An algorithm for real-time dosimetry in intensity-modulated radiation therapy using the radioluminescence signal from Al2O3:C.
Although the radioluminescence (RL) signal from optical fibre Al(2)O(3):C dosemeters used in medical applications is essentially proportional to dose rate, the crystals used so far are imperfect in the sense that their RL sensitivity changes with accumulated dose. A computational algorithm has been developed that corrects for these sensitivity changes. We further report on a new system that effectively separates the RL signal generated in the crystal from fluorescence and Cerenkov emission generated in the optical fibre cable using a gating technique in connection with pulsed linear accelerator radiation beams. The dosimetry system has been used for dose measurements in a phantom during an intensity-modulated radiation therapy (IMRT) treatment with 6 MV photons. The RL measurement results are in excellent agreement (i.e. within 1%) with both the OSL results and the dose delivered according to the treatment planning system. RL signals from Al(2)O(3):C can be used for real-time dose rate measurements with a time resolution of approximately 0.1 s and a spatial resolution only limited by the size of the detector (<0.5 mm).
Andersen
C E
CE
Risø National Laboratory, Radiation Research Department, DK-4000 Roskilde, Denmark. claus.anderson@risoe.dk
Marckmann
C J
CJ
Aznar
M C
MC
Bøtter-Jensen
L
L
Kjaer-Kristoffersen
F
F
Medin
J
J
D000465:Algorithms; D000537:Aluminum Oxide / Q000737:chemistry* / Q000528:radiation effects*; D002244:Carbon / Q000737:chemistry / Q000528:radiation effects; D003199:Computer Systems; D006801:Humans; D011879:Radiotherapy Dosage; D011881:Radiotherapy, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000379:methods*; D012062:Relative Biological Effectiveness; D013819:Thermoluminescent Dosimetry / Q000379:methods*
D002244:Carbon; D000537:Aluminum Oxide