Radiochromic film use to record dose profile variations in chest CT scan

The CT scans generate higher doses in patients than those caused by other types of diagnostic radiology using the attenuation of X-ray beams. Technological advances have increased the clinical applications of computed tomography (CT) and consequently the demand for these exams. Dose reduction strategies are difficult to implement because of a lack of proper guidance on the CT scanning. However, CT offers the possibility of adjusting the image acquisition parameters according to the patient physical profile and the diagnostic application for which it is intended to scan. Knowledge of the dose distribution is important when thinking about varying the acquisition parameters to reduce the dose. In this work was used a PMMA chest phantom to observe the dose deposition in 5 areas. Radiochromic film strips were placed inside the chest phantom, in peripheral and in the central region. The phantom was placed in the scanner isocenter and it was performed the irradiation of its central region using a chest acquisition protocol. After the phantom CT scan the radiochromic film strips were processed for obtaining digital images. Digital images were reworked to obtain the dose variation profiles for each position. The results showed a wide variation in absorbed dose by the phantom, either within a same position along the length of the film strip, as in the comparison among the five regions which the strips are placed. In this second case the dose variations were even greater. (author)