IRRADIATOR SHARED RESOURCE – PROJECT SUMMARY/ABSTRACT The Irradiator Shared Resource (ISR), formerly known as the Cesium-137 Irradiator Shared Resource, was established in 1991 with a Cesium-137 gamma-ray irradiator to provide accurate, cost-effective, convenient, and reliable access to ionizing radiation to Yale University investigators for irradiations of molecular compounds, cell cultures, animal and human tumor cells, and whole animals. In 2022, the Yale Cancer Center (YCC) Shared Resources Oversight Committee recommended the expansion of the Cesium-137 Irradiator Shared Resource to include four additional kilovoltage x-ray irradiators and one advanced image-guided small animal research irradiator (being installed in 2023) and name the expanded resource as Irradiator Shared Resource for the coming funding cycle. The ISR will have six irradiators offering both gamma- and x-rays with a wide range of dose rates, collimation, and controlled environment for delivering precise irradiations to biological or chemical samples. It will continue to serve as an essential and comprehensive resource for YCC researchers who are studying the effects of radiation on biological samples, animals, and cells in culture or are using radiation as part of their experiments to create mutations for studying the biologic effect of radiation, or of mutations themselves, or for immunosuppression. In the last 5 years, approximately 12 (and 34) YCC investigators per year have used the Cs-137 (and x-ray) irradiators. During the most recent funding period (FY22), 10 (and 29) YCC Principal Investigators used the Cs-137 (and x-ray) irradiators. Among the total irradiator usage, 86% (and 95%) of the gamma-ray (and x-ray) use were by YCC members from four research programs. Most of the use came from Cancer Immunology (CI) and Radiobiology & Genome Integrity (RGI) research programs, followed by the Genomics, Genetics and Epigenetics (GGE) and Cancer Signaling Network (CSI) research programs. The results from many basic research studies that involved the irradiators have enabled YCC physicians to improve their ability to detect and treat cancer efficaciously. The overall objective of the ISR is to continue provide centralized and comprehensive irradiation services to cancer researchers at YCC. The specific aims of the ISR are: 1) Provide all YCC members with convenient and reliable access to state-of-the-art gamma-ray and kilovoltage x-ray irradiators, with cost-effective irradiation services for all YCC members; 2) Provide expert radiation physics and technical consultation to YCC members on the experimental design involving the gamma- or x-ray irradiators; 3) Provide hands-on training for the staff of YCC members to ensure accurate, efficient, and safe use of the irradiators at all times; and 4) Ensure irradiator availability of 24 hrs/day, 365 days/year to YCC cancer investigator through proactive irradiator maintenance and quality assurance.