Single crystal CVD diamond detector for high resolution dose measurement for IMRT and novel radiation therapy needs

One of the main aims for the improvement of the metrology during cancer treatment is the development of new tools for the real time measurement of the dose delivered to the patient. In the frame of The MAESTRO project (Methods and Advanced Equipment for Simulation and Treatment in Radio-Oncology, 6th FP) CEA-LIST in collaboration with the Gustave Roussy Institute (IGR in France) and the Institute of Nuclear Physics (IFJ in Poland) have realised clinical tests towards the use of single crystal diamond detectors (SCDD) for dose measurements for Intensity Modulated Radiation Therapy (IMRT). We present here a summary of the most significant steps realised with our dosimeter for the evaluation of IMRT clinical tests. After a brief presentation of the optimised single crystal diamond growth performed at CEA, we probed the performances of the SCDD with conventional radiotherapy fields. Performance evaluated in agreement with IAEA 398 Code of practise allows the dosimeter to be tested in IMRT beams. The evaluation of the doses measured with our 0.534 mm3 SCDD is compared respectively to that obtained with the 0.125 cm3 air ionisation chamber (IC) and with the TPS (Treatment Planning System) calculations respectively. The results exhibit a good agreement between the doses evaluated with the SCDD, the IC and TPS calculations. These very promising results show the potentiality of diamond for such a use and open up the field towards novel applications such as for very small beam dosimetry. For this specific topic a new miniaturised dosimeter is currently being developed at CEA and is briefly presented here.