Related Experiment Video
Updated: Feb 13, 2026

Gene Regulation and Targeted Therapy in Gastric Cancer Peritoneal Metastasis: Radiological Findings from Dual Energy CT and PET/CT
Published on: January 22, 2018
Helical CT with variable target noise levels for dose reduction in chest, abdomen and pelvis CT
Patrik Rogalla1, Madhusudan Paravasthu1, Christin Farrell1
1Joint Department of Medical Imaging, University of Toronto, Princess Margaret Cancer Centre, 3-918, 610 University Avenue, Toronto, Ontario, M5G 2M9, Canada.
Objectives:
To evaluate a contiguous helical CT protocol with two different target noise levels in chest/abdomen/pelvis CT.
Methods:
41 patients (study group) underwent a helical scan (P1) with two different target noise levels (SDs), SD = 16 for chest and SD = 13 for abdomen/pelvis. Two further protocols were planned but not executed: a single helical scan with only one SD (SD = 13) for the entire scan range (P2), and two separate helical scans overlapping over the liver and same SD settings as for P1 (P3). All DLPs were recorded. Image quality was assessed qualitatively and quantitatively on all scans. The control group consisted of 40 patients, was scanned with protocol P3 and analysed using the same metrics.
Results:
DLPs (mean/SD) for P1, P2 and P3 were 859.5/392.9, 1040.2/510.5 and 1027.4/469.4, respectively. P1 offered a mean dose reduction of 17.4% compared to P2, and 16.3% compared to P3 (both p < 0.001). There were no differences in image quality between both patient groups (p > 0.3).
Conclusion:
Contiguous helical scanning of the chest/abdomen/pelvis with variable target noise levels results in approximately 17% dose reduction if compared to a single acquisition with only abdominal dose settings or two separate acquisitions of the chest and abdomen/pelvis.
Key Points:
• Low dose chest and standard abdomen CTs can be combined. • Variable SD CT scanning allows for radiation dose reduction. • Variable SD CT scanning maintains image quality.
More Related Videos
Related Concept Videos
Veins of the Abdomen and Pelvis
The inferior vena cava is fed by numerous smaller veins. The lumbar veins, for instance, drain the posterior abdominal wall, emptying both directly into the inferior vena cava and into the...
Radiological Investigation I: X-ray and CT
Imaging Studies I: CT and MRI
Description of the Procedures
Computed Tomography (CT) scan:
Computed Tomography (CT) scans use X-ray technology to generate detailed images of bones, organs, and tissues. During the scan, the patient lies on a moving table...
Imaging Studies for Cardiovascular System V: CT
Imaging Studies for Cardiovascular System VI: Calcium -Scoring CT
Muscles of the Abdomen
Anterolateral Region
The anterolateral region comprises five paired muscles classified into the lateral and...

