Couch modeling optimization for tomotherapy planning and delivery. Issue 8 (25th July 2019)

• Record Type: Journal Article
• Authors: Okada, Wataru; Tanooka, Masao; Sano, Keisuke; Shibata, Mayuri; Doi, Hiroshi; Miyazaki, Masayoshi; Nakahara, Ryuta; Sueoka, Masaki; Suzuki, Hitomi; Fujiwara, Masayuki; Inomata, Taisuke; Yamakado, Koichiro
• Is Part Of: Journal of applied clinical medical physics. Volume 20:Issue 8(2019)
• Page Start: 114
• Page End: 121
• Publication Date: 2019-07-25
• Subjects: TomoTherapy -- couch modeling -- treatment planning system -- planning support system; Medical physics -- Periodicals; Clinical medicine -- Periodicals; Health Physics; Clinical Medicine; Electronic journals; Periodicals; Periodicals; Fulltext; Internet Resources; 610.153
• DOI: 10.1002/acm2.12686
• Languages: English
• ISSNs: 1526-9914

Abstract

Abstract: We sought to validate new couch modeling optimization for tomotherapy planning and delivery. We constructed simplified virtual structures just above a default setting couch through a planning support system (MIM Maestro, version 8.2, MIM Software Inc, Cleveland, OH, USA). Based on ionization chamber measurements, we performed interactive optimization and determined the most appropriate physical density of these virtual structures in a treatment planning system (TPS). To validate this couch optimization, Gamma analysis and these statistical analyses between a three‐dimensional diode array QA system (ArcCHECK, Sun Nuclear, Melbourne, FL, USA) results and calculations from ionization chamber measurements were performed at 3%/2 mm criteria with a threshold of 10% in clinical QA plans. Using a virtual model consisting of a center slab density of 4.2 g/cm 3 and both side slabs density of 1.9 g/cm 3, we demonstrated close agreement between measured dose and the TPS calculated dose. Agreement was within 1% for all gantry angles at the isocenter and within 2% in off‐axis plans. In validation of the couch modeling in a clinical QA plan, the average gamma passing rate improved approximately 0.6%–5.1%. It was statistically significant ( P < 0.05) for all treatment sites. We successfully generated an accurate couch model for a TomoTherapy TPS by interactively optimizing the physical density of the couch using a planning support system. This modeling proved to be an efficient way of correcting the dosimetric effects of the treatment couch in tomotherapy planning and delivery.