Purpose
To develop a methodology for the use of a commercial detector array in dosimetry audits of rotational radiotherapy.
Materials and methods
The methodology was developed as part of the development of a national audit of rotational radiotherapy. Ten cancer centres were asked to create a rotational radiotherapy treatment plan for a three-dimensional treatment-planning-system (3DTPS) test and audited. Phantom measurements using a commercial 2D ionisation chamber (IC) array were compared with measurements using 0.125 cm3 IC, Gafchromic film and alanine pellets in the same plane. Relative and absolute gamma index (¦Ã) comparisons were made for Gafchromic film and 2D-Array planes, respectively.
Results
Comparisons between individual detectors within the 2D-Array against the corresponding IC and alanine measurement showed a statistically significant concordance correlation coefficient (both ¦Ñc > 0.998, p < 0.001) with mean difference of ?1.1 ¡À 1.1 % and ?0.8 ¡À 1.1 % , respectively, in a high dose PTV. In the ¦Ã comparison between the 2D-Array and film it was that the 2D-Array was more likely to fail planes where there was a dose discrepancy due to the absolute analysis performed.
Conclusions
It has been found that using a commercial detector array for a dosimetry audit of rotational radiotherapy is suitable in place of standard systems of dosimetry.
