Silicon diodes as an alternative to diamond detectors for depth dose curves and profile measurements of photon and electron radiation.
BACKGROUND
Depth dose curves and lateral dose profiles should correspond to relative dose to water in any measured point, what can be more or less satisfied with different detectors. Diamond as detector material has similar dosimetric properties like water. Silicon diodes and ionization chambers are also commonly used to acquire dose profiles.


METHODS
The authors compared dose profiles measured in an MP3 water phantom with a diamond detector 60003, unshielded and shielded silicon diodes 60008 and 60012 and a 0.125-cm(3) thimble chamber 233642 (PTW, Freiburg, Germany) for 6- and 25-MV photons. Electron beams of 6, 12 and 18 MeV were investigated with the diamond detector, the unshielded diode and a Markus chamber 23343.


RESULTS
The unshielded diode revealed relative dose differences at the water surface below +10% for 6-MV and +4% for 25-MV photons compared to the diamond data. These values decreased to less than 1% within the first millimeters of water depth. The shielded diode was only required to obtain correct data of the fall-off zones for photon beams larger than 10 x 10 cm(2) because of important contributions of low-energy scattered photons. For electron radiation the largest relative dose difference of -2% was observed with the unshielded silicon diode for 6 MeV within the build-up zone. Spatial resolutions were always best with the small voluminous silicon diodes.


CONCLUSIONS
Relative dose profiles obtained with the two silicon diodes have the same degree of accuracy as with the diamond detector.
Scherf
Christian
C
Department of Radiotherapy and Oncology, Center of Radiology, University Hospital, Johann Wolfgang Goethe University Frankfurt/Main, Frankfurt/Main, Germany. Christian.Scherf@kgu.de
Peter
Christiane
C
Moog
Jussi
J
Licher
Jörg
J
Kara
Eugen
E
Zink
Klemens
K
Rödel
Claus
C
Ramm
Ulla
U
D018130:Diamond; D004583:Electrons / Q000627:therapeutic use*; D006801:Humans; D019047:Phantoms, Imaging; D017785:Photons / Q000627:therapeutic use*; D011874:Radiometry / Q000295:instrumentation*; D011880:Radiotherapy Planning, Computer-Assisted; D011882:Radiotherapy, High-Energy / Q000295:instrumentation*; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D012825:Silicon
D018130:Diamond; D012825:Silicon