kVp
Peak kilovoltage across the X-ray tube. Sets the energy spectrum of the X-ray photons; together with mA·s (tube current × exposure time), determines the radiographic exposure. Higher kVp = higher-energy photons, greater penetration, lower image contrast.
Typical clinical kVp ranges:
- Mammography: 25–40 kVp (low-energy for soft-tissue contrast).
- Pediatric / extremity DR: 50–70 kVp.
- Adult chest / abdomen DR: 80–125 kVp.
- CT: 80–140 kVp standard; modern scanners offer 70–80 kVp pediatric / dose-saving and dual-kVp / spectral options.
- Interventional fluoro: 70–120 kVp depending on procedure.
- Photon-counting CT: spectral-by-default, doesn't fit the conventional kVp framing cleanly.
Why it matters to buyers: Determines dose and image contrast. Higher kVp protocols reduce patient dose on thicker anatomy but also reduce contrast — especially soft-tissue contrast. Lower kVp is increasingly used in pediatric, vascular, and dual-energy CT for the contrast benefit at acceptable dose.
Why it matters to engineers: Generator output limits, tube rating, and dose calculations all reference kVp. Drift from commanded kVp is a generator-calibration issue caught at annual physicist survey. kVp-linearity is a routine QA metric on every X-ray-producing system.