Program Information
Standard Field of View (sFOV) as Compared to Extended Field of View (eFOV) CT Image Based Treatment Planning
B Liu1*, D Zhang2 , B Bai3 , A liu4 , J Wong5 , (1) City of Hope Medical Center, Duarte, CA, (2) Toshiba America Medical Systems, Tustin, CA, (3) Toshiba America Medical Systems, Tustin, CA, (4) city of Hope Medical Center, Duarte, CA, (5) City of Hope, Duarte, CA
Presentations
SU-I-GPD-J-50 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose: To evaluate the dosimetric impact of treatment plans based on extended field of view (eFOV) as compared with standard field of view (sFOV) images acquired by Toshiba’s Aquilion Large Bore (LB) CT scanner.
Methods: Toshiba’s Aquilion LB CT scanner provides a 90cm gantry aperture with 70cm sFOV, and 85cm eFOV. Using this CT scanner, we simulated 3 scenarios: A solid water phantom (10x30x40 cm) was positioned at (a) the anterior of the sFOV with phantom within the sFOV; (b) the anterior of the sFOV but 3cm of the phantom is beyond the boundary of the sFOV; and (c) the center of sFOV. A 3D and a rapidArc plan were made based on CT of scenario (c), then copied to the CT images of scenarios (a) and (b), based on rigid-body registration, with the eFOV used for scenario (b). Dose calculations for these 3 scenarios were compared.
Results: Dose calculation of 3D and rapidArc plans for scenarios (a) and (c) are essentially the same. Whereas for scenario (b) using eFOV, in which the CT image is distorted and the HU is clearly different for the phantom part that is beyond the sFOV border, the dose calculation differs by about 2% from the dose calculation based on scenario (a) or (c), in which phantom is completely within sFOV.
Conclusion: Toshiba's LB CT provides accurate dose calculation within 70cm sFOV. However, phantom study shows that plans based on eFOV may have 2% dose error for eFOV that is 3cm beyond the sFOV boundary.
Funding Support, Disclosures, and Conflict of Interest: This paper is based on the collaboration of City of Hope and Toshiba America Medical Systems, using Toshiba's Aquilion Large Bore CT scanner
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