Toraks, Abdominopelvik ve Torako-abdominopelvik BT Tetkiklerinde z-Aksta (Kraniokaudal Düzlemde) Standart Tarama Uzunluğundan Daha Fazla Mesafe Taranmasının Nedenlerinin Araştırılması
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Yar O. “Investigation the Causes of Scanning Beyond the Standard Scanning Length in z-Axis (Craniocaudal Plane) in Thorax, Abdominopelvic and Thoraco-abdominopelvic CT Examinations ”, Hacettepe University, Faculty of Medicine, Department of Radiology, Thesis in Radiology, Ankara, 2018. The aim of this study is to determine the frequency of excessive z-axis coverage of single-phase thorax CT, abdominopelvic CT, thoraco-abdominopelvic CT, stone protocol abdomen CT and pulmonary CT angiography examinations and evaluate the factors that may be associated with extra scanning in CT. The above-mentioned CT examinations which performed in Hacettepe University Hospitals between March 1, 2018 and April 1, 2018 during 24 hours of day are included in our study. The number of cases included in the study is 1531 and the number of examinations is 2032. According to accepted reference points determined for CT examinations, the lengths of over-scanned z-axis are measured. Excessive scan frequency, the ratio of over-scanned length to the acceptable scan length are evaluated according to the gender, age, type of examination, indication of examination, the time of acquisition of the examination, the presence of some factors that may affect the determination of the scan range in topogram, the throughput of CT equipments, the experience of the attendant CT technicians. In terms of the cranial side, 80.2% (n: 1631) of the examinations were scanned in acceptable range while 18.4% (n: 373) of the examinations were over-scanned and 1.4% (n: 28) of examinations were less-scanned in z-axis. %51,2 (n:1039) of the examinations were scanned in acceptable range in the caudal side, while %48,5 (n: 985) of the examinations were over-scanned and %0,3 (n: 8) of examinations were less-scanned in z-axis. While the frequency of over-scanning in z-axis was not significantly different between genders, statistically significant differences in terms of over-scanning in z-axis were obtained between the age groups, types of examinations, indications for examination, some conditions that may affect determination of the scan range in topogram, acquisition time of CT examination and technician’s experience. Taking measures for cases and settings with high over-scanning frequency will reduce the effective radiation dose of exposed cases. Continuous education programs for radiologists and technicians regarding radiation safety should be established in radiology departments. Keywords: CT, extra z-axis coverage, radiation safety.