Replacing a 64-Slice CT Within a Nine-Day Shutdown

Rank by whether they block safe operation, not by cost or schedule convenience.

1. Floor loading (critical). 2,100 kg on 1.2 x 0.9 m is about 1.94 tonnes/m2, roughly 19 kPa, against a 3.0 kPa floor rating. This cannot be waved through with a spreader plate alone; a structural engineer must confirm the slab and the raised-floor pedestals, and reinforcement or a purpose-built plinth must be designed. Nothing is installed until this is signed off.
2. Electrical supply (critical). 63 A against an 80 A requirement will trip at high mA protocols or during tube heating. Upgrade the isolator, cable, breaker and protective coordination, check voltage drop and confirm generator changeover and any UPS support. Re-check that the earth leakage and RCD arrangements suit a medical location.
3. HVAC capacity (major). The unit can hold 22 +/- 1 degrees C only at 60% of peak load; at full load the room will drift beyond the vendor's environmental envelope, causing thermal shutdowns and shortened tube life. Either upgrade the air handling unit or formally accept a documented operating restriction on high-demand protocols.
4. Chilled water (minor but verify). 18 kW spare exceeds the 7.2 kW heat load, but confirm flow rate, temperature differential and redundancy, since the spare capacity may be shared.
5. Radiation shielding and licensing (major). A 128-slice unit with higher workload changes the shielding calculation; the radiation protection adviser must confirm the existing 2 mm lead equivalence and the control room layout. The irradiating apparatus licence under the local Radiation Ordinance must be in place before clinical use.
6. Access route, door widths, rigging, ceiling rail reuse and floor finish - practical items that commonly cause the slip.

Do not confirm the nine-day window until items 1, 2 and 5 have fixed dates; the vendor's schedule assumes they are already done.

Remote witnessing of safety-critical commissioning is not acceptable; remote support for the vendor's own engineer is.

• Reject remote-only witness for mechanical installation verification, electrical safety tests, radiation survey and dose measurements. These are the tests where an error is discovered only after it hurts someone, and the hospital must have its own competent person present.
• Acceptance plan content:
  1. Installation verification against the vendor's site planning manual - anchoring, clearances, access, cable routing.
  2. Electrical safety per IEC 60601-1: protective earth continuity, earth leakage, enclosure leakage, applied-part leakage; record values and compare with the acceptance specification.
  3. Tube conditioning and calibration by the vendor, with outputs recorded.
  4. Dosimetry: CTDIvol and DLP for representative adult and paediatric protocols, compared with the vendor's reference values and your diagnostic reference levels; radiation survey of the suite and adjacent rooms by the RPA.
  5. Image quality using a recognised phantom: uniformity, noise, high- and low-contrast resolution, slice thickness, CT number accuracy, geometric accuracy.
  6. Integration: DICOM conformance, worklist, PACS routing, reporting, dose management system, contrast injector interface.
  7. Clinical workflow validation on real patients before the go-live date, not on the same day.
• Commercial protection. Retain 10% of the contract value until acceptance is signed, apply the agreed liquidated damages for delay, and require the vendor's commissioning report and test data to be handed over.
• Witness competence. Name the hospital witness (medical physicist or senior biomedical engineer) and ensure they are on site throughout the critical tests, with authority to stop the process.

Manage clinical continuity first, contract second, reputation third.

• Quantify the gap. Establish how many CT slots per day are lost, which patient groups are affected (inpatient, emergency, oncology follow-up, outpatients) and what interim capacity exists: the old scanner if it has not yet been decommissioned, a neighbouring hospital, extended hours on other modalities, or a mobile CT. Publish the interim pathway before the planned shutdown, not after.
• Protect urgent pathways. Agree with the clinical leads which referrals bypass normal booking: suspected stroke, trauma, suspected malignancy, and inpatient deterioration. Diverting the routine list is easier to defend than diverting the urgent one.
• Contract and escalation. Notify the vendor in writing that the milestone is at risk, reference the contract's delay provisions, and separate the hospital's own scope (the electrical upgrade) from the vendor's obligations. If the hospital's works caused the delay, the liquidated damages position is weak; be honest internally about that.
• Report upward accurately. Give the COO a one-page status with a revised date, the confidence level, the interim capacity and the risks. Avoid optimistic dates that will slip again; a second missed date damages credibility more than the first.
• Recover schedule safely. Compressing commissioning is the wrong lever. Instead, run the electrical works in parallel with mechanical installation where physically possible, and pre-book the RPA survey and the acceptance witness. Never trade acceptance testing for a go-live date.
• Post-project review. Record the interface gaps that the original plan missed - structural, electrical, HVAC, shielding - and feed them into a standard pre-installation checklist for the next modality.