CBCT Radiation Dose Calculator

This calculator estimates effective radiation dose from a dental cone-beam CT (CBCT) scan by starting from a reference dose for the selected field of view (FOV), then scaling it for tube voltage, tube current, exposure time, voxel size, and rotation arc relative to a reference protocol (90 kVp, 8 mA, 8 s, 360°). Tube voltage (kVp) has a markedly superlinear relationship to dose in this model -- the calculator scales dose by kVp to a power of roughly 2.5, reflecting the well-established physics that higher-energy X-ray beams both penetrate more and interact with tissue more strongly than a simple linear relationship would predict -- so a given percentage change in kVp moves the estimate more than the same percentage change in tube current or exposure time. Tube current and exposure time each scale dose linearly instead, but both are allowed a far wider practical range on this calculator (1-20 mA and 0.1-40 s) than kVp's narrower 60-120 clinical range, so across their full available settings either one can still produce a larger total dose swing than kVp does across its own. Voxel size works in the opposite direction from the other technical settings: a smaller voxel (higher spatial resolution) requires more radiation to maintain image quality, so dose rises as voxel size falls, and vice versa -- the classic resolution-versus-dose tradeoff central to the ALARA (As Low As Reasonably Achievable) principle in diagnostic imaging.

Patient age has no effect on the raw effective dose figure itself; it only scales the separate age-adjusted dose output, reflecting that children's developing tissue is more radiosensitive per unit of absorbed radiation, not that a scanner delivers a physically different dose based on who sits in it. This tool produces a planning-level estimate from published FOV reference ranges and standard scaling relationships -- it is not a substitute for manufacturer-specific dose output data, a physicist's dose survey, or the DAP (dose-area product) readout a modern CBCT unit reports for the actual exposure performed, and should not be used as the sole basis for clinical dose-justification decisions. The operator annual dose and its percentage of the ICRP occupational limit are a further illustrative planning estimate on top of the patient dose figure -- they assume a fixed 0.1% scatter fraction for a shielded operator at 2m, which is not a cited measured value, and real operator exposure depends heavily on room shielding, distance, and workflow (many practices have the operator step out of the room entirely during exposure). A facility radiation safety survey or personal dosimeter reading should be used for any actual occupational-exposure determination.