Correlations between the shifts in prompt gamma emission profiles and the changes in daily target coverage during simulated pencil beam scanning proton therapy.

Correlations between the shifts in prompt gamma emission profiles and the changes in daily target coverage during simulated pencil beam scanning proton therapy.
Phys Med Biol. 2019 Mar 28;:
Authors: Lens E, Jagt TZ, Hoogeman MS, Schaart DR
Abstract
The aim of this study was to investigate the feasibility of using prompt gamma (PG) ray emission profiles to monitor changes in dose to the planning target volume (PTV) during pencil beam scanning (PBS) proton therapy as a result of day-to-day variation in patient anatomy.
 For 11 prostate patients, we simulated treatment plan delivery using the patients' daily anatomy as observed in the planning CT and 7-9 control CT scans, including the detected PG profiles resulting from the 5%, 10%, and 20% most intense proton pencil beams. For each patient, we determined the changes in dosimetric parameters for the high- and low-dose PTVs between the simulations performed using the planning CT scan and the different control CT scans and correlated these to changes in the PG emission profiles.
 Changes in coverage of the high- and low-dose PTV correlated most strongly with the median and mean absolute PG emission profile shifts of the 5% most intense pencil beams, respectively. With a mean Pearson correlation coefficient of -0.76 (SD: 0.17) for the high-dose PTV and of -0.60 (SD: 0.51) for the low-dose PTV.
 We showed, as a proof of principle, that PG emission profiles obtained ...

Source: Physics in Medicine and Biology - March 27, 2019 Category: Physics Authors: Lens E, Jagt TZ, Hoogeman MS, Schaart DR Tags: Phys Med Biol Source Type: research