ESTRO meets Asia 2024 - Abstract Book

S327

Physics – Motion management and adaptive radiotherapy

ESTRO meets Asia 2024

The dose calculation system could be used to predict regions of high and low dose on a patient-specific basis, and has the potential to be used compare different TSET treatment techniques, such as rotational TSET and the Stanford method. The 3D models produced using photogrammetry can be rigged, allowing adjustment of poses to allow simulation of other techniques or positioning errors. Further registration work is required to allow automatic calculation of dose across non-mirrored treatment positions. Whole body imaging may have additional utility in monitoring treatment response or progression, through body surface area calculations.

Keywords: total skin electron therapy, Monte Carlo

References:

[1] Nevelsky A, Borzov E, Daniel S, Bar-Deroma R (2017) Room scatter effects in Total Skin Electron Irradiation: Monte Carlo simulation study. J Appl Clin Med Phys 18 (1): 196-201. https://doi.org/10.1002/acm2.12039

[2] Karzmark CJ, Anderson J, Buffa A, et al. (1987) Report No. 023 – Total Skin Electron Therapy: Technique and Dosimetry. American Association of Physicists in Medicine, New York, USA. https://doi.org/10.37206/22

[3] Kairn T, Wilks R, Yu L, Lancaster C, Crowe SB (2020) In vivo monitoring of total skin electron dose using optically stimulated luminescence dosimeter. Rep Pract Oncol Radiother 25 (1): 35-40. https://doi.org/10.1016/j.rpor.2019.12.011

202

Proffered Paper

Strategy to tackle uncertainty in breast VMAT: Robust optimization vs. Virtual bolus

Jeffrey C.F. Lui, Alex P.Y. Cheung, Francis K.H. Lee

Department of Clinical Oncology, Queen Elizabeth Hospital, Hong Kong, Hong Kong

Purpose/Objective:

Target swelling and setup uncertainties in breast are known to compromise spatial accuracy in the delivery of radiotherapy, potentially leading to severe underdosing of the target. This study aimed to compare robust optimization and virtual bolus method for breast VMAT treatment planning, to address anatomical and geometrical uncertainties.

Material/Methods:

A total of 6 patients with left breast tumors were retrospectively selected from those who underwent VMAT treatment at Queen Elizabeth Hospital, Hong Kong. The target and OARs were delineated according to relevant published guideline [1] and reviewed by experienced oncologists. The prescribed dose to the PTV was 40.05 Gy delivered in 15 fractions. Three VMAT plans were created for each patient, which included a non-robust plan optimized using a conventional treatment planning approach (NR), a plan utilizing robust optimization (RO), and a plan employing the virtual bolus method (VB). Both the NR and RO plans were created using RayStation (RayStation R12A, RaySearch Laboratories, Sweden), while the VB plans were created using Eclipse (Eclipse 16.1, Varian Medical Systems, USA) to align with