BACKGROUND: CT optimization has a special importance in children. Smaller body size accentuates the importance of patient positioning affecting both radiation dose and image quality. OBJECTIVE: To determine the effect of vertical positioning on organ dose, image noise and contrast in pediatric chest CT examination. MATERIALS AND METHODS: Chest scans of a pediatric 5-year anthropomorphic phantom were performed in different vertical positions (-6 cm to +5.4 cm) with a 64-slice CT scanner. Organ doses were measured with metal-oxide-semiconductor field-effect transistor (MOSFET) dosimeters. Image noise and contrast were determined from the CT number histograms corresponding to different tissues. RESULTS: Significant changes in organ doses resulting from vertical positioning were observed, especially in radiosensitive anterior organs. The breast dose increased up to 16% and the thyroid dose up to 24% in lower positions. The noise was increased up to 45% relative to the centre position in the highest and lowest vertical positions, with a particular increase observed on the anterior and posterior sides, respectively. Off-centering also affected measured image contrast. CONCLUSION: Vertical off-centering markedly affects organ doses and measured image-quality parameters in pediatric chest CT examination. Special attention should be given to correct patient centering when preparing patients for CT scans, especially when imaging children.
BACKGROUND: CT optimization has a special importance in children. Smaller body size accentuates the importance of patient positioning affecting both radiation dose and image quality. OBJECTIVE: To determine the effect of vertical positioning on organ dose, image noise and contrast in pediatric chest CT examination. MATERIALS AND METHODS: Chest scans of a pediatric 5-year anthropomorphic phantom were performed in different vertical positions (-6 cm to +5.4 cm) with a 64-slice CT scanner. Organ doses were measured with metal-oxide-semiconductor field-effect transistor (MOSFET) dosimeters. Image noise and contrast were determined from the CT number histograms corresponding to different tissues. RESULTS: Significant changes in organ doses resulting from vertical positioning were observed, especially in radiosensitive anterior organs. The breast dose increased up to 16% and the thyroid dose up to 24% in lower positions. The noise was increased up to 45% relative to the centre position in the highest and lowest vertical positions, with a particular increase observed on the anterior and posterior sides, respectively. Off-centering also affected measured image contrast. CONCLUSION: Vertical off-centering markedly affects organ doses and measured image-quality parameters in pediatric chest CT examination. Special attention should be given to correct patient centering when preparing patients for CT scans, especially when imaging children.
Authors: Mannudeep K Kalra; Michael M Maher; Thomas L Toth; Bernhard Schmidt; Bryan L Westerman; Hugh T Morgan; Sanjay Saini Journal: Radiology Date: 2004-10-21 Impact factor: 11.105
Authors: Ranish Deedar Ali Khawaja; Sarabjeet Singh; Atul Padole; Alexi Otrakji; Diego Lira; Da Zhang; Bob Liu; Andrew Primak; George Xu; Mannudeep K Kalra Journal: Radiat Prot Dosimetry Date: 2017-08-01 Impact factor: 0.972
Authors: C J Sullivan; K P Murphy; P D McLaughlin; M Twomey; K N O'Regan; D G Power; M M Maher; O J O'Connor Journal: Eur Radiol Date: 2014-12-13 Impact factor: 5.315