The Construction and Goals of the Chest & Abdomen protocol
Use this protocol when both Chest and Abdomen are requested. This is a common request in breast cancer and lymphoma patients, as well as many other types of cancer.
If your spiral CT scanner is capable of rapidly scanning the entire chest and abdomen in a single breath-hold, then you may not need for this protocol. The Chest protocol might be better, if you can adjust for the speed of a fast multi-slice scanner.
At the time this protocol was initially created, our spiral CT scanner has tube loading limits, which prevented it from scanning the entire chest & abdomen in a single spiral. Two spirals were required, separated by an approximately 13 second pause for tube cooling and operator button-pushing. The operator button-pushing required to re-start the 2nd spiral, is an additional source of timing variability. Even after the availability of fast multi-slice CT scanners, there is still a role for scanning the chest separately from the abdomen, in two breath holds instead of one, with correct timing adjusted to optimize the chest and abdomen separately.
In general, the construction and goals of this protocol are similar to the Chest protocol, but the necessity of additional delay and timing variability between the 1st and 2nd spiral, makes it more difficult for the CT scan Chest & Abdomen protocol to consistently achieve its optimum scan delays.
To illustrate the reasoning in constructing this protocol, consider this example: For the 63-77kg weight category, it is desired to start scanning the top of the liver at a minimum of 62 seconds. Subtract 13 seconds for inter-spiral delay, subtract another 13 seconds to scan the chest, means starting to scan the top of the chest at 36 seconds after the start of contrast injection. The patients with short chests will have the top of the liver started scanning by 62 seconds. The average chest length patients will have the top of the liver started scanning by 67 seconds.
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