An open source solution for an in-house built dynamic platform for the validation of stereotactic ablative body radiotherapy for VMAT and IMRT.

An in-house solution for the verification of dose delivered to a moving phantom as required for the clinical implementation of lung stereotactic ablative body radiation therapy was developed. The superior-inferior movement required to simulate tumour motion during a normal breathing cycle was achieved via the novel use of an Arduino Uno™, a low-cost open-source microcontroller board connected to a high torque servo motor. Slow CT imaging was used to acquire the image set and a 4D cone beam CT (4D-CBCT) verified the efficacy of contoured margins before treatment on the moving phantom. Treatment fields were delivered to a section of a CIRS™ anthropomorphic phantom. Dose verification to the dynamic phantom with Gafchromic EBT3 film using 3 %-1 mm gamma analysis acceptance criteria registered an absolute dose pass rate for IMRT and VMAT of 98 and 96.6 %, respectively. It was verified that 100 % of the PTV received the prescribed dose of 12 Gy per fraction using the dynamic phantom, and no major discrepancy between planned and measured results due to interplay between multileaf collimator sequences and target motion was observed. This study confirmed that the use of an in-house solution using open source hardware and software with existing quality assurance equipment was appropriate in validating a new treatment technique.