A planning study of simultaneous integrated boost with forward IMRT for multiple brain metastases

The objective of this study was to evaluate the dose conformity and feasibility of whole-brain radiotherapy with a simultaneous integrated boost by forward intensity-modulated radiation therapy in patients with 1 to 3 brain metastases. Forward intensity-modulated radiation therapy plans were generated for 10 patients with 1 to 3 brain metastases on Pinnacle 6.2 Treatment Planning System. The prescribed dose was 30 Gy to the whole brain (planning target volume [PTV]_wbrt) and 40 Gy to individual brain metastases (PTV_boost) simultaneously, and both doses were given in 10 fractions. The maximum diameters of individual brain metastases ranged from 1.6 to 6 cm, and the summated PTVs per patient ranged from 1.62 to 69.81 cm³. Conformity and feasibility were evaluated regarding conformation number and treatment delivery time. One hundred percent volume of the PTV_boost received at least 95% of the prescribed dose in all cases. The maximum doses were less than 110% of the prescribed dose to the PTV_boost, and all of the hot spots were within the PTV_boost. The volume of the PTV_wbrt that received at least 95% of the prescribed dose ranged from 99.2% to 100%. The mean values of conformation number were 0.682. The mean treatment delivery time was 2.79 minutes. Ten beams were used on an average in these plans. Whole-brain radiotherapy with a simultaneous integrated boost by forward intensity-modulated radiation therapy in 1 to 3 brain metastases is feasible, and treatment delivery time is short.