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Reliability block diagram templates

RBD — Radiotherapy Treatment Chain

One year of a linear accelerator bunker treated as a delivery chain, where the magnetron, multileaf collimator and single treatment couch are strictly in series behind a duplex record-and-verify system.

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Linear accelerator treatment chain — bunker 2Mission 8 760 h · 1.00 yr · 11 blocks · 2 redundant arrangements · R 0.005311parallel · R 0.883669Chiller 1R 0.658927 · A 0.99957Chiller 2R 0.658927 · A 0.99957MagnetronR 0.099733 · A 0.99842Waveguide and circulatorR 0.826600 · A 0.99948Electron gunR 0.481909 · A 0.99933Multileaf collimatorR 0.377822 · A 0.99944Dual ion chamber dosimetryR 0.929601 · A 0.99997Cone beam imaging panelR 0.614672 · A 0.99944Treatment couch and drivesR 0.713964 · A 0.99954parallel · R 0.981547Record and verify server AR 0.864158 · A 0.99997Record and verify server BR 0.864158 · A 0.99997System reliability0.005311Unreliability0.9947System MTTF1 698 h · 70.8 dAvailability0.995638Reliability importance — Birnbaum ∂R/∂Rᵢ, with criticality share1Magnetron0.053255crit 4.82%2Multileaf collimator0.014058crit 0.88%3Electron gun0.011021crit 0.57%4Cone beam imaging panel0.008641crit 0.33%5Treatment couch and drives0.007439crit 0.21%6Waveguide and circulator0.006425crit 0.11%7Dual ion chamber dosimetry0.005714crit 0.04%8Chiller 10.002050crit 0.07%+3 more blocks not shownWeakest link: Magnetron — R 0.099733, Birnbaum 0.053255, 4.82% of system failure. Improving this one block moves the system number further than improving any other.Redundancy check: removing any one of the 4 branches makes its own group measurably more likely to fail — the least of them by 193%. Every one of them is earning its place.

Make it your own.

title "Linear accelerator treatment chain — bunker 2"
mission 8760h

# A linac has almost no redundancy inside the bunker: this diagram exists to
# show how little the duplicated IT actually buys the patient list.
block magnetron  "Magnetron"                    mtbf: 3800h    mttr: 6h
block waveguide  "Waveguide and circulator"     mtbf: 46000h   mttr: 24h
block gun        "Electron gun"                 mtbf: 12000h   mttr: 8h
block mlc        "Multileaf collimator"         mtbf: 9000h    mttr: 5h
block dosimetry  "Dual ion chamber dosimetry"   mtbf: 120000h  mttr: 4h
block couch      "Treatment couch and drives"   mtbf: 26000h   mttr: 12h
block imaging    "Cone beam imaging panel"      mtbf: 18000h   mttr: 10h
block rvA        "Record and verify server A"   mtbf: 60000h   mttr: 2h
block rvB        "Record and verify server B"   mtbf: 60000h   mttr: 2h
block chiller1   "Chiller 1"                    mtbf: 21000h   mttr: 9h
block chiller2   "Chiller 2"                    mtbf: 21000h   mttr: 9h

series {
  parallel { chiller1; chiller2 }
  magnetron
  waveguide
  gun
  mlc
  dosimetry
  imaging
  couch
  parallel { rvA; rvB }
}