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

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 (PTV_WNRT) and 50 Gy to individual brain metastases (PTV_boost) delivered simultaneously in 10 fractions. In plan B, the prescribed dose was 30 Gy to the PTV_WNRT and 40 Gy to the PTV_boost. 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 PTV_boost 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 PTV_WNRT 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.