Iterative reconstruction improves image quality and reduces radiation dose in trauma protocols; A human cadaver study

Johannes Clemens Godt; Cathrine K Johansen; Anne Catrine T Martinsen; Anselm Schulz; Helga M Brøgger; Kristin Jensen; Arne Stray-Pedersen; Johann Baptist Dormagen

doi:10.1177/20584601211055389

Iterative reconstruction improves image quality and reduces radiation dose in trauma protocols; A human cadaver study

Acta Radiol Open. 2021 Nov 18;10(10):20584601211055389. doi: 10.1177/20584601211055389. eCollection 2021 Oct.

Authors

Johannes Clemens Godt^{1

2}, Cathrine K Johansen¹, Anne Catrine T Martinsen^{3

4

5}, Anselm Schulz^{1

5}, Helga M Brøgger¹, Kristin Jensen⁵, Arne Stray-Pedersen^{2

6}, Johann Baptist Dormagen¹

Affiliations

¹ Department of Radiology and Nuclear Medicine, Oslo University Hospital Ullevål, Oslo, Norway.
² Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
³ The Research Department, Sunnaas Rehabilitation Hospital, Norway.
⁴ Faculty of Health Sciences, Oslo Metropolitan University, Oslo, Norway.
⁵ Department of Diagnostic Physics, Oslo University Hospital, Oslo, Norway.
⁶ Department of Forensic Sciences, Oslo University Hospital, Oslo, Norway.

Abstract

Background: Radiation-related cancer risk is an object of concern in CT of trauma patients, as these represent a young population. Different radiation reducing methods, including iterative reconstruction (IR), and spilt bolus techniques have been introduced in the recent years in different large scale trauma centers.

Purpose: To compare image quality in human cadaver exposed to thoracoabdominal computed tomography using IR and standard filtered back-projection (FBP) at different dose levels.

Material and methods: Ten cadavers were scanned at full dose and a dose reduction in CTDIvol of 5 mGy (low dose 1) and 7.5 mGy (low dose 2) on a Siemens Definition Flash 128-slice computed tomography scanner. Low dose images were reconstructed with FBP and Sinogram affirmed iterative reconstruction (SAFIRE) level 2 and 4. Quantitative image quality was analyzed by comparison of contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR). Qualitative image quality was evaluated by use of visual grading regression (VGR) by four radiologists.

Results: Readers preferred SAFIRE reconstructed images over FBP at a dose reduction of 40% (low dose 1) and 56% (low dose 2), with significant difference in overall impression of image quality. CNR and SNR showed significant improvement for images reconstructed with SAFIRE 2 and 4 compared to FBP at both low dose levels.

Conclusions: Iterative image reconstruction, SAFIRE 2 and 4, resulted in equal or improved image quality at a dose reduction of up to 56% compared to full dose FBP and may be used a strong radiation reduction tool in the young trauma population.

Keywords: X-ray; computed tomography; image processing; iterative image reconstruction; radiation dose.