The result of these improvements is quite remarkable. Whole body scans in fewer than 10-seconds. The gantry rotates every 0.37 seconds. In 2005, we were excited to learn that this new speed allowed for the imaging of the heart in 5-beats. The first reports considered this quite a breakthrough. But, technology was moving faster than we could digest the change. In a few months it was 3-beats and seemingly overnight it was 1.

Entire body scans are being performed with slice thicknesses of 1-1.5 mm. Each study is generating 500-1000 images. Remember technology breeding technology? Now there is a demand for computer assisted detection (CAD) to handle all of the images produced with each study.


Collecting, processing, archiving and transmitting all of the data resulting from a study is no small matter. Storage devices, network capability and bandwidth are required to move and store the patient studies. This is another example of technology breeding technology.

Lastly, everyone assumes if the scanning is faster, then the radiation dose is less than in conventional analog film imaging. Unfortunately, this is not the case. In CR and DDR imaging, the dose to the patient is similar to film based imaging. But, the dose can be higher because the image appears instantaneously and is easy to do over if not done properly the first time. It is not unusual for an image to be repeated. Film, on the other hand, is a gatekeeper. It has to be developed and there is a quantifiable cost for repeat scans.

One assumes that volume CT almost demands the delivery of a lower dose. It's faster so the dose must be lower. It isn't. When used for CT angiography, the dose rate from a single X-ray source CT is substantially higher than that received by the patient during conventional angiography.

The vendors are working on making alterations to the volume CT scanners to lower the dose. These changes will most likely cause an early obsolescence of the equipment already installed.

Digital X-ray's Market Applications

The applications for digital X-ray can be split into those for volume CT and those in standard radiography.

For CT scanners with 64-slices or higher, with a single or dual source X-ray source, the preeminent application is CT angiography (CT-A). The ability to freeze the motion of the heart and image it in 5 beats or less is phenomenal.

Radiologists and cardiologists see this new technology as a real breakthrough. By studying patients with known or suspected heart disease, examining their anatomy and simultaneously performing a calcium scan, the cardiologist gets a full picture of the condition of a particular patient's heart.

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