ESTRO meets Asia 2024 - Abstract Book

S325

Physics – Motion management and adaptive radiotherapy

ESTRO meets Asia 2024

Keywords: IMRT, Head and neck,CBCT

References:

1.J. Wang et al., ‘The clinical feasibility and effect of online cone beam computer tomography-guided intensity modulated radiotherapy for nasopharyngeal cancer’, Radiotherapy and Oncology, vol. 90, no. 2, pp. 221–227, Feb. 2009, doi: 10.1016/j.radonc.2008.08.017. 2.M. van Herk, ‘Errors and margins in radiotherapy’, Seminars in Radiation Oncology, vol. 14, no. 1, pp. 52–64, Jan. 2004, doi: 10.1053/j.semradonc.2003.10.003. 3.J. C. Stroom and B. J. M. Heijmen, ‘Geometrical uncertainties, radiotherapy planning margins, and the ICRU-62 report’, Radiotherapy and Oncology, vol. 64, no. 1, pp. 75–83, Jul. 2002, doi: 10.1016/S0167-8140(02)00140-8.

149

Proffered Paper

Monte Carlo calculation of total skin electron therapy dose using whole-body photogrammetry models

Scott B Crowe 1,2,3 , Naasiha Cassim 1 , Jenna Luscombe 1 , Katie McMahon 4,5 , Tanya Kairn 1,2,3

1 Cancer Care Services, Royal Brisbane & Women's Hospital, Brisbane, Australia. 2 School of Electrical Engineering & Computer Science, University of Queensland, Brisbane, Australia. 3 School of Chemistry & Physics, Queensland University of Technology, Brisbane, Australia. 4 Herston Imaging Research Facility, Royal Brisbane & Women's Hospital, Brisbane, Australia. 5 School of Clinical Sciences, Queensland University of Technology, Brisbane, Australia

Purpose/Objective:

Total skin electron therapy (TSET) is a treatment modality employed in the management of mycosis fungoides. It involves the delivery of large megavoltage electron fields at an extended source-to-surface distance, to produce a homogeneous whole-body skin dose. These treatments are manually planned based on a prescribed dose at a calibration point, and delivered using an arrangement of beams and patient positions that are validated through phantom measurements performed at technique commissioning. Accurate dose calculations are prevented by the lack of whole-body CT images of patients in treatment positions, and support for the treatment geometry within planning systems. This study developed a Monte Carlo (MC) dose calculation technique using synthetic CT images derived from whole-body photogrammetry models of healthy volunteers.

Material/Methods:

A dose calculation model was developed using the BEAMnrc and DOSXYZnrc MC codes, using Varian-supplied 6E phase space files for a TrueBeam linear accelerator. The simulation geometry featured paired beams at two gantry rotations (90±16.9°), a 6 mm PMMA spoiler at 2.5 m from isocentre, and a 20 cm base upon which patients stand for treatment, as shown in Figure 1.