We learn how biomeds manage the pressure of keeping CT scanners up and running with minimum disruption of hospital routine.
Imagine you owned a million-dollar piece of earth-moving equipment that was making you so much money you hated to shut it down for an oil change.
That is analogous to the pressure on clinical engineers and technicians who have to stop the flow of patient imaging for close to 4 hours every 3 months, minimum, to perform routine preventive maintenance (PM) on computed tomography (CT) scanners. Heavily used scanners may need even more frequent PMs. If the routine PM is not performed, the machine will inevitably stall, and then the repairs will take longer. That, too, is a matter of time.
“Time is the biggest hurdle a CT engineer has to deal with,” says service engineer Greg Adamson, a senior CT specialist for Livingston Technologies, a for-profit division of the nonprofit St Boniface Health System, which operates hospitals and clinics in New Jersey. Adamson works out of Toms River where his home site is the Community Medical Center. The medical center has four CTs and operates “the busiest emergency room on the East Coast,” he says.
It is not just CT scanners that need maintenance, of course. Other modalities also need PM, but CT scanners are so reliable and durable and their images are so valuable that they have become one of the workhorses of radiology. Stopping them is an annoyance to everyone.
“Most CT departments run a very tight and very full schedule,” says Adamson, “with a 30-days-or-more waiting period for the next patient opening in some facilities. This makes unscheduled downtime very stressful. It affects patient care almost immediately. A 4-hour delay can create ripples throughout the hospital for days.”
Adamson has learned to plan PMs in advance. “I schedule my PMs a year in advance,” he says. “I schedule early in the morning at the first of the month. That way the clinical staff will know there is a 4-hour window, and no patients will be scheduled in that 4 hours on that machine. It’s a necessary evil, but that way I may have no downtime on that machine for the whole month.”
Overall, Adamson services 12 scanners. “If I’m doing a main scanner that operates on a 12-hour shift I’ll do that PM once a month, otherwise quarterly. I used to base them on slice counts, but that’s no longer valid, it’s more like the scanning times.”
Richard Cunningham is a service engineer for TSS/Imaging a division of Providence Health Systems in Portland, Ore. He agrees that time pressure is a factor in servicing CTs.
“There is increased pressure to keep the CT running all the time,” he says. “Our three CTs are averaging 70 to 75 patients per day. That is outpatient, inpatient, and the ER. The other day they did 98 patients on a machine. That was the most they had ever done.”
Cunningham says it is vital that the service engineer has full access to the CT vendor’s operational software. Understanding that software allows the CE to access the scanner, he says, and to talk knowledgeably to the vendor’s technical specialists if necessary. “If a system has been down more than 5 or 6 hours, we will call the vendor and say we need some help on this.”
Cunningham says it took him a year or two and many hours of study and training before he got comfortable enough to work “without having someone on the other end of the phone.
“Having the knowledge is one thing; having the experience is another,” he says.
Even the Smell
A lot has to be done in the 4 hours that the CT scanner is shut down for PM—another time pressure on the service engineer. It involves both mechanical- and computer-system reviews.
“PMs are pretty straightforward,” says John Engel, a senior systems-training specialist for DITEC, a Cleveland-based company that runs maintenance classes on CT and other imaging modalities. “CT is fundamentally an x-ray system, so if you understand x-ray, to understand CT is not that difficult. The CT adds rotation and an automated patient transport system.”
Engel says the mechanical side of the PM involves cleaning and oiling and replacing air filters. “Cleanliness is next to godliness. You make sure the voltages are correct. You want to make sure the patient transport answers commands and the gantry is tilted correctly.”
Then there is the equally important software side of the machine. “One can look at a CT as being a sort of computer,” says Engel. Software-controlled settings may have to be adjusted. If changes are made, then backup copies of the altered software have to be created in case of a computer failure. A quality control of the imaging has to be performed. “If a test scan is run and it comes out right, that generally means everything is working correctly,” Engel says.
The archiving system on the CT’s computer also needs to be checked. “The CT has several hard drives usually. We have to make sure the drives work,” Engel says. He adds that archived images may have to be transferred to backup tapes.
Roy J. Hall is senior instructor at the Philips Medical Systems training center in Cleveland. He trains Philips’ in-house CT technicians as well as independents who work for facilities that have installed Philips’ scanners.
Calibration software, by law, must be provided to any purchaser of a scanner. That software includes diagnostic programs for each of the subsystems of a scanner, to guide technicians to any parts that have to be replaced. These days, Hall says, most replacement is of modular components like a chassis or a circuit board, rather than tiny individual parts. “The machines are easier to service than they used to be, and the reliability is a lot better too,” he says.
Hall agrees that rigorous PM is the key to keeping a scanner operating. “It’s amazing how important just being observant is,” he says. “[The engineer] has to look for anything that’s worn or metal shavings or loose hardware in the bottom of the machine—any telltale sign—before there are major problems. It might be even what something smells like. The service engineer can save a lot of money by catching something small before it gets big.”
X-ray Tube Mayhem
Finding little pieces of loose hardware in a scanner is quite possible, given the enormous physical stresses that are placed on the CT as the x-ray tube rotates. Livingston Technology’s Adamson has computed these stresses. He expresses them in g-forces, multiples of Earth’s gravitational pull. He says the stresses exceed 40 g’s. “A 1-lb object mounted on the outer edge of the scan frame would exceed 40 lbs of force on its mounting point. The x-ray tube weighs in at around 200 lbs, and it’s mounted on the outermost edge of the scan frame, that’s equal to 9,600 lbs.”
That is one reason Adamson checks his scan-frame fittings carefully, making sure that the hardware is tight. “We have had things come loose. It’s not dangerous to the patient but in the gantry it destroys everything in its path.”
Because x-ray tubes last only a year or so, replacing them is one of the many non-PM tasks that cut into service engineers’ schedules. While most CT downtime is computer related, replacing x-ray tubes is also a cumbersome and costly physical task. Better x-ray tubes rank high on some people’s wish list.
“In the real world a frequent problem is that the x-ray tube will die,” says DITEC’s Engel. “When you replace a tube you have to recalibrate the entire system. The new one has to be calibrated so the vertical x-ray output is through the exact center of the scanner. The vendor software can usually do this. Some vendors will only do the calibration if it’s their tube, which runs the cost up.”
“They are only about 1% efficient,” says Phillips’ Hall. “They will burn off 99% of their energy as heat. For 60 kW in you may get only 100 W out. We would love to see x-ray tubes with even 5% efficiency. That would be a great thing.”
While service engineers do not get directly involved in patient care, the work they perform does impact the clinical aspect of scanning. This is particularly true with the monitoring of radiation dosage settings. As CT scanners add to their slice counts and the number of rotations through which a patient is scanned—64-slice scanners are on the near horizon—patient radiation exposure is becoming an increasingly sensitive issue. While the technician operating the CT scanner during a study can overcome faults on the machine by raising the dosage, this is not an attractive alternative. An important task for service engineers is checking dosage software and hardware faults that can effect dosage.
“Part of the PM is to verify dosage,” says Adamson. “That is usually done on a yearly basis working with the (medical) physicist. A filter can get stuck, so the technician has to bump dosage. It’s really rare, but it can happen. That is my problem, absolutely.”
For service engineers who maintain scanners at multiple sites—and most of them do—traveling between site repairs can become another time-related pressure. “Travel time is a big issue,” says Adamson. He says nighttime repairs often have to be scheduled so that the scanner will not be shut down during business hours.
To keep the travel time of its SEs to a minimum, Toshiba America Medical Systems (TAMS) has taken two steps not uncommon in the industry.
“Better than 93% of our customers are under (maintenance) contracts with us,” says Brian Turnbull, vice president of the TAMS technology services business unit based in Tustin, Calif. “There are no parts available on the market so [we do] the service ourselves.”
TAMS cross-trains its SEs on multiple modalities so that the SE can service different modalities at a location. TAMS deploys its SEs according to a “service-city concept,” says Turnbull. “We draw a radius of 50 miles around a city. All the equipment within that radius will be serviced out of that one center. You can get anywhere in that radius in 2 hours or less. We have 140 service cities where 85% of the activity is.”
For areas outside a service city, TAMS service engineers extend the radius to 100 or even 150 miles. In those cases, says Turnbull, the customer is billed less for a maintenance contract since repairs and maintenance take more travel time. “There isn’t a piece of equipment out there that does not have a service engineer assigned to it,” says Turnbull.
Beyond establishing service cities, TAMS tries to handle as many scanner problems as it can over the phone with a solution center where experts field calls from customers. “What we have found is that 35% to 40% of all service calls can be resolved over the phone,” says Turnbull. “An example would be software applications. The customer will say ‘I was doing this yesterday and I can’t do it today.’ The service engineer will talk them through a procedure that gets that customer back on line.”
For Your Eyes Only
Service engineers have another time-consuming job: interfacing with the technicians and radiologists whose machines they work on. What seems to be a scanner problem sometimes isn’t that at all.
Providence Health’s Cunningham recalls a complaint from a radiologist that the images from a CT were not as sharp and clear as they had been. Cunningham could find nothing wrong with the machine. It turned out that the view box where the radiologist was interpreting needed new lights. “I wasn’t going to tell him that,” Cunningham says, “but after the lights were changed he said the CT images looked a lot better.”
Actually, problems of individual eyesight are more common than might be thought. “Image quality is in the eye of the beholder,” says TAMS’ Turnbull. “The image can change or the person’s eyes can change. We have come to realize that maybe the interpreter’s eyes have changed. In that case you get all the readers together and you get them to agree the image is the proper one. You put that image snapshot in your file and then if needed you bring it back to compare.”
Turnbull estimates that only 40% of a technician’s job time is actually spent on technical tasks and that the rest is spent “managing the customer.” And that includes dealing with eyesight differences.
“The company that comes up with a machine that can conform to the images that different readers like has got itself a gold mine,” Turnbull says. “It’s almost cost prohibitive today.”
George Wiley is a contributing writer for 24×7.