Technology for bolus verification in proton therapy

Abstract

To ensure the conformal depth-dose distribution of a proton beam within a target volume, complex shaped range shifters (so-called boluses), which account for the heterogeneous structure of patient tissue and organs in the beam path, were calculated and manufactured. The precise manufacturing of proton compensators used for patient treatment is a vital step in quality assurance in proton therapy. In this work a software-hardware complex that verifies the quality and precision of bolus manufacturing at the Medico-Technical Complex (MTC) was developed. The boluses consisted of a positioning system with two photoelectric biosensors. We evaluated 20 boluses used in proton therapy of five patients. A total number of 2562 experimental points were measured, of which only two points had values that differed from the calculated value by more than 0.5 mm. The other data points displayed a deviation within ±0.5 mm from the calculated value. The technology for bolus verification developed in this work can be used for the high precision testing of geometrical parameters of proton compensators in radiotherapy.