Medical linear accelerators (LINACs) deliver lethal radiation beams calibrated to destroy malignant tumors while sparing healthy tissue. Beam calibration sensor drift or leaf collimator motor encoder slippage can deliver massive, irreversible radiation overdoses. This case study details the implementation of real-time independent field telemetry interlocks.
Ionization chamber sensor readings are processed by physically separate microcontroller channels that compare emitted beam energy with treatment plan parameters every 500 microseconds.
If beam intensity exceeds plan margins by more than 2.5%, hardware crowbar circuits short-circuit the radiofrequency magnetron drive within 45 microseconds, terminating radiation delivery before biological injury can occur.