Dosimetric study of particle radiotherapy for glioma patients / 中华放射肿瘤学杂志

ABSTRACT

Objective:To investigate the dosimetric difference between glioma patients treated by particle (proton+ carbon ion) and photon radiotherapy.Methods:Twelve previously-treated glioma patients were selected, and given with the same total dose of 60.00 Gy [RBE]. Two types of planning target volumes (PTVs) including PTV-ion and PTV-photon were expended from clinical target volumes according to range uncertainty and patient setup errors. Based on PTV-ion, proton plans with sequential carbon ion boost (particle plan) were created. Following the same prescription, two types of photon intensity-modulated radiotherapy (IMRT) plans were established to achieve similar target coverage and compare the dose of organs at risk.Results:Target coverages of three types of plans had no statistical difference (all P>0.05). The median integral dose of normal brain of all patients receiving particle plan was merely 44.90% of the minimum number from photon plans ( P<0.001). Compared with the minimum number from photon plans, particle radiotherapy decreased the mean dose of brain stem[(6.83±6.22) Gy[RBE] vs. (15.10±10.11) Gy[RBE], P=0.001)], the maximum dose of chiasm[(47.76±20.80) Gy[RBE] vs. (49.59±20.52) Gy[RBE], P=0.009)] and the mean dose of contralateral hippocampus (0.26±9.08) Gy[RBE] vs. (16.28±11.14) Gy[RBE], P=0.002), respectively. Conclusions:Particle radiotherapy can achieve similar target coverage while maintaining lower normal tissue doses to the photon radiotherapy. Photon planion can increase the doses to adjuvant normal tissues.