PAT-1302-INFO-THERACARCHETYPE: Information Asymmetry Chokepoint
Software Race Condition with Removed Hardware Interlocks
Sub-Type: Radiation Therapy Computerized Mode Desynchronization
VEC:AUTH:0.88•COUP:0.89•LAT:0.71•OVR:0.92
Authority Gradient
0.88
Feedback Coupling
0.89
Telemetry Latency
0.71
Override Suppression
0.92
Structural Pattern Audit Brief
Critical Multi-Node (Level 4)PAT-1302-INFO-THERAC
Radiation therapy machine removes electro-mechanical hardware interlocks and relies entirely on software. Fast-typing operators edit treatment parameters in under 8 seconds, triggering a software race condition that fires a 25,000-rad raw electron beam instead of 200 rads.
Failure Invariant Breach
Operator_Fast_Keying -> Software_Race_Condition (Turntable State Unaligned) -> 25k_Rad_Beam_Fire
Absent Safety Recovery Mechanism
Physical microswitch hardware interlocks on high-energy beam delivery
Fundamental Invariant Rules
INV-01:Life-critical physical radiation and energy devices must never replace physical mechanical safety interlocks solely with software flags.
Engineered Resilience & Mitigation Strategies
MIT-01:Mandatory hardwired mechanical beam position interlocks independent of software control
MIT-02:Formal mathematical model checking on all concurrent medical device state machines
Canonical Incident Manifestations (1)
FDA-AE-1986-0321Biomedical Devices & Radiation Oncology
Therac-25: Software Race Condition & 25,000-Rad Lethal Radiation Overdoses
Physical hardware interlock Constraint_Boundaries were removed in favor of software flags. High-speed user input triggered an unhandled race condition in concurrent Decision_Nodes, firing maximum raw energy into biological nodes.
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