Computed vs Digital Radiography

Jul 6, 2023

Intra-Oral Dental Radiology

Let’s start with the assertion that whole-mouth intra-oral dental radiographs are essential for all dental patients as discussed in this prior post – https://vetdentedu.ca/2022/08/02/why-veterinarians-must-do-whole-mouth-intra-oral-dental-radiographs-and-why-owners-must-insist-on-this/. That post includes a link to my 43-minute video lecture on this – https://youtu.be/ZBc4bQ-HbFA.

So, now we know you need to take intra-oral dental radiographs, what technology are you going to use to capture those images? I will not bother talking about analog film – it is a dead technology. So, you are going to have to decide between Digitial Radiography (DR) or Computed Radiography (CR). I’ll tell you right now that if you are only going to get one or the other, I absolutely and most emphatically recommend CR. Now I will tell you why.

Digital Radiography systems are based on a single, bulky, rigid, expensive size 2 sensor attached by wire to a computer. These systems do have some advantages such as shortest time from click to pic (time from pushing the x-ray generator actuating button until the image appears on the computer screen) and you get to see the resulting image without having to remove the sensor from the mouth (so you can review the positions of the sensor and the x-ray tube head in light of the image you got from that set-up which can be useful during training).

This is a Sopix2 DR sensor. I had this sensor for over ten years and liked it, in its place.

This is the ScanX Duo, a CR system that I am told is being discontinued (sadly). Other CR systems are available and I may be talking about them in the coming months.

These are the common sizes of PSP sensor plates for CR systems. DR sensors are about the same as a size 2 plate. You can see that the size 0 and 1 are much smaller and the 3 and 4 are much larger, allowing much more flexibility. Also, these thin, flexible plates are relatively less expensive, so there is less risk on placing these inside a live patient’s mouth.

Computed Radiography utilizes thin, flexible, inexpensive Phosphor Sensor Plates (PSPs) that are available in a variety of sizes from quite small to relatively large. The PSPs are placed in the mouth and exposed, then removed from the mouth and placed in a scanner (the expensive part of the system) to be read and then the image is sent to the computer screen.

So why am I so adamant that CR is the way to go? Well, the DR system works great when you just want one quick shot of a relatively small area (like an intra-op/post-op view to check on completeness of an extraction) but when doing a whole-mouth series in a large dog, or looking at a larger structure like a canine tooth in a large dog or a tumor, the DR sensor is just too small, meaning that you need way more exposures to image everything (increasing time taken and radiation exposure) and you are trying to interpret small images of large structures – its really challenging. Image trying to appreciate a mountain vista through a peep-hole. You want a big, large picture window to really get a sense of what you are seeing.

This is a ‘whole-mouth’ study that was obtained with a DR system and sent to me as part of a referral. The study includes 44 images, many of low or no diagnostic value and there are several teeth for which there are no diagnostic images at all. Trying to interpret a study like this is like trying to appreciate a mountain vista through a peephole.

Compare that DR study with the CR study below.

Here is a whole-mouth study of a 30 kg dog done in 12 shots using size 4 and size 2 PSPs. Every tooth plus a lot of the surrounding area has been imaged. You can also see this study, laid out in a logical fashion, with each tooth labeled, at this link – https://vetdentedu.ca/2023/01/02/normal-canine-dental-radiographs/

Looking at those two studies, which set of images would you would rather have to work with? Unfortunately, the DR study is hardly worth the effort it took to obtain, and it would have taken a lot of effort. The CR study shows every tooth and surrounding structures much more clearly, with less distortion and was obtained with only 12 exposures, saving a lot of time and radiation exposure.

But it is not just large dogs that benefit from CR’s various sensor sizes. Micro-dogs really need the small, size 0 and 1 sensors to get images of all teeth.

This is Rosie, a 1.1 kg teacup poodle. While not the smallest dog I ever worked on, she is pretty tiny. How are we going to get a thick, rigid size 2 DR sensor into the back of her mouth to image her molars?

Here is Rosie’s whole-mouth study done using size 0, 1 and 2 PSPs. Every tooth, as well as lots of the surrounding architecture, is imaged with minimal distortion.

Now, that all said, I have found that my DR system was great for the majority of cats. My example of normal feline dental radiographs was obtained with my Sopix2 sensor and here it is – https://vetdentedu.ca/2023/01/02/normal-feline-dental-radiographs/.

So, for the last ten+ years of my career in practice I had both ScanX CR and Sopix2 DR systems and used them both daily. However, if I could only have one, I would have chosen the CR system without a moment’s hesitation. The availability of thin, flexible PSPs in multiple sizes makes it the obvious choice.

Many of the images in this post and more can be found in a Facebook post from Hale Veterinary Clinic’s page. Here is the link to that post (if the link/post is not showing up on your page, try a different browser or go to the Facebook page for Hale Veterinary Clinic and scroll to the posting from 14 July, 2022):