Published in Cancer Detection and Prevention 1995; 19(4):367-373.
New Thermoluminescent baso(4):eu Sheet for in Vivo Measurement of Spatial Dose Distribution in Radiation TherapyaDepts of Oncoradiology and Radiology, Nara Medical Univ, Nara, Japan; bOkayama Univ of Science, Okayama, Japan; and cDept of Physics, Okayama Univ, Okayama, Japan
Address all correspondence and reprint requests to: Kazuro Iwata, Ph.D., Dept of Oncoradiology, Nara Medical Univ, Shijo-cho 840, Kashihara-city, Nara 634, Japan
ABSTRACT: A new highly sensitive thermoluminescent (TL) sheet has been studied as a means of in vivo measurement of spatial dose distribution of radiation therapy. This TL sheet (40 cm x 50 cm x 0.2 mm), which is composed of teflon mixed with BaSO(4):Eu doped powder, is very flexible and can be cut to the desired size. The TL sheet was found to have a linear response with a very wide dynamic range of at least 0.002 cGy to 5000 cGy absorbed dose. In addition, this sheet does not need be shielded, because of its insensitivity to room light, and therefore the sheet can detect low-energy electrons decreased by a few millimeter thick air for (3)H(maximum B-ray energy: 18 KeV). The spatial dose distribution was printed out with a newly developed digital readout system. In addition, another high- resolution dosimetry system, which exposes X-ray film with TL photons emitted from the irradiated TL sheet at constant room temperature, is reported. Clinically, the in vivo dose distribution on the surface of the rectal cancer for intracavitary radiation therapy was determined. The applicability of TL sheet for in vivo measurement of dose distribution is discussed.