IAEA Develops Brachytherapy Dosimetry Audit Methodology

An initial meeting of the project’s research teams from 10 different countries (Brazil, China, Croatia, Greece, India, Iran, Mexico, the Russian Federation, South Africa and Spain) explored various potential audit designs. Central to such a methodology are phantoms, which are specially designed devices that medical physicists use to assess radiation doses with the requisite accuracy.

With simulations providing a theoretical basis, the IAEA’s Dosimetry Laboratory was able to create a small, lightweight and easy-to-transport phantom. The device measures 16 centimetres by 8 centimetres by 3 centimetres and contains a radiophotoluminescent dosimeter to measure delivered doses and radiochromic films to check the accuracy of the source’s position. The phantom can be constructed from widely available materials and can be used with interstitial plastic catheters. This means the phantom does not require a specific manufacturer, making it cost-effective, accessible and practical for hospitals and facilities around the world. 

The methodology utilizes a reference treatment plan that can be used on all major commercially available treatment planning systems and HDR afterloader systems and was tested in 54 centres internationally. With some facilities performing more than one irradiation, the IAEA received a total of 59 measurements — 45 of which were irradiated with iridium-192 and 14 with a cobalt-60 source across 49 different brachytherapy afterloaders of various models.  

“The results of this multicentre pilot study validate the dosimetry audit methodology, demonstrating its accuracy, reliability and accessibility for global use,” noted Alexis Dimitriadis, the laboratory’s previous Quality Manager in the IAEA Division of Human Health. The method’s development and testing as well as its Monte Carlo simulated correction factors have been published in the journal Physics and Imaging in Radiation Oncology. 

“A testament to the vital role the IAEA’s human health programme plays in supporting countries around the world, the study builds on existing scientific endeavours within the field of dosimetry audits for radiotherapy,” said Jamema Swamidas, Head of DOL in the IAEA Division of Human Health. “Its results contribute to the coordinated research project’s overarching aim and ongoing work on a multi-level audit methodology that includes an end-to-end audit of the entire brachytherapy workflow from imaging to treatment planning to delivery.” 

The IAEA encourages hospitals to apply to participate in the newly launched dosimetry audit when they commission their HDR brachytherapy afterloaders.