High-quality polycrystalline CVD diamond for conformal radiotherapy applications

A bidimensional dosimeter made with a state-of art polycrystallineChemical Vapour Deposited (pCVD) diamond for applications in clinical radiotherapy has been manufactured in the framework of the DIAPIX project (INFN CSN5). It is constituted by a large area (2.5x2.5cm2) pCVD diamond film equipped with in-house electrical contacts on the front and rear surfaces in transverse geometry. Upper contact, made on the growth side of the film, is in form of a squared matrix of 24x24 pixels, pixel size 0.8 mm x 0.8mm, 300nm thick, pitch 1mm. Optimization of the operational conditions has been performed studying a few pixels along the matrix. Instability effects due to trapping -detrapping mechanisms were observed to be negligible at low bias. These results confirm that the pCVD diamond device is suitable for mapping the bidimensionally conformed dose in an Intensity Modulated Radiation Therapy (IMRT) treatment.