Development of a Micro-Computed Tomography–Based Image-Guided Conformal Radiotherapy System for Small Animals

Department of Radiation Oncology, Stanford University, Stanford, CA 94305-5847, USA.
International journal of radiation oncology, biology, physics (Impact Factor: 4.26). 09/2010; 78(1):297-305. DOI: 10.1016/j.ijrobp.2009.11.008
Source: PubMed


To report on the physical aspects of a system in which radiotherapy functionality was added to a micro-computed tomography (microCT) scanner, to evaluate the accuracy of this instrument, and to and demonstrate the application of this technology for irradiating tumors growing within the lungs of mice.
A GE eXplore RS120 microCT scanner was modified by the addition of a two-dimensional subject translation stage and a variable aperture collimator. Quality assurance protocols for these devices, including measurement of translation stage positioning accuracy, collimator aperture accuracy, and collimator alignment with the X-ray beam, were devised. Use of this system for image-guided radiotherapy was assessed by irradiation of a solid water phantom as well as of two mice bearing spontaneous MYC-induced lung tumors. Radiation damage was assessed ex vivo by immunohistochemical detection of gammaH2AX foci.
The positioning error of the translation stage was found to be <0.05 mm, whereas after alignment of the collimator with the X-ray axis through adjustment of its displacement and rotation, the collimator aperture error was <0.1 mm measured at isocenter. Computed tomography image-guided treatment of a solid water phantom demonstrated target localization accuracy to within 0.1 mm. Gamma-H2AX foci were detected within irradiated lung tumors in mice, with contralateral lung tissue displaying background staining.
Addition of radiotherapy functionality to a microCT scanner is an effective means of introducing image-guided radiation treatments into the preclinical setting. This approach has been shown to facilitate small-animal conformal radiotherapy while leveraging existing technology.

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Available from: Phuoc T Tran
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    • "Discussion RT is a standard treatment for GBM as well as other brain and head and neck cancers. Until the development of commercially available small animal image-guided microirradiators like the SARRP, preclinical research in these disease sites was limited by small animal radiation techniques that lagged decades behind current clinical practice in the precise targeting of tumor volumes and the sparing of normal tissue [2] [3]. Previously, only superficial tumors could be targeted with any degree of precision using crude lead blocking to shield the surrounding normal tissue. "
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    • "Recognizing the pressing need to bridge this translational gap for radiation research, several groups have initiated development of small animal irradiators [5] [6]. Our group has developed a small animal radiation research platform (SARRP) incorporating: 1) a gantry and robotic stage that supports isocentric and noncoplanar conformal irradiation and 2) on-board cone-beam CT (CBCT) guidance to facilitate coregistration with other imaging and accurate repositioning for fractionated therapy [7]. "
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    Full-text · Article · Apr 2012 · Translational oncology
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