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The Relationship of CT Mean Modulated Dose-Length Product and Body Mass Index During Routine 18F- FDG PET/CT Studies
International Journal of Medical Imaging
Volume 3, Issue 5, September 2015, Pages: 94-97
Received: Oct. 11, 2014; Accepted: Oct. 29, 2014; Published: Aug. 7, 2015
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Simon Atkins, The Institute of Nuclear Medicine, University College Hospital London, London, NW1 2BU, UK; Epworth Radiation Oncology, Epworth Healthcare, Richmond, VIC 3121, Australia
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AIM: To determine the relationship of body mass index (BMI) on the mean dose length product (DLP) values acquired using modulated (automatic exposure control) and standard computed tomography (CT) scanning protocols as part of a typical 18F-FDG PET/CT study. METHODS: A retrospective study was performed and the dose-length product and BMI values from routine 18F-FDG PET/CT scans of 51 patients were recorded. The scans were performed on a 16-slice PET/CT scanner by using an automatic exposure control (AEC) system. DLP, BMI, age, sex and number of bed positions were documented for each patient. RESULTS: Twenty-four women and 27 men were included in the study (mean age, 52.5 years). The mean BMI was 24.76 kg/m2. The mean modulated DLP was 528.25 mGy/cm. Patients were grouped according to BMI (normal: BMI <25, overweight: BMI 25 – 30, obese: BMI >30) and age (≤18 years, 19 – 59 years, ≥ 60 years). The mean modulated DLP decreased by 22.77% for patients in the normal BMI group (P < 0.001). The obese group of patient’s mean modulated DLP was 26.29% higher (P < 0.01). The DLP decreased by 22.43% for patients aged 60 years and above compared with patients in the 19 – 59 age group. CONCLUSION: The use of modulated scanning protocol significantly reduces the integrated dose received from a whole body CT scan for patients with a BMI < 25. Increasing patient size (BMI >25) significantly increases the integrated dose received. The possible change in body composition with age may also indicate a reduction in dose received from a whole body CT scan using AEC.
Dose-Length Product, Body Mass Index, Automatic Exposure Control
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Simon Atkins, The Relationship of CT Mean Modulated Dose-Length Product and Body Mass Index During Routine 18F- FDG PET/CT Studies, International Journal of Medical Imaging. Vol. 3, No. 5, 2015, pp. 94-97. doi: 10.11648/j.ijmi.20150305.12
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