A Study on the Exposure Dose for Patients with a Brain Disease at the Emergency Center Education Program for Professionals in Radiation Emergency Medicine

Abstract

According to the report of the International Commission on Radiological Protection (ICRP), an exposure dose is recommended that is necessary and as small as possible to reduce both exposure and the number of exposed people as much as possible (as low as reasonably achievable, ALARA). Measures should be taken to comply with the basic concept of optimization. In practice, however, some of the patients, transported to the emergency center, often require multiple radiological examinations such as portable imaging, computed tomography (CT) scan and angiography. An increase of radiation exposure is a concern for patients. By inserting the thermoluminescent dosimeter (TLD) into a tissue-equivalent phantom, the equivalent dose at each site in the actual test, including the effective dose for the whole body was evaluated. The head dose in the head three dimensions digital subtraction angiography(3D-DSA) analysis was 8.957 mGy, and the dose in the salivary gland was higher than that in the head (11.44 mGy). The exposure range along the body axis during the head 3D-DSA imaging included the cervical area. The parotid gland is because of the short distance to the X-ray tube as compared to the head, showed a high value. According to the total equivalent dose among three test types, the head dose was the highest (49.3 mGy; target organ). This value is lower than the threshold (3 Gy) for temporary hair loss, as proposed in ICRP Publication 59, and radiation failure was considered less likely to occur. The results of calculation of the dose at each site from the TLD dosimeter data showed an effective dose in each examination: head portable imaging 0.06 mSv, head CT imaging 0.84 mSv, head 3D-DSA imaging 0.4 mSv, and total 1.3 mSv. The dose was found to decline sharply in the organs of the trunk because they were away from the range of radiation exposure. With a head X-ray examination, the body area below the sternum does not appear to contribute significantly to the effective dose. In order to perform optimization of ALARA measures as well as radiation dose, because it is necessary to know the exposure dose in each of the X-ray examination, to determine the equivalent dose or effective dose in each body part using a tissue-equivalent phantom .In future, I am planning to evaluate the equivalent dose and effective dose at each site, including imaging of other organs.