ESTRO meets Asia 2024 - Abstract Book

S306

Physics – Detectors, dose measurement and phantoms

ESTRO meets Asia 2024

to balloon surface agreed well with TG-43 reference data (Figure 2), but there was an 8.1% difference at the edge of the film between calculated and measured doses, 13.6±0.3 and 14.7±1.3 Gy respectively. The high quoted uncertainty was due to repeated inflation and deflation of the single-use balloon, which resulted in displacement of source channel by approximately 3 mm. The quoted attenuation of >90% for rigid shielding was confirmed with a measured attenuation of 98.9%.

Figure 2. Comparison of dose fall-off in phantom geometry.

For two of the sources routinely calibrated over one year, the mean variations between subsequent well chamber measurements were 0.3 and 0.4%, with a maximum variation of 1.4% observed. The control (or tolerance) limit calculated from Shewhart control charts for these datasets was 1.2%. Control limits could not be appropriately determined for the other source, due to a non-transient 10% increase in RAKR after 4 months since starting use.

Conclusion:

Dose was successfully verified, despite the inherent challenges of sharp dose gradients, balloon applicators, and the low beam energy. Issues with the balloon source channel displacement highlighted the importance of visual inspection during clinical procedures. Source RAKR was relatively stable, with one exception, which highlights the need for pre-treatment calibration measurements.

Keywords: intraoperative, Axxent, brachytherapy

356

Proffered Paper

Development of level 3 3D dosimetry audit using PRESAGE dosimeter in bespoke anthropomorphic phantom

Muhammad Zamir Mohyedin 1 , Hafiz Zin 2 , Ahmad Taufek Abdul Rahman 1

1 Faculty of Applied Science, Universiti Teknologi MARA, Shah Alam, Malaysia. 2 Advanced Medical & Dental Institute, Universiti Sains Malaysia, Penang, Malaysia

Purpose/Objective: