Studying the dose level for different X-ray energy conventional radiography by TLD-100

The purpose of this study was to investigate the x-ray energy dependence of the measured response of detectors (TLD-100) and to estimate the accurate dose delivered to patients during routine X-ray examinations. The response of thermoluminescent dosimeters TLD as a function of low energy range was determined using the X-ray tube at the Ionizing Radiation Met. Lab in the National Institute of Standards, (Secondary Standard Dosimetry Lab (SSLD) Cairo, Egypt. The X-ray dose was measured at 25, 50 and 100 kVp nominal x-ray energies. TLD-100 linearity, reproducibility and relative sensitivity were studied. Several sets of TLD-100 were to different x-ray beam energy to determine the calibration coefficient of the TLD system and the correction factors applied for the dose calculation (readings (nC)/radiation dose (mGy)) was determined in the dose range (0.69 mGy to 350 mGy). The radiation dose to the patient was estimated in diagnostic radiology for the existing working protocols (skull, pelvis, abdomen, and lumbar Spine). TLD-100 was exposed at various nominal energy used for diagnostic (40-100 kVp) and various tube current (50-120 mA) which is normally used in clinical X-ray examinations. The TLD-100 was exposed three times for each kVp value, and the exposure doses were measured in mGy. The obtained results showed a linear behavior of the TLD-100 response as a function of X-ray dose with estimated uncertainty within 10%. This indicates a good accuracy when assessing the entrance dose in diagnostic radiology procedures). The sensitivity of the TLD cards showed a standard deviation of 4.7%. Moreover, the dose-nC factor has the same value (within the standard uncertainty). Mean Entrance Skin Dose for skull, pelvis, abdomen, and lumbar spine were 0.46 ± 0.01, 1.5 ± 0.05, 7.3 ± 0.21 and 9.2 ± 0.29 mGy respectively. The obtained results reflect the agreement with the recommended values and will be useful for the formulation of national reference levels as recommended by the International Atomic Energy Agency (IAEA) SAFETY STANDARDS SERIES No. GSR Part 3 2014.