Modern parameter | Old information (pre-1927) |
---|---|
Peak high-voltage (kVp) | Equivalent spark gap on functioning tube |
Hardness X-rays according to penetrometer or half value layer in water | |
Electrical information on primary and secondary circuit | |
Tube current (mA)a | Average current, after 1904 often specified |
Electrical information on primary and secondary circuit | |
Exposure time (min, s)a | Explicitly specified duration of exposure |
Target (anode) material | Explicit or implicit: before 1912 platinum (Pt), then replacement by tungsten (W) |
Filtration | Implicit: no filter added, i.e. tube envelope only. Later sometimes specified filter |
Exposure geometry | Focus-plate or focus-patient distance, field size, type of study |
Backscatter factor | kVp-info, filtration, object thickness, expo-geometry. Explicit BSF seldom & later |