Influence of target dose heterogeneity on dose sparing of normal tissue in peripheral lung tumor stereotactic body radiation therapy

Radiation Oncology

Zheran Liu¹  Ruidan Li¹  Ling He¹  Zhigong Wei¹  Xiaoli Mu¹  Xingchen Peng¹  Lianlian Yang¹  Jingjing Wang¹  Jianghong Xiao²  Yan Wang³ 

[1] Department of Biotherapy, Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan, China;Department of Radiation Oncology, Cancer Center, West China Hospital, Sichuan University, No.37 Guoxue Alley, Wuhou District, 610041, Chengdu, Sichuan, China;School of Computer Science, Sichuan University, 610000, Chengdu, China;

关键词: Dose heterogeneity;    Dose sparing;    Stereotactic body radiation therapy;    Volumetric-modulated arc therapy;   

DOI  :  10.1186/s13014-021-01891-6

来源: Springer

【 摘 要 】

ObjectiveTo evaluate the influence of target dose heterogeneity on normal tissue dose sparing for peripheral lung tumor stereotactic body radiation therapy (SBRT).MethodsBased on the volumetric-modulated arc therapy (VMAT) technique, three SBRT plans with homogeneous, moderate heterogeneous, and heterogeneous (HO, MHE, and HE) target doses were compared in 30 peripheral lung tumor patients. The prescription dose was 48 Gy in 4 fractions. Ten rings outside the PTV were created to limit normal tissue dosage and evaluate dose falloff.ResultsWhen MHE and HE plans were compared to HO plans, the conformity index of the PTV was increased by approximately 0.08. The median mean lung dose (MLD), V5, V10, V20 of whole lung, D2%, D1cc, D2cc of the rib, V30 of the rib, D2% and the maximum dose (Dmax) of the skin, and D2% and Dmax of most mediastinal organs at risk (OARs) and spinal cord were reduced by up to 4.51 Gy or 2.8%. Analogously, the median Dmax, D2% and mean dose of rings were reduced by 0.71 to 8.46 Gy; and the median R50% and D2cm were reduced by 2.1 to 2.3 and 7.4% to 8.0%, respectively. Between MHE and HE plans there was little to no difference in OARs dose and dose falloff beyond the target. Furthermore, the dose sparing of rib V30 and the mean dose of rings were negatively correlated with the rib and rings distance from tumor, respectively.ConclusionsFor peripheral lung tumor SBRT, target conformity, normal tissue dose, and dose falloff around the target could be improved by loosening or abandoning homogeneity. While there was negligible further dose benefit for the maximum target dose above 125% of the prescription, dose sparing of normal tissue derived from a heterogeneous target decreased as the distance from the tumor increased.

【 授权许可】

CC BY