Application of full-field organ dose modulation on cervical- thoraco-abdominopelvic contrast-enhanced computed tomograph
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ORIGINAL ARTICLE
Application of full‑field organ dose modulation on cervical‑ thoraco‑abdominopelvic contrast‑enhanced computed tomography Yongxia Zhao1 · Xue Geng2 · Dongxue Li1 · Tianle Zhang1 · Yize Xu1 Received: 20 August 2020 / Accepted: 9 October 2020 © Japan Radiological Society 2020
Abstract Background and objective To study the radiation dose and image quality on the use of full-field organ dose modulation (ODM) on cervical-thoracic-abdominal-pelvic contrast-enhanced computed tomography (CT) scanning on female chemotherapy patients. Methods Eighty female chemotherapy patients undergoing cervical-thoracic-abdominal-pelvic contrast-enhanced CT were prospectively enrolled and randomly divided into two groups: group A and group B, each with 40 patients. Full-field ODM technique was used on group A and regular scanning patterns were used on group B. We calculated and recorded the signalto-noise ratio (SNR), contrast-to-noise ratio (CNR), subjective scores, mean tube currents of the anterior, left, posterior, and right aspects of the thyroid, breast, and ovary layers of all the images. The CT dose index volume (CTDIvol) and doselength product (DLP) of each patient were recorded and the effective radiation dose (ED) was calculated. The above data were statistically analyzed. Results There were no statistically significant differences in the SNR, CNR, and image quality scores of the thyroid, breast, and ovary layers of groups A and B during the arterial and venous phases (P > 0.05). The tube current on the anterior, left, posterior, and right aspects of the thyroid, breast, and ovary layers during the arterial and venous phases (thyroid: 324.46 ± 53.2 and 327.97 ± 61.34; breast: 243.13 ± 50.04 and 248.32 ± 60.33; ovary: 332.28 ± 71.50 and 339.78 ± 76.69; respectively) of group A were (statistically) significantly lower than those of group B (thyroid: 407.60 ± 96.81 and 402.73 ± 90.15; breast: 313.00 ± 106.68 and 315.20 ± 106.73; ovary: 457.78 ± 106.56 and 459.63 ± 106.27; respectively) (P 0.05
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Scanning parameters Group A was examined with full-field ODM and group B was given routine scan protocol. ODM is a tube current modulation technique to reduce the tube current (mA) when the X-ray tube is in the anterior position relative to the patient. This technique builds on the SmartmA AEC feature to further reduce the dose to radiosensitive organs. When ODM is enabled, the mA is reduced during an angular range of 90 degrees for head protocols and 120° for body protocols. ODM was applied to the entire scan range in our study. Other scanning parameters of the two groups were consistent: tube voltage was 120 kVp, a three-dimensional Smart mA modulation technique was used, the mA ranged from 200 to 600 mA, the Gantry rotation time was 0.5 s, the noise index was 6.0, at a thickness of 2.5 cm, and the scan field of view was 50 cm × 50 cm, the pitch of 0.992:1; the matrix of 512 by 512; the detector coverage was 80 mm; the patient table speed was 158.75 mm/s; the frame rotation speed was 0.5 s/circle; and the recons
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