Highly reduced-dose CT of the lumbar spine in a human cadaver model

Abstract

Purpose Feasibility of a highly reduced-dose lumbar spine CT protocol using iterative reconstruction (IR) in a human cadaver model. Materials and methods The lumbar spine of 20 human cadavers was repeatedly examined using three different reduced-dose protocols (RDCT) with decreasing reference tube current-exposure time products (RDCT-1: 50 mAs; RDCT-2: 30 mAs; RDCT-3: 10 mAs) at a constant tube voltage of 140 kV. A clinical standard-dose protocol (SDCT) served as the reference (reference tube current–exposure time product: 70 mAs; tube voltage: 140 kV). Images were reconstructed using filtered back projection (FBP) and two increasing levels of IR: IRL4 and IRL6. A five-point scale was used by two observers to assess the diagnostic quality of anatomical structures (cortical and trabecular bone, intervertebral foramina, pedicles and intervertebral joints, spinous and transverse processes). Objective image noise (OIN) was measured. Results were interpreted using a linear mixed-effects regression model. Results RDCT-2 with IRL6 (1.2 ± 0.5mSv) was the lowest reduced-dose protocol which provided diagnostically acceptable and equivalent image quality compared to the SDCT (2.3 ± 1.1mSV) with FBP (p > 0.05). All RDCT protocols achieved a significant reduction of the mean (±SD) effective radiation doses (RDCT-1: 1.7±0.9mSv; RDCT-2: 1.2±0.5mSv; RDCT-3: 0.4±0.2mSv; p < 0.05) compared to SDCT. OIN was lower in all RDCT protocols with the application of IRL4 and IRL6, compared to the SDCT with FBP (p < 0.05). Conclusion Highly reduced-dose lumbar spine CT providing diagnostically acceptable image quality is feasible using IR in this cadaver model and may be transferred into a clinical setting.

The Small Pixel Effect in Ultra-High-Resolution Photon-Counting CT of the Lumbar Spine

“…3,4 Because physically active individuals are more often affected by spinal fractures, radiation protection and dose efficiency remain concerning issues when deciding on an appropriate scan protocol. 5,6 Finding the sweet spot between necessary radiation exposure and diagnostically acceptable image quality is a perennial challenge whenever technical advancements are introduced to clinical routine. 7,8 Most recently, the emergence of photon-counting CT (PCCT) systems has prompted a substantial increase in image quality for various diagnostic applications.…”

“…Whether patients are involved in high-velocity traffic accidents or falls from greater heights, standard radiography frequently fails to adequately visualize injury patterns for planning of surgical treatment 3,4 . Because physically active individuals are more often affected by spinal fractures, radiation protection and dose efficiency remain concerning issues when deciding on an appropriate scan protocol 5,6 . Finding the sweet spot between necessary radiation exposure and diagnostically acceptable image quality is a perennial challenge whenever technical advancements are introduced to clinical routine 7,8 …”