All implemented guidelines include reference doses that are defined as diagnostic reference levels (DRLs) or guidance levels. Guidelines to optimize the protection of patients during CT procedures have been provided by various international organizations. However, modern CT scanners have a wide variety of exposure factors and involve techniques that allow dose optimization to the patient. Because of this potential radiation risk from this increased use of CT makes it important that CT doses be kept as low as reasonably achievable. In spite of this constructive contributions of CT to modern healthcare, attention must also be given to the health risk associated with the ionizing radiation received during a CT exam. This lead to a substantial increase in the collective dose, as reported by international organizations (ICRP 2000 and United Nations Scientific Committee 2000). But we have to accept the fact that with the vast improvement of technology, patients benefited from a quicker and more accurate diagnosis and precise anatomic information for planning therapeutic procedures. However, CT can be responsible for the increase of carcinogenesis. Advances in CT imaging techniques have resulted in a significant increase in the frequency of CT examinations in both adult and children, replacing more and more radiographic examinations. The use of helical, multislice CT (MSCT) is rapidly growing due to technological improvements in the modern machines. The results of our study showed that the CTDIvol and DLP values taken from images done using the protocols set by the Ct machine developers are higher than the reference levels which indicate that manufacturers are focusing their efforts toward improving image quality rather than the minimizing the dose that can be given to the patient. After Dose optimization the CTDIvol and DLP values were significantly reduced to have lower values than the reference levels. For Group I, the CTDIvol and DLP values were higher than the reference levels. Measured (CTDIvol, DLP) were compared to international reference levels. Each study was also reviewed for image quality. For each examination the weighted volume CT dose index (CTDIvol) and dose length product (DLP) were recorded and noise is measured.
We were able to adjust the adjustable factors such as noise index, scan time, pitch, rotation time and slice thickness. Group II: 243 patients were imaged according to the protocols set by our team after optimization. 383 patients in Group I: were imaged according to the protocols set by the manufacturer. For each type of CT examination, two groups of patients were considered. We included 626 patients in this study and investigated radiation dose for three anatomical regions, head, chest and abdomen and pelvis. A single detector CT was considered, to represent typical practice in King Hamad University Hospital. The purpose of this study is to find an optimization approach to minimize the absorbed dose to adult patients undergoing CT examination, while maintain the diagnostic image quality.
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