On January 21, Gale Pierce has mailed me this query:
Hello Stan, I would like to know, approximately how many MRI scans are done on a monthly basis at any one MRI facility? Rough estimate, of course. Thank you, Gale Pierce.
Dear Gale, I am sorry it took me so long to react, but it is not easy to find out, and the numbers vary a lot from one place to another.
On a sessions-per-scanner basis it is anywhere between 10 and 30 sessions (patients) a day. There are machines exploited around the clock and then there are those used only half the time. Much depends upon the organization of the whole facility, which can have any number of scanners. The most important factor appears to be patient preparation which should be done in parallel in separate rooms prior to getting anywhere near a scanner. Another important factor is the type of data to be acquired - some facilities concentrate on a screening-like routine, others do more in depth, specialized assays.
While some types of images (not all!) can be obtained in less than a minute, a typical session takes anywhere between half an hour and a couple of hours, compatibly with patient preparation and positioning time, instrument setup and tuning (this is patient specific), the particular type of assay to be carried out, the state and cooperation of the patient (anaesthetized, sedated, wakeful, claustrophobic, infant, ...), the use of any particular contrast agents and the modality of their deployment, and the need for any exploratory scans as opposed to clean scans (the number of scans per session deemed good and significant enough to be archived is typically anywhere between 1 and 10).
Most facilities specify 20-45 minutes per session which, for standard scanning, is a reasonable specification to hand out to the patients, but it is nearly impossible to maintain as an overall operating average of the facility.
Then there are daily check-up and calibration times, monthly regular maintenance, and any down-time due to technical trouble-shooting.
To sum it up, the facility's overall organization affects the average throughput of each scanner much more than the scanner's capacity to produce scans. So if you think you are a good manager, you might try to plan 20 sessions a day. Afterwards, if you manage to get more, you merit a medal. But if you get less, don't despair, you are in good company!