MONIDIAM project

The objective of this project is to conduct preliminary studies required for the development of an online monitoring system for intensity modulated conformal radiotherapy (IMRT) and for hadrontherapy, using thin and large area diamond detectors.

This system will address several issues currently under study by the partner teams:

- The real-time control during treatment of the radiation field defined by collimation blades, with a detector located upstream of the patient, with subsequent flux measurement at each point. This will enable the control of the dose and dose rate in real time;

- The same flux control during hadrontherapy with protons or carbon ions;

- A time stamp of incoming ions or ion bunches during hadrontherapy. This tagging is necessary for quality control based on the detection of secondary radiation (prompt gamma, secondary protons).

CVD diamond detectors (Chemical Vapor Deposition), mono- or poly-crystalline, have a number of assets to address these issues:

- The atomic number is low and similar to that of living tissues, with a subsequent low absorption of incident radiation;

- They are radioresistant, i.e. they may be capable of prolonged clinical use (several years);

- Their electronic properties (thermal conductivity, large electronic gap, high charge mobility and low capacitance) make them very fast detectors with low noise at room temperature.

During the project, beam measurements have been performed, and a dedicated test bench was set to characterize the response of detectors made out of commercial CVD wafers. This enables us to define the requirements for such versatile clinical applications. The actual performances of actual detectors are not satisfactory enough to enable clinical operation, and the developments that have been initiated during this project will be ongoing during the next years by the partners.

2x2 cm² polycrystalline detector, monted on 50 Ω adapted frame