title: Physiologically gated micro-beam radiation therapy using electronically controlled field emission x-ray source array.
abstract: Micro-beam radiation therapy (MRT) uses parallel planes of high dose narrow (10-100 um in width) radiation beams separated by a fraction of a millimeter to treat cancerous tumors. This experimental therapy method based on synchrotron radiation has been shown to spare normal tissue at up to 1000Gy of entrance dose while still being effective in tumor eradication and extending the lifetime of tumor-bearing small animal models. Motion during the treatment can result in significant movement of micro beam positions resulting in broader beam width and lower peak to valley dose ratio (PVDR), and thus can reduce the effectiveness of the MRT. Recently we have developed the first bench-top image guided MRT system for small animal treatment using a high powered carbon nanotube (CNT) x-ray source array. The CNT field emission x-ray source can be electronically synchronized to an external triggering signal to enable physiologically gated firing of x-ray radiation to minimize motion blurring. Here we report the results of phantom study of respiratory gated MRT. A simulation of mouse breathing was performed using a servo motor. Preliminary results show that without gating the micro beam full width at tenth maximum (FWTM) can increase by 70% and PVDR can decrease up to 50%. But with proper gating, both the beam width and PVDR changes can be negligible. Future experiments will involve irradiation of mouse models and comparing histology stains between the controls and the gated irradiation.
authors.affiliation: University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Pavel
authors.initials: P
authors.lastname: Chtcheprov
authors.affiliation: University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Hadsell
authors.affiliation: University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Laurel
authors.initials: L
authors.lastname: Burk
authors.affiliation: University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Rachel
authors.initials: R
authors.lastname: Ger
authors.affiliation: University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.affiliation: University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Hong
authors.initials: H
authors.lastname: Yuan
authors.affiliation: University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Yueh Z
authors.initials: YZ
authors.lastname: Lee
authors.affiliation: University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Sha
authors.initials: S
authors.lastname: Chang
authors.affiliation: University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Jianping
authors.initials: J
authors.lastname: Lu
authors.affiliation: University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Otto
authors.initials: O
authors.lastname: Zhou
keywords: CNT Cathodes; Field Emission; MRT; Micro-beam Radiation Therapy; Physiological Gating