Assessment of the dose distribution of Minibeam radiotherapy for lung tumors in an anthropomorphic phantom: A feasibility study.

Background: Microbeam radiotherapy (MRT) is a treatment in which radiation field is divided into several separate fields of 10-100 μm width and 100-400 μm spacing. In this treatment, normal tissue can tolerate high doses that are delivered to its small volumes.

Objective: MCNPX 2.4 Monte Carlo code was used to calculate the dose distribution of MRT in a lung tumor in a simulated Rando phantom.

Methods: The effects of tissue inhomogeneities, using contrast media and changing the number of beams were investigated. Dose volume histograms and beam profiles of target and organs at risk were assessed and the dose uniformity in the target region was evaluated using homogeneity. The conformity indices also used to quantify the conformation of the shape of prescribed isodose volume to the shape and size of the target.

Results: Tissue inhomogeneity of this region did not interfere significantly with target dose homogeneity. The use of contrast media or increasing the number of beams improved target dose homogeneity and decreased the dose to surrounding tissues.

Conclusions: The results suggest that further investigation and evaluation of MRT for treatment of chest tumors is worthwhile.