OBJECTIVE: To establish standards for determining local, regional, and national Dose Reference Level in Brazil, according to clinical indication in CT procedures.
JUSTIFICATION: The present work proposes the development of a pilot program to establish standards for data collection required for determination of diagnostic reference level associated to CT clinical indication. This study was implemented in accordance to the statements of the Bonn: Call for Actions for Radiological Protection and aims to improve patient safety regarding exposure to ionizing radiation in Brazil,
METHODS: The methodology is characterized as observational, cross-sectional, and multicenter study, including 15 hospitals in 8 states in Brazil, from July to September 2021. The data collection was done using specially designed Excel spreadsheets and Google Forms. Demographic and procedure-dependent information were recorded from hospital information systems. Technical and dose related information were collected from DICOM headers. These data from different brands of scanners were validated by local hospital supervisors. Samples of Structured Dose Report were verified. Reported data included patient´s age, gender, weight, height, CT scan modality, clinical indication, DLP per series, CTDIvol, voltage, current, use of TCM, use of iterative reconstruction, pitch, range, contrast administration, calibration phantom type (16/32), slice thickness and Automatic Exposure Control. A total of 10 clinical indications for 5 anatomical areas (head, cervical spine/neck, chest, abdomen-pelvis, chest-abdomen-pelvis) were identified. The descriptive statistical analysis of the demographic and DLP and CTDI-vol data was done using boxplot graphics.
RESULTS: The minimum and maximum value of 3rd quartiles for CTDIvol (in mGy) and DLP (in mGy.cm) for the most frequent clinical indications in the evaluated sample (total of 885 adult patients) were: headache: N=206, CTDIvol (33.9, 59.8), DLP (702.5, 1034.3); kidney stones: N=138, CTDIvol (7.7, 9.2), DLP (422.6, 510); pneumonia: N=132, CTDIvol (7.1, 25), DLP (271.3, 1232); N=83, sinusitis: CTDIvol (9.8, 27.5), DLP (195.8, 521.6); and cranial trauma: N=71, CTDIvol (35.3, 91.3), DLP (626.1, 1491.1). Brazilian National Health Surveillance Agency recommends as a standard patient the weight range of 60 to 75 kg and height range of 160 to 175 cm. However, in the preliminary sample, the patients demography showed a second prevalent weight range, from 75 to 90 kg and a height range less than 160 cm, especially in women.
CONCLUSION: This project is pioneering the determination of dose level by clinical indication for CT. examinations in the country. Data will continue to be collected and further analysis will be carried out.
Keywords: Dose local level; Computed tomography; Clinical indications; Patient safety; Radiological protection