Feasibility of simultaneous integrated boost with forward intensity-modulated radiation therapy for multiple brain metastases

Abstract

Aim of the study: To evaluate the feasibility of whole-brain radiotherapy (WBRT) with a simultaneous integrated boost (SIB) by forward intensity-modulated radiation therapy (IMRT) in patients with 1-3 brain metastases. Material and methods: Two forward IMRT plans were implemented among 18 patients. In plan A, the prescribed dose was 30 Gy to the whole brain (PTVWBRT) and 50 Gy to individual brain metastases (PTVboost) delivered simultaneously in 10 fractions. In plan B, the prescribed dose was 30 Gy to the PTVWBRT and 40 Gy to the PTVboost. Plans were evaluated with regard to conformation number (CN), prescription isodose volume to target volume ratio (PITV), target coverage (TC), homogeneity index (HI), and the volume receiving at least 95% of the prescribed dose (V95). Plan A was implemented for 5 of these patients, and plan B was used for the remaining patients. Results: The mean values of CN, PITV, TC, and HI for the PTVboost were 0.71, 1.32, 0.97, and 0.07, respectively, for plan A and 0.65, 1.47, 0.97, and 0.05, respectively, for plan B. The mean values of TC, HI, and V95 for the PTVWBRT were 0.98, 0.45, and 99.71%, respectively, for plan A and 0.97, 0.27, and 99.61%, respectively, for plan B. All patients completed the planned radiotherapy (RT) schedule with no acute and late RT-related toxicity greater than grade 2. Conclusions: It is feasible to deliver WBRT with a SIB via forward IMRT for patients with 1-3 brain metastases with good dose conformity and acceptable toxicity.