Bigger is always better right? Wrong. With digital radiography bigger is most definitely not always better.
Digital radiography vendors and sales people sell products based on the assumption that more pixels equates to a better image. Unfortunately, there is more to image quality than pixel number. Additionally, more pixels can create big problems with teleradiology.
The following are images we received through our teleradiology service at www.sighthoundradiology.com . See if you can tell which image is the 6 megapixel image and which is the 16 megapixel image.
Image 1:
Image 2:
In both of these series, Image 1 is from a detector that generates 16 megapixel, 16 bit images. Image 2 is from a detector that generates 6 megapixel, 12 bit images. You don't have to be a radiologist to see that in both cases, image 2 is a much better image. This simple example shows that more megapixels is not always better. As I tell people I consult with, "if you have 473,441 billion blurry, poorly exposed pixels you still don't have an image you make a diagnosis on. You just have a poorly exposed, blurry image with alot of pixels. Dont focus on the pixel number. Focus on image quality."
The main difference between these images is image processing. All things being equal, it appears that the “special sauce” that a vendor applies to an image is the main determinant of image quality. The bottom line is that more pixels is not always better.
What about CCD?
CCD cameras are classified and sold by their pixel number. CCD cameras are called 6x, 9x, or 16x referring to the number of pixels in the camera. The higher the pixel number, the more expensive the system. Unfortunately, veterinarians look at the pixel number (and cost) and make an erroneous conclusion that more is better regardless of the vendor making the camera. Again, this is not always true.
The differences between a 6x and 9x camera are far greater than the number of pixels. There are many components to a CCD camera and the image that is produced. Some of these are the lens, the detector type, the chip, and the software processing that is applied to an image. Do not be fooled. All 16x cameras are not better than all 9x cameras. You must fully evaluate each vendors equipment and not just look at the pixel number. One vendors 9x camera may outperform another vendors 16x camera.
…And why more pixels may even give you a headache
Digital radiographic images are very large. Most vendors images are between 4mb-8mb. However, with the newer 16mp, 16 bit digital radiography systems we are now receiving images from some vendors that are greater than 20mb each! I know that it is difficult to fully understand how big a megabyte is so use this analogy... if a generic digital image is the size of a lime, these newer images are watermelons!
The importance of this "image bloat" cannot be overstated. Extremely large file sizes can make teleradiology extremely difficult and in many cases impossible.
With a good broadband connection, most digital radiographic images will take about 3-5 minutes to upload. For a full study, it can take 10 minutes. With the newer, bloated images, it can take 20 minutes for a single image; 40 minutes for a 2 view thorax; GI series - forget about it! The files are too big for most internet connections and software sold with these systems is inadequate to use to send these types of files efficiently.
The good news is that if you have a system that generates huge images, there is special software that your radiologist has available to them that can make it possible for you to use these huge files in teleradiology applications. It is always a good idea to consult with your veterinary radiologist prior to installing your digital radiography system. A list of radiologists across the country that can help you with your purchasing decision and have the ability to receive files of any size can be found at www.dvminsight.com. DVMinsight is a service and software provider that radiologists use to provide teleradiology services to veterinarians they work with.
