Background and Aims

Seven proton therapy centers collaborating within INSPIRE project participated in the mailed dosimetry audit of proton therapy treatment units utilizing spot scanning beams organized by EURADOS WG9 'Radiation dosimetry in radiotherapy'.

Methods

Prototype assembly for positioning the detectors in the water phantom has been developed and tested during simultaneous irradiation at IFJ PAN in Krakow and PTC in Prague in June 2020. Alanine, radiophotoluminescent and thermoluminescent detectors from five European institutes have been irradiated with 10 x 10 cm² single layer field and 10 x 10 x 10 cm³ plan.

Results

Very good agreement between the two centers has been obtained for alanine, RPL and TL detectors. Based on the results of the initial experimental campaign, the assembly for detector positioning has been modified. As a next step, one assembly for each participating center has been produced including the corresponding number of water-proof detector holders. In the frame of INSPIRE join research activity, audit manuals, detectors and holder assemblies were distributed to participating centers. Audit irradiations took place in all centers during March-April 2021.

Conclusions

The obtained results provide an indication of dosimetric agreement between centers and bases for definition of standardization procedures in dosimetry of active scanning proton beams. After a successful initial experience, mailed audit of scanning proton beams may become a part of clinical routine helping in standardization of active proton beam dosimetry.

This work was partially supported from the European Union's H2020 Research and Innovation Programme, under Grant Agreement No: 730983 (INSPIRE project).