Positional radiotherapy beam dosimetry using a laser heated thermoluminescent plate.
A 4-W, laser-based system for the positional readout of thermoluminescent (TL) plates was utilized to obtain dose profiles for a 60Co radiotherapy beam. Experimentally obtained glow curves for LiF resulting from the rapid heating rates characteristic of laser heating agreed well with results predicted using a first-order kinetic model. Excellent system linearity was obtained for sensitivity to 60Co. The useful dynamic range for this tissue-equivalent system could extend over 8 orders of magnitude. A minimum detectable signal of 1.2 R was estimated for the presently configured system, whose spatial resolution is limited by the laser beam diameter, 1.7 mm. Depth dose profiles for the radiotherapy beam obtained using the prototype laser TL system with a specially designed composite 2.2 cm x 3.3 cm x 0.254 mm LiF plate agreed to within 14% of ionization chamber measured doses.
Kearfott
K J
KJ
School of Mechanical Engineering, Georgia Institute of Technology, Atlanta 30332-0225.
Grupen-Shemansky
M E
ME
D003037:Cobalt Radioisotopes / Q000627:therapeutic use; D006801:Humans; D007834:Lasers; D011879:Radiotherapy Dosage; D013819:Thermoluminescent Dosimetry / Q000295:instrumentation*
D003037:Cobalt Radioisotopes