of polycaprolactam-PA-6, i.e. material with high mechanical strength, low water absorption (making measurements repeatable) and a density comparable to that of human soft tissues. The appropriate treatment procedure is carried out in a dynamic mode, which is focused on specific properties of the tomotherapy machine. It means that a phantom situated on the couch moves to the inside of the rotating linear accelerator.A total of 18 procedures were implemented in order to calculate the following parameters: couch velocity, dose rate value at a depth, Dose Ratio coefficients, dose variation (so-called Dose Flatness) coefficients, and the time of gantry rotation. Reference intervals for these parameters were determined to be as follows: for the couch velocity: ±1.2%, the average dose rate measured at depth: ±1.8%, the calculated values of the coefficients Dose Ratio: ±0.5% and Dose Flatness: (0.53–0.65)%, the time of gantry rotation: ±3%.The final results showed that during a single irradiation procedure, which lasts 5 min, the cylindrical stepwedge phantom allows to precisely determine the values of the above-mentioned parameters. Its use in the daily dosimetric measurements can ensure better control of the work of the tomotherapy machine.Development of cylindrical stepwedge phantom for routine quality controls of a helical tomotherapy machine - Corrected ProofKrzysztof Mikołajczyk, Tomasz Piotrowski10.1016/j.ejmp.2011.12.003Physica Medica: European Journal of Medical Physics (2012)2012-01-03Physica Medica: European Journal of Medical Physics2012-01-03ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179711001578/abstract?rss=yesAbstract: The objective of this study is to develop an automatic clip localization procedure for breast cancer patient setup based on Digital Tomosynthesis (DTS) and to characterize its performance with respect to the overall registration accuracy and robustness. The study was performed under an IRB-approved protocol for 12 breast cancer patients with surgical clips implanted around the tumor cavity. The registration of DTS images to planning CTs was performed using an automatic algorithm developed to overcome specific challenges of localization and registration of clips in the breast setup images. The automatic method consisted of auto-segmentation (intensity-based thresholding with a priori knowledge about clip size and location to distinguish clips from bony features) and auto-registration of the segmented clip clusters. To determine the inherent accuracy and robustness of the registration algorithm, additional simulated DTS data was analyzed. The developed algorithm is efficient in removing false positives and negatives and provides an accuracy of better than 2.3mm for 60° and 3.3mm for 40° DTS. When incorporated in clinical software, this algorithm helps to facilitate fast and accurate setup evaluation with minimal dose delivered to patients.Automation of clip localization in Digital Tomosynthesis for setup of breast cancer patients - Corrected ProofSook Kien Ng, Yulia Lyatskaya, Dzmitry Stsepankou, Jurgen Hesser, Jennifer R. Bellon, Julia S. Wong, Piotr Zygmanski10.1016/j.ejmp.2011.12.001Physica Medica: European Journal of Medical Physics (2011)2011-12-30Physica Medica: European Journal of Medical Physics2011-12-30ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS112017971100158X/abstract?rss=yesAbstract: We designed and evaluated an innovative computer-aided-learning environment based on the on-line integration of computer controlled medical diagnostic devices and a medical information system for use in the preclinical medical physics education of medical students. Our learning system simulates the actual clinical environment in a hospital or primary care unit. It uses a commercial medical information system for on-line storage and processing of clinical type data acquired during physics laboratory classes. Every student adopts two roles, the role of ‘patient’ and the role of ‘physician’. As a ‘physician’ the student operates the medical devices to clinically assess ‘patient’ colleagues and records all results in an electronic ‘patient’ record. We also introduced an innovative approach to the use of supportive education materials, based on the methods of adaptive e-learning. A survey of student feedback is included and statistically evaluated.The results from the student feedback confirm the positive response of the latter to this novel implementation of medical physics and informatics in preclinical education. This approach not only significantly improves learning of medical physics and informatics skills but has the added advantage that it facilitates students’ transition from preclinical to clinical subjects.On-line integration of computer controlled diagnostic devices and medical information systems in undergraduate medical physics education for physicians - Corrected ProofJosef Hanus, Tomas Nosek, Jiri Zahora, Ales Bezrouk, Vladimir Masin10.1016/j.ejmp.2011.12.002Physica Medica: European Journal of Medical Physics (2011)2011-12-26Physica Medica: European Journal of Medical Physics2011-12-26ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179711001414/abstract?rss=yesAbstract: Purpose: To develop a new automatic exposure control (AEC) technique based on the contrast-to-noise ratio (CNR) and provide constant lesion detectability.Methods: Lesion detectability is affected by factors such as image noise, lesion contrast, and lesion size. We performed ROC analysis to assess the relationship between the optimum CNR and the lesion diameter at various levels of lesion contrast. We then developed a CNR-based AEC algorithm based on lesion detectability. Using CNR- based AEC algorithm, we performed visual evaluation of low-contrast detectability by 5 radiologists on a low-contrast module of the Catphan phantom, a contrast-difference level of 1.0% (difference in the CT number = 10 HU), and objects 3.0–9.0 mm in diameter.Results: On step-and-shoot scans the mean detection fraction with CNR-based AEC remained almost constant from 88 to 99 % regardless of the lesion size. We observed the same trend on helical scans, the mean detection fraction with CNR-based AEC exhibited a high score from 91 to 100%. Although CNR-based AEC maintains higher CNR for smaller size or lower contrast lesion, radiation dose on 3 mm lesion resulted in about 13 times larger than that of 9 mm lesion size. CTDIvol for the CNR-based AEC technique changed dramatically with the SDZ from 7.5 to 100.0 mGy for step-and-shoot scans and from 9.1 to 121.5 mGy for helical scans.Conclusions: From the viewpoint of ROC analysis-based CNR for lesion detection, CNR-based AEC potentially provide image quality advantages for clinical implementation.Automatic exposure control at MDCT based on the contrast-to-noise ratio: Theoretical background and phantom study - Corrected ProofYoshinori Funama, Yoshiaki Sugaya, Osamu Miyazaki, Daisuke Utsunomiya, Yasuyuki Yamashita, Kazuo Awai10.1016/j.ejmp.2011.11.004Physica Medica: European Journal of Medical Physics (2011)2011-12-19Physica Medica: European Journal of Medical Physics2011-12-19ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS112017971100144X/abstract?rss=yesAbstract: During radiotherapy, ionizing irradiation interacts with biological systems to produce free radicals, which attacks various cellular components. The hematopoietic system is well-known to be radiosensitive and its damage may be life-threatening. Melatonin synergistically acts as an immunostimulator and antioxidant. In this study we used a total of 120 rats with 20 rats in each group. Group 1 did not receive melatonin or irradiation (Control group), Group 2 received only 10 mg/kg melatonin (Mel group), Group 3 exposed to dose of 2 Gy irradiation (2 Gy Rad group), Group 4 exposed to 8 Gy irradiation (8 Gy Rad group), Group 5 received 2 Gy irradiation plus 10 mg/kg melatonin (Mel +2 Gy Rad group) and Group 6 received 8 Gy irradiation plus 10 mg/kg melatonin (Mel+8 Gy Rad group). Following exposure to radiation, five rats from each group were sacrificed at 4, 24, 48 and 72 h. Exposure to different doses of irradiation resulted in a dose-dependent decline in the antioxidant enzymes activity and lymphocyte count (LC) and an increase in the nitric oxide (NO) levels of the serum. Pre-treatment with melatonin (10 mg/kg) ameliorates harmful effects of 2 and 8 Gy irradiation by increasing lymphocyte count(LC) as well as antioxidant enzymes activity and decreasing NO levels at all time-points. In conclusion 10 mg/kg melatonin is likely to be a threshold concentration for significant protection against lower dose of 2 Gy gamma irradiation compared to higher dose of 8 Gy. Therefore, it seems that radio-protective effects of melatonin are dose-dependent.Radio-protective effects of melatonin against irradiation-induced oxidative damage in rat peripheral blood - Corrected ProofAlireza Shirazi, Ehsan Mihandoost, Mehran Mohseni, Mahmoud Ghazi-Khansari, Seied Rabie Mahdavi10.1016/j.ejmp.2011.11.007Physica Medica: European Journal of Medical Physics (2011)2011-12-16Physica Medica: European Journal of Medical Physics2011-12-16ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179711001438/abstract?rss=yesAbstract: Introduction and purpose: The Valencia applicators which are accessories of the microSelectron-HDR afterloader (Nucletron, Veenendaal, The Netherlands) are designed to treat skin lesions. These cup-shaped applicators are an alternative to superficial/orthovoltage x-ray treatment units. They limit the irradiation to the required area using tungsten-alloy shielding, and are equipped with a tungsten-alloy flattering filter allowing the treatment of skin tumors, the oral cavity, vaginal cuff, etc. The tungsten-alloy thickness to shield radiation is not the same in all parts of the applicators. This fact led us to question whether the leakage radiation differs depending on where it is measured, and whether this may be relevant in some clinical cases. The purpose of this work is to study from the radiation protection point of view the radiation leakage of the Valencia applicators, and provide a solution for current users and for the manufacturer.Methods and materials: Simulations based on the Monte Carlo (MC) method using the Geant4 code have been realized studying the dose rate distribution in air around the cup of the Valencia applicators. An experimental study with radiochromic film has also been done to measure the dose distribution in the back side of the applicators and to compare it with MC results.Results and conclusions: Radiation leakage of up to 170% of the prescribed dose has been found at the back surface of these applicators. Although this side is not usually directed to the patient, in some applications such as the treatment of a lesion on the nose, special care must be taken to avoid unexpected and unnecessary irradiation of the eyes. A possible solution could be to add additional shielding to the applicator in order to reduce this leakage or to put some shielding to protect the eyes. Additionally, a new concept design of the Valencia applicators using more shielding material in the applicator backside is proposed.Radiation leakage study for the Valencia applicators - Corrected ProofD. Granero, J. Perez-Calatayud, F. Ballester, Z. Ouhib10.1016/j.ejmp.2011.11.006Physica Medica: European Journal of Medical Physics (2011)2011-12-12Physica Medica: European Journal of Medical Physics2011-12-12ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179711001402/abstract?rss=yesAbstract: The aim of this paper is to clarify some physical–mechanical aspects involved in the carbon dioxide angiography procedure (CO2 angiography), with a particular attention to a possible damage of the vascular wall.CO2 angiography is widely used on patients with iodine intolerance. The injection of a gaseous element, in most cases manually performed, requires a long training period. Automatic systems allow better control of the injection and the study of the mechanical behaviour of the gas.CO2 injections have been studied by using manual and automatic systems. Pressures, flows and jet shapes have been monitored by using a cardiovascular mock. Photographic images of liquid and gaseous jet have been recorded in different conditions, and the vascular pressure rises during injection have been monitored.The shape of the liquid jet during the catheter washing phase is straight in the catheter direction and there is no jet during gas injection. Gas bubbles are suddenly formed at the catheter’s hole and move upwards: buoyancy is the only governing phenomenon and no bubbles fragmentation is detected. The pressure rise in the vessel depends on the injection pressure and volume and in some cases of manual injection it may double the basal vascular pressure values.CO2 angiography is a powerful and safe procedure which diffusion will certainly increase, although some aspects related to gas injection and chamber filling are not jet well known. The use of an automatic system permits better results, shorter training period and limitation of vascular wall damage risk.Mechanical aspects of CO2 angiography - Corrected ProofIvan Corazza, Pier Luca Rossi, Giacomo Feliciani, Luca Pisani, Sebastiano Zannoli, Romano Zannoli10.1016/j.ejmp.2011.11.003Physica Medica: European Journal of Medical Physics (2011)2011-12-05Physica Medica: European Journal of Medical Physics2011-12-05ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179711001384/abstract?rss=yesAbstract: NMR studies with hyperpolarized xenon as functionalized sensor or contrast agent recently made notable progress in developing a new approach for detecting molecular markers and parameters of biomedical interest. Combining spin polarization enhancement with novel indirect detection schemes easily enables a 107-fold signal gain, thus having promising potential to solve the NMR sensitivity problem in many applications. Though an inert element, 129Xe has exquisite NMR properties to sense molecular environments. This review summarizes recent developments in the production of hyperpolarized xenon and the design and detection schemes of xenon biosensors.Xenon for NMR biosensing – Inert but alert - Corrected ProofLeif Schröder10.1016/j.ejmp.2011.11.001Physica Medica: European Journal of Medical Physics (2011)2011-11-28Physica Medica: European Journal of Medical Physics2011-11-28REVIEW PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179711001396/abstract?rss=yesAbstract: Purpose: To extend the application of current radiation therapy (RT) based normal tissue complication probability (NTCP) models of radiation-induced fibrosis (RIF) of the breast to include the effects of fractionation, inhomogeneous dose, incomplete recovery, and time after the end of radiotherapy in partial breast irradiation (PBI).Materials and methods: An NTCP Lyman model with biologically effective uniform dose (BEUD) with and without a correction for the effect of incomplete repair was used. The time to occurrence of RIF was also taken into account. The radiobiological parameters were determined by fitting incidences of moderate/severe RIF in published randomized studies on RT of the breast. The NTCP model was used to calculate the risk of toxicity in 35 patients treated with intensity modulated, non-accelerated PBI and the result was compared with observed incidence of RIF.Results: With α/β fixed at 3Gy the parameters of the model without correction for incomplete repair extracted from fitting were: 50% complication probability biologically effective dose BEUD50 = 107.2 Gy (95%CI = 95.9–118.6 Gy), volume parameter n = 0.06 (95%CI = 0–0.23), and slope of dose response m = 0.22, (95%CI = 0.20–0.23). After including the correction for incomplete repair with repair halftime for subcutaneous tissue of τ = 4.4 h we obtained BEUD50 = 105.8 Gy (95%CI = 96.9–114.6Gy), n = 0.15 (95%CI = 0–0.33), m = 0.22 (95%CI = 0.20–0.23). Average NTCP predicted by these models, 4.3% and 2.0% respectively, offered a good agreement with RIF incidence in our patients, 5.7%, after an average follow-up of 12 months.Conclusion: The NTCP models of RIF, incorporating the effects of fractionation, volume effect, and latency of toxicity look promising to model PBI. Clinical validation from a prospective PBI treatment study is under development and will help test this preliminary result.Complication probability model for subcutaneous fibrosis based on published data of partial and whole breast irradiation - Corrected ProofMichele Avanzo, Joseph Stancanello, Marco Trovò, Rajesh Jena, Mario Roncadin, Mauro G. Trovò, Elvira Capra10.1016/j.ejmp.2011.11.002Physica Medica: European Journal of Medical Physics (2011)2011-11-28Physica Medica: European Journal of Medical Physics2011-11-28ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179711001372/abstract?rss=yesAbstract: Purpose: To assess the potential of cone beam CT (CBCT) derived adaptive RapidArc treatment for esophageal cancers in reducing the dose to organs at risk (OAR).Methods and materials: Ten patients with esophageal cancer were CT scanned in free breathing pattern. The PTV is generated by adding a 3D margin of 1 cm to the CTV as per ICRU 62 recommendations. The double arc RapidArc plan (Clin_RA) was generated for the PTV. Patients were setup using kV orthogonal images and kV-CBCT scan was acquired daily during first week of therapy, then weekly. These images were exported to the Eclipse TPS. The adaptive CTV which includes tumor and involved nodes was delineated in each CBCT image set for the length of the PTV. The composite CTV from first week CBCT was generated using Boolean union operator and 5 mm margin was added circumferentially to generate adaptive PTV (PTV1). Adaptive RapidArc plan (Adap_RA) was generated. NTCP and DVH of the OARs of the two plans were compared. Similarly, PTV2 was generated from weekly CBCT. PTV2 was evaluated for the coverage of 95% isodose of Adap_RA plan.Results: The PTV1 and PTV2 volumes covered by 95% isodose in adaptive plans were 93.51 ± 1.17% and 94.59 ± 1.43% respectively. The lung V10Gy, V20Gy and mean dose in Adap_RA plan was reduced by 17.43% (p = 0.0012), 34.64% (p = 0.0019) and 16.50% (p = 0.0002) respectively compared to Clin_RA. The Adap_RA plan reduces the heart D35% and mean dose by 17.35% (p = 0.0011) and 17.16% (p = 0.0012). No significant reduction in spinal cord and liver doses were observed. NTCP for the lung (0.42% vs. 0.08%) and heart (1.39% vs. 0.090%) was reduced significantly in adaptive plans.Conclusion: The adaptive re-planning strategy based on the first week CBCT dataset significantly reduces the doses and NTCP to OARs.Adaptive volumetric modulated arc treatment planning for esophageal cancers using cone beam computed tomography - Corrected ProofPadmanaban Sriram, S.A. Syamkumar, J. Sam Deva Kumar, Sukumar Prabakar, Rajasekaran Dhanabalan, Nagarajan Vivekanandan10.1016/j.ejmp.2011.10.006Physica Medica: European Journal of Medical Physics (2011)2011-11-14Physica Medica: European Journal of Medical Physics2011-11-14TECHNICAL NOTEShttp://www.physicamedicaonline.com/article/PIIS1120179711001359/abstract?rss=yesAbstract: Pencil beam algorithms are still considered as standard photon dose calculation methods in Radiotherapy treatment planning for many clinical applications. Despite their established role in radiotherapy planning their performance and clinical applicability has to be continuously adapted to evolving complex treatment techniques such as adaptive radiation therapy (ART). We herewith report on a new highly efficient version of a well-established pencil beam convolution algorithm which relies purely on measured input data. A method was developed that improves raytracing efficiency by exploiting the capability of modern CPU architecture for a runtime reduction. Since most of the current desktop computers provide more than one calculation unit we used symmetric multiprocessing extensively to parallelize the workload and thus decreasing the algorithmic runtime. To maximize the advantage of code parallelization, we present two implementation strategies – one for the dose calculation in inverse planning software, and one for traditional forward planning. As a result, we could achieve on a 16-core personal computer with AMD processors a superlinear speedup factor of approx. 18 for calculating the dose distribution of typical forward IMRT treatment plans.Boosting runtime-performance of photon pencil beam algorithms for radiotherapy treatment planning - Corrected ProofM. Siggel, P. Ziegenhein, S. Nill, U. Oelfke10.1016/j.ejmp.2011.10.004Physica Medica: European Journal of Medical Physics (2011)2011-11-10Physica Medica: European Journal of Medical Physics2011-11-10REVIEW PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179711001347/abstract?rss=yesAbstract: Background: In some clinical situations breast or chest wall radiotherapy for cancer is given in association with supraclavicular fossa irradiation. Often the treatment is delivered by two tangential fields to the breast or chest wall and an anterior field that irradiates the supraclavicular region. The tissue between the breast or chest wall and the supraclavicular region may be under or overdosed, because of the junction between the two tangential fields and the anterior field.Purpose: To present a new isocentric technique for exact geometric matching between the two tangential fields and the anterior field.Methods: Patients are positioned with both arms raised. Using three-dimensional trigonometry, two half-fields, with isocenter between the breast and the supraclavicular region, are easily matched. The tangential fields have a collimator rotation to protect the lung without additional shielding. The correct gantry, collimator and couch positions are defined for the anterior field to match the tangential fields.Conclusions: A general formula for exact geometric matching in radiotherapy of the breast and supraclavicular fossa is presented. The method does not require additional shielding to eliminate divergence other than the four independent jaws. The result is simple to implement in modern delivery facilities.A new isocentric technique for exact geometric matching in the radiotherapy of the breast and ipsilateral supraclavicular fossa using dual asymmetric jaws - Corrected ProofNando Romeo10.1016/j.ejmp.2011.10.003Physica Medica: European Journal of Medical Physics (2011)2011-11-07Physica Medica: European Journal of Medical Physics2011-11-07ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179711001360/abstract?rss=yesAbstract: Aim of the study was to evaluate the performance of a tube current modulation (TCM) system (SUREExposure 3D).On a 64 detector-row CT scanner (Aquilion 64, Toshiba), performance of fixed tube current, longitudinal TCM, and volumetric TCM acquisitions were assessed. A homogeneous cone-shaped phantom and an anthropomorphic phantom were used. Tube current and noise profiles were quantitatively analysed by box and whisker plots when phantom size, acquisition, and reconstruction parameters were varied.At similar median noise, fixed tube current scanning showed a noise range of 16.8–38.3 HU, while longitudinal TCM showed a range of 19.4–31.4 HU and volumetric TCM showed an even lower range of 20.7–28.7 HU. When acquisitions resulting in similar image quality (noise) were compared, the use of volumetric compared to longitudinal TCM resulted in a variable radiation dose reduction up to 6.6%.In conclusion, SUREExposure 3D resulted in more uniform image quality at a lower dose. Volumetric TCM shows improved results over longitudinal TCM.Performance of longitudinal and volumetric tube current modulation in a 64-slice CT with different choices of acquisition and reconstruction parameters - Corrected ProofAart J. Van der Molen, Raoul M.S. Joemai, Jacob Geleijns10.1016/j.ejmp.2011.10.005Physica Medica: European Journal of Medical Physics (2011)2011-11-07Physica Medica: European Journal of Medical Physics2011-11-07TECHNICAL NOTEShttp://www.physicamedicaonline.com/article/PIIS1120179711001335/abstract?rss=yesAbstract: The advent of high angular resolution diffusion imaging (HARDI) has opened up new perspectives for the delineation of crossing and branching fiber pathways. However, image acquisition under clinical conditions with limited measurement time faces the problem of poor spatial and angular resolution and the technique’s high susceptibility to noise. In this paper we present a straightforward spatial filter for ODF fields that uses the data-inherent structural information around a voxel as part of a directionally selective method for angular smoothing and radial regularization (ASRR). Especially in regions where fibers cross (multimodal voxels), the method allows us to reduce noise, improve the accuracy of ODF diffusion peaks, and strengthen signals of non-dominant fibers. Moreover, we propose a dynamic scheme in which regularization is applied only to ODFs classified as multimodal. The approach is quantitatively evaluated on synthetic datasets of various configurations. With an in vivo dataset of a human subject, measured under clinical imaging conditions, we demonstrate the method’s ability to improve tractography of non-dominant transcallosal fiber pathways and the long fibers of the superior longitudinal fasciculus.Angular smoothing and radial regularization of ODF fields: Application on deterministic crossing fiber tractography - Corrected ProofK.M. Otto, H.-H. Ehricke, V. Kumar, U. Klose10.1016/j.ejmp.2011.10.002Physica Medica: European Journal of Medical Physics (2011)2011-11-03Physica Medica: European Journal of Medical Physics2011-11-03ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179711001323/abstract?rss=yesAbstract: Gold nanoparticles were prepared and loaded into the bilayer of dipalmitoylphosphatidylcholine (DPPC) liposomes, named as gold-loaded liposomes. Biophysical characterization of gold-loaded liposomes was studied by transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy as well as turbidity and rheological measurements. FTIR measurements showed that gold nanoparticles made significant changes in the frequency of the CH2 stretching bands, revealing that gold nanoparticles increased the number of gauche conformers and create a conformational change within the acyl chains of phospholipids. The transmission electron micrographs (TEM) revealed that gold nanoparticles were loaded in the liposomal bilayer. The zeta potential of DPPC liposomes had a more negative value after incorporating of Au NPs into liposomal membranes. Turbidity studies revealed that the loading of gold nanoparticles into DPPC liposomes results in shifting the temperature of the main phase transition to a lower value. The membrane fluidity of DPPC bilayer was increased by loading the gold nanoparticles as shown from rheological measurements. Knowledge gained in this study may open the door to pursuing liposomes as a viable strategy for Au NPs delivery in many diagnostic and therapeutic applications.Biophysical characterization of gold nanoparticles-loaded liposomes - Corrected ProofMohsen Mahmoud Mady, Mohamed Mahmoud Fathy, Tareq Youssef, Wafaa Mohamed Khalil10.1016/j.ejmp.2011.10.001Physica Medica: European Journal of Medical Physics (2011)2011-10-24Physica Medica: European Journal of Medical Physics2011-10-24ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179711001311/abstract?rss=yesAbstract: Thermal ablation therapies, based on electromagnetic field sources (interstitial or intracavitary antennas) at radio and microwave frequencies, are increasingly used in medicine due to their proven efficacy in the treatment of many diseases (tumours, stenosis, etc). Such techniques need standardized procedures, still not completely consolidated, as to analyze the behaviour of antennas for treatment optimisation. Several tissue-equivalent dielectric simulators (also named phantoms) have been developed to represent human head tissues, and extensively used in the analysis of human exposure to the electromagnetic emissions from hand-held devices; yet, very few studies have considered other tissues, as those met in ablation therapies. The objective of this study was to develop phantoms of liver and kidney tissue to experimentally characterise interstitial microwave antennas in reference conditions. Phantom properties depend on the simulated target tissue (liver or kidney) and the considered frequency (2.45 GHz in this work), addressing the need for a transparent liquid to easily control the positioning of the probe with respect to the antenna under test. An experimental set-up was also developed and used to characterise microwave ablation antenna performances. Finally, a comparison between measurements and numerical simulations was performed for the cross-validation of the experimental set-up and the numerical model. The obtained results highlight the fundamental role played by dielectric simulators in the development of microwave ablation devices, representing the first step towards the definition of a procedure for the ablation treatment planning.Design and realisation of tissue-equivalent dielectric simulators for dosimetric studies on microwave antennas for interstitial ablation - Corrected ProofV. Lopresto, R. Pinto, R. Lodato, G.A. Lovisolo, M. Cavagnaro10.1016/j.ejmp.2011.09.001Physica Medica: European Journal of Medical Physics (2011)2011-10-17Physica Medica: European Journal of Medical Physics2011-10-17ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179711001177/abstract?rss=yesAbstract: This article describes and particularly explains a new phenomenon of persistent microbicidal effect of water previously exposed to the low-temperature plasma, which cannot be attributed to the acidification only. The direct microbicidal action of plasma is well documented, being mediated by number of reactive particles with a short lifetime. However, we observed the microbicidal effect also in exposed water stored for a month, where it must be mediated by stable particles. In water and in phosphate-buffered saline, the formation of NOx and corresponding acids, H2O2 and O3 was confirmed after exposition to the low-temperature plasma generated in air by DC negative glow corona and positive streamer discharge. The time course of acidification, H2O2 and O3 formation were deremined. Except uncertain traces of HCN, SIFT-MS analysis of exposed liquids reveals no additional reactive compounds. The microbicidal effect persists almost unchanged during 4 weeks of storage, although O3 completely and H2O2 almost disappears. Staphylococcus epidermidis and Escherichia coli were inactivated within 10 min of incubation in exposed liquids, Candida albicans needs at least 1 h. The solutions prepared by artificial mixing of reactive compounds mimic the action of exposed water, but in lesser extent. The acid milieu is the main cause of the microbicidal effect, but the possibility of still unidentified additional compound remains open.The persistent microbicidal effect in water exposed to the corona discharge - Corrected ProofJaroslav Julák, Vladimír Scholtz, Soňa Kotúčová, Olga Janoušková10.1016/j.ejmp.2011.08.001Physica Medica: European Journal of Medical Physics (2011)2011-09-19Physica Medica: European Journal of Medical Physics2011-09-19ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179711001189/abstract?rss=yesAbstract: Fiducial markers are widely used in image-guided radiation therapy to correct for setup error and organ motion. These markers, however, can cause dose perturbations in the target volume for patients undergoing external-beam radiation therapy. The goal of this study was to determine the dosimetric impact of various types of fiducial markers commonly used in patients receiving photon radiation therapy. Monte Carlo simulations based on a newly developed EGSnrcMP user code were used to investigate three types of gold fiducial markers and a carbon marker. A single photon field with each fiducial in various orientations and two parallel-opposed beams were simulated at 6-MV and 18-MV energies. The results indicated that dose perturbations depended on marker size, material, and orientation, as well as on incident beam energy. Maximum dose perturbations were found for a single 6-MV beam. The increase in dose reached a factor of 1.58 near the upstream surface of the gold marker because of electron backscatter. At the downstream surface, the dose was reduced to a factor of 0.53 at the same point without the marker. For the 18-MV beam, the maximum dose factor was 1.48 and the minimum dose factor was 0.66. For the two parallel-opposed beams, the maximum dose reduction was within 5% at 6 MV and 2% at 18 MV. Dose enhancement, however, remained significant, reaching factors of 1.20 and 1.33 for the two energies near the fiducial surface. Carbon fiducials caused dose perturbations of only ∼1%.Dosimetric impact of fiducial markers in patients undergoing photon beam radiation therapy - Corrected ProofOleg N. Vassiliev, Rajat J. Kudchadker, Deborah A. Kuban, Steven J. Frank, Seungtaek Choi, Quynh Nguyen, Andrew K. Lee10.1016/j.ejmp.2011.08.002Physica Medica: European Journal of Medical Physics (2011)2011-08-29Physica Medica: European Journal of Medical Physics2011-08-29ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179711001165/abstract?rss=yesAbstract: We model the dynamics of the F0 component of the F0F1-ATPase mitochondrion-based nano-motor operating in a stochastically-fluctuating medium that represents the intracellular environment. The stochastic dynamics are modeled via Langevin equation of motion wherein fluctuations are treated as white noise. We have investigated the influence of an applied alternating electric field on the rotary motion of the F0 rotor in such an environment. The exposure to the field induces a temperature rise in the mitochondrion’s membrane, within which the F0 is embedded. The external field also induces an electric potential that promotes a change in the mitochondrion’s transmembrane potential (TMP). Both the induced temperature and the change in TMP contribute to a change in the dynamics of the F0. We have found that for external fields in the radio frequency (RF) range, normally present in the environment and encountered by biological systems, the contribution of the induced thermal effects, relative to that of the induced TMP, to the dynamics of the F0 is more significant. The changes in the dynamics of the F0 part affect the frequency of the rotary motion of the F0F1-ATPase protein motor which, in turn, affects the production rate of the ATP molecules.Modelling the influence of thermal effects induced by radio frequency electric field on the dynamics of the ATPase nano-biomolecular motors - Corrected ProofA. Lohrasebi, S. Mohamadi, S. Fadaie, H. Rafii-Tabar10.1016/j.ejmp.2011.07.004Physica Medica: European Journal of Medical Physics (2011)2011-08-08Physica Medica: European Journal of Medical Physics2011-08-08ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179711000937/abstract?rss=yesAbstract: A Monte Carlo (MC) simulation for calculating absorbed dose has been developed and applied for dental applications with an i-CAT cone beam CT (CBCT) system. To validate the method a comparison was made between calculated and measured dose values for two different clinical protocols. Measurements with a pencil CT chamber were performed free-in-air and in a CT dose head phantom; measurements were also performed with a transmission ionization chamber. In addition for each protocol a total number of 58 thermoluminescence dosemeters (TLD) were packed in groups and placed at 16 representative anatomical locations of an anthropomorphic phantom (Remab system) to assess absorbed doses. To simulate X-ray exposure, a software application based on the EGS4 package was applied. Dose quantities were calculated for different voxelized models representing the CT ionization and transmission chambers, the TLDs, and the phantoms as well. The dose quantities evaluated in the comparison were the accumulated dose averaged along the rotation axis (), the volume average dose, for the dosimetric phantom, the dose area product (DAP) and the absorbed dose for the TLDs. Absolute differences between measured and simulated outcomes were ≤2.1% for free-in-air doses; ≤6.2% in the 5 cavities of the CT dose head phantom; ≤13% for TLDs inside the primary beam. Such differences were considered acceptable in all cases and confirmed the validity of the MC program for different geometries.In conclusion, the devised MC simulation program can be a robust tool to optimize protocols and estimate patient doses for CBCT units in dental, oral and maxillofacial radiology.Validation of a Monte Carlo simulation for dose assessment in dental cone beam CT examinations - Corrected ProofJ.J. Morant, M. Salvadó, R. Casanovas, I. Hernández-Girón, E. Velasco, A. Calzado10.1016/j.ejmp.2011.06.047Physica Medica: European Journal of Medical Physics (2011)2011-08-02Physica Medica: European Journal of Medical Physics2011-08-02ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179711001037/abstract?rss=yesAbstract: X-knife and gamma knife techniques are well-established for cranial stereotactic radiosurgery (SRS). Due to differences in their radiation delivery methods, some of the dosimetric parameters of these two techniques differ which may have clinical significance. There are many dosimetric studies comparing linear accelerator based techniques such as X-knife with gamma knife but generally from different institutions. We carried out a retrospective comparative study of the dosimetric parameters of the SRS treatments performed at our centre with X-knife (circular cones) and gamma knife. Our results indicate that the dose conformity and dose fall-off in the vicinity of the target volumes were better for patients treated with gamma knife as compared to X-knife. However, the dose fall-off pattern shows a reversal at a larger distance from the target. It was better for the X-knife as compared to gamma knife in the low dose region.Comparative clinical dosimetry with X-knife and gamma knife - Corrected ProofM.K. Semwal, Sukhvir Singh, A. Sarin, S. Bhatnagar, H.C. Pathak10.1016/j.ejmp.2011.07.003Physica Medica: European Journal of Medical Physics (2011)2011-08-01Physica Medica: European Journal of Medical Physics2011-08-01TECHNICAL NOTEShttp://www.physicamedicaonline.com/article/PIIS1120179711000925/abstract?rss=yesAbstract: Purpose: The clinical medical physicist is part of a team responsible for safe and competent provision of radiation-based diagnostic examinations and therapeutic practices. To ensure that the physicist can provide an adequate service, sufficient education and training is indispensable. The aim of this study is to provide a structured description of the present status of the clinical medical physicist education and training framework in 25 European, 2 North American and 2 Australasian countries.Methods: For this study, data collection was based on a questionnaire prepared by the European Federation of Organizations in Medical Physics (EFOMP) and filled-in either by the corresponding scientific societies-organizations or by the authors.Results: In the majority of cases, a qualified medical physicist should have an MSc in medical physics and 1–3 years of clinical experience. Education and training takes place in both universities and hospitals and the total duration of the programs ranges from 2.5 to 9 years. In 56% of all European countries, it is mandatory to hold a diploma or license to work as a medical physicist, the situation being similar in Australasian and 4 states of USA. Generally, there are national registers of medical physicists with inclusion on the register being voluntary. There are renewal mechanisms in the registers usually based on a Continuing Professional Development (CPD) system.Conclusions: In conclusion, a common policy is followed in general, on topics concerning education and training as well as the practice of the medical physicist profession, notwithstanding the presence of a few differences.The Education and training of clinical medical physicists in 25 European, 2 North American and 2 Australasian countries: Similarities and differences - Corrected ProofA.P. Stefanoyiannis, S. Christofides, K. Psichis, D.S. Geoghegan, I. Gerogiannis, W.H. Round, X. Geronikola-Trapali, I. Armeniakos, P.A. Kaplanis, A. Prentakis, S.N. Chatziioannou10.1016/j.ejmp.2011.07.001Physica Medica: European Journal of Medical Physics (2011)2011-07-27Physica Medica: European Journal of Medical Physics2011-07-27REVIEW PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179711000913/abstract?rss=yesAbstract: Purpose: Dynamic delivery of intensity modulated beams (dIMRT) requires not only accurate verification of leaf positioning but also a control on the speed of motion. The latter is a parameter that has a major impact on the dose delivered to the patient. Time consumed in quality assurance (QA) procedures is an issue of relevance in any radiotherapy department. Electronic portal imaging dosimetry (EPID) can be very efficient for routine tests. The purpose of this work is to investigate the ability of our EPID for detecting small errors in leaf positioning, and to present our daily QA procedures for dIMRT based on EPID.Methods and materials: A Varian 2100 CD Clinac equipped with an 80 leaf Millennium MLC and with amorphous silicon based EPID (aS500, Varian) is used. The daily QA program consists in performing: Stability check of the EPID signal, Garden fence test, Sweeping slit test, and Leaf speed test.Results and discussion: The EPID system exhibits good long term reproducibility. The mean portal dose at the centre of a 10 × 10 cm2 static field was 1.002 ± 0.004 (range 1.013–0.995) for the period evaluated of 47 weeks. Garden fence test shows that leaf position errors of up to 0.2 mm can be detected. With the Sweeping slit test we are able to detect small deviations on the gap width and errors of individual leaves of 0.5 and 0.2 mm. With the Leaf speed test problems due to motor fatigue or friction between leaves can be detected.Conclusions: This set of tests takes no longer than 5 min in the linac treatment room. With EPID dosimetry, a consistent daily QA program can be applied, giving complete information about positioning/speed MLC.QA of dynamic MLC based on EPID portal dosimetry - Corrected ProofJ. Richart, M.C. Pujades, J. Perez-Calatayud, D. Granero, F. Ballester, S. Rodriguez, M. Santos10.1016/j.ejmp.2011.06.046Physica Medica: European Journal of Medical Physics (2011)2011-07-25Physica Medica: European Journal of Medical Physics2011-07-25TECHNICAL NOTEhttp://www.physicamedicaonline.com/article/PIIS1120179711000949/abstract?rss=yesAbstract: PET scanners require routine monitoring and quality control (QC) to ensure proper scanner performance. QC helps to ensure that PET equipment performs as specified by the manufacturer and that there have not been significant changes in the system response since acceptance. In this work we describe the maintenance history and we report on the results obtained from the PET system QC testing program over 5 years at two centers, both utilizing a Siemens Biograph 16 HiRez PET/CT system. QC testing programs were based on international standards and included the manufacturer’s daily QC, monthly uniformity and sensitivity, quarterly cross-calibration and annual resolution and image quality.For the Winnipeg and Novara sites, two and one PET detector blocks have been replaced, respectively. Neither system has had other significant PET system related hardware replacements. The manufacturer’s suggested daily QC was sensitive to detecting problems in the function of PET detector elements. The same test was not sensitive for detecting long term drifts in the systems: the Novara system observed a significant deterioration over five years of testing in the sensitivity which exhibited a decrease of 16% as compared to its initial value measured at system installation. The measure of the energy spectrum, showed that the 511keV photopeak had shifted to a position of 468keV. This shift was corrected by having service personnel perform a complete system calibration and detector block setup.We recommend including tests of system energy response and of sensitivity as part of a QC program since they can provide useful information on the actual performance of the scanner. A modification of the daily QC test by the manufacturer is suggested to monitor the long term stability of the system. Image quality and spatial resolution tests have proven to be of limited value for monitoring the system over time.Five-year experience of quality control for a 3D LSO-based whole-body PET scanner: Results and considerations - Corrected ProofR. Matheoud, A.L. Goertzen, L. Vigna, J. Ducharme, G. Sacchetti, M. Brambilla10.1016/j.ejmp.2011.07.002Physica Medica: European Journal of Medical Physics (2011)2011-07-25Physica Medica: European Journal of Medical Physics2011-07-25ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179711000470/abstract?rss=yesAbstract: The operation of the bowtie filter in x-ray CT is correct if the object being scanned is properly centered in the scanner’s field-of-view. Otherwise, the dose delivered to the patient and image noise will deviate from optimal setting. We investigate the effect of miscentering on image noise and surface dose on three commercial CT scanners. Six cylindrical phantoms with different size and material were scanned on each scanner. The phantoms were positioned at 0, 2, 4 and 6 cm below the isocenter of the scanner’s field-of-view. Regression models of surface dose and noise were produced as a function of miscentering magnitude and phantom’s size. 480 patients were assessed using the calculated regression models to estimate the influence of patient miscentering on image noise and patient surface dose in seven imaging centers. For the 64-slice CT scanner, the maximum increase of surface dose using the CTDI-32 phantom was 13.5%, 33.3% and 51.1% for miscenterings of 2, 4 and 6 cm, respectively. The analysis of patients’ scout scans showed miscentering of 2.2 cm in average below the isocenter. An average increase of 23% and 7% was observed for patient dose and image noise, respectively. The maximum variation in patient miscentering derived from the comparison of imaging centers using the same scanner was 1.6 cm. Patient miscentering may substantially increase surface dose and image noise. Therefore, technologists are strongly encouraged to pay greater attention to patient centering.Impact of miscentering on patient dose and image noise in x-ray CT imaging: Phantom and clinical studies - Corrected ProofM.A. Habibzadeh, M.R. Ay, A.R. Kamali Asl, H. Ghadiri, H. Zaidi10.1016/j.ejmp.2011.06.002Physica Medica: European Journal of Medical Physics (2011)2011-07-11Physica Medica: European Journal of Medical Physics2011-07-11ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179711000317/abstract?rss=yesAbstract: This is the third of a series of articles targeted at biomedical physicists providing educational services to other healthcare professions, whether in a university faculty of medicine/health sciences or otherwise (e.g., faculty of science, hospital-based medical physics department). The first paper identified the past and present role of the biomedical physicist in the education of the healthcare professions and highlighted issues of concern. The second paper reported the results of a comprehensive SWOT (strengths, weaknesses, opportunities, threats) audit of that role. In this paper we present a strategy for the development of the role based on the outcomes of the SWOT audit. The research methods adopted focus on the importance of strategic planning at all levels in the provision of educational services. The analytical process used in the study was a pragmatic blend of the various theoretical frameworks described in the literature on strategic planning research as adapted for use in academic role development. Important results included identification of the core competences of the biomedical physicist in this context; specification of benchmarking schemes based on experiences of other biomedical disciplines; formulation of detailed mission and vision statements; gap analysis for the role. The paper concludes with a set of strategies and specific actions for gap reduction.A strategic development model for the role of the biomedical physicist in the education of healthcare professionals in Europe - Corrected ProofC.J. Caruana, M. Wasilewska-Radwanska, A. Aurengo, P.P. Dendy, V. Karenauskaite, M.R. Malisan, S. Mattson, J.H. Meijer, D. Mihov, V. Mornstein, E. Rokita, E. Vano, M. Weckstrom, M. Wucherer10.1016/j.ejmp.2011.05.001Physica Medica: European Journal of Medical Physics (2011)2011-07-04Physica Medica: European Journal of Medical Physics2011-07-04ORIGINAL PAPERhttp://www.physicamedicaonline.com/article/PIIS1120179711000329/abstract?rss=yesAbstract: We aimed to analyze the optimal conditions to carry out the periodical statistical control tests of the gamma camera count rate performance. First we focused in reproducing the actual R20 value of the gamma camera response. Second we studied the variability of this parameter in the statistical control test. We performed a reference measurement, which consisted of the determination of the complete curve relating observed and incident count rates, the counting model describing it and the reference R20. This reference determined the conditions for the statistical control tests and the way to analyze the results obtained. Results from three different gamma cameras were studied. Each gamma camera showed a different behavior and required specific data analysis. The optimal conditions to perform the statistical control test were determined in each case. Our procedure provides the information necessary to correlate the average value of R20 obtained in the quality control test with the reference one. The critical requirement to perform any statistical control test, that is to have a reduced variability of the control variable, can be fulfilled in this case only for relatively high activities.Quality control for system count rate performance with scatter in gamma cameras - Corrected ProofD. Guirado, J.C. Ramírez, J.M. de la Vega, M. Vilches, A.M. Lallena10.1016/j.ejmp.2011.05.002Physica Medica: European Journal of Medical Physics (2011)2011-06-06Physica Medica: European Journal of Medical Physics2011-06-06TECHNICAL NOTES