Procedure | Approach | Notes |
MPI (136) | Weight-based radiotracer use | Smaller subjects may receive lower radiotracer dose. |
Single-isotope protocols | Dual-isotope imaging with 201Tl rest and 99mTc stress protocols have higher dose estimates than single-isotope protocols. | |
Lower-dose radiotracer | High sensitivity of newer scanners with solid-state detectors allows for rapid scanning or lower-dose injection, reducing estimated dose by almost a third compared with conventional SPECT (139); new software reconstructions (140–142,152) allow for half-time or quarter-time image acquisition, which can be used to perform reduced-dose imaging at full-time acquisition. | |
Stress-only MPI* | Rest imaging can be avoided, and throughput is faster. | |
PET MPI | PET perfusion radiotracers (13N-ammonia and 82Rb) result in lower effective radiation dose than do SPECT radiotracers (Table 12). | |
Compared with 2-dimensional PET, 3-dimensional imaging uses lower radiotracer dose and consequently has lower radiation dose to patients. | ||
CT (144) | Prospective ECG-triggered imaging | When available, prospective ECG-triggered imaging or high-pitch acquisition is preferred over retrospective gating to reduce dose (63); reduce padding to minimize dose (64). |
ECG dose modulation | Reducing tube current during systolic phases reduces dose by ∼25%–40%, depending on heart rate and settings (143,144). | |
Low-kV imaging | There is 53% reduction in median dose estimates for 100-kV scan, compared with 120 kV scan (144); this is particularly helpful in patients with low body mass index or for specific indications (65). | |
Low-mA imaging with iterative reconstruction algorithms | Technique uses low tube current combined with adaptive statistical iterative reconstruction (instead of filtered backprojection) of images to minimize image noise level and maintain image quality (66). | |
SPECT/CTA and PET/CTA | Personalized protocol | For example, use of prospective ECG-triggered axial coronary CTA and low-dose stress-only cardiac SPECT (97) or PET may reduce collective radiation dose by approximately 40%. |
↵* Stress-only imaging can be considered in highly selected cohorts with very low likelihood of coronary artery disease and when attenuation correction is available.
CTA = CT angiogram; MPI = myocardial perfusion imaging.