Production of new thermoluminescent mini-dosimeters.
A method of producing CaSO4:Dy thermoluminescent mini-dosimeters was reported in 1986 by B W Wessels for determination of the in vivo absorbed dose in radioimmunotherapy, a field in which absorbed dose gradients are important. These dosimeters, which undergo dissolution when used in a liquid environment, showed a sensitivity loss of up to 30% after 4 days of immersion in our tests. Moreover, several studies have shown that biocompatibility problems can occur during in vivo studies in animals. This paper describes the production and testing of a new type of thermoluminescent mini-dosimeter obtained by microextrusion of a mixture of LiF:Mg,Cu,P polypropylene and plastic adjuvants. These dosimeters, in the form of long 400 microm diameter filaments, can be cut to the desired length. The production process allows an LiF:Mg,Cu,P load of up to 50%. Results obtained in external irradiation indicate that these new miniature LiF:Mg,Cu,P dosimeters have good sensitivity (about 1.6 times that of CaSO4:Dy mini-TLDs), homogeneous response within a production batch (mean +/-4%), response stability in water (0.7% of variation in sensitivity after 2 weeks of immersion) and stability in aqueous solutions at different pH. LiF:Mg,Cu,P mini-dosimeters appear to be highly promising for internal dosimetry, and evaluation is in progress in animals.
Martin
S
S
INSERM Unité 463, Nantes, France.
Lisbona
A
A
Richard
J
J
Morteau
S
S
Denizot
B
B
Bardiès
M
M
D002133:Calcium Sulfate; D003037:Cobalt Radioisotopes; D004355:Drug Stability; D004419:Dysprosium; D019047:Phantoms, Imaging; D011138:Polytetrafluoroethylene; D016499:Radioimmunotherapy; D011879:Radiotherapy Dosage; D013819:Thermoluminescent Dosimetry / Q000295:instrumentation* / Q000379:methods
D003037:Cobalt Radioisotopes; D004419:Dysprosium; D011138:Polytetrafluoroethylene; D002133:Calcium Sulfate