Varian Millennium MLC & HD120 MLC Periodic Maintenance Inspection PMI Procedure CTB ML-422 PDF Download

Description

Varian CTB ML-422 Rev J — Millennium MLC & HD120 MLC PMI Procedure with Checklist

This is the Varian Customer Technical Bulletin CTB ML-422, Revision J (DWG No. 100056637), the definitive 30-page Periodic Maintenance Inspection (PMI) procedure and checklist document for the Varian Millennium MLC and HD120 MLC systems. Published September 2018, this customer-version document provides every procedure needed to perform a complete MLC PMI, along with the official PMI checklist (Appendix B) and full initialization examples for all supported software versions (Appendix A). This is one of the most operationally critical MLC service documents a radiotherapy department can hold.

Products Covered

• Millennium MLC — Product Code H54, Varian 120-leaf multi-leaf collimator
• HD120 MLC — Product Code H56, High Definition 120-leaf MLC
• MLC software versions v6.8 through v8.5 (Windows XP and WES7 platforms)
• Controller types: VME Bus Controller, Low Profile Controller (LPC), Clinac Console and MLC Controller (CCMC)

PMI Task Coverage — Quarterly, Semi-Annual, and Annual

• 3.1 MLC Initialization Verification (Quarterly) — Terminal commands and verification of clean initialization; initialization examples for v6.8, v7.2, and v7.4 in Appendix A
• 3.2 Computer Cleaning and Inspection (Annual) — MLC workstation/4DITC workstation, VME Bus Controller, LPC/CCMC; event log cleanup paths for WinXP and WES7
• 3.3 MLC Head Assembly Inspection (Quarterly) — Fiber optic cables, signal cable connectors, cable tie wraps, secondary feedback card chip seating, head fan operation (all 4 MMLC fans), power supply fan
• 3.4 MLC Power Supply Measurements (Semi-Annual) — Five-rail voltage verification with stated tolerances: 15V Motor Power (15.0–15.1V), +15V (±0.2V), -15V (±0.2V), +5V high (≤5.25V), +5V low (≥4.95V)
• 3.5 MLC Optical Beam Measurements (Quarterly) — IR beam peak value (>65 mV at TP3) and offset value (+15 mV ±10 mV at TP1) on both optical receiver boards
• 3.6 MLC PWM Test (Quarterly) — Critical-to-reliability leaf friction/motor wear test; tolerance tables for Millennium (Full Leaves ≤14%, Half Leaves ≤22%) and HD120 (Half Leaves ≤22%, Quarter Leaves ≤24%); commands for v6.8 and v7.x+
• 3.7 Leaf Backlash Test (Quarterly) — Detects worn T-nuts; service threshold ≥0.200 mm; diagnostic commands for v6.8, v7.2, and v7.4+; data archiving paths
• 3.8 Leaf Performance Test (Quarterly, v7.4+) — diagPerformanceTest at two gantry/collimator angle pairs; PWM Summary of Worst Leaves review; service threshold >95 average PWM
• 3.9 Statistical Data Analysis (Quarterly) — 25 autocycles at four gantry quadrants; diagPosILShow analysis; Plan-Act tolerance >0.080 mm triggers service; Act-Sec thresholds 1.000 mm (leaf) / 0.300 mm (carriage)
• 3.10 Field Alignment Verification (Annual) — Touch test results ±0.20 mm threshold; sysoffset.txt recording for v7+; MMLC Field Alignment Wizard and field alignment bar PN 1107271 for v6.8
• 3.11 Lubrication (Annual) — Carriage lead screws and rails; SuperLube grease (or Varian PN P1016045-001 for converted MLCs); notice on lubricant compatibility stickers
• 3.12 Essential Spare Parts Inventory (Quarterly) — Basic spares per drawing P1002039; extended spares per drawing 1105376
• 3.13 PMI Wrap-Up (Quarterly) — Cover reinstallation, final verification, service report

Appendices

• Appendix A — Full initialization terminal output examples for MLC v7.4 with LPC, v7.4 with VME Bus Controller, v7.2, and v6.8 — enabling verification of correct initialization sequence
• Appendix B — Official PMI Checklist with quarterly/semi-annual/annual frequency columns, initials/date fields, MLC software parameter recording section (SysOffsets.txt values and mlcxcal.txt values)

Why This Manual Is Indispensable

The Varian Millennium and HD120 MLC are the beam-shaping systems at the heart of IMRT and RapidArc treatments. This CTB is the OEM-recommended minimum PMI requirement for both systems and includes quantitative pass/fail thresholds for every test — not just procedural descriptions. A facility without this document cannot execute a properly documented MLC PMI or demonstrate compliance with manufacturer maintenance requirements. The PWM test (Section 3.6) is explicitly designated Critical to Reliability (CTR), and the specific CNRR references (CNRR2, CNRR4, CNRR10) confirm its regulatory weight. The complete checklist in Appendix B makes this immediately usable as a working field document.

Instant PDF Download

This 30-page technical bulletin is delivered instantly as a PDF upon purchase, ready to view on any device or print for field use.