Application segmentation delineates the end‑use environments that drive demand for scintillators in radiation detectors. Medical imaging (including PET, SPECT, and CT) accounts for the largest share, reflecting hospitals’ need for high‑resolution, fast‑response crystals; this sub‑segment contributes roughly 35 % of total market revenue. Nuclear security—border monitoring, portal monitors, and safeguards—relies on rugged, high‑efficiency scintillators, representing about 25 % of the market. Industrial non‑destructive testing (pipeline inspection, weld verification) utilizes robust, cost‑effective materials, adding an estimated 20 % to overall size. Scientific research (particle physics, astrophysics) demands specialized, low‑background scintillators, supporting 15 % of revenue. Finally, homeland security applications such as radiological threat detection occupy a smaller niche, roughly 5 % of the market. Together, these application categories form the core of the Scintillators for Radiation Detector segmentation, each quantifiable through distinct adoption rates and pricing structures. Growth projections indicate an annual compound increase of 6 % driven by expanding PET scanner installations and stricter border‑control regulations, which further amplifies each segment’s revenue contribution.