ESTRO 2024 - Abstract Book

S4811

Physics - Quality assurance and auditing

ESTRO 2024

References:

1. Scientific RT GmbH, SciMoCa.

2. Simon Stevens et al., 2023, Phys. Med. Biol., vol 68, 18TR02

3. IPEM-OTM-RTSIG · GitHub

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Clinical Implementation of Prosoma Core for SRS treatments.

Anna Bangiri 1,2 , Jonathan D Allred 1 , Keith Langmack 1

1 Nottingham Univerisity Hospitals NHS Trust, Radiotherapy Physics, NOttingham, United Kingdom. 2 University of Nottingham, School of Medicine, Nottingham, United Kingdom

Purpose/Objective:

The aim of this project was to clinically implement Prosoma Core as a second dose calculation software and log file analyser to replace the film based Patient Specific Quality Assurance (PSQA) process for Stereotactic Radiosurgery (SRS) treatments.

Material/Methods:

MedCom produced a beam model using measured data from our VersaHD linacs, optimised to match the beam model used within the Monaco TPS used at our centre. A script was written to add the Monaco couch model to the Prosoma Core calculation as the former does not export density overrides. For the gamma analysis it was initially decided to use the same criteria as used in the film based PSQA process of 5%2mm with a 20% dose threshold. Clinical patients were exported to Prosoma Core and recalculated, and the dose distributions were compared to those produced by Monaco. A total of 64 patient plans were used, with a variety of isocentre positions, size and number of PTVs treated within each plan, as well as different fractionations in order to mimic the full range of clinical plans. Once the treatment plans had be recalculated, the tolerances were calculated in order to establish a 5% fail rate of the Prosoma Core gamma analysis and overall plan dose deviation so that film based PSQA is still performed within the department. The equations used for setting these tolerances was: Tolerance = Mean – (1.96 x Standard deviation).

A total of 60 clinical patients were tested on the linacs with Prosoma Core recording the logfiles, while the plan was delivered on the STEEV phantom and a 2D dose distribution measured using EBT-XD film (95% global gamma pass