Temperature response of two photographic films and TLDs suitable for patient dosimetry of high dose fluoroscopic procedures.
When making direct measurements of skin entrance dose for patients undergoing interventional x-ray procedures the dosimeter may be placed near or in direct contact with the skin. The response of such dosimeters to heating during x-ray exposure must be known for accurate dosimetry. Two photographic films and MgB4O7 TLDs used for patient dose monitoring were exposed under different temperature conditions. Film dose response curves were obtained at room temperature and body temperature (22 degrees C and 38 degrees C). The TLD response at room and body temperature was also checked at 14 Gy. Dose response curves of FGP film show at most a 22+/-2% increase in predicted dose at 37 degrees C in the range of 0.3 to 2.8 Gy. LOC4 film showed less than a 2% difference in response between 22 and 37 degrees C over a range of 1 to 11 Gy. The TLDs showed less than a 2% difference at a dose of 14 Gy. Uncertainty in skin dose estimation is less than 2% using LOC4 film and MgB4O7 TLD arrays. Uncertainty in temperature during exposure of Kodak fine grain positive film may lead to errors in dose estimates of +/-11%. Arrays of TLDs and copy film are more suitable for measurements of high doses and are less sensitive to temperature changes during exposure than the fine grain film.
Lien
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Radiology Department, University of Minnesota, Minneapolis 55455, USA.
Geise
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D004307:Dose-Response Relationship, Radiation; D005069:Evaluation Studies as Topic; D006283:Health Physics; D006801:Humans; D010781:Photography / Q000295:instrumentation*; D011874:Radiometry / Q000295:instrumentation*; D013696:Temperature; D013819:Thermoluminescent Dosimetry / Q000295:instrumentation*