PARENT SESSION
1:30 PM to 3:30 PM
Wednesday, April 24, 2002
Poster Session 27 Models and Theories
Room: Nevada Exhibition Center

(P32-313) An image guided small animal conformal radiation research platform.

Wong, John^*,1, Jaffray, David¹, Siewerdsen, Jeff¹, Oldham, Mark¹, Laub, Wolfram¹, Armour, Elwood¹, ¹ Deptment of Radiation Oncology, Royal Oak, MI

ABSTRACT-
Modern radiation therapy employs sophisticated three-dimensional (3D) imaging and planning methods to deliver very high doses that conform tightly to tumors while sparing surrounding critical organs. Inadvertently, the dose distributions to the tumor and normal tissues can be much more non-uniform than conventional treatment. Thus, traditional understanding of radiation response of tumor and normal tissues based on uniform irradiation no longer applies. At present, animal radiation research does not bear geometric resemblance to human treatment and cannot address adequately the effectiveness and radiation toxicity of new conformal strategies. The goal of our research is to develop a small animal radiation research (SARR) platform that mimics modern human treatment. This paper presents the design concepts of the isocentric SARR platform to accommodate laboratory animals ranging from mice to rabbits. The intent is to study (1) radiation response of tumor and normal tissues that mimics conformal treatment, (2) specific interactions of the tumor with its normal tissue environment and (3) the efficacy of "targeted" gene therapy. Imaging, delivery and treatment planning capabilities will be "down-sized" to ~ 200 to 100 m resolution. On-board 3D x-ray imaging based on cone-beam CT with a flat-panel amorphous silicon detector has been achieved. Orthovoltage x-rays or gamma ray sources are being studied to confine energy deposition. Three dimensional treatment planning will be performed using the well-benchmarked EGS4 Monte Carlo code. Most challenging is the significant reduction of radiation output as the field size decreases. Several approaches are under investigation which include the use of multiple radiation sources, novel focussing x-ray lens and magnetic field confinement. Results from our modeling and dosimetry experiments will be shown.

KEYWORDS: conformal, therapy, animal