Dose Imaging Detectors for Radiotherapy Based on Gas Electron Multipliers

Period of Performance: 07/01/2009 - 02/28/2010


Phase 1 SBIR

Recipient Firm

Parttec, Ltd.
2620 N. Walnut Street, Suite 805
Bloomington, IN 47404
Principal Investigator


DESCRIPTION (provided by applicant): In this SBIR project, PartTec will develop a detector that can support the high precision requirements of Intensity Modulated Proton Therapy, the next-generation Proton Therapy. There are no detectors currently available that meet the design goals of this project, in particular high spatial and timing resolution. While efforts have been started in this area, there is no commercially available alternative to the detector anticipated by this proposal. Proton therapy has been offered with ever-increasing precision for more than 40 years. Proton therapy provides superior tumor control and vastly diminishes post-treatment side effects when compared to conventional external beam therapies, surgery and chemotherapy. Because of these substantial benefits, proton therapy is an important radiation therapy treatment option. Most solid tumors, particularly those located near critical structures, can be treated with proton therapy. The superior dose distribution of proton therapy allows treatment for patients for whom there was previously no option such as patients with recurrent cancers or patients who can no longer tolerate other therapies. Approximately 50% of children treated with proton therapy have reduced incidence of secondary malignancies and reduced risk of neuropsychologic and intellectual deficits. The proposed project is highly focused on producing a detector that will meet current needs of the Oncologists, Medical Physicists, Dosimetrists and Therapists who are delivering Proton Therapy to their patients. The next step in the Development of Proton Therapy is the Intensity Modulated Proton Therapy (IMPT). This innovation uses "pencil beam" scanning of the Proton Beam across the tumor, from one side to the other and from top to bottom. At the same time, the depth of the beam penetration is controlled, enabling its energy to be deposited into very small three-dimensional voxels within the tumor. Conventional Proton Therapy facilities with passive beam spreading and uniform scanning beams will also benefit from development of new, high precision detectors for on-line beam monitoring and quality assurance. In Phase I of this proposal PartTec will develop an innovative position sensitive Gas Electron Multiplier (GEM) detector system for two-dimensional dose imaging in particle therapy. PartTec believes such detectors will be capable of providing linear response, better than one millimeter spatial resolution, microsecond time resolution, and accurate reproduction of the Bragg peak shape if used as depth dose profilers. The GEM offers fast performance, robustness and flexibility in the detector design, allowing for various pickup electrode layouts and the option to cascade GEMs in order to improve the signal to noise ratio. Depending on the measurement requirements, 2D readout will be performed with either a CCD camera or segmented pickup electrodes and charge-integrating front-end electronics. In Phase II of this proposal, PartTec's research will be extended to include the depth dose (3D) profiling capabilities o such a detector. PUBLIC HEALTH RELEVANCE: All Medical Providers want to provide their patients with the best, most precise and safe cancer treatments available. The hope is for radiotherapy that destroys cancer cells while avoiding injury to non-cancerous cells. Proton Therapy, especially Intensity Modulated Proton Therapy (IMPT), offers that hope. Along with development of treatment delivery methods, there is the need for a new generation of detectors that monitor and report the precise alignment of the proton beam. In this SBIR project, PartTec, Ltd. will develop such a beam detector that will expand and improve overall treatment options for the public.