In vivo verification of radiation dose delivered to healthy tissue during radiotherapy for breast cancer

17th International Conference on the Use of Computers in Radiation Therapy

物理学;计算机科学

Lonski, P.^1,2 ; Taylor, M.L.^2 ; Hackworth, W.^1 ; Phipps, A.^3 ; Franich, R.D.^2 ; Kron, T.^1,2

Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Australia^1

School of Applied Sciences, RMIT University, Melbourne, Australia^2

Radiation Therapy, Peter MacCallum Cancer Centre, East Melbourne, Australia^3

关键词: Anisotropic analytical algorithms;    Breast Cancer;    Calculation results;    Different treatments;    Healthy tissues;    LiF:Mg ,Cu ,P;    Thermoluminescent dosimeters;    Treatment planning systems;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/489/1/012015/pdf
DOI  :  10.1088/1742-6596/489/1/012015

学科分类：计算机科学（综合）

来源: IOP

【 摘 要 】

Different treatment planning system (TPS) algorithms calculate radiation dose in different ways. This work compares measurements made in vivo to the dose calculated at out-of-field locations using three different commercially available algorithms in the Eclipse treatment planning system. LiF: Mg, Cu, P thermoluminescent dosimeter (TLD) chips were placed with 1 cm build-up at six locations on the contralateral side of 5 patients undergoing radiotherapy for breast cancer. TLD readings were compared to calculations of Pencil Beam Convolution (PBC), Anisotropic Analytical Algorithm (AAA) and Acuros XB (XB). AAA predicted zero dose at points beyond 16 cm from the field edge. In the same region PBC returned an unrealistically constant result independent of distance and XB showed good agreement to measured data although consistently underestimated by ∼0.1 % of the prescription dose. At points closer to the field edge XB was the superior algorithm, exhibiting agreement with TLD results to within 15 % of measured dose. Both AAA and PBC showed mixed agreement, with overall discrepancies considerably greater than XB. While XB is certainly the preferable algorithm, it should be noted that TPS algorithms in general are not designed to calculate dose at peripheral locations and calculation results in such regions should be treated with caution.