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Feng H, Holmes JM, Vora SA, Stoker JB, Bues M, Wong WW, Sio TS, Foote RL, Patel SH, Shen J, Liu W. Modelling small block aperture in an in-house developed GPU-accelerated Monte Carlo-based dose engine for pencil beam scanning proton therapy. Phys Med Biol 2024; 69:10.1088/1361-6560/ad0b64. [PMID: 37944480 PMCID: PMC11009986 DOI: 10.1088/1361-6560/ad0b64] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 11/09/2023] [Indexed: 11/12/2023]
Abstract
Purpose. To enhance an in-house graphic-processing-unit accelerated virtual particle (VP)-based Monte Carlo (MC) proton dose engine (VPMC) to model aperture blocks in both dose calculation and optimization for pencil beam scanning proton therapy (PBSPT)-based stereotactic radiosurgery (SRS).Methods and materials. A module to simulate VPs passing through patient-specific aperture blocks was developed and integrated in VPMC based on simulation results of realistic particles (primary protons and their secondaries). To validate the aperture block module, VPMC was first validated by an opensource MC code, MCsquare, in eight water phantom simulations with 3 cm thick brass apertures: four were with aperture openings of 1, 2, 3, and 4 cm without a range shifter, while the other four were with same aperture opening configurations with a range shifter of 45 mm water equivalent thickness. Then, VPMC was benchmarked with MCsquare and RayStation MC for 10 patients with small targets (average volume 8.4 c.c. with range of 0.4-43.3 c.c.). Finally, 3 typical patients were selected for robust optimization with aperture blocks using VPMC.Results. In the water phantoms, 3D gamma passing rate (2%/2 mm/10%) between VPMC and MCsquare was 99.71 ± 0.23%. In the patient geometries, 3D gamma passing rates (3%/2 mm/10%) between VPMC/MCsquare and RayStation MC were 97.79 ± 2.21%/97.78 ± 1.97%, respectively. Meanwhile, the calculation time was drastically decreased from 112.45 ± 114.08 s (MCsquare) to 8.20 ± 6.42 s (VPMC) with the same statistical uncertainties of ~0.5%. The robustly optimized plans met all the dose-volume-constraints (DVCs) for the targets and OARs per our institutional protocols. The mean calculation time for 13 influence matrices in robust optimization by VPMC was 41.6 s and the subsequent on-the-fly 'trial-and-error' optimization procedure took only 71.4 s on average for the selected three patients.Conclusion. VPMC has been successfully enhanced to model aperture blocks in dose calculation and optimization for the PBSPT-based SRS.
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Affiliation(s)
- Hongying Feng
- College of Mechanical and Power Engineering, China Three Gorges University, Yichang, Hubei 443002, People’s Republic of China
- Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ 85054, United States of America
- Department of Radiation Oncology, Guangzhou Concord Cancer Center, Guangzhou, Guangdong, 510555, People’s Republic of China
| | - Jason M Holmes
- Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ 85054, United States of America
| | - Sujay A Vora
- Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ 85054, United States of America
| | - Joshua B Stoker
- Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ 85054, United States of America
| | - Martin Bues
- Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ 85054, United States of America
| | - William W Wong
- Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ 85054, United States of America
| | - Terence S Sio
- Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ 85054, United States of America
| | - Robert L Foote
- Department of Radiation Oncology, Mayo Clinic, Rochester, MN 55902, United States of America
| | - Samir H Patel
- Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ 85054, United States of America
| | - Jiajian Shen
- Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ 85054, United States of America
| | - Wei Liu
- Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ 85054, United States of America
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2
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Tominaga Y, Suga M, Takeda M, Yamamoto Y, Akagi T, Kato T, Tokumaru S, Yamamoto M, Oita M. Dose-volume comparisons of proton therapy for pencil beam scanning with and without multi-leaf collimator and passive scattering in patients with lung cancer. Med Dosim 2023; 49:13-18. [PMID: 37940436 DOI: 10.1016/j.meddos.2023.10.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 10/05/2023] [Accepted: 10/06/2023] [Indexed: 11/10/2023]
Abstract
This study evaluated the dose distributions of proton pencil beam scanning (PBS) with/without a multileaf collimator (MLC) compared to passive scattering (PS) for stage I/II lung cancers. Collimated/uncollimated (PBS+/PBS-) and PS plans were created for 20 patients. Internal-clinical-target-volumes (ICTVs) and planning-target-volumes (PTVs) with a 5 mm margin were defined on the gated CTs. Organs-at-risk (OARs) are defined as the normal lungs, spinal cord, esophagus, and heart. The prescribed dose was 66 Gy relative-biological-effectiveness (RBE) in 10 fractions at the isocenter and 50% volume of the ICTVs for the PS and PBS, respectively. We compared the target and OAR dose statistics from the dose volume histograms. The PBS+ group had a significantly better mean PTV conformity index than the PBS- and PS groups. The mean dose sparing for PBS+ was better than those for PBS- and PS. Only the normal lung doses of PBS- were worse than those of PS. The overall performance of the OAR sparing was in the order of PBS+, PBS-, and PS. The PBS+ plan showed significantly better target homogeneity and OAR sparing than the PBS- and PS plans. PBS requires collimating systems to treat lung cancers with the most OAR sparing while maintaining the target coverage.
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Affiliation(s)
- Yuki Tominaga
- Medical Co. Hakuhokai, Osaka Proton Therapy Clinic, Konohana-ku, Osaka 554-0022, Japan.
| | - Masaki Suga
- Hyogo Ion Beam Medical Center, Tatsuno, Hyogo 679-5165, Japan
| | - Mikuni Takeda
- Hyogo Ion Beam Medical Center, Tatsuno, Hyogo 679-5165, Japan
| | - Yuki Yamamoto
- Hyogo Ion Beam Medical Center, Tatsuno, Hyogo 679-5165, Japan
| | - Takashi Akagi
- Hyogo Ion Beam Medical Center, Tatsuno, Hyogo 679-5165, Japan
| | - Takahiro Kato
- Depertment of Radiological Sciences, School of Health Sciences, Fukushima, Medical University, Fukushima 960-1295, Japan; Depertment of Radiation Physics and Technology, Southern Tohoku Proton Therapy Center, Koriyama, Fukushima 963-8052, Japan
| | - Sunao Tokumaru
- Hyogo Ion Beam Medical Center, Tatsuno, Hyogo 679-5165, Japan
| | - Michinori Yamamoto
- Medical Co. Hakuhokai, Osaka Proton Therapy Clinic, Konohana-ku, Osaka 554-0022, Japan
| | - Masataka Oita
- Faculty of Interdisciplinary Science and Engineering in Health Systems, Okayama University, Okayama 700-8558, Japan
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Nabha R, De Saint-Hubert M, Marichal J, Esser J, Van Hoey O, Bäumer C, Verbeek N, Struelens L, Sterpin E, Tabury K, Marek L, Granja C, Timmermann B, Vanhavere F. Biophysical characterization of collimated and uncollimated fields in pencil beam scanning proton therapy. Phys Med Biol 2023; 68. [PMID: 36821866 DOI: 10.1088/1361-6560/acbe8d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 02/23/2023] [Indexed: 02/25/2023]
Abstract
Objective. The lateral dose fall-off in proton pencil beam scanning (PBS) technique remains the preferred choice for sparing adjacent organs at risk as opposed to the distal edge due to the proton range uncertainties and potentially high relative biological effectiveness. However, because of the substantial spot size along with the scattering in the air and in the patient, the lateral penumbra in PBS can be degraded. Combining PBS with an aperture can result in a sharper dose fall-off, particularly for shallow targets.Approach. The aim of this work was to characterize the radiation fields produced by collimated and uncollimated 100 and 140 MeV proton beams, using Monte Carlo simulations and measurements with a MiniPIX-Timepix detector. The dose and the linear energy transfer (LET) were then coupled with publishedin silicobiophysical models to elucidate the potential biological effects of collimated and uncollimated fields.Main results. Combining an aperture with PBS reduced the absorbed dose in the lateral fall-off and out-of-field by 60%. However, the results also showed that the absolute frequency-averaged LET (LETF) values increased by a maximum of 3.5 keVμm-1in collimated relative to uncollimated fields, while the dose-averaged LET (LETD) increased by a maximum of 7 keVμm-1. Despite the higher LET values produced by collimated fields, the predicted DNA damage yields remained lower, owing to the large dose reduction.Significance. This work demonstrated the dosimetric advantages of combining an aperture with PBS coupled with lower DNA damage induction. A methodology for calculating dose in water derived from measurements with a silicon-based detector was also presented. This work is the first to demonstrate experimentally the increase in LET caused by combining PBS with aperture, and to assess the potential DNA damage which is the initial step in the cascade of events leading to the majority of radiation-induced biological effects.
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Affiliation(s)
- Racell Nabha
- Radiation Protection Dosimetry and Calibration Expert Group, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium.,KU Leuven, Department of Oncology, Laboratory of Experimental Radiotherapy, Leuven, Belgium
| | - Marijke De Saint-Hubert
- Radiation Protection Dosimetry and Calibration Expert Group, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
| | | | - Johannes Esser
- West German Proton Therapy Centre Essen, Essen, Germany.,West German Cancer Center (WTZ), University Hospital Essen, Essen, Germany
| | - Olivier Van Hoey
- Radiation Protection Dosimetry and Calibration Expert Group, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
| | - Christian Bäumer
- West German Proton Therapy Centre Essen, Essen, Germany.,West German Cancer Center (WTZ), University Hospital Essen, Essen, Germany.,TU Dortmund University, Department of Physics, Dortmund, Germany.,German Cancer Consortium (DKTK), Heidelberg, Germany
| | - Nico Verbeek
- West German Proton Therapy Centre Essen, Essen, Germany.,West German Cancer Center (WTZ), University Hospital Essen, Essen, Germany
| | - Lara Struelens
- Radiation Protection Dosimetry and Calibration Expert Group, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
| | - Edmond Sterpin
- KU Leuven, Department of Oncology, Laboratory of Experimental Radiotherapy, Leuven, Belgium.,UCLouvain, Institut de Recherche Expérimentale et Clinique, MIRO Lab, Brussels, Belgium
| | - Kevin Tabury
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
| | | | | | - Beate Timmermann
- West German Proton Therapy Centre Essen, Essen, Germany.,West German Cancer Center (WTZ), University Hospital Essen, Essen, Germany.,German Cancer Consortium (DKTK), Heidelberg, Germany.,Department of Particle Therapy, University Hospital Essen, Essen, Germany
| | - Filip Vanhavere
- Radiation Protection Dosimetry and Calibration Expert Group, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium.,KU Leuven, Department of Oncology, Laboratory of Experimental Radiotherapy, Leuven, Belgium
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4
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Nelson NP, Culberson WS, Hyer DE, Geoghegan TJ, Patwardhan KA, Smith BR, Flynn RT, Yu J, Gutiérrez AN, Hill PM. Dosimetric delivery validation of dynamically collimated pencil beam scanning proton therapy. Phys Med Biol 2023; 68:055003. [PMID: 36706460 PMCID: PMC9940016 DOI: 10.1088/1361-6560/acb6cd] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 01/27/2023] [Indexed: 01/28/2023]
Abstract
Objective. Pencil beam scanning (PBS) proton therapy target dose conformity can be improved with energy layer-specific collimation. One such collimator is the dynamic collimation system (DCS), which consists of four nickel trimmer blades that intercept the scanning beam as it approaches the lateral extent of the target. While the dosimetric benefits of the DCS have been demonstrated through computational treatment planning studies, there has yet to be experimental verification of these benefits for composite multi-energy layer fields. The objective of this work is to dosimetrically characterize and experimentally validate the delivery of dynamically collimated proton therapy with the DCS equipped to a clinical PBS system.Approach. Optimized single field, uniform dose treatment plans for 3 × 3 × 3 cm3target volumes were generated using Monte Carlo dose calculations with depths ranging from 5 to 15 cm, trimmer-to-surface distances ranging from 5 to 18.15 cm, with and without a 4 cm thick polyethylene range shifter. Treatment plans were then delivered to a water phantom using a prototype DCS and an IBA dedicated nozzle system and measured with a Zebra multilayer ionization chamber, a MatriXX PT ionization chamber array, and Gafchromic™ EBT3 film.Main results. For measurements made within the SOBPs, average 2D gamma pass rates exceeded 98.5% for the MatriXX PT and 96.5% for film at the 2%/2 mm criterion across all measured uncollimated and collimated plans, respectively. For verification of the penumbra width reduction with collimation, film agreed with Monte Carlo with differences within 0.3 mm on average compared to 0.9 mm for the MatriXX PT.Significance. We have experimentally verified the delivery of DCS-collimated fields using a clinical PBS system and commonly available dosimeters and have also identified potential weaknesses for dosimeters subject to steep dose gradients.
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Affiliation(s)
- Nicholas P Nelson
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin—Madison, 1111 Highland Avenue, Madison, WI, 53705, United States of America,Author to whom any correspondence should be addressed
| | - Wesley S Culberson
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin—Madison, 1111 Highland Avenue, Madison, WI, 53705, United States of America
| | - Daniel E Hyer
- Department of Radiation Oncology, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, IA, 52242, United States of America
| | - Theodore J Geoghegan
- Department of Radiation Oncology, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, IA, 52242, United States of America
| | - Kaustubh A Patwardhan
- Department of Radiation Oncology, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, IA, 52242, United States of America
| | - Blake R Smith
- Department of Radiation Oncology, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, IA, 52242, United States of America
| | - Ryan T Flynn
- Department of Radiation Oncology, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, IA, 52242, United States of America
| | - Jen Yu
- Department of Radiation Oncology, Miami Cancer Institute, Baptist Health South Florida, 8900 N. Kendall Drive, Miami, FL, 33176, United States of America
| | - Alonso N Gutiérrez
- Department of Radiation Oncology, Miami Cancer Institute, Baptist Health South Florida, 8900 N. Kendall Drive, Miami, FL, 33176, United States of America
| | - Patrick M Hill
- Department of Human Oncology, School of Medicine and Public Health, University of Wisconsin—Madison, 600 Highland Avenue, Madison, WI, 53792, United States of America
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Behrends C, Bäumer C, Verbeek NG, Wulff J, Timmermann B. Optimization of proton pencil beam positioning in collimated fields. Med Phys 2023; 50:2540-2551. [PMID: 36609847 DOI: 10.1002/mp.16209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 12/24/2022] [Accepted: 12/26/2022] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND The addition of static or dynamic collimator systems to the pencil beam scanning delivery technique increases the number of options for lateral field shaping. The collimator shape needs to be optimized together with the intensity modulation of spots. PURPOSE To minimize the proton field's lateral penumbra by investigating the fundamental relations between spot and collimating aperture edge position. METHODS Analytical approaches describing the effect of spot position on the resulting spot profile are presented. The theoretical description is then compared with Monte Carlo simulations in TOPAS and in the RayStation treatment planning system, as well as with radiochromic film measurements at a clinical proton therapy facility. In the model, one single spot profile is analyzed for various spot positions in air. Further, irradiation setups in water with different energies, the combination with a range shifter, and two-dimensional proton fields were investigated in silico. RESULTS The further the single spot is placed beyond the collimating aperture edge ('overscanning'), the sharper the relative lateral dose fall-off and thus the lateral penumbra. Overscanning up to 5 mm $5\,\text{mm}$ reduced the lateral penumbra by about 20% on average after a propagation of 13 cm $13\,\text{cm}$ in air. This benefit from overscanning is first predicted by the analytical proofs and later verified by simulations and measurements. Corresponding analyses in water confirm the benefit in lateral penumbra with spot position optimization as observed theoretically and in air. The combination of spot overscanning with fluence modulation facilitated an additional improvement. CONCLUSIONS The lateral penumbra of single spots in collimated scanned proton fields can be improved by the method of spot overscanning. This suggests a better sparing of proximal organs at risk in smaller water depths at higher energies, especially in the plateau of the depth dose distribution. All in all, spot overscanning in collimated scanned proton fields offers particular potential in combination with techniques such as fluence modulation or dynamic collimation for optimizing the lateral penumbra to spare normal tissue.
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Affiliation(s)
- Carina Behrends
- West German Proton Therapy Centre Essen (WPE), Essen, Germany.,Department of Physics, TU Dortmund University, Dortmund, Germany.,West German Cancer Centre (WTZ), University Hospital Essen, Essen, Germany
| | - Christian Bäumer
- West German Proton Therapy Centre Essen (WPE), Essen, Germany.,Department of Physics, TU Dortmund University, Dortmund, Germany.,West German Cancer Centre (WTZ), University Hospital Essen, Essen, Germany.,German Cancer Consortium (DKTK), Heidelberg, Germany
| | - Nico Gerd Verbeek
- West German Proton Therapy Centre Essen (WPE), Essen, Germany.,West German Cancer Centre (WTZ), University Hospital Essen, Essen, Germany.,Faculty of Medicine, University of Duisburg-Essen, Essen, Germany
| | - Jörg Wulff
- West German Proton Therapy Centre Essen (WPE), Essen, Germany.,West German Cancer Centre (WTZ), University Hospital Essen, Essen, Germany
| | - Beate Timmermann
- West German Proton Therapy Centre Essen (WPE), Essen, Germany.,West German Cancer Centre (WTZ), University Hospital Essen, Essen, Germany.,German Cancer Consortium (DKTK), Heidelberg, Germany.,Faculty of Medicine, University of Duisburg-Essen, Essen, Germany.,Department of Particle Therapy, University Hospital Essen, Essen, Germany
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Tominaga Y, Sakurai Y, Miyata J, Harada S, Akagi T, Oita M. Validation of pencil beam scanning proton therapy with multi-leaf collimator calculated by a commercial Monte Carlo dose engine. J Appl Clin Med Phys 2022; 23:e13817. [PMID: 36420959 PMCID: PMC9797166 DOI: 10.1002/acm2.13817] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 08/10/2022] [Accepted: 10/01/2022] [Indexed: 11/25/2022] Open
Abstract
This study aimed to evaluate the clinical beam commissioning results and lateral penumbra characteristics of our new pencil beam scanning (PBS) proton therapy using a multi-leaf collimator (MLC) calculated by use of a commercial Monte Carlo dose engine. Eighteen collimated uniform dose plans for cubic targets were optimized by the RayStation 9A treatment planning system (TPS), varying scan area, modulation widths, measurement depths, and collimator angles. To test the patient-specific measurements, we also created and verified five clinically realistic PBS plans with the MLC, such as the liver, prostate, base-of-skull, C-shape, and head-and-neck. The verification measurements consist of the depth dose (DD), lateral profile (LP), and absolute dose (AD). We compared the LPs and ADs between the calculation and measurements. For the cubic plans, the gamma index pass rates (γ-passing) were on average 96.5% ± 4.0% at 3%/3 mm for the DD and 95.2% ± 7.6% at 2%/2 mm for the LP. In several LP measurements less than 75 mm depths, the γ-passing deteriorated (increased the measured doses) by less than 90% with the scattering such as the MLC edge and range shifter. The deteriorated γ-passing was satisfied by more than 90% at 2%/2 mm using uncollimated beams instead of collimated beams except for three planes. The AD differences and the lateral penumbra width (80%-20% distance) were within ±1.9% and ± 1.1 mm, respectively. For the clinical plan measurements, the γ-passing of LP at 2%/2 mm and the AD differences were 97.7% ± 4.2% on average and within ±1.8%, respectively. The measurements were in good agreement with the calculations of both the cubic and clinical plans inserted in the MLC except for LPs less than 75 mm regions of some cubic and clinical plans. The calculation errors in collimated beams can be mitigated by substituting uncollimated beams.
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Affiliation(s)
- Yuki Tominaga
- Department of Radiotherapy, Medical Co. HakuhokaiOsaka Proton Therapy ClinicOsakaJapan,Division of Radiological TechnologyGraduate School of Interdisciplinary Science and Engineering in Health SystemsOkayama UniversityOkayamaJapan
| | - Yusuke Sakurai
- Department of Radiotherapy, Medical Co. HakuhokaiOsaka Proton Therapy ClinicOsakaJapan
| | - Junya Miyata
- Division of Radiological TechnologyGraduate School of Interdisciplinary Science and Engineering in Health SystemsOkayama UniversityOkayamaJapan,Department of Radiological technologyKurashiki Central HospitalOkayamaJapan
| | | | | | - Masataka Oita
- Division of Radiological TechnologyGraduate School of Interdisciplinary Science and Engineering in Health SystemsOkayama UniversityOkayamaJapan
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Holmes J, Shen J, Shan J, Patrick CL, Wong WW, Foote RL, Patel SH, Bues M, Liu W. Technical Note: Evaluation and 2nd check of a commercial Monte Carlo dose engine for small-field apertures in pencil beam scanning proton therapy. Med Phys 2022; 49:3497-3506. [PMID: 35305269 DOI: 10.1002/mp.15604] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 02/19/2022] [Accepted: 03/02/2022] [Indexed: 11/10/2022] Open
Abstract
PURPOSE To evaluate the accuracy of the RayStation Monte Carlo dose engine (RayStation MC) in modeling small-field block apertures in proton pencil beam scanning. Furthermore, we evaluate the suitability of MCsquare as a 2nd check for RayStation MC. METHODS We have enhanced MCsquare to model block apertures. To test the accuracy of both RayStation MC and the newly enhanced MCsquare, we compare the dose predictions of each to in-water dose measurements obtained using diode detectors and radiochromic film. Nine brass apertures with openings of 1, 2, 3, 4, and 5 cm and either 2 cm or 4 cm thickness were used in the irradiation of a water phantom. Two measurement setups were used, one with a range shifter and 119.7 MeV proton beam energy and the other with no range shifter and 147 MeV proton beam energy. To further test the validity of RayStation MC and MCsquare in modeling block apertures and to evaluate MCsquare as a 2nd check tool, ten small-field (average target volume 8.3 cm3 ) patient treatment plans were calculated by each dose engine followed by a statistical comparison. RESULTS Comparing to the absolute dose measurements in water, RayStation MC differed by 1.2% ± 1.0% while MCsquare differed by -1.8% ± 3.7% in the plateau region of a pristine Bragg peak. Compared to the in-water film measurements, RayStation MC and MCsquare both performed well with an average 2D-3D gamma passing rate of 99.4% and 99.7% (3%/3mm) respectively. A t-test comparing the agreement with the film measurements between RayStation MC and MCsquare suggested that the relative spatial dose distributions calculated by MCsquare and RayStation MC were statistically indistinguishable. Directly comparing the dose calculations between MCsquare and RayStation MC over ten patients resulted in an average 3D-3D gamma passing rates of 98.5% (3%/3mm) and 94.1% (2%/2mm) respectively. CONCLUSION The validity of RayStation MC algorithm for use with patient-specific apertures has been expanded to include small apertures. MCsquare has been enhanced to model apertures and was found to be an adequate 2nd check of RayStation MC in this scenario. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Jason Holmes
- Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ, 85054, USA
| | - Jiajian Shen
- Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ, 85054, USA
| | - Jie Shan
- Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ, 85054, USA
| | | | - William W Wong
- Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ, 85054, USA
| | - Robert L Foote
- Department of Radiation Oncology, Mayo Clinic, Rochester, MN, 55902, USA
| | - Samir H Patel
- Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ, 85054, USA
| | - Martin Bues
- Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ, 85054, USA
| | - Wei Liu
- Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ, 85054, USA
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8
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Treatment of ocular tumors through a novel applicator on a conventional proton pencil beam scanning beamline. Sci Rep 2022; 12:4648. [PMID: 35301371 PMCID: PMC8931109 DOI: 10.1038/s41598-022-08440-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 03/03/2022] [Indexed: 11/23/2022] Open
Abstract
Treatment of ocular tumors on dedicated scattering-based proton therapy systems is standard afforded due to sharp lateral and distal penumbras. However, most newer proton therapy centers provide pencil beam scanning treatments. In this paper, we present a pencil beam scanning (PBS)-based ocular treatment solution. The design, commissioning, and validation of an applicator mount for a conventional PBS snout to allow for ocular treatments are given. In contrast to scattering techniques, PBS-based ocular therapy allows for inverse planning, providing planners with additional flexibility to shape the radiation field,
potentially sparing healthy tissues. PBS enables the use of commercial Monte Carlo algorithms resulting in accurate dose calculations in the presence of heterogeneities and fiducials. The validation consisted of small field dosimetry measurements of point doses, depth doses, and lateral profiles relevant to ocular therapy. A comparison of beam properties achieved through the applicator against published literature is presented. We successfully showed the feasibility of PBS-based ocular treatments.
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9
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Wulff J, Koska B, Janson M, Bäumer C, Denker A, Geismar D, Gollrad J, Timmermann B, Heufelder J. Technical Note: Impact of Beam Properties for Uveal Melanoma Proton Therapy - An In-Silico Planning Study. Med Phys 2022; 49:3481-3488. [PMID: 35218037 DOI: 10.1002/mp.15573] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 02/19/2022] [Accepted: 02/21/2022] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To evaluate the impact of beam quality in terms of distal fall-off (DFO, 90% to 10%) and lateral penumbra (LP, 80% to 20%) of single beam ocular proton treatment (OPT) and to derive resulting ideal requirements for future systems. METHODS Nine different beam models with DFO varying between 1 mm and 4 mm and LP between 1 mm and 4 mm were created. Beam models were incorporated into the RayStation with RayOcular TPS version 10 B (RaySearch Laboratories, Sweden). Each beam model was applied for eight typical clinical cases, covering different sizes and locations of uveal melanoma. Plans with and without an additional wedge were created, resulting in 117 plans with a total prescribed median dose of 60 Gy(RBE) to the CTV. Treatment plans were analyzed in terms of V20-V80 penumbra volume, D1 (dose to 1% of the volume) for optic disc and macula, optic nerve V30 (volume receiving 30 Gy(RBE), i.e. 50% of prescription), as well as average dose to lens and ciliary body. A LP dependent aperture margin was based on estimated uncertainties, ranging from 1.7 mm to 4.0 mm. RESULTS V20-V80 showed a strong influence by LP, while DFO was less relevant. The optic disc D1 reached an extra dose of up to 3000 cGy(RBE), comparing the defined technical limit of DFO = LP = 1 mm with DFO = 3 mm/ LP = 4 mm. The latter may result from a pencil-beam scanning (PBS) system with static apertures. Plans employing a wedge showed an improvement for organs at risk (OAR) sparing. CONCLUSION Plan quality is strongly influenced by initial beam parameters. The impact of LP is more pronounced when compared to DFO. The latter becomes important in the treatment of posterior tumors near the macula, optic disc or optic nerve. The plan quality achieved by dedicated OPT nozzles in single- or double-scattering design might not be achievable with modified PBS systems. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- J Wulff
- West German Proton Therapy Centre Essen (WPE), Essen, Germany.,University Hospital Essen, Essen, Germany.,West German Cancer Centre (WTZ), Essen, Germany
| | - B Koska
- West German Proton Therapy Centre Essen (WPE), Essen, Germany.,University Hospital Essen, Essen, Germany.,West German Cancer Centre (WTZ), Essen, Germany
| | - M Janson
- RaySearch Laboratories, Stockholm, Sweden
| | - C Bäumer
- West German Proton Therapy Centre Essen (WPE), Essen, Germany.,University Hospital Essen, Essen, Germany.,West German Cancer Centre (WTZ), Essen, Germany.,German Cancer Consortium (DKTK), Heidelberg, Germany.,TU Dortmund University, Dortmund, Germany
| | - A Denker
- Helmholtz-Zentrum Berlin für Materialien und Energie, Protonentherapie, Germany.,Beuth-Hochschule für Technik, Berlin, Germany
| | - D Geismar
- West German Proton Therapy Centre Essen (WPE), Essen, Germany.,University Hospital Essen, Essen, Germany.,West German Cancer Centre (WTZ), Essen, Germany.,Department of Particle Therapy, Essen, Germany
| | - J Gollrad
- Charité - Universitätsmedizin Berlin, Department of Radiation Oncology and Radiotherapy, Berlin, Germany
| | - B Timmermann
- West German Proton Therapy Centre Essen (WPE), Essen, Germany.,University Hospital Essen, Essen, Germany.,West German Cancer Centre (WTZ), Essen, Germany.,German Cancer Consortium (DKTK), Heidelberg, Germany.,Department of Particle Therapy, Essen, Germany
| | - J Heufelder
- Charité - Universitätsmedizin Berlin, Department of Ophthalmology, Berlin, Germany.,Charité - Universitätsmedizin Berlin, BerlinProtonen am Helmholtz-Zentrum für Materialien und Energie, Berlin, Germany
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10
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Depauw N, Kooy HM, Daartz J, Bussiere M, Batin E, Madden T, Williams M, Schuemann J, Clasie BM. Implementation of apertures in a proton pencil-beam dose algorithm. Biomed Phys Eng Express 2022; 8. [PMID: 35158343 DOI: 10.1088/2057-1976/ac550b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 02/14/2022] [Indexed: 11/11/2022]
Abstract
The use of field-specific apertures, routine in scattered or uniform-scanned proton fields, are still a necessity in pencil-beam scanned (PBS) fields to sharpen the penumbral edge at low energies and in high fraction dose application beyond that achievable with small spot size. We describe a model implemented in our clinical pencil-beam algorithm that models the insertion of a shaped aperture, including shapes adapted per energy layer such as may be achieved with a multi-leaf collimator. The model decomposes the spot transport into discrete steps. The first step transport a uniform intensity field of high-resolution sub-pencil-beams at the layer energy through the medium. This transport only considers primary scattering in both the patient and an optional range-shifter. The second step models the aperture areas and edge penumbral transition as a modulation of the uniform intensity. The third step convolves individual steps over the uniform-transported field including the aperture-modified intensities. We also introduce an efficient model based on a Clarkson sector integration for nuclear scattered halo protons. This avoids the explicit modeling of long range halo protons to the detriment of computational efficiency in calculation and optimization. We demonstrate that the aperture effect is primarily due to in-patient and shifter scattering with a small contribution from the apparent beam source position. The model provides insight into the primary physics contributions to the penumbra and the nuclear halo. The model allowed us to fully deploy our PBS capacity at our two-gantry center without which PBS treatments would have been inferior compared to scattered fields with apertures. Finally, Monte Carlo calculations have (nearly) replaced phenomenological pencil-beam models for collimated fields. Phenomenological models do, however, allow exposition of underlying clinical phenomena and closer connection to representative clinical observables.
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Affiliation(s)
- Nicolas Depauw
- Department of Radiation Oncology, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts, 02114, UNITED STATES
| | - Hanne M Kooy
- Department of Radiation Oncology, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts, 02114, UNITED STATES
| | - Juliane Daartz
- Department of Radiation Oncology, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts, 02114, UNITED STATES
| | - Marc Bussiere
- Department of Radiation Oncology, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts, 02114, UNITED STATES
| | - Estelle Batin
- Department of Radiation Oncology, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts, 02114, UNITED STATES
| | - Thomas Madden
- Department of Radiation Oncology, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts, 02114, UNITED STATES
| | - Michael Williams
- Department of Radiation Oncology, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts, 02114, UNITED STATES
| | - Jan Schuemann
- Department of Radiation Oncology, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts, 02114, UNITED STATES
| | - Benjamin M Clasie
- Department of Radiation Oncology, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts, 02114, UNITED STATES
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11
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Conceptual Design of a Novel Nozzle Combined with a Clinical Proton Linac for Magnetically Focussed Minibeams. Cancers (Basel) 2021; 13:cancers13184657. [PMID: 34572884 PMCID: PMC8467416 DOI: 10.3390/cancers13184657] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 09/09/2021] [Accepted: 09/14/2021] [Indexed: 11/23/2022] Open
Abstract
Simple Summary Proton minibeam radiation therapy (pMBRT) is a novel therapeutic strategy that combines the tissue sparing potential of submillimetric, spatially fractionated beams (minibeams) with the improved ballistics of protons to enhance the tolerance of normal tissue and allow a dose escalation in the tumour. This approach could allow a more effective treatment of radioresistant tumours and has already shown excellent results for rat gliomas. To exploit the full potential of pMBRT, it should be delivered using magnetically focussed and scanned minibeams. However, such an implementation has not yet been demonstrated at clinically relevant beam energies. In this work, we therefore present a new design combining our recently developed minibeam nozzle with the first clinical proton linear accelerator. We show the suitability of this combination for the generation of magnetically focussed and scanned minibeams with clinically relevant parameters as well as for the delivery of conventional pencil beam scanning techniques. Abstract (1) Background: Proton minibeam radiation therapy (pMBRT) is a novel therapeutic approach with the potential to significantly increase normal tissue sparing while providing tumour control equivalent or superior to standard proton therapy. For reasons of efficiency, flexibility and minibeam quality, the optimal implementation of pMBRT should use magnetically focussed minibeams which, however, could not yet be generated in a clinical environment. In this study, we evaluated our recently proposed minibeam nozzle together with a new clinical proton linac as a potential implementation. (2) Methods: Monte Carlo simulations were performed to determine under which conditions minibeams can be generated and to evaluate the robustness against focussing magnet errors. Moreover, an example of conventional pencil beam scanning irradiation was simulated. (3) Results: Excellent minibeam sizes between 0.6 and 0.9 mm full width at half maximum could be obtained and a good tolerance to errors was observed. Furthermore, the delivery of a 10 cm × 10 cm field with pencil beams was demonstrated. (4) Conclusion: The combination of the new proton linac and minibeam nozzle could represent an optimal implementation of pMBRT by allowing the generation of magnetically focussed minibeams with clinically relevant parameters. It could furthermore be used for conventional pencil beam scanning.
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12
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Hyer DE, Bennett LC, Geoghegan TJ, Bues M, Smith BR. Innovations and the Use of Collimators in the Delivery of Pencil Beam Scanning Proton Therapy. Int J Part Ther 2021; 8:73-83. [PMID: 34285937 PMCID: PMC8270095 DOI: 10.14338/ijpt-20-00039.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 10/19/2020] [Indexed: 12/29/2022] Open
Abstract
Purpose The development of collimating technologies has become a recent focus in pencil beam scanning (PBS) proton therapy to improve the target conformity and healthy tissue sparing through field-specific or energy-layer–specific collimation. Given the growing popularity of collimators for low-energy treatments, the purpose of this work was to summarize the recent literature that has focused on the efficacy of collimators for PBS and highlight the development of clinical and preclinical collimators. Materials and Methods The collimators presented in this work were organized into 3 categories: per-field apertures, multileaf collimators (MLCs), and sliding-bar collimators. For each case, the system design and planning methodologies are summarized and intercompared from their existing literature. Energy-specific collimation is still a new paradigm in PBS and the 2 specific collimators tailored toward PBS are presented including the dynamic collimation system (DCS) and the Mevion Adaptive Aperture. Results Collimation during PBS can improve the target conformity and associated healthy tissue and critical structure avoidance. Between energy-specific collimators and static apertures, static apertures have the poorest dose conformity owing to collimating only the largest projection of a target in the beam's eye view but still provide an improvement over uncollimated treatments. While an external collimator increases secondary neutron production, the benefit of collimating the primary beam appears to outweigh the risk. The greatest benefit has been observed for low- energy treatment sites. Conclusion The consensus from current literature supports the use of external collimators in PBS under certain conditions, namely low-energy treatments or where the nominal spot size is large. While many recent studies paint a supportive picture, it is also important to understand the limitations of collimation in PBS that are specific to each collimator type. The emergence and paradigm of energy-specific collimation holds many promises for PBS proton therapy.
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Affiliation(s)
- Daniel E Hyer
- Department of Radiation Oncology, University of Iowa, Iowa City, IA, USA
| | - Laura C Bennett
- Department of Radiation Oncology, University of Iowa, Iowa City, IA, USA
| | | | - Martin Bues
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, AZ, USA
| | - Blake R Smith
- Department of Radiation Oncology, University of Iowa, Iowa City, IA, USA
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13
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Bäumer C, Plaude S, Khalil DA, Geismar D, Kramer PH, Kröninger K, Nitsch C, Wulff J, Timmermann B. Clinical Implementation of Proton Therapy Using Pencil-Beam Scanning Delivery Combined With Static Apertures. Front Oncol 2021; 11:599018. [PMID: 34055596 PMCID: PMC8149965 DOI: 10.3389/fonc.2021.599018] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 04/06/2021] [Indexed: 11/13/2022] Open
Abstract
Proton therapy makes use of the favorable depth-dose distribution with its characteristic Bragg peak to spare normal tissue distal of the target volume. A steep dose gradient would be desired in lateral dimensions, too. The widespread spot scanning delivery technique is based, however, on pencil-beams with in-air spot full-widths-at-half-maximum of typically 1 cm or more. This hampers the sparing of organs-at-risk if small-scale structures adjacent to the target volume are concerned. The trimming of spot scanning fields with collimating apertures constitutes a simple measure to increase the transversal dose gradient. The current study describes the clinical implementation of brass apertures in conjunction with the pencil-beam scanning delivery mode at a horizontal, clinical treatment head based on commercial hardware and software components. Furthermore, clinical cases, which comprised craniopharyngiomas, re-irradiations and ocular tumors, were evaluated. The dosimetric benefits of 31 treatment plans using apertures were compared to the corresponding plans without aperture. Furthermore, an overview of the radiation protection aspects is given. Regarding the results, robust optimization considering range and setup uncertainties was combined with apertures. The treatment plan optimizations followed a single-field uniform dose or a restricted multi-field optimization approach. Robustness evaluation was expanded to account for possible deviations of the center of the pencil-beam delivery and the mechanical center of the aperture holder. Supplementary apertures improved the conformity index on average by 15.3%. The volume of the dose gradient surrounding the PTV (evaluated between 80 and 20% dose levels) was decreased on average by 17.6%. The mean dose of the hippocampi could be reduced on average by 2.9 GyRBE. In particular cases the apertures facilitated a sparing of an organ-at-risk, e.g. the eye lens or the brainstem. For six craniopharyngioma cases the inclusion of apertures led to a reduction of the mean dose of 1.5 GyRBE (13%) for the brain and 3.1 GyRBE (16%) for the hippocampi.
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Affiliation(s)
- Christian Bäumer
- West German Proton Therapy Centre Essen, Essen, Germany
- West German Cancer Center (WTZ), University Hospital Essen, Essen, Germany
- German Cancer Consortium (DKTK), Heidelberg, Germany
- Faculty of Physics, TU Dortmund University, Dortmund, Germany
| | - Sandija Plaude
- West German Proton Therapy Centre Essen, Essen, Germany
- West German Cancer Center (WTZ), University Hospital Essen, Essen, Germany
| | - Dalia Ahmad Khalil
- West German Proton Therapy Centre Essen, Essen, Germany
- West German Cancer Center (WTZ), University Hospital Essen, Essen, Germany
- Department of Particle Therapy, University Hospital Essen, Essen, Germany
| | - Dirk Geismar
- West German Proton Therapy Centre Essen, Essen, Germany
- West German Cancer Center (WTZ), University Hospital Essen, Essen, Germany
- German Cancer Consortium (DKTK), Heidelberg, Germany
- Department of Particle Therapy, University Hospital Essen, Essen, Germany
| | - Paul-Heinz Kramer
- West German Proton Therapy Centre Essen, Essen, Germany
- West German Cancer Center (WTZ), University Hospital Essen, Essen, Germany
| | - Kevin Kröninger
- Faculty of Physics, TU Dortmund University, Dortmund, Germany
| | | | - Jörg Wulff
- West German Proton Therapy Centre Essen, Essen, Germany
- West German Cancer Center (WTZ), University Hospital Essen, Essen, Germany
| | - Beate Timmermann
- West German Proton Therapy Centre Essen, Essen, Germany
- West German Cancer Center (WTZ), University Hospital Essen, Essen, Germany
- German Cancer Consortium (DKTK), Heidelberg, Germany
- Department of Particle Therapy, University Hospital Essen, Essen, Germany
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14
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Grewal HS, Ahmad S, Jin H. Characterization of penumbra sharpening and scattering by adaptive aperture for a compact pencil beam scanning proton therapy system. Med Phys 2021; 48:1508-1519. [PMID: 33580550 DOI: 10.1002/mp.14771] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 12/12/2020] [Accepted: 02/08/2021] [Indexed: 12/26/2022] Open
Abstract
PURPOSE To quantitatively access penumbra sharpening and scattering by adaptive aperture (AA) under various beam conditions and clinical cases for a Mevion S250i compact pencil beam scanning proton therapy system. METHODS First, in-air measurements were performed using a scintillation detector for single spot profile and lateral penumbra for five square field sizes (3 × 3 to 18 × 18 cm2 ), three energies (33.04, 147.36, and 227.16 MeV), and three snout positions (5, 15, and 33.6 cm) with Open and AA field. Second, treatment plans were generated in RayStation treatment planning system (TPS) for various combination of target size (3- and 10-cm cube), target depth (5, 10, and 15 cm) and air gap (5-20 cm) for both Open and AA field. These plans were delivered to EDR2 films in the solid water and penumbra reduction by AA was quantified. Third, the effect of the AA scattered protons on the surface dose was studied at 5 mm depth by EDR2 film and the RayStation TPS computation. Finally, dosimetric advantage of AA over Open field was studied for five brain and five prostate cases using the TPS simulation. RESULTS The spot size changed dramatically from 3.8 mm at proton beam energy of 227.15 MeV to 29.4 mm at energy 33.04 MeV. In-air measurements showed that AA substantially reduced the lateral penumbra by 30% to 60%. The EDR2 film measurements in solid water presented the maximum penumbra reduction of 10 to 14 mm depending on the target size. The maximum increase of 25% in field edge dose at 5 mm depth as compared to central axis was observed. The substantial penumbra reduction by AA produced less dose to critical structures for all the prostate and brain cases. CONCLUSIONS Adaptive aperture sharpens the penumbra by factor of two to three depending upon the beam condition. The absolute penumbra reduction with AA was more noticeable for shallower target, smaller target, and larger air gap. The AA-scattered protons contributed to increase in surface dose. Clinically, AA reduced the doses to critical structures.
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Affiliation(s)
- Hardev S Grewal
- Department of Radiation Oncology, University of Oklahoma Health Sciences Center, 800 NE 10th street SCC L100, Oklahoma City, OK, 73104, USA.,Oklahoma Proton Center, 5901 W Memorial Rd, Oklahoma City, OK, 73142, USA
| | - Salahuddin Ahmad
- Department of Radiation Oncology, University of Oklahoma Health Sciences Center, 800 NE 10th street SCC L100, Oklahoma City, OK, 73104, USA
| | - Hosang Jin
- Department of Radiation Oncology, University of Oklahoma Health Sciences Center, 800 NE 10th street SCC L100, Oklahoma City, OK, 73104, USA
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15
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Rana S, Storey M, Manthala Padannayil N, Shamurailatpam DS, Bennouna J, George J, Chang J. Investigating the utilization of beam-specific apertures for the intensity-modulated proton therapy (IMPT) head and neck cancer plans. Med Dosim 2020; 46:e7-e11. [PMID: 33246881 DOI: 10.1016/j.meddos.2020.10.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Revised: 10/11/2020] [Accepted: 10/28/2020] [Indexed: 12/16/2022]
Abstract
Intensity-modulated proton therapy (IMPT) planning for the head and neck (HN) cancer often requires the use of the range shifter, which can increase the lateral penumbrae of the pencil proton beam in the patient, thus leading to an increase in unnecessary dose to the organs at risks (OARs) in proximity to the target volumes. The primary goal of the current study was to investigate the dosimetric benefits of utilizing beam-specific apertures for the IMPT HN cancer plans. The current retrospective study included computed tomography datasets of 10 unilateral HN cancer patients. The clinical target volume (CTV) was divided into low-risk CTV1 and high-risk CTV2. Total dose prescriptions to the CTV1 and CTV2 were 54 Gy(RBE) and 70 Gy(RBE), respectively, with a fractional dose of 2 Gy(RBE). All treatment plans were robustly optimized (patient setup uncertainty = 3 mm; range uncertainty = 3.5%) on the CTVs. For each patient, 2 sets of plans were generated: (1) without beam-specific aperture (WOBSA), and (2) with beam-specific aperture (WBSA). Specifically, both the WOBSA and WBSA of the given patient used identical beam angles, air gap, optimization structures, optimization constraints, and optimization settings. Target coverage and homogeneity index were comparable in both the WOBSA and WBSA plans with no statistical significance (p > 0.05). On average, the mean dose in WBSA plans was reduced by 12.1%, 2.9%, 3.0%, 3.8%, and 5.2% for the larynx, oral cavity, parotids, superior pharyngeal constrictor muscle, and inferior pharyngeal constrictor muscle, respectively. The dosimetric results of the OARs were found to be statistically significant (p < 0.05). The use of the beam-specific apertures did not deteriorate the coverage and homogeneity in the target volume and allowed for a reduction in mean dose to the OARs with an average difference up to 12.1%.
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Affiliation(s)
- Suresh Rana
- Department of Medical Physics, Oklahoma Proton Center, Oklahoma City, OK 73142, USA; Department of Radiation Oncology, Miami Cancer Institute, Baptist Health South Florida, Miami, FL, USA; Department of Radiation Oncology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA.
| | - Mark Storey
- Department of Radiation Oncology, Oklahoma Proton Center, Oklahoma City, OK 73142, USA
| | | | | | - Jaafar Bennouna
- Department of Radiation Oncology, Miami Cancer Institute, Baptist Health South Florida, Miami, FL, USA
| | - Jerry George
- Department of Radiation Oncology, Miami Cancer Institute, Baptist Health South Florida, Miami, FL, USA
| | - John Chang
- Department of Radiation Oncology, Oklahoma Proton Center, Oklahoma City, OK 73142, USA
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16
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Proton therapy for head and neck squamous cell carcinomas: A review of the physical and clinical challenges. Radiother Oncol 2020; 147:30-39. [PMID: 32224315 DOI: 10.1016/j.radonc.2020.03.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 02/21/2020] [Accepted: 03/05/2020] [Indexed: 12/12/2022]
Abstract
The quality of radiation therapy has been shown to significantly influence the outcomes for head and neck squamous cell carcinoma (HNSCC) patients. The results of dosimetric studies suggest that intensity-modulated proton therapy (IMPT) could be of added value for HNSCC by being more effective than intensity-modulated (photon) radiation therapy (IMRT) for reducing side effects of radiation therapy. However, the physical properties of protons make IMPT more sensitive than photons to planning uncertainties. This could potentially have a negative effect on the quality of IMPT planning and delivery. For this review, the three French proton therapy centers collaborated to evaluate the differences between IMRT and IMPT. The review explored the effects of these uncertainties and their management for developing a robust and optimized IMPT treatment delivery plan to achieve clinical outcomes that are superior to those for IMRT. We also provide practical suggestions for the management of HNSCC carcinoma with IMPT. Because metallic dental implants can increase range uncertainties (3-10%), patient preparation for IMPT may require more systematic removal of in-field alien material than is done for IMRT. Multi-energy CT may be an alternative to calculate more accurately the dose distribution. The practical aspects that we describe are essential to guarantee optimal quality in radiation therapy in both model-based and randomized clinical trials.
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17
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Bäumer C, Fuentes C, Janson M, Matic A, Timmermann B, Wulff J. Stereotactical fields applied in proton spot scanning mode with range shifter and collimating aperture. ACTA ACUST UNITED AC 2019; 64:155003. [DOI: 10.1088/1361-6560/ab2ae7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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