Objective: This study aims to establish diagnostic reference levels and radiation-induced risk for the diagnostic CT-scans and the radiotherapy planning CT-scans of the thorax in the regional hospital of Agadir, Morocco.
Material and Method: Data from two groups of patients undergoing thoracic CT-scans with either diagnostic CT-scans (G1, n=120) or Radiotherapy planning CT-scans (G2, n=120) are collected. All acquisitions were helical. DRLs is calculated for each type of thoracic CT-scan by estimating the 75% percentile of the CTDIvol and the DLP. The total cancer risk RC was calculated according to the ICRP publication 103.
The data are statistically analyzed by SPSS Statistics V21.0. The Pearson’s rank correlation coefficient is chosen to study the relationship between the following parameters: DLP, CTDIvol, effective dose, and the cancer risk.
Results: DRLs in terms of CTDIvol and DLP for radiotherapy planning of thorax were 19.37mGy and 851.9 mGy.cm respectively. In diagnostic CT-scans, DRLs in terms of CTDIvol for pulmonary embolism, infectious lung disease,Chronic Obstructive Pulmonary Disease (COPD) were 11.13mGy, 10.26mGy, and 7.37mGy respectively, and DRLs in terms of DLP were 417,73 mGy.cm, 451,9 mGy.cmand 317,78 mGy.cmrespectively. The cancer risk for radiotherapy planning CT-scans is ranged between 209 and 1564 with a mean value of 715 per 1 million of CT-scan. For diagnostic CT-scans, the cancer risk is ranged between 199 and 626 with a mean value of 357 per 1 million for pulmonary embolism, between 238 and 668 with a mean value of 369 per 1 million for infectious lung disease, and between 130 and 393 with a mean value of 244 per 1 million for COPD.
Conclusion: Optimizing the doses received by patients in medical imaging, particularly CT, has become an obligation. Reviewing practices and procedures and promoting a radiation protection culture can help to better manage the radiation doses received by the public.
