title: Clinical evaluation of an immbolization system for stereotactic body radiotherapy using helical tomotherapy.
abstract: In this study, a clinical evaluation of the Body Pro-Lok™ System combined with the TomoTherapy megavoltage computed tomography (MVCT) was performed for lung and liver stereotactic body radiotherapy (SBRT) to reduce interfractional setup uncertainty. Twenty patients treated with 3-5 fractions of SBRT were analyzed retrospectively. The Body Pro-Lok™ system was used in both CT simulation and during patient treatment setup. Patients were immobilized with a vacuum cushion placed posteriorly over the thoracic region, an abdominal compression plate, and a knee and foot sponge. Pretreatment MVCT scans of the TomoTherapy HI-ART II unit were fused with the planning kVCT before delivery of each fraction to determine the interfractional setup error. A total of 84 shifts were analyzed to assess the interfractional setup accuracy. Results showed that the mean interfractional setup errors and standard deviations were -0.9 ± 3.1 mm, 1.2 ± 5.5 mm, and 6.5 ± 2.6 mm for lateral (IEC-X), longitudinal (IEC-Y), and vertical (IEC-Z) variations, respectively. The maximum motion was 17.1 mm in the longitudinal direction. When all 3 translational coordinates were analyzed, a mean composite displacement vector of 8.2 ± 2.0 mm (range 4.1-11.7 mm) was obtained for all patients. Based on the findings, image-guided SBRT using the Body Pro-Lok™ system in conjunction with the MVCT of TomoTherapy is capable of minimizing interfractional setup error and improving treatment accuracy.
authors.affiliation: Department of Radiation Oncology, School of Medicine, Cancer Therapy and Research Center, The University of Texas Health Science Center-San Antonio, San Antonio, TX 78229, USA. gutierrezan@uthscsa.edu
authors.forename: Alonso N
authors.initials: AN
authors.lastname: Gutiérrez
authors.forename: Sotirios
authors.initials: S
authors.lastname: Stathakis
authors.forename: Richard
authors.initials: R
authors.lastname: Crownover
authors.forename: Carlos
authors.initials: C
authors.lastname: Esquivel
authors.forename: Chengyu
authors.initials: C
authors.lastname: Shi
authors.forename: Niko
authors.initials: N
authors.lastname: Papanikolaou
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D007103:Immobilization / Q000295:instrumentation*; D008113:Liver Neoplasms / Q000601:surgery*; D008175:Lung Neoplasms / Q000601:surgery*; D016634:Radiosurgery / Q000295:instrumentation*; D020266:Radiotherapy, Conformal / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome