Introduction: Nowadays the use of cone beam computed tomography in dental imaging is increasing, although this method has a much lower dose than conventional CT scans, it delivers a higher dose than the panoramic and periapical patients therefore, , the aim of this study was to investigate the factors affecting the patients' dose in dental CBCTs and methods of optimizing and reducing the patients' dose. Various factors such as the use of thyroid collar, lead goggles, field size, device type, imaging parameters such as tube voltage and current, alternating or pulsed radiation; type, amount and shape of the filter, 360 degree or partial rotation of tube and scan time, can affect the absorbed dose of the patient in dental CT scans. Among these, the use of thyroid collar (42% reduction), lead goggles (6% reduction),the smallest possible field of view ( up to 90%), pulse irradiation, patient sitting position and 180o rotation angle instead of 360o (more than 50% reduction) cause significant reduction in the organ doses and effective dose of the patients. It should also be kept in mind that measures taken to reduce the patients' dose should not impair image quality and, depending on the patient's condition, the radiographer will select the dose reduction parameters without degrading the image quality.
Introduction: Angiography and angioplasty expose cardiologists to a high level of X-ray comparing other radiographic methods, due to the high dose of radiation and the presence of the physician beside the patient bed during the procedure. Therefore, this study was designed to measure the absorbed dose in some important organs and extremities in cardiologists during different angiography and angioplasty procedures in catheterization lab. Methods: The entrance skin dose and extremity absorbed dose of the physicians in 100 angiography and angioplasty procedures were measured by TLD chips. The points on the physicians’ body, which were measured in this study, included: thyroid, right and left chest, right and left wrists, and left leg. The correlation of entrance skin dose in these six points to the exposure parameters is also evaluated. Results: The left leg has maximum dose and maximum correlation with total DAP for all three physicians in all procedure types. There was a weak correlation between left wrist absorbed dose and number of views among three physicians. Also, the maximum annual absorbed dose of the physicians in the left leg was lower than 150 mSv. Conclusion: According to the results of this study, it can be stated that periodic leg and hand dosimetry during operation is necessary for interventional cardiologists. Results also showed that, regardless of the type of procedure, the characteristics of device output, especially DAP, have a direct role in the absorbed dose of the organs and extremities, especially those outside the shield.
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