Posted on 15 July 2014
In 2013 Paris hospital la Pitié-Salpêtrière turned to France’s national metrology lab for ionizing radiation, LNHB (Laboratoire national Henri-Becquerel), to conduct a dosimetry study of the Gamma Knife® Perfexion™ stereotactic radiotherapy system. The study aimed to determine the dose delivered by the system’s 192 radiation beams by using alanine dosimetry read by electron paramagnetic resonance (EPR) spectroscopy—a method that the lab had already used for other radiotherapy systems that also use very narrow beams.
The irradiations were carried out on anthropomorphic head phantoms in which dosimeters calibrated in reference conditions (the LNHB co-60 source) had been positioned.
A comparative analysis of the data confirmed that the dose calculated by the Gamma Knife® treatment planning system and the dose measured by ESR were consistent, with a difference of less than 1% between the prescribed dose and the measured dose.
To take these encouraging results a step further, CEA LIST researchers are now investigating the potential benefits of using alanine in powder form to eliminate any effects caused by the excipients in the alanine tablets used currently. Their findings could be of use for all radiotherapy devices delivering small-field radiation.
