Log file based Monte Carlo calculations for proton pencil beam scanning therapy.

Log file based Monte Carlo calculations for proton pencil beam scanning therapy.
Phys Med Biol. 2018 Dec 12;:
Authors: Winterhalter C, Meier G, Oxley D, Weber DC, Lomax AJ, Safai S
Abstract
Patient specific quality assurance is crucial to guarantee safety in proton pencil beam scanning. In current clinical practice, this requires extensive, time consuming measurements. Additionally, these measurements do not consider the influence of density heterogeneities in the patient and are insensitive to delivery errors.
 In this work, we investigate the use of log file based Monte Carlo calculations for dose reconstructions in the patient CT, which takes the combined influence of calculational and delivery errors into account. 
 For one example field, 86%/90% of the voxels agree within ± 3% when taking either calculational or delivery uncertainties into account (analytical vs Monte Carlo calculation/Monte Carlo from planned vs Monte Carlo from log file). 78% agree when considering both uncertainties simultaneously (nominal field versus Monte Carlo from log files).
 We then show the application of the log file based Monte Carlo calculations as a patient specific quality assurance tool for a set of five patients (16 fields) treated for different indications. For all fields, absolute dose scaling factors based on the log file Monte Carlo agree within ± 3% to the measurement based absolute dose scaling. Relative comparis...

Source: Physics in Medicine and Biology - December 12, 2018 Category: Physics Authors: Winterhalter C, Meier G, Oxley D, Weber DC, Lomax AJ, Safai S Tags: Phys Med Biol Source Type: research