Radiation Protection Dosimetry Advance Access published online on March 6, 2008
Radiation Protection Dosimetry, doi:10.1093/rpd/ncn067
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ON THE NEED FOR QUALITY ASSURANCE IN SUPERFICIAL KILOVOLTAGE RADIOTHERAPY
The Brody School of Medicine at ECU, Department of Radiation Oncology, Greenville, NC, USA
* Corresponding author: motah{at}ecu.edu
Received October 26, 2007, amended January 2, 2008, accepted February 6, 2008
External auditing of beam output and energy qualities of four therapeutic X-ray machines were performed in three radiation oncology centres in northeastern Brazil. The output and half-value layers (HVLs) were determined using a parallel-plate ionisation chamber and high-purity aluminium foils, respectively. The obtained values of absorbed dose to water and energy qualities were compared with those obtained by the respective institutions. The impact on the prescribed dose was analysed by determining the half-value depth (D1/2). The beam outputs presented percent differences ranging from –13 to +25%. The ratio between the HVL in use by the institution and the measurements obtained in this study ranged from 0.75 to 2.33. Such deviations in HVL result in percent differences in dose at D1/2 ranging from –52 to +8%. It was concluded that dosimetric quality audit programmes in radiation therapy should be expanded to include dermatological radiation therapy and such audits should include HVL verification.