Clay as Thermoluminescence Dosemeter in Diagnostic Radiology Applications

ABSTRACT

As part of efforts to isolate and utilize local and naturally occurring materials for development of thermoluminescece dosemeters and other technologies; an earlier report had shown that Nigerian clay showed prospects of utility as a thermoluminescence dosemeter (TLD). This paper reports the investigation of the basic thermoluminescence properties of clay at x-rays in the diagnostic radiology range; including dose monitoring in abdominal radiography. Clay sourced from Calabar; Nigeria; was tested for thermoluminescence response after irradiation at diagnostic radiology doses; including application in abdominal radiography dose monitoring in a clinical setting. Results show that thermoluminescence (TL) output in natural clay is very low; but demonstrates enhanced performance with the addition of common salt. Specific TL characteristics of good repeatability for individual and batched pellets (variability index of 3.08) and a high degree of trap emptying were observed. It had a glow curve peak at 275 C; with traces of spurious thermoluminescence emission at the reader anneal temperature. There was evidence of good batch homogeneity ( 30) and a similar pattern of dose absorption in abdominal radiography with commercial Lithium Fluoride (LiF TLD-100). A high fading rate (over 30in twelve hours) and low sensitivity (12 times less than LiF TLD-100) however; signal the unacceptability of clay as aTLD in diagnostic radiology in the forms studied. Clay demonstrates poor TL response at diagnostic radiology doses. However; it's water absorbing property offers a means of overcoming the hygroscopic nature of common salt. This could be explored to improve the use of sodium chloride as a radiation detector