Enabling remote medical physics services for medical accelerator quality assurance through a novel, table-top imaging device

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Executive Summary Radiation Therapy is an effective component of the treatment strategy for patients suffering from cancer. Advanced techniques such as intensity modulated radiation therapy (IMRT), image-guided RT (IGRT), stereotactic body RT (SBRT) and stereotactic radiosurgery (SRS) improve outcomes and are delivered using medical linear accelerators (i.e., ‘linacs”). SBRT is especially appealing given that the precise treatments are delivered in 1-5 daily treatment fractions, as opposed to the 20-40 fractions required for conventional techniques. Providing SBRT in rural settings can improve access by administering these precise, abbreviated treatments to patients who have difficulty traveling to large, regional medical centers. Further, adoption of automated techniques for quality control and enhanced tele-dosimetry can support peer review, improve quality, reduce dependence on (local) expertise and reduce operating costs. The quality assurance (QA) that medical physicists provide is critical for safe treatments, yet there is a shortage of qualified medical physicists (QMPs), both in the US and globally. At the same time, more centers are introducing modern techniques that are more precise but intrinsically have more risk, due the high doses and geometric precision required. There is widespread noncompliance with industry standard QA protocols in the US and internationally. Existing QA devices have not evolved sufficiently to provide the precision, versatility and efficiency that is needed for high precision RT. Given these exacerbated safety risks, the market needs a paradigm shift in how QA is performed in modern RT. Wild Dog Physics (WDP) proposes to design and test a new-generation QA device that addresses these unmet medical needs. When complete, it will be more precise, efficient, and comprehensive than any QA solution currently on the market. The proposed project seeks to develop a clinical prototype to be tested in the Radiation Therapy clinic at the University of Kentucky, as well as regional partner organizations located in rural, underserved areas. The prototype will be developed using the following milestones: Design and build i) a novel, a small-form-factor optical tunnel (SFFOT), ii) a laminated side wall with a scintillating phosphor screen and ‘switchable film’ outer layer to facilitate ambient light rejection and iii), a hybrid beam quality / compact CT phantom. The project will culminate with the construction of an integrated prototype that will be tested for technical and clinical performance. Towards this end, the specific aims of this project are: Specific Aim 1: Build and test the 3 primary subcomponents of an integrated device; a) a SFFOT that can collect an image(s) of the entire useful interior surface, transmit the image(s) to an electronic camera sensor through a small form-factor (< 5 cm diameter) passive optical chain; b) a laminated side wall consisting of an outer, electronically polarizing optical layer, and an inner radio-luminescent layer, and c) a hybrid ‘dose phantom’ to be integrated onto one side of the device which will serve as a tissue-equivalent phantom so that beam quality metrics can be monitored and to host CT image quality test objects. Specific Aim 2: Construct and test a clinical prototype; The system’s ability to monitor machine performance in a clinical setting will be validated. Sensitivity to detecting changes in relative and absolute radiation output, as well as field edge positioning will be measured, with success criteria defined as 0.5% and 0.5 mm. Data acquisition time for monthly QA tests will be measured and success defined as less than 30 minutes. The consolidation of multiple device functions combined with the ease of use and measurement precision enable a paradigm shift in how medical physics services and quality assurance are rendered. Sparse but efficient daily QA protocols will be replaced with comprehensive data collection and automated analysis, at no additional cost in time or staffing. High precision radiation treatments can be safely brought to rural and underserved areas, with safety, efficiency and precision improved in any center using the innovation. To date, we have established the feasibility of constructing a single device that can acquire comprehensive QA metrics in less than 60 minutes. Presently, all subsystems have been tested and found to perform as required. A three-dimensional prototype has been built and is being validated by our clinical partner at the UK Radiation Medicine department. WDP is in the process of seeking SBIR Phase 2 funding to further develop the technology to the point of commercialization.