- Email: [email protected]
[P179] Small field correction factors determination for the IBA razor nano chamber and the IBA razor chamber
Abstracts / Physica Medica 52 (2018) 99–187
Finally, manual contours estimated a consistently faster rate of tumour shrinkage (0.018 cm3/day) than automatically propagated contours (0.014 cm3/day). A linear fit between the manual and propagated gradients per patient found a slope of 0.68 (1 for perfect agreement). Conclusions. The results show that automatic contour propagation performance is acceptable for use in wider research studies. There are differences between the manual and propagated contours, with the clinician estimated a larger rate of tumour shrinkage, which is suggestive of an observer bias. We will now apply this technique to investigate tumour shrinkage and outcome in the CONVERT trial patients. https://doi.org/10.1016/j.ejmp.2018.06.476
[P177] 3D Rapid manufacturing bolus vs commercial bolus – Skin dose comparison Anabela Dias a,*, Susana Gonçalves a, Fernando Jorge Monteiro b a Portuguese Oncology Institute of Porto (Ipo Porto), Medical Physics, Radiobiology and Radiation Protection Group, Ipo Porto Research Center (CI-Ipop), Medical Physics Service, Porto, Portugal b I3s- Instituto de Investigação e Inovação Em Saúde ( U.Porto), InebInstituto de Engenharia Biomédica( U.Porto), Universidade Do PortoFaculdade de Engenharia, Rua Dr. Roberto Frias, S/N 4200 465, Porto, Portugal ⇑ Corresponding author.
Purpose. Most of the breast treatments uses a megavoltage photon beams. This kind of energy exhibits a skin-sparing effect that is a concern in some stages of both breast conservative and postmastectomy irradiation. To overwhelm this effect a bolus material is placed on the skin. However, when using commercial noncustomized bolus, small air gaps can occur in certain regions of the treatment area where the bolus cannot establish the perfect match with the irregular skin of the patient, altering locally the expected skin dose. The objective of this study is to verify the improvement in the breast radiotherapy treatment using a customized bolus produced by 3D rapid manufacturing (3D-RM) techniques, and compare it with the commercial ones. Measurement of the surface dose and comparisons with the doses calculated by the Treatment Planning System (TPS) were also performed. Methods. The customized 3D rapid manufactured bolus was prepared for an anthropomorphic female phantom breast area. 3DCRT treatment plans for right breast were performed on CT scans of the phantom both with the customized and commercial bolus. The skin dose was measured in 5 points on the phantom breast surface using a MOSFET-based system. Results. A better fitting to the surface of the phantom was observed for the customized bolus, reducing the air gaps and improving the daily positioning on the irregular breast surfaces. The average differences between calculated and measured doses in the customized and commercial bolus ranged from 2 to 10%. However, the highest dose difference (approximately 10%) was observed for the commercial bolus. Conclusions. The 3D rapid manufactured bolus can reduce the uncertainty in the daily positioning and help to overcome the dose discrepancy due to unwanted air gaps affecting breast cancer radiation therapy. With the commercial bolus a higher dose difference relatively to TPS was observed. The skin dose increase is observed in the same proportion for both boluses. https://doi.org/10.1016/j.ejmp.2018.06.477
151
[P178] Dosimetric evaluation of DIBH and FB techniques by using vmat for left breast cancer Bora Tas a, Ismail Faruk Durmus b,* a
Yeni Yuzyil University Gaziosmanpsa Hospital, Radiation Oncology, Istanbul, Turkey b Yeni Yuzyil University Gaziosmanpsa Hospital, Istanbul, Turkey ⇑ Corresponding author. Purpose. Radiotherapy is an effective treatment method for managing breast cancer, but patients may have cardiac disease as a late radiation effect after completing radiotherapy. The left anterior descending coronary artery (LAD) dose and mean heart dose are playing a major role for cardiac disease. We aimed to compare deep inspiration breath-hold (DIBH) and free breathing (FB) techniques dosimetrically for left breast radiotherapy while using VMAT method. Methods. Sixteen early stage left breast cancer patient’s treatment planning were performed using Monaco 5.11Ò TPS (Elekta AB, Sweden) for DIBH and FB techniques. We used CatalystÒ (C-RAD AB, Sweden) optical surface guided radiotherapy gating device for DIBH technique. The prescribe dose was 60 Gy to tumor bed and 46 Gy to breast in 28 fractions by simultane integrated boost (SIB). We aimed to achieve a similar dose conformality for PTV (tumor bed) and PTV (whole breast) while optimizing two technique’s plan, then we compared mean heart dose, max. heart dose, mean LAD dose, V20 Gy, V10 Gy and V5 Gy doses percentage of lung volume. Results. A statistically significant interaction existed between heart, LAD doses and DIBH technique. We determined an average %20 lower max. heart doses, %32 lower mean heart doses and %27 lower mean LAD doses with DIBH technique, also, an average lung volume were enlarged %66. We didn’t determine significant percentage difference for V20 Gy, V10 Gy and V5 Gy doses of lung volume between two techniques. Conclusions. However, we achieved an average 3.7 Gy mean heart doses, 9.2 Gy mean LAD doses and 42.4 Gy max. heart doses with FB technique by using VMAT method, Darby et al. [1] have shown that the relative risk of ishemic heart disease increases with %7.4 per Gy increased mean heart dose. Hence, we even reduced significantly mean heart, max. heart and mean LAD doses with DIBH technique. Therefore, DIBH technique while using VMAT method may reduce cardiac disease possibility for left breast radiotherapy. References 1. Darby SC, Ewertz M, McGale P, et al. Risk of ishemic heart disease in women after radsßotherapy for breast cancer. N Engl J Med 2013;368:987–98. https://doi.org/10.1016/j.ejmp.2018.06.478
[P179] Small field correction factors determination for the IBA razor nano chamber and the IBA razor chamber Andrea Girardi a,*, Thierry Gevaert a, Mark De Ridder a a Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Department of Radiotherapy, Brussels, Belgium ⇑ Corresponding author.
Purpose. The aim of this study was to measure small beam output factors (OFs) using the IBA Razor Nano Chamber (RNC) and the IBA Razor Chamber (RC) and to determine correction factors for comparison with Gafchromic EBT3 films.
152
Abstracts / Physica Medica 52 (2018) 99–187
Methods. The detectors were irradiated with 6 MV photon beams using a Varian TrueBeam STx system equipped with a HD multileaf collimator (MLC). Fields ranging from 0.5 0.5 to 10 10 cm2 were defined by both the X-Y collimator jaws and the MLC. The microchambers were used in parallel configuration at a sourcesurface distance of 100 cm and at 10 cm depth in a Sun Nuclear 3D SCANNER water phantom. Polarity correction factors kpol were evaluated for both the chambers and used to correct the raw measurements. Films were irradiated inside a Solid Water phantom in the same geometry. Results. Deviations from unity of kpol were observed for field size less than 1 cm and greater than 2 cm, ranging from 0.943 to 1.025 for the RNC and from 0.970 to 1.005 for the RC. The output factors corrected for the polarity showed an underestimation for the smallest beam for both the detectors with respect to films (k = 1.033 and 1.052 for the RNC and the RC respectively). Correction factors values for beams ranging from 8 to 30 mm were close to unity. Conclusions. OFs corrected for the RNC and the RC were in agreement with films, although an underestimation has been observed for the smallest beam connected to a small volume averaging effect. The similar behavior of the two ionization chambers is probably due to the same size of the electrode diameter (2 mm). Both the detectors could be used for output factors measurements in small beam geometry, albeit the magnitude of the polarity effect suggests to correct the readings carried out with the two chambers in order to achieve a better accuracy.
or a subset of Monte Carlo studies was discussed. A checklist with the items that were deemed necessary and feasible to describe in a journal manuscript was developed, with the items separated by the sections they belong to in the manuscript. A template for an optional suggested table was also developed in which some of the methods used for the simulation could be described in summary form. Once finalized, the checklist was disseminated among a larger international group of medical physicists experts in Monte Carlo simulations, seeking their and their lab members’ feedback on the document. Results. The recommendation checklist includes 20 specific items, affecting the Title, Methods, Results, and Discussion of a manuscript. Some items are very simple (e.g., identifying in the Title that the study is a Monte Carlo study) while others are more extensive (e.g., describing the simulation geometry), with explanation on the level of detail suggested. The feedback on the draft guidelines received from all scientists consulted was very positive, regarding the need for such guidance, the items included in the document, and in its perceived ease-of-use. Conclusions. It is envisioned that the use of these guidelines will improve the description of Monte Carlo studies published in medical physics peer-reviewed literature. In addition to potentially providing a reference for authors and journal reviewers, the guidelines could be especially useful for scientists entering the field and writing their first manuscript. The RECORDS guidelines can be found at https://doi.org/10.1002/mp.12702. https://doi.org/10.1016/j.ejmp.2018.06.480
https://doi.org/10.1016/j.ejmp.2018.06.479
[P180] Records: Guidelines for publication of monte carlo studies Ioannis Sechopoulos a,*, D.W.O. Rogers b, Magdalena BazalovaCarter c, Wesley E. Bolch d, Emily Heath b, Michael F. McNitt-Gray e, Josep Sempau f, Jeffrey F. Williamson g a Radboud University Medical Center, Department of Radiology and Nuclear Medicine, Dutch Expert Centre for Screening, Nijmegen, Netherlands b Carleton University, Physics Department, Ottawa, Canada c University of Victoria, Department of Physics and Astronomy, Victoria, Canada d University of Florida, Department of Biomedical Engineering, Gainesville, United States e University of California, Los Angeles, David Geffen School of Medicine, Department of Radiological Sciences, Los Angeles, United States f Universitat Politecnica de Catalunya, Physics Department and Institute of Energy Technologies, Barcelona, Spain g Virginia Commonwealth University, Department of Radiation Oncology, Richmond, United States ⇑ Corresponding author.
Purpose. To improve the description of medical physics studies involving Monte Carlo simulations included in scientific literature by developing a set of recommendations on the information that should be included in this type of manuscript. Methods. An international group of medical physicists with backgrounds in imaging and therapy and with extensive experience in Monte Carlo studies, including the Editor-in-Chief of a medical physics journal, was formed. The group first aimed to identify, by expert opinion, what information is crucial to allow a reader to determine the validity and scope of a Monte Carlo-based study. Then, the level of detail required, and the potential applicability of these items to all
[P181] Establishing margins from clinical to planning target volume for low-risk prostate cancer radiotherapy: A multi institutional study Goran Kolarevic a,*, Aleksandar Kostovski a, Slavica Maric a, Drazan Jaros a, Tatjana Ignjic a, Justyna Krupka b, Agata Nowak c, Katia Katsari d,e, Chryssa Paraskevopoulou d,f a
International Medical Centers, Affidea, Department for Radiotherapy, Banja Luka, Bosnia and Herzegovina b Affidea Cancer Medical Center, Department for Radiotherapy, Poznan, Poland c Affidea Cancer Medical Center, Department for Radiotherapy, Walbrzych, Poland d Affidea B.V., Amsterdam, The Netherlands e Department for Radiotherapy, Amsterdam, The Netherlands f Department for Radiotherapy, Athens, Greece ⇑ Corresponding author. Purpose. The aim of this study was to determine the appropriate margins from clinical target volume (CTV) to planning target volume (PTV) in low risk prostate cancer irradiation, in terms of image guided radiotherapy (IGRT) protocol from three radiotherapy (RT) centers. Methods. Twenty patients with low risk prostate cancer were selected from each RT center for retrospective review. Prescribed dose of 78 Gy in 39 fractions was delivered with volumetric modulated arc therapy (VMAT). Pretreatment preparation was applied in accordance with institutional protocol. Cone beam computed tomography (CBCT) was daily co-registered with planning Computed Tomography (CT), using two registration protocols: bone match and prostate (soft tissue) match. Based on this data, set up errors and inter-fraction prostate motion were calculated in three RT centers. Literature data for delineation errors and intra-fraction motions were used to determine CTV-PTV margins for different imaging
Finally, manual contours estimated a consistently faster rate of tumour shrinkage (0.018 cm3/day) than automatically propagated contours (0.014 cm3/day). A linear fit between the manual and propagated gradients per patient found a slope of 0.68 (1 for perfect agreement). Conclusions. The results show that automatic contour propagation performance is acceptable for use in wider research studies. There are differences between the manual and propagated contours, with the clinician estimated a larger rate of tumour shrinkage, which is suggestive of an observer bias. We will now apply this technique to investigate tumour shrinkage and outcome in the CONVERT trial patients. https://doi.org/10.1016/j.ejmp.2018.06.476
[P177] 3D Rapid manufacturing bolus vs commercial bolus – Skin dose comparison Anabela Dias a,*, Susana Gonçalves a, Fernando Jorge Monteiro b a Portuguese Oncology Institute of Porto (Ipo Porto), Medical Physics, Radiobiology and Radiation Protection Group, Ipo Porto Research Center (CI-Ipop), Medical Physics Service, Porto, Portugal b I3s- Instituto de Investigação e Inovação Em Saúde ( U.Porto), InebInstituto de Engenharia Biomédica( U.Porto), Universidade Do PortoFaculdade de Engenharia, Rua Dr. Roberto Frias, S/N 4200 465, Porto, Portugal ⇑ Corresponding author.
Purpose. Most of the breast treatments uses a megavoltage photon beams. This kind of energy exhibits a skin-sparing effect that is a concern in some stages of both breast conservative and postmastectomy irradiation. To overwhelm this effect a bolus material is placed on the skin. However, when using commercial noncustomized bolus, small air gaps can occur in certain regions of the treatment area where the bolus cannot establish the perfect match with the irregular skin of the patient, altering locally the expected skin dose. The objective of this study is to verify the improvement in the breast radiotherapy treatment using a customized bolus produced by 3D rapid manufacturing (3D-RM) techniques, and compare it with the commercial ones. Measurement of the surface dose and comparisons with the doses calculated by the Treatment Planning System (TPS) were also performed. Methods. The customized 3D rapid manufactured bolus was prepared for an anthropomorphic female phantom breast area. 3DCRT treatment plans for right breast were performed on CT scans of the phantom both with the customized and commercial bolus. The skin dose was measured in 5 points on the phantom breast surface using a MOSFET-based system. Results. A better fitting to the surface of the phantom was observed for the customized bolus, reducing the air gaps and improving the daily positioning on the irregular breast surfaces. The average differences between calculated and measured doses in the customized and commercial bolus ranged from 2 to 10%. However, the highest dose difference (approximately 10%) was observed for the commercial bolus. Conclusions. The 3D rapid manufactured bolus can reduce the uncertainty in the daily positioning and help to overcome the dose discrepancy due to unwanted air gaps affecting breast cancer radiation therapy. With the commercial bolus a higher dose difference relatively to TPS was observed. The skin dose increase is observed in the same proportion for both boluses. https://doi.org/10.1016/j.ejmp.2018.06.477
151
[P178] Dosimetric evaluation of DIBH and FB techniques by using vmat for left breast cancer Bora Tas a, Ismail Faruk Durmus b,* a
Yeni Yuzyil University Gaziosmanpsa Hospital, Radiation Oncology, Istanbul, Turkey b Yeni Yuzyil University Gaziosmanpsa Hospital, Istanbul, Turkey ⇑ Corresponding author. Purpose. Radiotherapy is an effective treatment method for managing breast cancer, but patients may have cardiac disease as a late radiation effect after completing radiotherapy. The left anterior descending coronary artery (LAD) dose and mean heart dose are playing a major role for cardiac disease. We aimed to compare deep inspiration breath-hold (DIBH) and free breathing (FB) techniques dosimetrically for left breast radiotherapy while using VMAT method. Methods. Sixteen early stage left breast cancer patient’s treatment planning were performed using Monaco 5.11Ò TPS (Elekta AB, Sweden) for DIBH and FB techniques. We used CatalystÒ (C-RAD AB, Sweden) optical surface guided radiotherapy gating device for DIBH technique. The prescribe dose was 60 Gy to tumor bed and 46 Gy to breast in 28 fractions by simultane integrated boost (SIB). We aimed to achieve a similar dose conformality for PTV (tumor bed) and PTV (whole breast) while optimizing two technique’s plan, then we compared mean heart dose, max. heart dose, mean LAD dose, V20 Gy, V10 Gy and V5 Gy doses percentage of lung volume. Results. A statistically significant interaction existed between heart, LAD doses and DIBH technique. We determined an average %20 lower max. heart doses, %32 lower mean heart doses and %27 lower mean LAD doses with DIBH technique, also, an average lung volume were enlarged %66. We didn’t determine significant percentage difference for V20 Gy, V10 Gy and V5 Gy doses of lung volume between two techniques. Conclusions. However, we achieved an average 3.7 Gy mean heart doses, 9.2 Gy mean LAD doses and 42.4 Gy max. heart doses with FB technique by using VMAT method, Darby et al. [1] have shown that the relative risk of ishemic heart disease increases with %7.4 per Gy increased mean heart dose. Hence, we even reduced significantly mean heart, max. heart and mean LAD doses with DIBH technique. Therefore, DIBH technique while using VMAT method may reduce cardiac disease possibility for left breast radiotherapy. References 1. Darby SC, Ewertz M, McGale P, et al. Risk of ishemic heart disease in women after radsßotherapy for breast cancer. N Engl J Med 2013;368:987–98. https://doi.org/10.1016/j.ejmp.2018.06.478
[P179] Small field correction factors determination for the IBA razor nano chamber and the IBA razor chamber Andrea Girardi a,*, Thierry Gevaert a, Mark De Ridder a a Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Department of Radiotherapy, Brussels, Belgium ⇑ Corresponding author.
Purpose. The aim of this study was to measure small beam output factors (OFs) using the IBA Razor Nano Chamber (RNC) and the IBA Razor Chamber (RC) and to determine correction factors for comparison with Gafchromic EBT3 films.
152
Abstracts / Physica Medica 52 (2018) 99–187
Methods. The detectors were irradiated with 6 MV photon beams using a Varian TrueBeam STx system equipped with a HD multileaf collimator (MLC). Fields ranging from 0.5 0.5 to 10 10 cm2 were defined by both the X-Y collimator jaws and the MLC. The microchambers were used in parallel configuration at a sourcesurface distance of 100 cm and at 10 cm depth in a Sun Nuclear 3D SCANNER water phantom. Polarity correction factors kpol were evaluated for both the chambers and used to correct the raw measurements. Films were irradiated inside a Solid Water phantom in the same geometry. Results. Deviations from unity of kpol were observed for field size less than 1 cm and greater than 2 cm, ranging from 0.943 to 1.025 for the RNC and from 0.970 to 1.005 for the RC. The output factors corrected for the polarity showed an underestimation for the smallest beam for both the detectors with respect to films (k = 1.033 and 1.052 for the RNC and the RC respectively). Correction factors values for beams ranging from 8 to 30 mm were close to unity. Conclusions. OFs corrected for the RNC and the RC were in agreement with films, although an underestimation has been observed for the smallest beam connected to a small volume averaging effect. The similar behavior of the two ionization chambers is probably due to the same size of the electrode diameter (2 mm). Both the detectors could be used for output factors measurements in small beam geometry, albeit the magnitude of the polarity effect suggests to correct the readings carried out with the two chambers in order to achieve a better accuracy.
or a subset of Monte Carlo studies was discussed. A checklist with the items that were deemed necessary and feasible to describe in a journal manuscript was developed, with the items separated by the sections they belong to in the manuscript. A template for an optional suggested table was also developed in which some of the methods used for the simulation could be described in summary form. Once finalized, the checklist was disseminated among a larger international group of medical physicists experts in Monte Carlo simulations, seeking their and their lab members’ feedback on the document. Results. The recommendation checklist includes 20 specific items, affecting the Title, Methods, Results, and Discussion of a manuscript. Some items are very simple (e.g., identifying in the Title that the study is a Monte Carlo study) while others are more extensive (e.g., describing the simulation geometry), with explanation on the level of detail suggested. The feedback on the draft guidelines received from all scientists consulted was very positive, regarding the need for such guidance, the items included in the document, and in its perceived ease-of-use. Conclusions. It is envisioned that the use of these guidelines will improve the description of Monte Carlo studies published in medical physics peer-reviewed literature. In addition to potentially providing a reference for authors and journal reviewers, the guidelines could be especially useful for scientists entering the field and writing their first manuscript. The RECORDS guidelines can be found at https://doi.org/10.1002/mp.12702. https://doi.org/10.1016/j.ejmp.2018.06.480
https://doi.org/10.1016/j.ejmp.2018.06.479
[P180] Records: Guidelines for publication of monte carlo studies Ioannis Sechopoulos a,*, D.W.O. Rogers b, Magdalena BazalovaCarter c, Wesley E. Bolch d, Emily Heath b, Michael F. McNitt-Gray e, Josep Sempau f, Jeffrey F. Williamson g a Radboud University Medical Center, Department of Radiology and Nuclear Medicine, Dutch Expert Centre for Screening, Nijmegen, Netherlands b Carleton University, Physics Department, Ottawa, Canada c University of Victoria, Department of Physics and Astronomy, Victoria, Canada d University of Florida, Department of Biomedical Engineering, Gainesville, United States e University of California, Los Angeles, David Geffen School of Medicine, Department of Radiological Sciences, Los Angeles, United States f Universitat Politecnica de Catalunya, Physics Department and Institute of Energy Technologies, Barcelona, Spain g Virginia Commonwealth University, Department of Radiation Oncology, Richmond, United States ⇑ Corresponding author.
Purpose. To improve the description of medical physics studies involving Monte Carlo simulations included in scientific literature by developing a set of recommendations on the information that should be included in this type of manuscript. Methods. An international group of medical physicists with backgrounds in imaging and therapy and with extensive experience in Monte Carlo studies, including the Editor-in-Chief of a medical physics journal, was formed. The group first aimed to identify, by expert opinion, what information is crucial to allow a reader to determine the validity and scope of a Monte Carlo-based study. Then, the level of detail required, and the potential applicability of these items to all
[P181] Establishing margins from clinical to planning target volume for low-risk prostate cancer radiotherapy: A multi institutional study Goran Kolarevic a,*, Aleksandar Kostovski a, Slavica Maric a, Drazan Jaros a, Tatjana Ignjic a, Justyna Krupka b, Agata Nowak c, Katia Katsari d,e, Chryssa Paraskevopoulou d,f a
International Medical Centers, Affidea, Department for Radiotherapy, Banja Luka, Bosnia and Herzegovina b Affidea Cancer Medical Center, Department for Radiotherapy, Poznan, Poland c Affidea Cancer Medical Center, Department for Radiotherapy, Walbrzych, Poland d Affidea B.V., Amsterdam, The Netherlands e Department for Radiotherapy, Amsterdam, The Netherlands f Department for Radiotherapy, Athens, Greece ⇑ Corresponding author. Purpose. The aim of this study was to determine the appropriate margins from clinical target volume (CTV) to planning target volume (PTV) in low risk prostate cancer irradiation, in terms of image guided radiotherapy (IGRT) protocol from three radiotherapy (RT) centers. Methods. Twenty patients with low risk prostate cancer were selected from each RT center for retrospective review. Prescribed dose of 78 Gy in 39 fractions was delivered with volumetric modulated arc therapy (VMAT). Pretreatment preparation was applied in accordance with institutional protocol. Cone beam computed tomography (CBCT) was daily co-registered with planning Computed Tomography (CT), using two registration protocols: bone match and prostate (soft tissue) match. Based on this data, set up errors and inter-fraction prostate motion were calculated in three RT centers. Literature data for delineation errors and intra-fraction motions were used to determine CTV-PTV margins for different imaging