Analysis of the long-term stability of the output of electron beams generated by the Novac11™ IORT accelerator.

ABSTRACT

AIM: The aim of the study was to analyze the long-term stability of electron beams generated by the Novac11™ IORT accelerator. BACKGROUND: Novac11™ (NRT®) is a mobile electron accelerator designed to irradiate small areas of tissue, up to 10 cm in diameter, with electron beams during surgical procedures. It is characterized by a great mobility guaranteed by a number of degrees of freedom enabling irradiation in the conditions of an operating theatre. MATERIALS AND METHODS: Over the period of January 2013 and September 2016, the measurement sessions of the output of clinically used beam qualities (6, 8 and 10 MeV) were carried out 41 times. Because of the unsatisfactory long-term stability, an extra procedure of tuning of the magnetron, suggested by the manufacturer, was introduced in October 2015, 15 measurements were performed since then. The output of the Novac11™ accelerator was measured in the reference conditions recommended by the IAEA Report 398, the measurements of the charge in the ionization chamber at the reference depth were carried out with a Dose1™ electrometer and a plane-parallel chamber PPC05™ from IBA®. RESULTS: The introduction of the tuning of the magnetron procedure resulted in satisfactory long-term stability of the measured outputs below 2%. CONCLUSIONS: After the introduction of the STV parameter tuning procedure, the long-term stability of the Novac11™ output increased considerably and is within the values declared by the manufacturer.