This proposal aims at developing advanced radiation detector materials for Time of Flight Positron Emission Tomography (ToF-PET) imaging by exploiting the novel concept of high performance multi-material radiation sensing heterostructures. These heterostructures will contribute to the development of next generation imaging technologies for diagnostic, monitoring and therapeutic applications, specifically, by substantially improving the capabilities of ToF-PET technology. These heterostructures will enable i) enhanced diagnostic power; ii) reduced risk to patients (dose efficiency); iii) increased procedural flexibility (i.e. planning of radiation dose strategies and reduced examination time); and eventually iv) direct ToF-PET imaging by rendering the currently time-consuming post-acquisition reconstruction stage obsolete. This effort will be supported by multi-disciplinary facilitation of the design, fabrication and characterisation of the heterostructures, in order to develop an advanced detector material solution for use in current and future ToF-PET detector modules. The output and impact of the research will be maximised through functional testing of the proposed heterostructure detector module. The proposal matches the aspirations of the EPSRC's Healthcare Technologies research theme by i) optimising treatment and care through effective diagnosis, patient-specific prediction and evidence-based intervention; ii) supporting the development of technologies to enhance efficacy, minimise costs and reduce risk to patients; and iii) bringing together a multidisciplinary team with expertise in material science, precision engineering and instrumentation, who will be further supported by external advisors, ToF-PET experts and industrial partners for providing guidance and ensuring the transformational impact of the proposed effort.