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Peters N, Wohlfahrt P, Bolsi A, Dahlgren C, De Marzi L, Ellerbrock M, Fracchiolla F, Free J, Gomà C, Góra J, Kajdrowicz T, MacKay R, Molinelli S, Nørrevang O, Rinaldi I, Rompokos V, Van der Tol P, Vermeren X, Richter C. OC-0667 Experimental assessment of inter-centre variation and accuracy in SPR prediction within the EPTN. Radiother Oncol 2019. [DOI: 10.1016/s0167-8140(19)31087-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Bizzocchi N, De Angelis C, Hrbacek J, Lomax A, Weber D, Bolsi A. EP-2105 Robustness comparison between 6-and 8fields SIB proton plans on head and neck patients. Radiother Oncol 2019. [DOI: 10.1016/s0167-8140(19)32525-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Matter M, Fachouri N, Nenoff L, Meier G, Bolsi A, Weber D, Lomax A, Albertini F. EP-2098 Measurement free patient specific verification for PBS proton plans – a quantitative evaluation. Radiother Oncol 2019. [DOI: 10.1016/s0167-8140(19)32518-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Winterhalter C, Zepter S, Shim S, Meier G, Bolsi A, Fredh A, Hrbacek J, Oxley D, Zhang Y, Weber DC, Lomax A, Safai S. Evaluation of the ray-casting analytical algorithm for pencil beam scanning proton therapy. Phys Med Biol 2019; 64:065021. [PMID: 30641496 DOI: 10.1088/1361-6560/aafe58] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
For pencil beam scanned (PBS) proton therapy, analytical dose calculation engines are still typically used for the optimisation process, and often for the final evaluation of the plan. Recently however, the suitability of analytical calculations for planning PBS treatments has been questioned. Conceptually, the two main approaches for these analytical dose calculations are the ray-casting (RC) and the pencil-beam (PB) method. In this study, we compare dose distributions and dosimetric indices, calculated on both the clinical dose calculation grid and as a function of dose grid resolution, to Monte Carlo (MC) calculations. The analysis is done using a comprehensive set of clinical plans which represent a wide choice of treatment sites. When analysing dose difference histograms for relative treatment plans, pencil beam calculations with double grid resolution perform best, with on average 97.7%/91.9% (RC), 97.9%/92.7% (RC, double grid resolution), 97.6%/91.0% (PB) and 98.6%/94.0% (PB, double grid resolution) of voxels agreeing within ±5%/± 3% between the analytical and the MC calculations. Even though these point-to-point dose comparison shows differences between analytical and MC calculations, for all algorithms, clinically relevant dosimetric indices agree within ±4% for the PTV and within ±5% for critical organs. While the clinical agreement depends on the treatment site, there is no substantial difference of indices between the different algorithms. The pencil-beam approach however comes at a higher computational cost than the ray-casting calculation. In conclusion, we would recommend using the ray-casting algorithm for fast dose optimization and subsequently combine it with one MC calculation to scale the absolute dose and assure the quality of the treatment plan.
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Speleers BA, Belosi FM, De Gersem WR, Deseyne PR, Paelinck LM, Bolsi A, Lomax AJ, Boute BG, Van Greveling AE, Monten CM, Van de Velde JJ, Vercauteren TH, Veldeman L, Weber DC, De Neve WC. Comparison of supine or prone crawl photon or proton breast and regional lymph node radiation therapy including the internal mammary chain. Sci Rep 2019; 9:4755. [PMID: 30894606 PMCID: PMC6427000 DOI: 10.1038/s41598-019-41283-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 02/22/2019] [Indexed: 12/25/2022] Open
Abstract
We report on a dosimetrical study comparing supine (S) and prone-crawl (P) position for radiotherapy of whole breast (WB) and loco-regional lymph node regions, including the internal mammary chain (LN_IM). Six left sided breast cancer patients were CT-simulated in S and P positions and four patients only in P position. Treatment plans were made using non-coplanar volumetric modulated arc photon therapy (VMAT) or pencil beam scanning intensity modulated proton therapy (IMPT). Dose prescription was 15*2.67 Gy(GyRBE). The average mean heart doses for S or P VMAT were 5.6 or 4.3 Gy, respectively (p = 0.16) and 1.02 or 1.08 GyRBE, respectively for IMPT (p = 0.8; p < 0.001 for IMPT versus VMAT). The average mean lung doses for S or P VMAT were 5.91 or 2.90 Gy, respectively (p = 0.002) and 1.56 or 1.09 GyRBE, respectively for IMPT (p = 0.016). In high-risk patients, average (range) thirty-year mortality rates from radiotherapy-related cardiac injury and lung cancer were estimated at 6.8(5.4-9.4)% or 3.8(2.8-5.1)% for S or P VMAT (p < 0.001), respectively, and 1.6(1.1-2.0)% or 1.2(0.8-1.6)% for S or P IMPT (p = 0.25), respectively. Radiation-related mortality risk could outweigh the ~8% disease-specific survival benefit of WB + LN_IM radiotherapy for S VMAT but not P VMAT. IMPT carries the lowest radiation-related mortality risks.
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Pelak M, Walser M, Bachtiary B, Bolsi A, Hrbacek J, Lomax A, Kliebsch U, Pica A, Weber D. PO-162 Patient outcome of pencil beam-scanning proton therapy in Head and Neck adenoid cystic carcinoma. Radiother Oncol 2019. [DOI: 10.1016/s0167-8140(19)30328-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Winterhalter C, Fura E, Tian Y, Aitkenhead A, Bolsi A, Dieterle M, Fredh A, Meier G, Oxley D, Siewert D, Weber DC, Lomax A, Safai S. Validating a Monte Carlo approach to absolute dose quality assurance for proton pencil beam scanning. ACTA ACUST UNITED AC 2018; 63:175001. [DOI: 10.1088/1361-6560/aad3ae] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Bolsi A, Peroni M, Amelio D, Dasu A, Stock M, Toma-Dasu I, Nyström PW, Hoffmann A. Practice patterns of image guided particle therapy in Europe: A 2016 survey of the European Particle Therapy Network (EPTN). Radiother Oncol 2018; 128:4-8. [DOI: 10.1016/j.radonc.2018.03.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2018] [Accepted: 03/10/2018] [Indexed: 12/17/2022]
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Snider JW, Schneider RA, Poelma-Tap D, Stieb S, Murray FR, Placidi L, Albertini F, Lomax A, Bolsi A, Kliebsch U, Malyapa R, Weber DC. Long-Term Outcomes and Prognostic Factors After Pencil-Beam Scanning Proton Radiation Therapy for Spinal Chordomas: A Large, Single-Institution Cohort. Int J Radiat Oncol Biol Phys 2018; 101:226-233. [DOI: 10.1016/j.ijrobp.2018.01.060] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 12/22/2017] [Accepted: 01/16/2018] [Indexed: 01/24/2023]
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Fredh A, Winterhalter C, Fura E, Bolsi A, Safai S, Weber D, Lomax A. EP-1815: Comparison of independent Monte Carlo calculations with measurements of spot scanned proton fields. Radiother Oncol 2018. [DOI: 10.1016/s0167-8140(18)32124-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Hoffmann A, Bolsi A, Peroni M. SP-0220: EPTN WP4: image guidance in particle therapy. Radiother Oncol 2018. [DOI: 10.1016/s0167-8140(18)30530-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Basler L, Poel R, Bolsi A, Lomax A, Tanadini-Lang S, Guckenberger M, Weber D. OC-0593: Dosimetric analysis of local failures in skull-base chordoma/chondrosarcoma following proton therapy. Radiother Oncol 2018. [DOI: 10.1016/s0167-8140(18)30903-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Placidi L, Pica A, Ahllhelm F, Walser M, Lomax A, Bolsi A, Weber D. EP-1958: LET evaluation for pediatric craniopharyngioma with cerebral vasculopathies after PBS proton therapy. Radiother Oncol 2018. [DOI: 10.1016/s0167-8140(18)32267-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Bojaxhiu B, Ahlhelm F, Walser M, Placidi L, Kliebsch U, Mikroutsikos L, Morach P, Bolsi A, Lomax T, Pica A, Weber DC. Radiation Necrosis and White Matter Lesions in Pediatric Patients With Brain Tumors Treated With Pencil Beam Scanning Proton Therapy. Int J Radiat Oncol Biol Phys 2018; 100:987-996. [DOI: 10.1016/j.ijrobp.2017.11.037] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 10/11/2017] [Accepted: 11/24/2017] [Indexed: 12/21/2022]
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Weber DC, Murray FR, Correia D, Bolsi A, Frei-Welte M, Pica A, Lomax AJ, Schneider R, Bachtiary B. Pencil beam scanned protons for the treatment of patients with Ewing sarcoma. Pediatr Blood Cancer 2017. [PMID: 28627000 DOI: 10.1002/pbc.26688] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND Few data exist regarding the clinical outcome of patients with Ewing sarcoma (EWS) treated with pencil beam scanning proton therapy (PT). We report the outcome of children, adolescents and young adults (AYA) treated with PT at the Paul Scherrer Institute. MATERIALS Thirty-eight patients (median age, 9.9 years) received a median dose of 54.9 Gy(RBE) (where RBE is relative biologic effectiveness). Size of the tumor ranged from 1.7 to 24 cm. Most common primary site was axial/pelvic (n = 27; 71%). Four patients (11%) presented with metastases at diagnosis. Twenty (53%) patients had chemo-PT only. Median follow-up was 49.6 months (range, 9.2-131.7). RESULTS The 5-year actuarial rate of local control (LC), distant metastasis-free survival (DMFS), and overall survival (OS) were 81.5%, 76.4%, and 83.0%, respectively. All local recurrences occurred in field and in patients with nonextremity primaries. Six patients died, all of tumor progression. Age < 10 years was a favorable factor of borderline significance for LC (P = 0.05) and OS (P = 0.05), but was significant for DMFS (P = 0.003). Tumor volume <200 ml was a significant prognostic factors for DMFS (P = 0.03), but not for OS (P = 0.07). Metastasis at diagnosis was a strong predictor of local failure (P = 0.003). Only two grade 3 late toxicities were observed. The 5-year actuarial rate of grade 3 toxicity-free survival was 90.9%. CONCLUSIONS These preliminary data suggest that the outcomes of children and AYA with EWS are good and PT was well tolerated with few late adverse events. The local and distant tumor control for older patients with large pre-PT tumor volumes remains problematic.
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Belosi MF, van der Meer R, Garcia de Acilu Laa P, Bolsi A, Weber DC, Lomax AJ. Treatment log files as a tool to identify treatment plan sensitivity to inaccuracies in scanned proton beam delivery. Radiother Oncol 2017; 125:514-519. [PMID: 29054379 DOI: 10.1016/j.radonc.2017.09.037] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 09/26/2017] [Accepted: 09/27/2017] [Indexed: 10/18/2022]
Abstract
Dose distributions delivered at Gantry 2 at the Paul Scherrer Institut (PSI) can be reconstructed on the patient anatomy based on machine log files. With the present work, the dependency of the log file calculation on the planning optimization technique and on other planning parameters, such as field direction and tumour size, has been investigated. Interestingly, and despite the typically higher modulation of Intensity Modulated Proton Therapy (IMPT) plans, the results for both Single Field Uniform Distribution and IMPT approaches have been found to be similar. In addition, complex fields with steep in-field dose gradients, such as Simultaneous Integrated Boost, and with couch movements in between the delivery, also resulted in good agreement between planned and reconstructed doses. Nevertheless, highly modulated plans can have regions of larger local dose deviations and attention should therefore be paid during the planning stage to the location of isolated, highly weighted pencil beams. We propose also, that further effort should be invested in order to predict field robustness to delivery fluctuations before the clinical delivery of the plan as part of the plan specific Quality Assurance.
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Murray FR, Snider JW, Bolsi A, Lomax AJ, Walser M, Kliebsch U, Schneider RA, Weber DC. Long-Term Clinical Outcomes of Pencil Beam Scanning Proton Therapy for Benign and Non-benign Intracranial Meningiomas. Int J Radiat Oncol Biol Phys 2017; 99:1190-1198. [PMID: 28939227 DOI: 10.1016/j.ijrobp.2017.08.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 07/24/2017] [Accepted: 08/04/2017] [Indexed: 10/19/2022]
Abstract
PURPOSE To assess and report long-term clinical outcomes regarding local control, overall survival, and toxicity-free survival after pencil beam scanning proton therapy for intracranial meningiomas at a single institution. PATIENTS AND METHODS Ninety-six patients (male/female, 29/67; median age 52.8 years) with intracranial meningiomas (World Health Organization [WHO] grade 1, n=61 [63.5%]; WHO grade 2, n=33 [34.4%]; WHO grade 3, n=2 [2.1%]) were treated with pencil beam scanning proton therapy (n=53 [55.2%] at diagnosis, n=17 [17.7%] at recurrence, and n=26 [27.1%] for tumor progression). Median gross tumor volume before PBSPT was 21.4 cm3 (range, 0.0-546.5 cm3), with a median planning target volume of 123.4 cm3 (range, 4.6-1142.0 cm3). Median duration of follow-up was 56.9 months (range, 12.1-207.2 months). Late toxicity was graded according to the Common Terminology Criteria for Adverse Events, version 4.0. RESULTS Thirteen failures (14%) (male/female, 6/7) were observed, of which the majority (n=9, 69%) were of non-benign histology. The 5-year actuarial local control and overall survival were 86.4% and 88.2%, respectively. Five-year grade ≥3 toxicity-free survival was 89.1%. On univariate analysis, local control was worse for patients with higher WHO grade (P≤.001), those treated after at least 1 recurrence (P=.006), those with non-skull base tumor location (P=.014), and males (P=.032). Significant prognosticators for 5-year overall survival were local control (P≤.001), age (P=.002), and timing of proton therapy (initial vs recurrence) (P=.002). CONCLUSIONS Pencil beam scanning proton therapy is an effective and safe treatment for patients with intracranial meningiomas, resulting in high local control rates with limited toxicity. Up-front radiation likely results in improved outcomes and should be considered, especially for patients with non-benign tumors and/or for those with incomplete resections.
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Weber DC, Abrunhosa-Branquinho A, Bolsi A, Kacperek A, Dendale R, Geismar D, Bachtiary B, Hall A, Heufelder J, Herfarth K, Debus J, Amichetti M, Krause M, Orecchia R, Vondracek V, Thariat J, Kajdrowicz T, Nilsson K, Grau C. Profile of European proton and carbon ion therapy centers assessed by the EORTC facility questionnaire. Radiother Oncol 2017; 124:185-189. [DOI: 10.1016/j.radonc.2017.07.012] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 07/12/2017] [Accepted: 07/13/2017] [Indexed: 11/28/2022]
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Badiyan SN, Ulmer S, Ahlhelm FJ, Fredh ASM, Kliebsch U, Calaminus G, Bolsi A, Albertini F, Leiser D, Timmermann B, Malyapa RS, Schneider R, Lomax AJ, Weber DC. Clinical and Radiologic Outcomes in Adults and Children Treated with Pencil-Beam Scanning Proton Therapy for Low-Grade Glioma. Int J Part Ther 2017; 3:450-460. [PMID: 31772995 PMCID: PMC6871558 DOI: 10.14338/ijpt-16-00031.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2016] [Accepted: 03/29/2017] [Indexed: 09/21/2023] Open
Abstract
PURPOSE We assessed clinical and radiologic outcomes in adults and children with low-grade glioma (LGG) of the brain treated with pencil-beam scanning (PBS) proton therapy (PT). MATERIALS AND METHODS Between 1997 and 2014, 28 patients were treated with PBS PT, 20 (71%) of whom were younger than 18 years. Median age at start of PT was 12.3 years (range, 2.2-53.0 years). Nine patients (32%) underwent at least a subtotal resection; 12 (43%) underwent biopsy; and 7 (25%) were diagnosed radiographically. Twelve patients (43%) had grade II and 9 (32%) had grade I gliomas. Eleven patients (39%) received chemotherapy before PT. A median dose of 54 Gy (relative biologic effectiveness) was administered. Radiologic response to PT was determined using the Response Evaluation Criteria in Solid Tumors (RECIST). Eight domains of quality of life (QoL) for 16 pediatric patients were assessed prospectively by patients' parents using the pediatric QoL proxy questionnaire. Progression-free survival and overall survival (OS) were estimated by the Kaplan-Meier method. Median follow-up was 42.1 months for living patients. RESULTS Ten patients (36%) developed local, clinical failure. Three patients (11%) died, all of tumor progression. Radiographic tumor response by RECIST was evaluable in 11 patients: 9 (82%) with stable disease, 1 (9%) with partial response, and 1 (9%) with complete response to PT. Three-year OS and progression-free survival were 83.4% and 56.0%, respectively. No ≥ grade III acute toxicities were observed. Grade III, late radiation necrosis developed in 1 patient (4%). No appreciable change in pediatric QoL proxy scores in children was noted in any of the 8 domains at any time point. CONCLUSION Treatment with PBS PT is effective for LGG, with minimal acute toxicity and, in children, no appreciable decline in QoL. More patients and longer follow-up are needed to determine the long-term efficacy and toxicity of PT for LGG.
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Belloni S, Peroni M, Safai S, Fattori G, Perrin R, Walser M, Niemann T, Kubik-Huch R, Lomax A, Weber D, Bolsi A. EP-1674: Experimental investigation of CT imaging approaches to deal with metal artefacts in proton therapy. Radiother Oncol 2017. [DOI: 10.1016/s0167-8140(17)32206-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Bojaxhiu B, Ahlhelm F, Walser M, Placidi L, Kliebsch U, Mikroutsikos L, Morach P, Bolsi A, Lomax T, Schneider R, Weber D. OC-0515: Radiation necrosis in children with brain tumours treated with pencil beam scanning proton therapy. Radiother Oncol 2017. [DOI: 10.1016/s0167-8140(17)30955-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Belosi M, Van der Meer R, Garcia de Acilu Laa P, Bolsi A, Weber D, Lomax A. OC-0230: Treatment log files as a tool to identify inaccuracies in scanned proton beam delivery and planning. Radiother Oncol 2017. [DOI: 10.1016/s0167-8140(17)30673-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Kountouri M, Walser M, Schneider R, Bolsi A, Lomax A, Weber D. PV-0049: Recurrent skull base and extra-cranial chordoma following proton therapy: clinical outcomes. Radiother Oncol 2017. [DOI: 10.1016/s0167-8140(17)30493-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Trnková P, Bolsi A, Albertini F, Weber DC, Lomax AJ. Factors influencing the performance of patient specific quality assurance for pencil beam scanning IMPT fields. Med Phys 2017; 43:5998. [PMID: 27806620 DOI: 10.1118/1.4964449] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE A detailed analysis of 2728 intensity modulated proton therapy (IMPT) fields that were clinically delivered to patients between 2007 and 2013 at Paul Scherrer Institute (PSI) was performed. The aim of this study was to analyze the results of patient specific dosimetric verifications and to assess possible correlation between the quality assurance (QA) results and specific field metrics. METHODS Dosimetric verifications were performed for every IMPT field prior to patient treatment. For every field, a steering file was generated containing all the treatment unit information necessary for treatment delivery: beam energy, beam angle, dose, size of air gap, nuclear interaction (NI) correction factor, number of range shifter plates, number of Bragg peaks (BPs) with their position and weight. This information was extracted and correlated to the results of dosimetric verification of each field which was a measurement of two orthogonal profiles using an orthogonal ionization chamber array in a movable water column. RESULTS The data analysis has shown more than 94% of all verified plans were within defined clinical tolerances. The differences between measured and calculated dose depend critically on the number of BPs, total thickness of all range shifter plates inserted in the beam path, and maximal range. An increase of the dose difference was observed with smaller number of BPs (i.e., smaller tumor) and smaller ranges (i.e., superficial tumors). The results of the verification do not depend, however, on the prescribed dose, NI correction, or the size of the air gap. There is no dependency of the transversal and longitudinal spot position precision on the beam angle. The value of NI correction depends on the number of spots and number of range shifter plates. CONCLUSIONS The presented study has shown that the verification method used at Centre for Proton Therapy at Paul Scherrer Institute is accurate and reproducible for performing patient specific QA. The results confirmed that the dose discrepancy is dependent on the size and location of the tumor.
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Placidi L, Bolsi A, Lomax AJ, Schneider RA, Malyapa R, Weber DC, Albertini F. Effect of Anatomic Changes on Pencil Beam Scanned Proton Dose Distributions for Cranial and Extracranial Tumors. Int J Radiat Oncol Biol Phys 2017; 97:616-623. [DOI: 10.1016/j.ijrobp.2016.11.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 10/31/2016] [Accepted: 11/08/2016] [Indexed: 10/20/2022]
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