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1.
Br J Radiol ; 93(1107): 20190920, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31944827

RESUMO

OBJECTIVE: For the past 20 years, Paul Scherrer Institut (PSI) has treated more than 1500 patients with deep-seated tumors using PSI-Plan, an in-house developed treatment planning system (TPS) used for proton beam scanning proton therapy, in combination with its home-built gantries. The goal of the present work is to benchmark the performance of a new TPS/Gantry system for proton therapy centers which have established already a baseline standard of care. METHODS AND MATERIALS: A total of 31 cases (=52 plans) distributed around 7 anatomical sites and 12 indications were randomly selected and re-planned using Eclipse™. The resulting plans were compared with plans formerly optimized in PSI-Plan, in terms of target coverage, plan quality, organ-at-risk (OAR) sparing and number of delivered pencil beams. RESULTS: Our results show an improvement on target coverage and homogeneity when using Eclipse™ while PSI-Plan showed superior plan conformity. As for OAR sparing, both TPS achieved the clinical constraints. The number of pencil beams required per plan was on average 3.4 times higher for PSI-Plan. CONCLUSION: Both systems showed a good capacity to produce satisfactory plans, with Eclipse™ being able to achieve better target coverage and plan homogeneity without compromising OARs. ADVANCES IN KNOWLEDGE: A benchmark between a clinically tested and validated system with a commercial solution is of interest for emerging proton therapy, equipped with commercial systems and no previous experience with proton beam scanning.


Assuntos
Benchmarking , Institutos de Câncer , Neoplasias/radioterapia , Terapia com Prótons/instrumentação , Melhoria de Qualidade , Planejamento da Radioterapia Assistida por Computador/normas , Algoritmos , Humanos , Terapia com Prótons/normas , Suíça
2.
Int J Radiat Oncol Biol Phys ; 106(2): 440-448, 2020 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-31928642

RESUMO

PURPOSE: Recent studies suggest that ultrahigh-dose-rate, "FLASH," electron radiation therapy (RT) decreases normal tissue damage while maintaining tumor response compared with conventional dose rate RT. Here, we describe a novel RT apparatus that delivers FLASH proton RT (PRT) using double scattered protons with computed tomography guidance and provide the first report of proton FLASH RT-mediated normal tissue radioprotection. METHODS AND MATERIALS: Absolute dose was measured at multiple depths in solid water and validated against an absolute integral charge measurement using a Faraday cup. Real-time dose rate was obtained using a NaI detector to measure prompt gamma rays. The effect of FLASH versus standard dose rate PRT on tumors and normal tissues was measured using pancreatic flank tumors (MH641905) derived from the KPC autochthonous PanCa model in syngeneic C57BL/6J mice with analysis of fibrosis and stem cell repopulation in small intestine after abdominal irradiation. RESULTS: The double scattering and collimation apparatus was dosimetrically validated with dose rates of 78 ± 9 Gy per second and 0.9 ± 0.08 Gy per second for the FLASH and standard PRT. Whole abdominal FLASH PRT at 15 Gy significantly reduced the loss of proliferating cells in intestinal crypts compared with standard PRT. Studies with local intestinal irradiation at 18 Gy revealed a reduction to near baseline levels of intestinal fibrosis for FLASH-PRT compared with standard PRT. Despite this difference, FLASH-PRT did not demonstrate tumor radioprotection in MH641905 pancreatic cancer flank tumors after 12 or 18 Gy irradiation. CONCLUSIONS: We have designed and dosimetrically validated a FLASH-PRT system with accurate control of beam flux on a millisecond time scale and online monitoring of the integral and dose delivery time structure. Using this system, we found that FLASH-PRT decreases acute cell loss and late fibrosis after whole-abdomen and focal intestinal RT, whereas tumor growth inhibition is preserved between the 2 modalities.


Assuntos
Órgãos em Risco/efeitos da radiação , Terapia com Prótons/instrumentação , Lesões Experimentais por Radiação/prevenção & controle , Proteção Radiológica/instrumentação , Radioterapia Guiada por Imagem/instrumentação , Abdome/efeitos da radiação , Animais , Proliferação de Células/efeitos da radiação , Desenho de Equipamento/métodos , Estudos de Viabilidade , Feminino , Fibrose , Raios gama , Intestino Delgado/patologia , Intestino Delgado/efeitos da radiação , Camundongos , Camundongos Endogâmicos C57BL , Tratamentos com Preservação do Órgão/instrumentação , Tratamentos com Preservação do Órgão/métodos , Órgãos em Risco/patologia , Neoplasias Pancreáticas/radioterapia , Terapia com Prótons/métodos , Proteção Radiológica/métodos , Radiometria/métodos , Radioterapia Guiada por Imagem/métodos , Espalhamento de Radiação , Células-Tronco/efeitos da radiação , Tomografia Computadorizada por Raios X
3.
Br J Radiol ; 93(1107): 20190598, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31782941

RESUMO

OBJECTIVES: To describe the measurements and to present the results of the beam commissioning and the beam model validation of a compact, gantry-mounted, spot scanning proton accelerator system with dynamic layer-by-layer field collimation. METHODS: We performed measurements of depth dose distributions in water, spot and scanned field size in air at different positions from the isocenter plane, spot position over the 20 × 20 cm2 scanned area, beam monitor calibration in terms of absorbed dose to water and specific field collimation measurements at different gantry angles to commission the system. To validate the beam model in the treatment planning system (TPS), we measured spot profiles in water at different depths, absolute dose in water of single energy layers of different field sizes and inversely optimised spread-out Bragg peaks (SOBP) under normal and oblique beam incidence, field size and penumbra in water of SOBPs, and patient treatment specific quality assurance in homogeneous and heterogeneous phantoms. RESULTS: Energy range, spot size, spot position and dose output were consistent at all gantry angles with 0.3 mm, 0.4 mm, 0.6 mm and 0.5% maximum deviations, respectively. Uncollimated spot size (one sigma) in air with an air-gap of 10 cm ranged from 4.1 to 16.4 mm covering a range from 32.2 to 1.9 cm in water, respectively. Absolute dose measurements were within 3% when comparing TPS and experimental data. Gamma pass rates >98% and >96% at 3%/3 mm were obtained when performing 2D dose measurements in homogeneous and in heterogeneous media, respectively. Leaf position was within ±1 mm at all gantry angles and nozzle positions. CONCLUSIONS: Beam characterisation and machine commissioning results, and the exhaustive end-to-end tests performed to assess the proper functionality of the system, confirm that it is safe and accurate to treat patients. ADVANCES IN KNOWLEDGE: This is the first paper addressing the beam commissioning and the beam validation of a compact, gantry-mounted, pencil beam scanning proton accelerator system with dynamic layer-by-layer multileaf collimation.


Assuntos
Ciclotrons , Terapia com Prótons/instrumentação , Absorção de Radiação , Ar , Calibragem , Certificação , Desenho de Equipamento , Humanos , Países Baixos , Imagens de Fantasmas , Terapia com Prótons/métodos , Radiometria/métodos , Reprodutibilidade dos Testes , Água
4.
Br J Radiol ; 93(1107): 20190820, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31746631

RESUMO

OBJECTIVE: To quantify how a control software upgrade changed beam delivery times and impacted efficiency and capacity of a multiroom proton therapy center. METHODS: A four-room center treating approximately 90 patients/day, treating for approximately 7 years with optimized operations, underwent a software upgrade which reduced room and energy switching times from approximately 30 to 20 s and approximately 4 s to ~0.5 s, respectively. The center uses radio-frequency identification data to track patient treatments and has software which links this to beam delivery data extracted from the treatment log server. Two 4-month periods, with comparable patient volume, representing periods before and after the software change, were retrospectively analyzed. RESULTS: A total of 16,168 and 17,102 fields were analyzed. For bilateral head and neck and prostate patients, the beam waiting time was reduced by nearly a factor of 3 and the beam delivery times were reduced by nearly a factor of 2.5. Room switching times were reduced more modestly. Gantry capacity has increased from approximately 30 patients to 40-45 patients in a 16-h daily operation. CONCLUSIONS: Many proton centers are striving for increased efficiencies. We demonstrated that reductions in energy and room switching time can significantly increase center capacity. Greater potential for further gains would come from improvements in setup and imaging efficiency. ADVANCES IN KNOWLEDGE: This paper provides detailed measured data on the effect on treatment times resulting from reducing energy and room switching times under controlled conditions. It helps validate the models of previous investigations to establish treatment capacity of a proton therapy center.


Assuntos
Institutos de Câncer/organização & administração , Fortalecimento Institucional/organização & administração , Eficiência Organizacional , Terapia com Prótons , Software , Institutos de Câncer/estatística & dados numéricos , Institutos de Câncer/provisão & distribução , Administração de Instituições de Saúde/estatística & dados numéricos , Humanos , Terapia com Prótons/instrumentação , Terapia com Prótons/estatística & dados numéricos , Estudos Retrospectivos , Fatores de Tempo , Tempo para o Tratamento/estatística & dados numéricos
5.
Br J Radiol ; 93(1107): 20190669, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31799859

RESUMO

OBJECTIVE: This study is part of ongoing efforts aiming to transit from measurement-based to combined patient-specific quality assurance (PSQA) in intensity-modulated proton therapy (IMPT). A Monte Carlo (MC) dose-calculation algorithm is used to improve the independent dose calculation and to reveal the beam modeling deficiency of the analytical pencil beam (PB) algorithm. METHODS: A set of representative clinical IMPT plans with suboptimal PSQA results were reviewed. Verification plans were recalculated using an MC algorithm developed in-house. Agreements of PB and MC calculations with measurements that quantified by the γ passing rate were compared. RESULTS: The percentage of dose planes that met the clinical criteria for PSQA (>90% γ passing rate using 3%/3 mm criteria) increased from 71.40% in the original PB calculation to 95.14% in the MC recalculation. For fields without beam modifiers, nearly 100% of the dose planes exceeded the 95% γ passing rate threshold using the MC algorithm. The model deficiencies of the PB algorithm were found in the proximal and distal regions of the SOBP, where MC recalculation improved the γ passing rate by 11.27% (p < 0.001) and 16.80% (p < 0.001), respectively. CONCLUSIONS: The MC algorithm substantially improved the γ passing rate for IMPT PSQA. Improved modeling of beam modifiers would enable the use of the MC algorithm for independent dose calculation, completely replacing additional depth measurements in IMPT PSQA program. For current users of the PB algorithm, further improving the long-tail modeling or using MC simulation to generate the dose correction factor is necessary. ADVANCES IN KNOWLEDGE: We justified a change in clinical practice to achieve efficient combined PSQA in IMPT by using the MC algorithm that was experimentally validated in almost all the clinical scenarios in our center. Deficiencies in beam modeling of the current PB algorithm were identified and solutions to improve its dose-calculation accuracy were provided.


Assuntos
Algoritmos , Método de Monte Carlo , Terapia com Prótons/normas , Garantia da Qualidade dos Cuidados de Saúde , Radioterapia de Intensidade Modulada/normas , Análise de Dados , Humanos , Terapia com Prótons/instrumentação , Terapia com Prótons/métodos , Controle de Qualidade , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos , Planejamento da Radioterapia Assistida por Computador/normas , Planejamento da Radioterapia Assistida por Computador/estatística & dados numéricos , Radioterapia de Intensidade Modulada/instrumentação , Radioterapia de Intensidade Modulada/métodos , Reprodutibilidade dos Testes , Síncrotrons
6.
Br J Radiol ; 93(1107): 20190578, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31868523

RESUMO

OBJECTIVES: Proton minibeam radiation therapy (pMBRT) is a novel therapeutic strategy that combines the benefits of proton therapy with the remarkable normal tissue preservation observed with the use of submillimetric spatially fractionated beams. This promising technique has been implemented at the Institut Curie-Proton therapy centre (ICPO) using a first prototype of a multislit collimator. The purpose of this work was to develop a Monte Carlo-based dose calculation engine to reliably guide preclinical studies at ICPO. METHODS: The whole "Y1"-passive beamline at the ICPO, including pMBRT implementation, was modelled using the Monte Carlo GATE v. 7.0 code. A clinically relevant proton energy (100 MeV) was used as starting point. Minibeam generation by means of the brass collimator used in the first experiments was modelled. A virtual source was modelled at the exit of the beamline nozzle and outcomes were compared with dosimetric measurements performed with EBT3 gafchromic films and a diamond detector in water. Dose distributions were recorded in a water phantom and in rat CT images (7-week-old male Fischer rats). RESULTS: The dose calculation engine was benchmarked against experimental data and was then used to assess dose distributions in CT images of a rat, resulting from different irradiation configurations used in several experiments. It reduced computational time by an order of magnitude. This allows us to speed up simulations for in vivo trials, where we obtained peak-to-valley dose ratios of 1.20 ± 0.05 and 6.1 ± 0.2 for proton minibeam irradiations targeting the tumour and crossing the rat head. Tumour eradication was observed in the 67 and 22% of the animals treated respectively. CONCLUSION: A Monte Carlo dose calculation engine for pMBRT implementation with mechanical collimation has been developed. This tool can be used to guide and interpret the results of in vivo trials. ADVANCES IN KNOWLEDGE: This is the first Monte Carlo dose engine for pMBRT that is being used to guide preclinical trials in a clinical proton therapy centre.


Assuntos
Dosimetria Fotográfica/métodos , Método de Monte Carlo , Terapia com Prótons/métodos , Animais , Benchmarking , Masculino , Órgãos em Risco , Imagens de Fantasmas , Terapia com Prótons/instrumentação , Hipofracionamento da Dose de Radiação , Lesões por Radiação/prevenção & controle , Dosagem Radioterapêutica , Ratos , Ratos Endogâmicos F344 , Espalhamento de Radiação
7.
Cancer Radiother ; 23(6-7): 617-624, 2019 Oct.
Artigo em Francês | MEDLINE | ID: mdl-31477441

RESUMO

Among over 100 proton therapy centres worldwide in operation or under construction, French proton therapy is coming to full maturity with the recent opening of the Nice (1991, upgrade in 2016) and Caen (2018) facilities next to the Orsay (1991, upgrade in 2010) centre. Proton therapy is a national priority for children and young adults in all three centres. The patient-related activity of the three French centres is coordinated via the Protonshare portal to optimise referral by type of indication and available expertise in coordination with the French society of radiation oncology SFRO and French radiotherapy centres. The centres are recognised by the French Health Care excellence initiative, promoted by the ministry of Foreign Affairs. The three centres collaborate structurally in terms of clinical research and are engaged at the international level in the participation to European databases and research initiatives. Concerted actions are now also promoted in preclinical research via the Radiotransnet network. Ongoing French developments in proton therapy are well presented in international hadron therapy meetings, including European Proton Therapy Network and Particle Therapy Cooperative Oncology Group. Proton therapy teaching in France is offered at several levels and is open to colleagues from all radiation oncology centres, so that they are fully informed, involved and trained to facility recognition of possible indications and thereby to contribute to appropriate patient referral. This close collaboration between all actors in French radiation oncology facilitates the work to demonstrate the required level of medical and scientific evidence for current and emerging indications for particle therapy. Based on that, the future might entail a possible creation of more proton therapy facilities in France.


Assuntos
Institutos de Câncer , Neoplasias/radioterapia , Terapia com Prótons , Radioterapia (Especialidade) , Adolescente , Adulto , Pesquisa Biomédica/organização & administração , Institutos de Câncer/organização & administração , Institutos de Câncer/provisão & distribução , Criança , Ciclotrons/provisão & distribução , Apoio Financeiro , França , Humanos , Cooperação Internacional , Terapia com Prótons/economia , Terapia com Prótons/instrumentação , Terapia com Prótons/métodos , Radioterapia (Especialidade)/educação , Radioterapia (Especialidade)/organização & administração , Adulto Jovem
8.
Phys Med ; 66: 15-20, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31542656

RESUMO

PURPOSE: The purpose of the current study is to (i) investigate the feasibility of utilizing the XRV-124 - a cone-shaped scintillation detector - to measure the spot size and spot position in pencil beam scanning proton therapy, and (ii) compare the spot sizes acquired by the XRV-124 with that of the widely used Lynx detector. METHODS: Spot position was tested by delivering a map of 30 spots at different locations to the XRV-124. Spot position test included energies 70-210 MeV. Spot size measurements were performed at the isocenter using the XRV-124 and Lynx detectors for a total of 32 energies (70-225 MeV at an increment of 5 MeV) at four cardinal gantry angles. RESULTS: The position (X, Y, and Z) of the radiation isocenter was within ±0.3 mm. For spots placed on the horizontal (X) and longitudinal (Y) axes of the spot map, both the X and Y locations of the spots were within ±0.5 mm. The spots placed diagonally in the map showed a higher deviation (±0.9 mm). In evaluating spot sizes acquired using the XRV-124 vs. Lynx, the results from the XRV were found to be slightly higher but within 0.2 mm for energies ≥130 MeV and within 0.4 mm for energies <130 MeV. CONCLUSIONS: It is feasible to utilize the XRV-124 to perform the quality assurance of position and size of a pencil proton beam around the radiation isocenter but within the usable XRV-124 cone area.


Assuntos
Terapia com Prótons/instrumentação , Contagem de Cintilação/instrumentação , Estudos de Viabilidade , Controle de Qualidade , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador
9.
Br J Radiol ; 92(1102): 20190382, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31287739

RESUMO

OBJECTIVES: To measure leakage ambient dose equivalent H*(10) from stray secondary neutron and photon radiation around proton therapy (PT) facility and evaluate adequacy of shielding design. METHODS AND MATERIALS: H*(10) measurement were carried out at 149 locations around cyclotron vault (CV), beam transport system (BTS) and first treatment room (GTR3) of a multiroom PT facility using WENDI-II and SmartIon survey meter. Measurement were performed under extreme case scenarios wherein maximum secondary neutrons and photons were produced around CV, BTS and GTR3 by stopping 230MeV proton of 300nA on beam degrader, end of BTS and isocenter of GTR3. Weekly time average dose rate (TADR) were calculated from H*(10) value measured at selective hot spots by irradiating actual treatment plans of mix clinical sites. RESULTS: The maximum total H*(10) were within 2 µSv/hr around CV, 5 µSv/hr around outer wall of BTS which increases up to 62 µSv/hr at the end of inside BTS corridor. Maximum H*(10) of 20.8 µSv/hr in treatment control console (P125), 23.4 µSv/hr behind the common wall between GTR3 and GTR2 (P132) and 25.7 µSv/hr above isocenter (P99) were observed around GTR3. Reduction of beam current from 6 to 3 nA and 1 nA at nozzle exit lead to decrease in total H*(10) at P125 from 20.8 to 11.35 and 4.62 µSv/hr. In comparison to extreme case scenario, H*(10) value at P125, P132 and P99 from clinically relevant irradiation parameters were reduce by a factor ranging from 8.6 for high range cube to 46.4 for brain clinical plan. The maximum weekly TADR per fraction was highest for large volume, sacral chordoma patient at 8.5 µSv/hr compare to 0.3 µSv/hr for brain patient. The calculated weekly TADR for 30 mix clinical cases and 15 fractions of 1 L cube resulted total weekly TADR of 83-84 µSv/hr at P125, P132 and P99. The maximum annual dose level at these hot spots were estimated at 4.37 mSv/Yr. CONCLUSION: We have carried out an extensive measurement of H*(10) under different conditions. The shielding thickness of our PT facility is adequate to limit the dose to occupational worker and general public within the permissible stipulated limit. The data reported here can bridge the knowledge gap in ambient dose around PT facility and can also be used as a reference for any new and existing proton facility for intercomparison and validation. ADVANCES IN KNOWLEDGE: First extensive investigation of neutron and photon H*(10) around PT facility and can bridge the knowledge gap on ambient dose.


Assuntos
Ciclotrons , Ambiente de Instituições de Saúde , Nêutrons , Fótons , Terapia com Prótons/instrumentação , Monitoramento de Radiação/métodos , Monitoramento de Radiação/instrumentação , Proteção Radiológica/métodos , Radiometria/instrumentação , Radiometria/métodos , Espalhamento de Radiação
10.
Health Phys ; 117(5): 509-525, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31211755

RESUMO

Patient-specific collimators used in proton therapy are activated after use. The aim of this work is to assess the residual activity in brass collimators considering clinical beams, so far studied only for monoenergetic beams, and to develop a model to calculate the activity. Eight brass collimators irradiated with different clinical and monoenergetic beams were included in the study. The collimators were analyzed with gamma spectrometry in the framework of three independent studies carried out at the two French proton therapy sites. Using FLUKA (a fully integrated particle physics Monte Carlo simulation package), simulations were performed to determine radionuclides and activities for all the collimators. The semiempirical model was built using data calculated with FLUKA for a range of clinical beams (different maximum proton energies, modulations, and doses). It was found that there was global coherence in experimental results from different studies. The relevant radionuclides at 1 mo postirradiation were Co, Co, and Zn, and additionally, Mn, Co, and Co for high-energy beams. For nondegraded monoenergetic beams, differences between FLUKA and spectrometry were within those reported in reference benchmark studies (±30%). Due to the use of perfect monochromatic sources in the FLUKA model, FLUKA results systematically underestimated experimental activities for clinical beams, especially for Zn, depending on the beam energy spread (modulation, degradation, beam line characteristics). To account for the energy spread, correction factors were derived for the semiempirical model. The model is applicable to the most relevant radionuclides and total amounts. Secondary neutrons have a negligible contribution to the activity during treatment with respect to proton activation.


Assuntos
Algoritmos , Modelos Estatísticos , Método de Monte Carlo , Terapia com Prótons/instrumentação , Terapia com Prótons/métodos , Radiometria/instrumentação , Humanos , Doses de Radiação
11.
J Appl Clin Med Phys ; 20(7): 48-57, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31237090

RESUMO

To improve the penumbra of low-energy beams used in spot-scanning proton therapy, various collimation systems have been proposed and used in clinics. In this paper, focused on patient-specific brass collimators, the collimator-scattered protons' physical and biological effects were investigated. The Geant4 Monte Carlo code was used to model the collimators mounted on the scanning nozzle of the Hokkaido University Hospital. A systematic survey was performed in water phantom with various-sized rectangular targets; range (5-20 cm), spread-out Bragg peak (SOBP) (5-10 cm), and field size (2 × 2-16 × 16 cm2 ). It revealed that both the range and SOBP dependences of the physical dose increase had similar trends to passive scattering methods, that is, it increased largely with the range and slightly with the SOBP. The physical impact was maximized at the surface (3%-22% for the tested geometries) and decreased with depth. In contrast, the field size (FS) dependence differed from that observed in passive scattering: the increase was high for both small and large FSs. This may be attributed to the different phase-space shapes at the target boundary between the two dose delivery methods. Next, the biological impact was estimated based on the increase in dose-averaged linear energy transfer (LETd ) and relative biological effectiveness (RBE). The LETd of the collimator-scattered protons were several keV/µm higher than that of unscattered ones; however, since this large increase was observed only at the positions receiving a small scattered dose, the overall LETd increase was negligible. As a consequence, the RBE increase did not exceed 0.05. Finally, the effects on patient geometries were estimated by testing two patient plans, and a negligible RBE increase (0.9% at most in the critical organs at surface) was observed in both cases. Therefore, the impact of collimator-scattered protons is almost entirely attributed to the physical dose increase, while the RBE increase is negligible.


Assuntos
Algoritmos , Melanoma/radioterapia , Terapia com Prótons/instrumentação , Terapia com Prótons/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Rabdomiossarcoma/radioterapia , Neoplasias Uveais/radioterapia , Criança , Simulação por Computador , Relação Dose-Resposta à Radiação , Humanos , Método de Monte Carlo , Órgãos em Risco/efeitos da radiação , Eficiência Biológica Relativa , Espalhamento de Radiação
12.
Med Phys ; 46(8): e678-e705, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31125441

RESUMO

PURPOSE:  Task Group (TG) 224 was established by the American Association of Physicists in Medicine's Science Council under the Radiation Therapy Committee and Work Group on Particle Beams. The group was charged with developing comprehensive quality assurance (QA) guidelines and recommendations for the three commonly employed proton therapy techniques for beam delivery: scattering, uniform scanning, and pencil beam scanning. This report supplements established QA guidelines for therapy machine performance for other widely used modalities, such as photons and electrons (TG 142, TG 40, TG 24, TG 22, TG 179, and Medical Physics Practice Guideline 2a) and shares their aims of ensuring the safe, accurate, and consistent delivery of radiation therapy dose distributions to patients. METHODS:  To provide a basis from which machine-specific QA procedures can be developed, the report first describes the different delivery techniques and highlights the salient components of the related machine hardware. Depending on the particular machine hardware, certain procedures may be more or less important, and each institution should investigate its own situation. RESULTS:  In lieu of such investigations, this report identifies common beam parameters that are typically checked, along with the typical frequencies of those checks (daily, weekly, monthly, or annually). The rationale for choosing these checks and their frequencies is briefly described. Short descriptions of suggested tools and procedures for completing some of the periodic QA checks are also presented. CONCLUSION:  Recommended tolerance limits for each of the recommended QA checks are tabulated, and are based on the literature and on consensus data from the clinical proton experience of the task group members. We hope that this and other reports will serve as a reference for clinical physicists wishing either to establish a proton therapy QA program or to evaluate an existing one.


Assuntos
Terapia com Prótons/instrumentação , Garantia da Qualidade dos Cuidados de Saúde , Humanos , Terapia com Prótons/efeitos adversos , Terapia com Prótons/normas , Radiometria , Cintilografia , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Segurança
13.
Zhongguo Yi Liao Qi Xie Za Zhi ; 43(2): 102-105, 2019 Mar 30.
Artigo em Chinês | MEDLINE | ID: mdl-30977605

RESUMO

er to detect the beam quality of the SC200 superconducting cyclotron,measure the beam at the extraction reference and the acceptance of the accelerator is realized.This article mainly introduces the design that use the scintillation screen at the extraction reference to measure the beam profile,position and use the Faraday cup to measure the current intensity with 2.5 level accuracy.The remoted controlling of probes and the acquisition and processing of signal based on LabVIEW and PLC.


Assuntos
Terapia com Prótons , Terapia com Prótons/instrumentação
14.
Phys Med ; 59: 55-63, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30928066

RESUMO

PURPOSE: At Centro Nazionale di Adroterapia Oncologica (CNAO, Pavia, Italy) ocular proton therapy (OPT) is delivered using a non-dedicated beamline. This paper describes the novel clinical workflow as well as technologies and methods adopted to achieve accurate target positioning and verification during ocular proton therapy at CNAO. METHOD: The OPT clinical protocol at CNAO prescribes a treatment simulation and a delivery phase, performed in the CT and treatment rooms, respectively. The patient gaze direction is controlled and monitored during the entire workflow by means of an eye tracking system (ETS) featuring two optical cameras and an embedded fixation diode light. Thus, the accurate alignment of the fixation light provided to the patient to the prescribed gazed direction is required for an effective treatment. As such, a technological platform based on active robotic manipulators and IR optical tracking-based guidance was developed and tested. The effectiveness of patient positioning strategies was evaluated on a clinical dataset comprising twenty patients treated at CNAO. RESULTS: According to experimental testing, the developed technologies guarantee uncertainties lower than one degree in gaze direction definition by means of ETS-guided positioning. Patient positioning and monitoring strategies during treatment effectively mitigated set-up uncertainties and exhibited sub-millimetric accuracy in radiopaque markers alignment. CONCLUSION: Ocular proton therapy is currently delivered at CNAO with a non-dedicated beamline. The technologies developed for patient positioning and motion monitoring have proven to be compliant with the high geometrical accuracy required for the treatment of intraocular tumors.


Assuntos
Neoplasias Oculares/radioterapia , Movimento , Posicionamento do Paciente/instrumentação , Terapia com Prótons/instrumentação , Planejamento da Radioterapia Assistida por Computador/instrumentação , Neoplasias Oculares/diagnóstico por imagem , Humanos , Síncrotrons , Tomografia Computadorizada por Raios X
15.
J Appl Clin Med Phys ; 20(4): 29-44, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30920146

RESUMO

PURPOSE: The main purpose of this study is to demonstrate the clinical implementation of a comprehensive pencil beam scanning (PBS) daily quality assurance (QA) program involving a number of novel QA devices including the Sphinx/Lynx/parallel-plate (PPC05) ion chamber and HexaCheck/multiple imaging modality isocentricity (MIMI) imaging phantoms. Additionally, the study highlights the importance of testing the connectivity among oncology information system (OIS), beam delivery/imaging systems, and patient position system at a proton center with multi-vendor equipment and software. METHODS: For dosimetry, a daily QA plan with spot map of four different energies (106, 145, 172, and 221 MeV) is delivered on the delivery system through the OIS. The delivery assesses the dose output, field homogeneity, beam coincidence, beam energy, width, distal-fall-off (DFO), and spot characteristics - for example, position, size, and skewness. As a part of mechanical and imaging QA, a treatment plan with the MIMI phantom serving as the patient is transferred from OIS to imaging system. The HexaCheck/MIMI phantoms are used to assess daily laser accuracy, imaging isocenter accuracy, image registration accuracy, and six-dimensional (6D) positional correction accuracy for the kV imaging system and robotic couch. RESULTS: The daily QA results presented herein are based on 202 daily sets of measurements over a period of 10 months. Total time to perform daily QA tasks at our center is under 30 min. The relative difference (Δrel ) of daily measurements with respect to baseline was within ± 1% for field homogeneity, ±0.5 mm for range, width and DFO, ±1 mm for spots positions, ±10% for in-air spot sigma, ±0.5 spot skewness, and ±1 mm for beam coincidence (except 1 case: Δrel  = 1.3 mm). The average Δrel in dose output was -0.2% (range: -1.1% to 1.5%). For 6D IGRT QA, the average absolute difference (Δabs ) was ≤0.6 ± 0.4 mm for translational and ≤0.5° for rotational shifts. CONCLUSION: The use of novel QA devices such as the Sphinx in conjunction with the Lynx, PPC05 ion chamber, HexaCheck/MIMI phantoms, and myQA software was shown to provide a comprehensive and efficient method for performing daily QA of a number of system parameters for a modern proton PBS-dedicated treatment delivery unit.


Assuntos
Neoplasias/radioterapia , Imagens de Fantasmas , Terapia com Prótons/instrumentação , Terapia com Prótons/métodos , Garantia da Qualidade dos Cuidados de Saúde/normas , Planejamento da Radioterapia Assistida por Computador/métodos , Humanos , Órgãos em Risco/efeitos da radiação , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada/métodos , Software
16.
Med Phys ; 46(4): 1922-1930, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30740709

RESUMO

PURPOSE: To demonstrate a novel theoretical optimization design which considers beam spot and trimmer positioning in addition to beamlet weighting for dynamically collimated proton therapy (DCPT) treatments. Prior to this, the previous methods of plan optimization used to study this emerging technology relied upon an intuitive selection criterion to fix the trimmers blades for a uniform grid of beam spots before determining the individual beamlet weights. To evaluate the potential benefit from this new optimization design, a treatment planning optimization study was performed in order to compare the algorithm's functionality against the existing methods of plan optimization. MATERIALS AND METHODS: A direct parameter optimization (DPO) method was developed to determine beam spot and trimmer positions cohesively with beamlet weighting for DCPT treatment plans. Gradients were numerically determined from applying small adjustments to the aforementioned parameters and quantifying the resulting impact on an objective function. This technique was compared to the conventional trimmer selection algorithm (TSA) which does not optimize spot position concurrently with trimmer position. Both planning methods were used to optimize a set of brain treatment plans, and the resulting dose distributions were compared with dose-volume histogram quantities in addition to target coverage, homogeneity, and conformity metrics. RESULTS: An overall improvement to the target conformity and healthy tissue sparing was achieved with DPO over TSA while maintaining an equivalent planning target volume (PTV) coverage index for the three brain patients evaluated in this study. On average, the conformity index improved by 5.5% when utilizing DPO. A similar improvement in reducing the dose to several organs at risk was also noted. CONCLUSION: Both the TSA and DPO planning methods can achieve highly conformal treatments with the dynamic collimation system (DCS) technology. However, an improvement in the target conformity and healthy tissue sparing was achieved by simultaneously optimizing beam spot position, trimmer location, and beamlet weights using DPO in comparison to the TSA technique.


Assuntos
Algoritmos , Neoplasias Encefálicas/radioterapia , Órgãos em Risco/efeitos da radiação , Terapia com Prótons/instrumentação , Terapia com Prótons/normas , Planejamento da Radioterapia Assistida por Computador/métodos , Humanos , Dosagem Radioterapêutica
17.
J Appl Clin Med Phys ; 20(3): 14-21, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30756466

RESUMO

This study determines the impact of change in aeration in sinonasal cavities on the robustness of passive-scattering proton therapy plans in patients with sinonasal and nasopharyngeal malignancies. Fourteen patients, each with one planning CT and one CT acquired during radiotherapy were studied. Repeat and planning CTs were rigidly aligned and contours were transferred using deformable registration. The amount of air, tumor, and fluid within the cavity containing the tumor were measured on both CTs. The original plans were recalculated on the repeat CT. Dosimetric changes were measured for the targets and critical structures. Median decrease in gross tumor volume (GTV) was 19.8% and correlated with the time of rescan. The median change in air content was 7.1% and correlated with the tumor shrinkage. The median of the mean dose Dmean change was +0.4% for GTV and +0.3% for clinical target volume. Median change in the maximum dose Dmax of the critical structures were as follows: optic chiasm +0.66%, left optic nerve +0.12%, right optic nerve +0.38%, brainstem +0.6%. The dose to the GTV decreased by more than 5% in 1 case, and the dose to critical structure(s) increased by more than 5% in three cases. These four patients had sinonasal cancers and were treated with anterior proton fields that directly transversed through the involved sinus cavities. The change in dose in the replanning was strongly correlated with the change in aeration (P = 0.02). We found that the change in aeration in the vicinity of the target and the arrangement of proton beams affected the robustness of proton plan.


Assuntos
Quimiorradioterapia , Linfoma Extranodal de Células T-NK/terapia , Carcinoma Nasofaríngeo/terapia , Terapia com Prótons/instrumentação , Planejamento da Radioterapia Assistida por Computador/métodos , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Terapia com Prótons/métodos
18.
Med Phys ; 46(4): 1852-1862, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30659616

RESUMO

PURPOSE: Only few centers worldwide treat intraocular tumors with proton therapy, all of them with a dedicated beamline, except in one case in the USA. The Italian National Center for Oncological Hadrontherapy (CNAO) is a synchrotron-based hadrontherapy facility equipped with fixed beamlines and pencil beam scanning modality. Recently, a general-purpose horizontal proton beamline was adapted to treat also ocular diseases. In this work, the conceptual design and main dosimetric properties of this new proton eyeline are presented. METHODS: A 28 mm thick water-equivalent range shifter (RS) was placed along the proton beamline to shift the minimum beam penetration at shallower depths. FLUKA Monte Carlo (MC) simulations were performed to optimize the position of the RS and patient-specific collimator, in order to achieve sharp lateral dose gradients. Lateral dose profiles were then measured with radiochromic EBT3 films to evaluate the dose uniformity and lateral penumbra width at several depths. Different beam scanning patterns were tested. Discrete energy levels with 1 mm water-equivalent step within the whole ocular energy range (62.7-89.8 MeV) were used, while fine adjustment of beam range was achieved using thin polymethylmethacrylate additional sheets. Depth-dose distributions (DDDs) were measured with the Peakfinder system. Monoenergetic beam weights to achieve flat spread-out Bragg Peaks (SOBPs) were numerically determined. Absorbed dose to water under reference conditions was measured with an Advanced Markus chamber, following International Atomic Energy Agency (IAEA) Technical Report Series (TRS)-398 Code of Practice. Neutron dose at the contralateral eye was evaluated with passive bubble dosimeters. RESULTS: Monte Carlo simulations and experimental results confirmed that maximizing the air gap between RS and aperture reduces the lateral dose penumbra width of the collimated beam and increases the field transversal dose homogeneity. Therefore, RS and brass collimator were placed at about 98 cm (upstream of the beam monitors) and 7 cm from the isocenter, respectively. The lateral 80%-20% penumbra at middle-SOBP ranged between 1.4 and 1.7 mm depending on field size, while 90%-10% distal fall-off of the DDDs ranged between 1.0 and 1.5 mm, as a function of range. Such values are comparable to those reported for most existing eye-dedicated facilities. Measured SOBP doses were in very good agreement with MC simulations. Mean neutron dose at the contralateral eye was 68 µSv/Gy. Beam delivery time, for 60 Gy relative biological effectiveness (RBE) prescription dose in four fractions, was around 3 min per session. CONCLUSIONS: Our adapted scanning proton beamline satisfied the requirements for intraocular tumor treatment. The first ocular treatment was delivered in August 2016 and more than 100 patients successfully completed their treatment in these 2 yr.


Assuntos
Neoplasias Oculares/radioterapia , Imagens de Fantasmas , Terapia com Prótons/instrumentação , Terapia com Prótons/normas , Planejamento da Radioterapia Assistida por Computador/normas , Síncrotrons/instrumentação , Desenho de Equipamento , Humanos , Método de Monte Carlo , Órgãos em Risco/efeitos da radiação , Dosagem Radioterapêutica , Água
19.
Phys Med Biol ; 64(8): 085005, 2019 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-30650402

RESUMO

A new methodology for assessing linear energy transfer (LET) and relative biological effectiveness (RBE) in proton therapy beams using thermoluminescent detectors is presented. The method is based on the different LET response of two different lithium fluoride thermoluminescent detectors (LiF:Mg,Ti and LiF:Mg,Cu,P) for measuring charged particles. The relative efficiency of the two detector types was predicted using the recently developed Microdosimetric d(z) Model in combination with the Monte Carlo code PHITS. Afterwards, the calculated ratio of the expected response of the two detector types was correlated with the fluence- and dose- mean values of the unrestricted proton LET. Using the obtained proton dose mean LET as input, the RBE was assessed using a phenomenological biophysical model of cell survival. The aforementioned methodology was benchmarked by exposing the detectors at different depths within the spread out Bragg peak (SOBP) of a clinical proton beam at iThemba LABS. The assessed LET values were found to be in good agreement with the results of radiation transport computer simulations performed using the Monte Carlo code GEANT4. Furthermore, the estimated RBE values were compared with the RBE values experimentally determined by performing colony survival measurements with Chinese Hamster Ovary (CHO) cells during the same experimental run. A very good agreement was found between the results of the proposed methodology and the results of the in vitro study.


Assuntos
Transferência Linear de Energia , Terapia com Prótons/instrumentação , Eficiência Biológica Relativa , Animais , Células CHO , Sobrevivência Celular , Cricetinae , Cricetulus , Humanos , Método de Monte Carlo , Terapia com Prótons/métodos
20.
Med Phys ; 46(4): 1821-1828, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30695108

RESUMO

PURPOSE: The objective of this technical note was to investigate the accuracy of proton stopping power relative to water (RSP) estimation using a novel dual-layer, dual-energy computed tomography (DL-DECT) scanner for potential use in proton therapy planning. DL-DECT allows dual-energy reconstruction from scans acquired at a single x-ray tube voltage V by using two-layered detectors. METHODS: Sets of calibration and evaluation inserts were scanned at a DL-DECT scanner in a custom phantom with variable diameter D (0 to 150 mm) at V of 120 and 140 kV. Inserts were additionally scanned at a synchrotron computed tomography facility to obtain comparative linear attenuation coefficients for energies from 50 to 100 keV, and reference RSP was obtained using a carbon ion beam and variable water column. DL-DECT monoenergetic (mono-E) reconstructions were employed to obtain RSP by adapting the Yang-Saito-Landry (YSL) method. The method was compared to reference RSP via the root mean square error (RMSE) over insert mean values obtained from volumetric regions of interest. The accuracy of intermediate quantities such as the relative electron density (RED), effective atomic number (EAN), and the mono-E was additionally evaluated. RESULTS: The lung inserts showed higher errors for all quantities and we report RMSE excluding them. RMSE for µ from DL-DECT mono-E was below 1.9%. For the evaluation inserts at D = 150 mm and V = 140 kV, RED RMSE was 1.0%, while for EAN it was 2.9%. RSP RMSE was below 0.8% for all D and V, which did not strongly affect the results. CONCLUSIONS: In this investigation of RSP accuracy from DL-DECT, we have shown that RMSE below 1% can be achieved. It was possible to adapt the YSL method for DL-DECT and intermediate quantities RED and EAN had comparable accuracy to previous publications.


Assuntos
Processamento de Imagem Assistida por Computador/métodos , Pulmão/efeitos da radiação , Neoplasias/radioterapia , Imagens de Fantasmas , Terapia com Prótons/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Tomografia Computadorizada por Raios X/métodos , Calibragem , Elétrons , Humanos , Órgãos em Risco/efeitos da radiação , Terapia com Prótons/instrumentação , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada/métodos , Síncrotrons/instrumentação , Água/química
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