AbstractObjective To explore the beam performance of GTR 360° PBS dedicated nozzle for IBA Proteus Plus proton system and evaluate the beam characteristics of PBS during acceptance test procedure (ATP) to meet the precision and safety requirements of clinical treatment. Methods According to the requirements of acceptance tests, the beam tests of PBS mainly included:test of integrated depth dose (IDD), test of maximum field size at the maximum and minimum ranges, field uniformity and informative PBS tests for the GTR 360°, test of lateral dose uniformity in a single field uniform dose in a cube, test of longitudinal dose uniformity in a single field uniform dose in a cube, and test of monitor unit reproducibility and proportionality. Results The maximum deviation measured of range, fall back accuracy and distal fall-off was 0.03g/m2, 0.01g/m2 and 0.078g/m2, respectively. Maximum field size at the maximum and minimum ranges was 30.2cm×40.2 cm and 30.1cm×40.1 cm, respectively. During the different gantry angles and ranges, the lowest γ passing rate of a pattern plan was 97%, the maximum deviation of the centrical beam spot size at the X and Y axes was -0.16 mm and -0.21 mm, and the worst symmetry was 0.80%. Compared with the centrical beam spot, the maximum size deviation of the other beam spots was 0.11 mm and 0.14 mm at the X and Y axes, and the maximum position accuracy deviation of the beam spot was 0.60 mm and 0.43 mm at the X and Y axes. The maximum deviation of lateral dose uniformity at at the X and Y axes was 0.55% and 0.80% in the high energy region, and 0.6% and 0.75% in the low energy region. The maximum deviation of longitudinal dose uniformity was 0.79% in the high energy region, and 2.22% in the low energy region. The monitor unit (MU) reproducibility factor was 0.106% and the maximum proportionality deviation was 0.67%. Conclusion The dedicated nozzle of PBS has passed all the beam performance acceptance tests, which meet the requirements of all parameters, and the whole system yields relatively high accuracy, repeatability and good stability.
Yang Tao,Qu Baolin,Xu Shouping et al. Acceptance tests of beam performance for pencil beam scanning (PBS) proton system of IBA[J]. Chinese Journal of Radiation Oncology, 2020, 29(12): 1075-1079.
Yang Tao,Qu Baolin,Xu Shouping et al. Acceptance tests of beam performance for pencil beam scanning (PBS) proton system of IBA[J]. Chinese Journal of Radiation Oncology, 2020, 29(12): 1075-1079.
[1] Knopf AC, Stützer K, Richter C, et al. Required transition from research to clinical application:reporton the 4D treatment planning workshops 2014 and 2015[J]. Phys Med, 2016, 32(7):874-882. DOI:10.1016/j.ejmp.2016.05.064.
[2] De Ruysscher D, Sterpin E, Haustermans K, et al. Tumour movement in proton therapy:solutions and remaining questions:a review[J]. Cancers (Basel), 2015, 7(3):1143-1153. DOI:10.3390/cancers7030829.
[3] Jäkel O, Karger CP, Debus J. The future of heavy ion radiotherapy[J]. Med Phys, 2008, 35(12):5653. DOI:10.1118/1.3002307.
[4] Mohan R, Bortfeld T. Proton therapy:clinical gains through current andfuture treatment programs[J]. Front Radiat Ther Oncol, 2011, 43:440-464. DOI:10.1159/000322509.
[5] Arduini G, Cambria R, Canzi C, et al. Physical specifications of clinical proton beams from a synchrotron[J]. Med Phys, 1996, 23(6):939. DOI:10.1118/1.597735.
[6] Farr JB, Dessy F, De Wilde O, et al. Fundamental radiological and geometric performance of two types of proton beam modulated discrete scanning systems[J]. Med Phys, 2013, 40(7):072101. DOI:10.1118/1.4807643.
[7] Pidikiti R, Patel BC, Maynard M R, et al. Commissioning of the world's first compact pencil-beam scanning proton therapy system[J]. J Appl Clin Med Phys, 2018, 19(1):94-105. DOI:10.1002/acm2.12225.
[8] Farr JB, Moskvin V, Lukose RC, et al. Development, commissioning, and evaluation of a new intensity modulated minibeam proton therapy system[J]. Med Phys, 2018, 45(9):4227-4237. DOI:10.1002/mp.13093.
[9] Pedroni E, Scheib S, Böhringer T, et al. Experimental characterization and physical modelling of the dose distribution of scanned proton pencil beams[J]. Phys Med Biol, 2005, 50(3):541-561. DOI:10.1088/0031-9155/50/3/011.
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