BELdART-2 (2013-2015) was the continuation of the BELdART-1 project. It encompassed mailed audits for advanced and dynamic radiotherapy techniques (e.g. IMRT, VMAT, Tomotherapy). The audit consisted in 2 parts:
1) Control of basic dosimetry in a water tank using alanine positioned with a 3D printed holder
2) End-to-end verification of plans delivered on an EasyCube phantom (Sun Nuclear)
BELdART-2 used a combination of alanine-EPR-dosimetry and radiochromic film dosimetry.
The project was financed by the College of Medicine-radiotherapy and the FOD Healthcare. Within the framework of BELdART-2, all Belgian centers were offered the possibility to participate to the dosimetry audit without charge.
EPR basic tests
The dose difference between planned and alanine dose was within 3% for all the centers for 10x10 cm² fields. For wedges fields where the field is corrected for the output of the day, the dose difference was within 2%.
Falling within the 2% criterion were 88.4% of the centers for the reference dose, 100% at 8 cm depth, 92.9% for 20 cm depth and 94.9% for SSD85. All the other centers were within 3% for these tests.
For 2x10 cm² fields, 79.0% of the centers were within 2% and 89.5% within 3%. All the centers were within 5%. The uncertainty was 1% (k=1).
EPR in the EasyCube phantom
The figure above shows the results for the high dose region (prostate and seminal vesicles). The dose difference between planned and alanine dose was within 3% for 87.5% of the centers for the prostate and 79.2% of the centers for the seminal vesicles. Only 1 center had more than 5% difference. The uncertainty was 1.2% (k=1).
We evaluated the films with gamma analysis (global) with 3%/3mm criterion and 10% threshold. 3% of the films had a passing rate <90%. 27% of the films had a passing rate between 95%-98% and 70% had a passing rate >98%.