Room: Exhibit Hall | Forum 3
Purpose: To characterize the achievable conformality of a novel kilovoltage intensity modulated radiotherapy system in the context of intracranial therapy.
Methods: A novel kilovoltage radiotherapy platform was developed using a conventional x-ray tube and a custom built multi-rod collimation system. An Eclipse beam model for the system was created using depth dose and profile data simulated in GEANT4. A 17-field treatment plan was created to treat a simulated baseline, a GEANT4 simulation of the plan was performed. The plan was delivered to the LUCY phantom and the dose distribution measured with radiochromic film. A further simulation was performed including simulated bony anatomy to evaluate the increased dose due to photoelectric enhancement. Dose escalation possibilities using iodine contrast were evaluated in light of the achieved conformality of the distribution.
Results: The measured distribution in the homogeneous phantom matched well with that of the Monte Carlo simulation. As expected, the out-of-target dose in the phantom exceeded that achievable with a conventional megavoltage delivery, with a peripheral dose of 40% in the kilovoltage plan. The simulation including bony anatomy showed high dose-to-bone, which indicated that as the largest obstacle to kilovoltage intracranial radiotherapy. However, further simulation of the plan including both bony anatomy and iodine contrast agent in the target volume indicated that dose escalation is indeed possible even in light of the increased dose-to-bone.
Conclusion: Measured distributions in a homogenous phantom with the kilovoltage intensity modulated radiotherapy system matched simulated distributions well and showed acceptable conformality. Further simulations including bony anatomy and iodine contrast indicate that increases in dose to bony anatomy can be overcome by large contrast enhancement in the target volume.