Equipment calibration is a fairly common question or sometimes a concern, particularly when someone doesn’t necessarily believe or want to believe their results are what they are whether a baseline or comparative analysis. Nonetheless, questions regarding the calibration, if it’s calibrated or how it’s calibrated are great and I’m happy to address these and shed a little more light on the topic.
At this time, we use the GE Healthcare Lunar unit in both our mobile and storefront operations. All machines use the current and latest version (v17) of the GE enCore software, both have advanced body composition modules including the CoreScan, Visceral Fat quantification module. They also have nice, pricey full-service maintenance contracts.
When it comes to the calibration of one of our DEXA scanners, the fact of the matter is, they are really, truly only calibrated on particular occasions when it’s only necessary. This is because they don’t require or need regular, true calibration, which is referred to as a ‘primary cal.’ A primary calibration is performed when a new unit is installed, a unit is de-installed and re-installed, or if particular mechanical components of a scanning system need to be replaced such as a Tube Head, High Voltage Power Supply, CSBC Board, Detector, or Detector Board and maybe a couple others.
In short, the scanner is always calibrated and can’t go out of calibration. Instead, parts or mechanical elements may fail, which would need to be replaced and if it was one of the aforementioned parts, it may require a new primary calibration. If and when a mechanical component does fail, it renders us unable to complete a body scan for whole body composition and therefore, there’s very, very little if not no possible way your results would be negatively affected by a calibration issue. Every mechanical failure or issue we have experienced has been a direct result of usage. Like anything, when you use a piece of equipment regularly, things can eventually wear out or break and require replacement.
However, every day, before being able to complete total body composition scans the scan system has to pass a 7-minute self test for several things such as mechanical issues with limit switches, etc. (these things are very, very, very sensitive, if anything is even slightly off, it will fail and we can’t scan), database validations, ramping and peaking x-ray, etc. If a self-test fails even one of the 20-30 quality assurance points we are unable to perform assessments until the issue has been professionally resolved by a GE field engineer.
The other fact of the matter is, if something is off we will receive errors messages in the form of a software notification, which prevents us from completing a scan. Most mechanical failures are minor and range from Transverse Errors where a belt or transverse motor has failed, a timeout issue where a cable as failed or broken due to repetitious motions, or where there’s an x-ray ramp failure or power source issue among a few other commons types.
The DEXA scan system design is actually pretty simple. There are not a ton of moving parts but the ones that do exist must work in perfect synchronization, otherwise, we get pinged with an error and we’re done until it can be remediated. In these cases, we have to occasionally force our customers to bear the ever frustrating burden of a last minute, forced event and/or appointment cancellation. Those scenarios can be a huge stressor for anyone involved. When the occasion calls for it, our protocol is to phone in GE technical support in order to get them on-site within their 72-hour obligation; they generally get to us sooner.
At the end of the day, your results are what they are but you can rest assured that our systems are always on otherwise they’re literally off. We take quality seriously and we’re here to help you. If you’ve been the victim of a ‘forced cancellation’ or ever become one, we apologize but please know we’re committed to getting you taken care of.