gms | German Medical Science

Objectives/Interrogation: Computed tomography(CT) imaging is often required for accurate diagnosis and treatment because of the complicated joint structure when trauma or disease occurs. There is a risk of exposing the main organs (brain, eye, thyroid, thymus, testis or ovary) to radiation exposure at the time of shooting. In the extremities, the use of recently developed mobile CBCT may reduce the risk of radiation exposure. The purpose of this study was to compare the radiation dose of major organs between mobile CBCT and MDCT and to evaluate the safety and usefulness of CBCT.

Methods: This is a prospective voluntary randomized study. This study was designed for adults who require CT scans for hand and foot disease or trauma from August 2017 to March 2018. The patients were divided into two groups of 20 patients each. Mobile CBCT was performed in group A and MDCT was performed in group B. Reference point corresponding to the major organs (brain, eye, thyroid, thymus, or testis or ovary) was set and attached a thermoluminescent dosimeter chip (TLD chip). After CT scan, the radiation dose irradiated on the TLD chip was measured.

Results and Conclusions: The surface dose at the center was not significantly different between group A and B. In hand CT scan, the surface dose of brain, eye, thyroid, and thymus was found to be 0.0022mGy, 0.0025mGy, 0.0038mGy, 0.0049mGy and 0.0023mGy respectively, in group A, while average dose of 0.5046mGy, 0.5255mGy, 0.1482mGy, 0.0909mGy and 0.0062mGy in group B. And there was a statistically significant difference between the two groups. In foot CT scan, Surface dose in gonads was 0.0032mGy in group A and 0.0443mGy in group B, which was lower in group A, which was statistically significant. The use of mobile CBCT in the CT of the hand and foot may reduce unnecessary radiation exposure to nearby organs other than the site. New studies are needed to reduce the radiation exposure of adjacent organs during the CT scan of the central part of the body adjacent to the critical organs such as the clavicle, spine, and pelvis. In the orthopedic area, it is considered that the conventional MDCT for extremity can minimize the damage caused by radiation exposure by performing radiation shielding on the part other than the center of scan.