CoreFull access
Tube Heat and Rating Charts
Over 99% of exposure energy becomes heat. Rating charts, cooling and warm-up keep the tube from failing early.
Heat units
More than 99% of the energy in an exposure becomes heat at the anode, and less than 1% becomes x-rays. Heat is tracked in heat units (HU) or joules. Heat units equal kVp × mA × seconds × a generator factor: 1.0 for single-phase, 1.35 for three-phase 6-pulse, 1.41 for three-phase 12-pulse, and about 1.4 to 1.45 for high-frequency. Joules measure the same energy in SI units. One HU is about 0.7 joule.