Clay as Thermoluminescence Dosemeter in Diagnostic Radiology Applications

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

Effect of delayed film processing and milliamperage changes on image quality

A study of the effect of delayed clinical processing and milliamperage changes on image quality was carried out at the Radiology Department; University of Calabar; Nigeria; using filmstrips exposed to x-radiation at milliamperage (mA) values of 50; 100; 200; 300; 400 and 500. Exposed film strips were processed over varied post exposure; peprocessing keeping times ranging from 0 hours (control) to the 18th day. Results show progressive decrease in optical densities measured on the film; with prolonged pre-processing keeping time; and this is more marked at low (50) mA procedures; and is less in high (500) mA procedures; at which mA also; the onset was highly delayed (commencing about the 12th hour). The implication of this in a developing economy is discussed

Assessment of chest radiographs for quality assurance and radiation protection

A retrospective study of 1000 chest radiographs randomly selected from various government and private owned hospitals in the southern part of Nigeria covering a period of twenty years was carried out. Accuracy in patient positioning; beam collimation and identification of radiographs were assessed as indicators for quality assurance and radiation protection. The result showed that for male 59 were rotated and 41 were not. For the female; 60 were rotated while 39 were not. 95.30 radiographs were inadequately collimated; and 69.30 were properly identified. This suggests poor quality and exposure of patients to unnecessary radiation though more attention was paid to identification of radiographs