Dose profile variation in head and neck CT scan using an anthropomorphic phantom

The use of ionizing radiation in medical diagnosis has generated an increase in the absorbed dose in the exposed population each year. In the USA, since the years 2008, Computed Tomography (CT) has become the technique that most contributed to the dose increase in the population. In the Brazilian Universal Health System (Sus), between 2001 and 2011, there was an increase of approximately of 14.7% in the number of head CT tests. The use of phantoms in CT dosimetry studies helps to optimize acquisition protocols aiming at reducing the dose absorbed by the patient. In this work, CT tests were performed to determine the dose profile in an adult patient using routine acquisition protocol for head, using an anthropomorphic head and neck phantom. A radiochromic film strip was used to record the absorbed dose variation along the longitudinal axis of the phantom from the head top to the first thoracic vertebra. The scans were performed on a Ge CT scanner of 64 channels, Light speed VCT model, in helical mode. The recorded absorbed dose values ranged from 16.40 to 25.60 mGy. The CTDI_vol values reported by the CT scanner were below the reference level for head CT scans according to the normative instruction of the Brazilian Ministry of Health. (author)