Calculation method for novel upright CT scanner isodose curves

• Published in: Journal of applied clinical medical physics Vol. 25; no. 7; pp. e14377 - n/a
• Main Authors: Kissick, Michael W., Panaino, Costanza, Criscuolo, Anthony, Hayes, John, Hoffman, Carson, Mackie, Rockwell, Schreuder, Andries N.
• Format: Journal Article
• Language: English
• Published: United States John Wiley & Sons, Inc 01.07.2024
• Subjects: Aluminum; Atoms & subatomic particles; Cancer therapies; CT isodose; CT upright tilting gantry; Design; Radiation therapy; Scanners; Simulation; TOPAS Monte‐Carlo modeling; United States > US; Massachusetts; TOPAS Monte‐Carlo modeling; CT upright tilting gantry; CT isodose
• ISSN: 1526-9914; 1526-9914
• DOI: 10.1002/acm2.14377

Purpose A computational method based on Monte‐Carlo calculations is presented and used to calculate isodose curves for a new upright and tilting CT scanner useful for radiation protection purposes. Methods The TOPAS code platform with imported CAD files for key components was used to construct a calculation space for the scanner. A sphere of water acts as the patient would by creating scatter out of the bore. Maximum intensity dose maps are calculated for various possible tilt angles to make sure radiation protection for site planning uses the maximum possible dose everywhere. Results The resulting maximum intensity isodose lines are more rounded than ones for just a single tilt angle and so closer to isotropic. These maximum intensity curves are closer to the isotropic assumption used in CTDI or DLP based methods of site planning and radiation protection. The isodose lines are similar to those of a standard CT scanner, just tilted upwards. There is more metal above the beam that lessens the dose above versus below isocenter. Conclusion Aside from the orientation, this upright scanner is very similar to a typical CT scanner, and nothing different for shielding needs to be done for this new upright tilting CT scanner, because an isotropic scatter source is often assumed for any CT scanner.