Acquisition Phase | Phase Included | Scan Delay | Respiration Phase | Anatomical Coverage |
Non Contrast | Yes | N/A | Inspiration | Carina through the apex of the heart |
Arterial Phase | Yes | Test bolus or bolus triggered | Inspiration | Carina through the apex of the heart |
Venous Phase | N/A | N/A | N/A | N/A |
Delayed Phase | N/A | N/A | N/A | N/A |
Scan Comments: The adaptive sequence mode is very useful when imaging patients with irregular heart rates to avoid reconstruction artifacts. Cardiac calcium scoring is routinely performed with a cardiac CTA to evaluate coronary artery disease (see Calcium Score protocols for scan details). All scans are performed using the ALARA principle. 3D post-processing is performed with this protocol. |
Technical Parameters | Parameters |
kVp | 120 |
Effective mAs | Use dose reduction software |
Care Dose Reference mAs | 320 |
Time (Rotation) | 0.28 sec (flex) |
Average Acquisition Time | HR Dependent |
Collimation | 128 x 0.6mm |
Pitch Value | HR Dependent |
Scan Direction | Craniocaudal |
Comments: Both the pitch and the scan time will vary based upon the patient's heart rate. 100kVp is used for most average size patients. ECG dose modulation is always performed. When using adaptive sequence, the radiation exposure can be limited to only the useful portion of the ECG wave, which will significantly reduce the radiation dose. Dose reduction software is used to reduce patient dose. |
Reconstruction Parameters | Best Phase | Thin Data | Thin Data | Multiphase |
Slice Thickness | 3 mm | 0.75 mm | 0.75 mm | 1 mm |
Reconstruction Spacing | 3 mm | 0.5 mm | 0.5 mm | 0.6 mm |
Reconstruction Algorithm | B26f ASA | I41f (3) | I46f (3) | I26f (3) |
Window Width and Level | 500/100 | 500/100 | 500/100 | 500/100 |
Reconstruction Comments: A 1.0 mm x 0.6 mm multiphase reconstruction is generated across the ECG pulsing range every 5-10% of the R-R interval. Open field reconstructions are also performed to evaluate extra cardiac pathology. |
Reconstruction Parameters | Lung | Soft Tissue Open Field | Thin Data Open Field |
Slice Thickness | 3 mm | 3 mm | 0.75mm |
Reconstruction Spacing | 3 mm | 3 mm | 0.5 mm |
Reconstruction Algorithm | B80f | B30f | B20f |
Window Width and Level | 1600/-500 | 410/10 | 410/10 |
Reconstruction Comments: A 1.0 mm x 0.6 mm multiphase reconstruction is generated across the ECG pulsing range every 5-10% of the R-R interval. Open field reconstructions are also performed to evaluate extra cardiac pathology. |
Contrast Parameters | Parameters |
Contrast Type | Non ionic |
Contrast Volume | 80-100ml |
Saline Flush | 30ml |
Injection Rate | 5-7 mL/sec |
Oral Contrast | N/A |
Contrast Volume | N/A |
Comments: Test Bolus is used to calculate the peak contrast enhancement to determine the correct scan delay. Bolus tracking can be used for patients with high heart rates (85bpm<). |
Other Comments: Selecting the correct range for ECG dose modulation is based primarily on the patient's heart rate and clinical indication. When multiphase images are not clinically indicated, the use of ECG dose modulation can significantly reduce the patient's exposure. See Cardiac CT Flow Chart below for more information on selecting the correct protocol based on the patient's heart rate and rhythm. Coronary CTA images should visualize the coronary arteries and left ventricle with adequate opacification of IV contrast. Images should limit venous contamination while flushing contrast out of the right ventricle to prevent image artifacts.