What actually fails on a gamma camera in Bangladeshi conditions, what a service contract has to say to be worth signing, how to work out your real cost of downtime, and how to price service into the tender.
A gamma camera in a district hospital stops mid-acquisition with a gantry fault. The local agent diagnoses a drive board. The board is not in the country. It is ordered, shipped, held at customs while paperwork is corrected, cleared, and fitted eleven weeks after the fault. During those eleven weeks the department sent its bone scan list elsewhere, most of those referrers did not come back, and the generator deliveries already contracted decayed in the hot lab. The board itself was not expensive. Everything around it was.
Service is the part of a nuclear medicine purchase negotiated last, after the price is fixed and the enthusiasm spent. It decides whether the asset performs for years or sits idle for months at a time. Getting it right is mostly a matter of writing the right things down before award, because afterwards the supplier has no reason to agree to any of it.
On a conventional scintillation camera the sodium iodide crystal is coupled to an array of photomultiplier tubes whose gains drift. Routine tuning corrects normal drift; a tube that fails outright produces a localised non-uniformity that a flood image shows immediately. The crystal itself is hygroscopic and lives inside a hermetic seal. If moisture gets past that seal the crystal degrades irreversibly and the detector is finished. In this climate that is the most expensive failure a scintillation camera has, and it is usually the result of years of poor environmental control rather than a single event.
Crystals also crack under thermal shock. A room cooled during the working day and then left to climb overnight because the plant is switched off to save electricity is a room slowly destroying its own detector. Cadmium zinc telluride systems avoid the crystal and photomultiplier problem, but their detector modules and readout electronics still want a stable temperature, so the need for continuous, dependable cooling does not go away.
Gantry rotation drives, encoders, belts, brakes and bearings wear. Couch drive and lift mechanisms take the heaviest duty cycle on the system. Collision sensors fail in ways that either stop the camera or, worse, do not. Cable chains fatigue and eventually break a conductor, which presents as an intermittent fault that is hard to diagnose remotely. None of this is exotic, and all of it is why a scheduled mechanical inspection is worth more than it looks.
Adding CT adds a second machine with its own failure profile. The X-ray tube is a consumable with a finite life and is normally the most expensive spare on the system. Whether it is included in the service contract is the most financially significant sentence in the document, and it is often buried in an exclusions annexe. Slip rings, the rotation bearing, detector modules and the high voltage generator are the other significant items. Price tube replacement into your lifetime cost model at tender stage, not in year five when the quotation arrives.
In Bangladeshi installations a large share of faults originate outside the imaging system: mains voltage that swings, generator changeover transients, UPS batteries never load tested, earthing measured once at handover and never again, air conditioning that fails in the hottest week of the year, and dust drawn into filters nobody cleans. Workstations fail in ordinary ways too, including operating systems that reach end of support.
| Task | Frequency | Who does it |
|---|---|---|
| Uniformity flood on each detector head | Daily, before the first patient | Technologist |
| Contamination survey of couch, collimator face and hot lab | Start and end of each working day | Technologist |
| Energy peaking check on each isotope in use | Daily or at each isotope change | Technologist |
| Spatial resolution and linearity with a resolution phantom | Weekly | Technologist, reviewed by physicist |
| Centre of rotation and tomographic uniformity | Monthly or per manufacturer schedule | Medical physicist |
| SPECT phantom acquisition and reconstruction review | Quarterly | Medical physicist |
| Mechanical inspection: drives, brakes, collision sensors, cable chains | At each preventive visit | Service engineer |
| Air conditioning service, filter cleaning, condensate check | Quarterly, more often in monsoon | Hospital engineering |
| UPS battery load test and voltage stabiliser check | Every six months | Hospital engineering |
| Earth resistance measurement | Annually and after any electrical work | Hospital engineering |
| Software and protocol backup, archive integrity check | Monthly | Biomedical engineer or IT |
The daily flood catches most detector faults early, provided somebody looks at it rather than merely acquiring it. Uniformity images filed unexamined for six months are a record of a failure nobody noticed. Plot the numbers and compare against the baseline recorded at handover. Leeds Test Objects flood, resolution and distortion phantoms and the SPECT IQ phantom cover the routine set, and a department that owns them has evidence when it argues that performance has degraded.
Ask for a two stage commitment rather than one number. Remote response, meaning an engineer on the phone or connected to the system, should be quick and is genuinely achievable. On site attendance depends on where you are and where the engineers live, and a promise that ignores geography will not be kept. A hospital in Dhaka can reasonably expect same day or next working day attendance from an agent with engineers in the city. A hospital in Sylhet, Rangpur or Cox's Bazar should negotiate a window that reflects the journey and put more weight on remote diagnostics, its own trained biomedical engineer, and local stock of the parts that fail most often.
One question separates suppliers more sharply than any other: does the company employ service engineers in Bangladesh trained on this model, or does every significant fault wait for a visitor from abroad. Ask for names, training records and the location of the engineers who will cover your system, and how many other systems of the same model they support here. An engineer who sees the model regularly diagnoses it faster than one reading the manual on the flight.
Hospitals reject a service contract as too expensive without calculating what it protects against. The calculation takes an afternoon and changes the conversation with the board. Use your own figures, not borrowed ones.
Under public procurement in Bangladesh, once a contract is awarded on price the buyer has very little bargaining power left. Service therefore has to sit inside the evaluated package, not in a follow-up negotiation.