| Summary: | 碩士 === 元培醫事科技大學 === 醫學影像暨放射技術系碩士班 === 104 === Lung cancer is ten leading causes of death in Taiwanbased on the statistical data from the Ministry of Health and Welfare in 2014.,
The earlier it is diagnosed the better the chance of getting early and effective treatment.Currently, low-dose multi-slice computed tomography (MSCT) is considered to be the most widely applicable modality for evaluation of lung cancer. The aim of this study was to compare the effective dose for imaging of lung within three different Medical Imagiing Systems.
This retrospective study was conducted fromJanuary 2015 to March 2015at Mackay Memorial Hospital. One hundred patients were randomly selected to perform lung CT scan without injecting contrast agent by three different computed tomographyscanner (A, B, C). f The CT settings were selected the procedure of low-dose lung cancer screening. The CT parameters were set as 120 kVp fixed tube voltage, 20 mAs tube current,and 1 mm slice thickness under automatic exposure control (AEC) (slice thickness) is. Each lung CT imaging was then examined for evidence of simplex lesions mist frosted glass nodules by two experienced radiologists.
The results showed that the volume CT dose index (CTDIvol) was significant lower at Group A (1.31 ± 0.22 mGy) than Group B (1.71 ± 0.29 mGy) and Group C (1.94 ± 0.43 mGy) (p <0.0001), The mean effective dose (E) were significant lower at Group A (0.63 ± 0.12 mSv) than Group B (0.92 ± 0.18 mSv) than Group C (0.95 mSv ± 0.23 mSv). The image interpretation of the smallest nodule diameter was 1.6 mm (Group A), 1.6 mm (Group B) and 1.4 mm (Group C). Patients with the body mass index (BMI) < 24 kg/m2, we observed the average effective dose was 0.58 mSv (n = 26, Group A), 0.81mSv (n =24, Group B), 0.85mSv (n =28, Group C). However, patients with BMI ≥ 24 kg/m2 we found the average effective dose was 0.68 mSv (n = 24, Group A), 1.02 mSv (n = 26, Group B), 1.09 mSv (n = 22, Group C).
The results of this study showed that the tube current, tube voltage, rotation time, collimation, pitch, the parameter of reconstruction, scout image, scan length BMIwould affect the radiation dose and image quality. We suggested that reducing tube current, tube voltage scan length and, increasing pitch and detectors, fasting scan time and setting automatic exposure control would reduce radiation dose and maintain good image quality while screening lung caner by using MSCTnt
Keywords: Low-dose CT, lung nodules, image quality, effective dose
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