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1.Particle Therapy Co-Operative Group, “Particle therapy facilities in operation: Information about technical equipment and patient statistics” (2014), pages retrieved from
2.A. J. Lomax, T. Bohringer, A. Bolsi, D. Coray, F. Emert, G. Goitein, M. Jermann, S. Lin, E. Pedroni, H. Rutz, O. Stadelmann, B. Timmermann, J. Verwey, and D. C. Weber, “Treatment planning and verification of proton therapy using spot scanning: Initial experiences,” Med. Phys. 31, 31503157 (2004).
3.M. T. Gillin, N. Sahoo, M. Bues, G. Ciangaru, G. Sawakuchi, F. Poenisch, B. Arjomandy, C. Martin, U. Titt, K. Suzuki, A. R. Smith, and X. R. Zhu, “Commissioning of the discrete spot scanning proton beam delivery system at the University of Texas MD Anderson Cancer Center, Proton Therapy Center, Houston,” Med. Phys. 37, 154163 (2010).
4.J. B. Farr, F. Dessy, O. De Wilde, O. Bietzer, and D. Schonenberg, “Fundamental radiological and geometric performance of two types of proton beam modulated discrete scanning systems,” Med. Phys. 40, 072101(8pp.) (2013).
5.S. Both, J. Shen, M. Kirk, L. Lin, S. Tang, M. Alonso-Basanta, R. Lustig, H. Lin, C. Deville, C. Hill-Kayser, Z. Tochner, and J. McDonough, “Development and clinical implementation of a universal bolus to maintain spot size during delivery of base of skull pencil beam scanning proton therapy,” Int. J. Radiat. Oncol., Biol., Phys. 90, 7984 (2014).
6.E. Pedroni, S. Scheib, T. Bohringer, A. Coray, M. Grossmann, S. Lin, and A. Lomax, “Experimental characterization and physical modelling of the dose distribution of scanned proton pencil beams,” Phys. Med. Biol. 50, 541561 (2005).
7.B. Schaffner, “Proton dose calculation based on in-air fluence measurements,” Phys. Med. Biol. 53, 15451562 (2008).
8.H. Lin, X. Ding, M. Kirk, H. Liu, H. Zhai, C. E. Hill-Kayser, R. A. Lustig, Z. Tochner, S. Both, and J. McDonough, “Supine craniospinal irradiation using a proton pencil beam scanning technique without match line changes for field junctions,” Int. J. Radiat. Oncol., Biol., Phys. 90, 7178 (2014).
9.H. Palmans, J. E. Symons, J. M. Denis, E. A. de Kock, D. T. Jones, and S. Vynckier, “Fluence correction factors in plastic phantoms for clinical proton beams,” Phys. Med. Biol. 47, 30553071 (2002).
10.U. Schneider, P. Pemler, J. Besserer, M. Dellert, M. Moosburger, J. de Boer, E. Pedroni, and T. Boehringer, “The water equivalence of solid materials used for dosimetry with small proton beams,” Med. Phys. 29, 29462951 (2002).
11.A. Luhr, D. C. Hansen, N. Sobolevsky, H. Palmans, S. Rossomme, and N. Bassler, “Fluence correction factors and stopping power ratios for clinical ion beams,” Acta Oncol. 50, 797805 (2011).
12.L. Al-Sulaiti, D. Shipley, R. Thomas, P. Owen, A. Kacperek, P. H. Regan, and H. Palmans, “Water equivalence of some plastic-water phantom materials for clinical proton beam dosimetry,” Appl. Radiat. Isot. 70, 10521057 (2012).
13.N. Kanematsu, Y. Koba, and R. Ogata, “Evaluation of plastic materials for range shifting, range compensation, and solid-phantom dosimetry in carbon-ion radiotherapy,” Med. Phys. 40, 041724 (6pp.) (2013).
14.B. Gottschalk, A. M. Koehler, R. J. Schneider, J. M. Sisterson, and M. S. Wagner, “Multiple coulomb scattering of 160 Mev protons,” Nucl. Instrum. Methods Phys. Res., Sect. B 74, 467490 (1993).
15.N. Kanematsu, “Alternative scattering power for gaussian beam model of heavy charged particles,” Nucl. Instrum. Methods Phys. Res., Sect. B 266, 50565062 (2008).
16.B. Gottschalk, “On the scattering power of radiotherapy protons,” Med. Phys. 37, 352367 (2010).
17.L. Hong, M. Goitein, M. Bucciolini, R. Comiskey, B. Gottschalk, S. Rosenthal, C. Serago, and M. Urie, “A pencil beam algorithm for proton dose calculations,” Phys. Med. Biol. 41, 13051330 (1996).
18.B. Schaffner, E. Pedroni, and A. Lomax, “Dose calculation models for proton treatment planning using a dynamic beam delivery system: An attempt to include density heterogeneity effects in the analytical dose calculation,” Phys. Med. Biol. 44, 2741 (1999).
19.M. J. Berger et al., “Stopping Power and Ranges for Protons and Alpha Particles,” International Commission on Radiation Units and Measurement (ICRU), Report No. 49 (1993).
20.G. O. Sawakuchi, U. Titt, D. Mirkovic, G. Ciangaru, X. R. Zhu, N. Sahoo, M. T. Gillin, and R. Mohan, “Monte Carlo investigation of the low-dose envelope from scanned proton pencil beams,” Phys. Med. Biol. 55, 711721 (2010).
21.G. O. Sawakuchi, X. R. Zhu, F. Poenisch, K. Suzuki, G. Ciangaru, U. Titt, A. Anand, R. Mohan, M. T. Gillin, and N. Sahoo, “Experimental characterization of the low-dose envelope of spot scanning proton beams,” Phys. Med. Biol. 55, 34673478 (2010).

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To quantitatively investigate the effect of range shifter materials on single-spot characteristics of a proton pencil beam.

An analytic approximation for multiple Coulomb scattering (“differential Moliere” formula) was adopted to calculate spot sizes of proton spot scanning beams impinging on a range shifter. The calculations cover a range of delivery parameters: six range shifter materials (acrylonitrile butadiene styrene, Lexan, Lucite, polyethylene, polystyrene, and wax) and water as reference material, proton beam energies ranging from 75 to 200 MeV, range shifter thicknesses of 4.5 and 7.0 g/cm2, and range shifter positions from 5 to 50 cm. The analytic method was validated by comparing calculation results with the measurements reported in the literature.

Relative to a water-equivalent reference, the spot size distal to a wax or polyethylene range shifter is 15% smaller, while the spot size distal to a range shifter made of Lexan or Lucite is about 6% smaller. The relative spot size variations are nearly independent of beam energy and range shifter thickness and decrease with smaller air gaps.

Among the six material investigated, wax and polyethylene are desirable range shifter materials when the spot size is kept small. Lexan and Lucite are the desirable range shifter materials when the scattering power is kept similar to water.


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