LOW-DOSE CT PROTOCOL OPTIMIZATION FOR THE ASSESSMENT OF ACUTE APPENDICITIS: THE OPTICAP PHANTOM STUDY

Area of Science:

• Radiology
• Medical Imaging
• Radiation Oncology

Background:

• ClinicalTrials.gov number, NCT01022567.

Purpose of the Study:

• To establish an optimal contrast-enhanced, low-dose computed tomography (CT) protocol for acute appendicitis assessment.
• To evaluate the impact of voltage, noise input (NI), and iterative reconstruction (IR) on radiation dose and image quality.

Main Methods:

• An anthropomorphic abdominal phantom with simulated contrast enhancement was scanned using 66 different protocols (80, 100, 120 kV; standard and strong IR; 11 NIs).
• Image quality metrics including Hounsfield Units (HUs), noise, contrast-to-noise ratio (CNR), and figure of merit (FOM) were measured.
• Two readers assessed visual image quality, comparing results against a reference protocol (120 kV, standard IR).

Main Results:

• Protocols using 100 kV with standard IR and 80 kV with both IR levels demonstrated higher CNR than the reference (p < 0.001).
• Noise levels were highest at 80 kV (p < 0.001), while 100 kV protocols yielded the highest FOM (p < 0.001).
• The 100 kV protocol with standard IR achieved high image quality scores with a significant dose reduction compared to the reference.

Conclusions:

• Reducing tube voltage is more effective than altering iterative reconstruction for optimizing radiation dose in contrast-enhanced abdominal CT.
• A 100 kV protocol with standard iterative reconstruction offers a promising approach for low-dose CT imaging in acute appendicitis evaluation.