EVALUATION OF RADIATION DOSE TO THYROID GLANDS DURING DIAGNOSTIC MAMMOGRAPHY; A COMPARISON OF CRANIO CAUDAL (CC) AND MEDIO LATERAL OBLIQUE (MLO) VIEWS.

Objectives: Mammogram plays a major role in diagnosing breast cancers in the medical imaging sector though it can cause a radiation hazard on thyroid gland. This study was design to determine the association of Entrance Surface Dose (ESD) for thyroid between the Cranio Caudal (CC) and Medio Lateral Oblique (MLO) projections. Methods: A total of 75 female patients with the mean age of 53.1 ? 8.9 years participated for the study. Breast was compressed in both the CC and the MLO views. ESD of the skin overlying thyroid was measured by an electronic pocket dosimeter at the level of the palpable thyroid cartilage. ESD for each projection, thickness of the compressed breast and the angle of the MLO view were recorded. The compression of breast thickness and the angle of MLO projections were evaluated with ESD of CC and MLO views. The data was analyzed using Minitab version 14.1. Results: All the patients were subjected to mammogram ESD of CC range from 2.4 to 8.3μSv/hr and ESD of MLO range from 2.1 to 9.5 μSv/hr. ESD values in MLO projections were significantly higher thanCC projections (p< 0.001). In addition, ESD values of CC and MLO projections are significantly increased with compression of breast thickness (CC: p = 0.032, MLO: p = 0.002). However, no significant associations were found between ESD and the angle of the MLO views (RMLO: p = 0.472, LMLO: p = 0.798). Conclusions: CC view might be effective for patients to be exposed to low amount of radiation to thyroid. In addition, radiation dose to the thyroid gland can be minimized, using proper compression of breast thickness