coronary CT at RCH

different coronary CT scan types at rch

Scans whole heart in one flash helical scan (red box in trace above)

Advantages

Disadvantages

Only works on consistent and low HR
One shot wonder. You only have what is captured in the one helical scan. No data manipulation afterwards
More prone to beam hardening and metallic artefacts

Scans blocks of the heart across multiple axial scans (red boxes in trace above). Not constantly scanning (on/off/on/off)

Will then stitch blocks together to create one image

The X-ray can be turned on for longer periods of the heart rate (increase size of red box) to increase amount of data obtained.

Advantages

Less prone to beam hardening under sampling and gives better dose modulation
Better for faster and irregular heart rates
Better for obese patients
Provides data from multiple different points in the cardiac cycle. Most of our scans will capture at least 5 different % time points available for reconstruction (eg 45%-70%)

Disadvantages

Mostly depends on the patient's heart rate. However other important factors can determine the protocol chosen:

Patient movement (better with Flash to minimize artefact)
Beam hardening artefacts: High patient BMI, metal implants, arms down (sometimes not enough dose produced on flash scans so step and shoot scan be better for this artefact reduction)
Anatomy: If a whole chest scan is needed as well then the gated CTA protocols may be better