Characterization of a synthetic single crystal diamond Schottky diode for radiotherapy electron beam dosimetry

• Published in: Medical physics (Lancaster) 2013-02, Vol.40 (2), p.021712-n/a
• Main Authors: Di Venanzio, C., Marinelli, Marco, Milani, E., Prestopino, G., Verona, C., Verona-Rinati, G., Falco, M. D., Bagalà, P., Santoni, R., Pimpinella, M.
• Format: Article
• Language: English
• Subjects: BEAM PROFILES; COMPARATIVE EVALUATIONS; diamond; Diamond - chemistry; DIAMONDS; DOSE RATES; DOSES; DOSIMETRY; Dosimetry/exposure assessment; Electrodes; Electromagnetic radiation detectors; electron beam dosimetry; ELECTRON BEAMS; Electrons; Field size; INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ionisation chambers; IONIZATION CHAMBERS; IRRADIATION; Junction diodes; LINEAR ACCELERATORS; Measurement of nuclear or x‐radiation; Particle beam detectors; Radiation Dosage; RADIATION PROTECTION AND DOSIMETRY; radiation therapy; RADIOLOGY AND NUCLEAR MEDICINE; Radiometry; RADIOTHERAPY; Radiotherapy - instrumentation; SCHOTTKY BARRIER DIODES; Schottky diodes; Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having at least one potential‐jump barrier or surface barrier; Capacitors or resistors with at least one potential‐jump barrier or surface barrier, e.g. pn‐junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof; Silicon; Silicon detectors; SILICON DIODES; SOLIDS; solid‐state nuclear track detectors; SPATIAL RESOLUTION; synthetic diamond detector; Therapeutic applications, including brachytherapy; Tracking and position‐sensitive detectors
• ISSN: 0094-2405; 2473-4209
• DOI: 10.1118/1.4774360

Purpose: To investigate the dosimetric properties of synthetic single crystal diamond based Schottky diodes under irradiation with therapeutic electron beams from linear accelerators. Methods: A single crystal diamond detector was fabricated and tested under 6, 8, 10, 12, and 15 MeV electron beams. The detector performances were evaluated using three types of commercial detectors as reference dosimeters: an Advanced Markus plane parallel ionization chamber, a Semiflex cylindrical ionization chamber, and ap-type silicon detector. Preirradiation, linearity with dose, dose rate dependence, output factors, lateral field profiles, and percentage depth dose profiles were investigated and discussed. Results: During preirradiation the diamond detector signal shows a weak decrease within 0.7% with respect to the plateau value and a final signal stability of 0.1% (1σ) is observed after about 5 Gy. A good linear behavior of the detector response as a function of the delivered dose is observed with deviations below ±0.3% in the dose range from 0.02 to 10 Gy. In addition, the detector response is dose rate independent, with deviations below 0.3% in the investigated dose rate range from 0.17 to 5.45 Gy/min. Percentage depth dose curves obtained from the diamond detector are in good agreement with the ones from the reference dosimeters. Lateral beam profile measurements show an overall good agreement among detectors, taking into account their respective geometrical features. The spatial resolution of solid state detectors is confirmed to be better than that of ionization chambers, being the one from the diamond detector comparable to that of the silicon diode. A good agreement within experimental uncertainties was also found in terms of output factor measurements between the diamond detector and reference dosimeters. Conclusions: The observed dosimetric properties indicate that the tested diamond detector is a suitable candidate for clinical electron beam dosimetry.