Dedicated photon-counting CT protocols enabled up to 40% radiation dose reduction and 33% iodine reduction while maintaining diagnostic image quality for thoracoabdominal aortic CTA.
Even the combined low-dose/low-contrast (LD/LC) protocol provided objective and subjective image quality comparable to third-generation energy-integrating CT despite simultaneously reducing both radiation and contrast dose.
Low-dose PCCT achieved higher contrast-to-noise ratio (CNR) than EID-CT despite substantially lower radiation exposure, highlighting the dose-efficiency advantage of photon-counting technology.
Access publication
Figure 4. Representative image quality of the CT protocols. CT angiography in different patients with comparable body mass index generated with EID-CT (A) and PCD-CT with reduced radiation dose (B), reduced contrast agent dose (C) and a combination of both (D)
Source: Hennes JL, Krompaß K, Huflage H, et al. Retrospective assessment of low-dose and low-contrast agent protocols for photon-counting CT angiography of the aorta. International Journal of Cardiovascular Imaging. 2026. doi:10.1007/s10554-026-03757-y.
Protocol
LD = low dose
LC= low contrast
Detail | Value |
|---|
Scanner | NAEOTOM Alpha (PCD-CT); comparator: SOMATOM Force (EID-CT) |
Scan area | Thoracoabdominal aortic CTA |
Scan mode | ECG-triggered high-pitch spiral |
Acquisition mode | Quantum Plus |
Scan direction | Cranio-caudal |
Tube voltage [kV] | 120 |
Effective mAs [mAs] | IQ-dependent |
IQ level | IQ64 (standard & LC); IQ42 (LD & LD/LC) |
Dose modulation | Automatic exposure control |
CTDIvol [mGy] | Standard PCCT: 4.5 ± 0.7 • LC: 4.8 ± 1.0 • LD: 3.3 ± 0.8 • LD/LC: 2.8 ± 0.8 • EID-CT: 5.3 ± 0.4 |
Rotation time [s] | 0.25 |
Pitch | 3.2 |
Matrix | 512 × 512 or 768 × 768 (PCCT, FOV-dependent); 512 × 512 (EID-CT) |
Field of view [mm] | 368 × 368 (adjusted to patient size) |
Slice collimation [mm] | PCCT: 144 × 0.4 EID-CT: 192 × 0.6 (effective) |
Slice width [mm] | 3.0 |
Reconstruction increment [mm] | 3.0 |
Reconstruction kernel | Bv36 |
Iterative reconstruction | QIR 3 (PCCT); ADMIRE 3 (EID-CT) |
Virtual monoenergetic images | 55 keV |
Contrast agent | Imeron 350 mg I/mL |
Contrast volume | Standard/LD: 60 mL • LC/LD-LC: 40 mL |
Flow rate | 3.5 mL/s (60 mL protocols); 2.5 mL/s (40 mL protocols) |
Iodine dose | Standard/LD: 21 g • LC/LD-LC: 14 g |
Bolus tracking | ROI in descending thoracic aorta, 100 HU threshold, 7 s delay |
Saline chaser | 30 mL (standard/LD); 20 mL (LC/LD-LC) |
Key Results
Parameter | Main finding |
|---|
Radiation dose | Low dose reduced CTDIvol by ~40% vs EID-CT (3.3 vs 5.3 mGy) |
Combined protocol | Low dose/Low contrast maintained diagnostic image quality despite simultaneous 40% radiation and 33% iodine reduction |
CNR | LD achieved significantly higher CNR than EID-CT (33.5 vs 25.1) |
Low-contrast protocol | LC maintained CNR comparable to EID-CT despite one-third less iodine |
Subjective image quality | LC rated superior to EID-CT; LD and LD/LC comparable to EID-CT |
Clinical implication | Patient-adapted low-dose and low-contrast PCCT protocols can substantially reduce radiation and iodine exposure without compromising diagnostic performance. |
