Abstract
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 cm IC, Gafchromic film and alanine pellets in the same plane. Relative and absolute gamma index (γ) 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 ρ > 0.998, p < 0.001) with mean difference of -1.1 ± 1.1% and -0.8 ± 1.1%, respectively, in a high dose PTV. In the γ 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. © 2013 Elsevier Ireland Ltd. All rights reserved.