Dose Reduction in Dental CT: A Phantom Study With Special Focus on Tin Filter Technique

Hackenbroch, Carsten; Schnaidt, Sebastian; Halt, Daniel; Wilde, Frank; Beer, Meinrad; Wunderlich, Arthur

doi:10.2214/ajr.19.22461

Cited by 16 publications

(16 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…By introducing modern software and hardware techniques such as IR and improved detectors as well as tin filtering in CT, significant dose savings can be achieved with modern scanners. In particular, tin filtering, as a relatively new and not yet widely used technique, because it has so far only been offered by one manufacturer, shows great potential 7,41–44 …”

Section: Discussionmentioning

confidence: 99%

Low-Dose CT Imaging of the Pelvis in Follow-up Examinations—Significant Dose Reduction and Impact of Tin Filtration

et al. 2022

Self Cite

View full text Add to dashboard Cite

Objectives: Low-dose (LD) computed tomography (CT) is still rarely used in musculoskeletal (MSK) radiology. This study evaluates the potentials of LD CT for follow-up pelvic imaging with special focus on tin filtration (Sn) technology for normal and obese patients with and without metal implants. Materials and Methods: In a phantom study, 5 different LD and normal-dose (ND) CT protocols with and without tin filtration were tested using a normal and an obese phantom. Iterative reconstruction (IR) and filtered back projection (FBP) were used for CT image reconstruction. In a subsequent retrospective patient study, ND CT images of 45 patients were compared with follow-up tin-filtered LD CT images with a 90% dose reduction. Sixty-four percent of patients contained metal implants at the follow-up examination. Computed tomography images were objectively (image noise, contrast-to-noise ratio [CNR], dose-normalized contrast-to-noise ratio [CNRD]) and subjectively, using a 6-point Likert score, evaluated. In addition, the figure of merit was calculated. For group comparisons, paired t tests, Wilcoxon signed rank test, analysis of variance, or Kruskal-Wallis tests were used, where applicable. Results: The LD Sn protocol with 67% dose reduction resulted in equal values in qualitative (Likert score) and quantitative image analysis (image noise) compared with the ND protocol in the phantom study. For follow-up examinations, dose could be reduced up to 90% by using Sn LD CT scans without impairment in the clinical study. However, metal implants resulted in a mild impairment of Sn LD as well as ND CT images. Cancellous bone (P < 0.001) was assessed worse and cortical bone ( P = 0.063) equally in Sn LD CT images compared with ND CT images. Figure of merit values were significant ( P ≤ 0.02) lower and hence better in Sn LD as in ND protocols. Obese patients benefited in particular from tin filtration in LD MSK imaging in terms of image noise and CNR ( P ≤ 0.05). Conclusions: Low-dose CT scans with tin filtration allow maximum dose reduction while maintaining high image quality for certain clinical purposes, for example, follow-up examinations, especially metal implant position, material loosening, and consolidation controls. Overweight patients benefit particularly from tin filter technology. Although metal implants decrease image quality in ND as well as in Sn LD CT images, this is not a relevant limitation for assessability.

show abstract

Section: Discussionmentioning

confidence: 99%

Low-Dose CT Imaging of the Pelvis in Follow-up Examinations—Significant Dose Reduction and Impact of Tin Filtration

et al. 2022

Self Cite

View full text Add to dashboard Cite

show abstract

“…For quantitative image analysis, the standard deviation of background noise was determined and the contrast-to-noise ratio (CNR) was calculated using the following formula 31,32 :…”

Section: Quantitative Image Analysismentioning

confidence: 99%

Metal Artifact Reduction With Tin Prefiltration in Computed Tomography

Hackenbroch¹,

Schüle

Halt

et al. 2021

Invest Radiol

Self Cite

View full text Add to dashboard Cite

Objectives: With the aging population and thus rising numbers of orthopedic implants (OIs), metal artifacts (MAs) increasingly pose a problem for computed tomography (CT) examinations. In the study presented here, different MA reduction techniques (iterative metal artifact reduction software [iMAR], tin prefilter technique, and dual-energy CT [DECT]) were compared. Materials and Methods: Four human cadaver pelvises with OIs were scanned on a third-generation DECT scanner using tin prefilter (Sn), dual-energy (DE), and conventional protocols. Virtual monoenergetic CT images were generated from DE data sets. Postprocessing of CT images was performed using iMAR. Qualitative (bony structures, MA, image noise) image analysis using a 6-point Likert scale and quantitative image analysis (contrast-to-noise ratio, standard deviation of background noise) were performed by 2 observers. Statistical testing was performed using Friedman test with Nemenyi test as a post hoc test. Results: The iMAR Sn 150 kV protocol provided the best overall assessability of bony structures and the lowest subjective image noise. The iMAR DE protocol and virtual monochromatic image (VMI) ± iMAR achieved the most effective metal artifact reduction (MAR) (P < 0.05 compared with conventional protocols). Bony structures were rated worse in VMI ± iMAR (P < 0.05) than in tin prefilter protocols ± iMAR. The DE protocol ± iMAR had the lowest contrast-to-noise ratio (P < 0.05 compared with iMAR standard) and the highest image noise (P < 0.05 compared with iMAR VMI). The iMAR reduced MA very efficiently. Conclusions: When considering MAR and image quality, the iMAR Sn 150 kV protocol performed best overall in CT images with OI. The iMAR generated new artifacts that impaired image quality. The DECT/VMI reduced MA best, but experienced from a lack of resolution of bony fine structures.

show abstract

“…However, reduction of metal artifacts at the expense of higher radiation doses is debatable, especially in young patients and patients with recurring examinations 8 . A similar effect can be seen when employing tin prefiltration, which increases photon penetration by reducing the amount of low-energy photons and therefore hardening the X-ray-beam 7 , 9 . While these protocol-based MAR approaches need to be established in advance of image acquisition, algorithms such as iterative reconstruction techniques can be executed retrospectively without negatively effecting the radiation dose.…”

Section: Introductionmentioning

confidence: 59%

“…Different approaches for metal artifact reduction (MAR) have been evaluated predominantly for conventional gantry-based, multidetector CT (MDCT) scanners in the past 6 , 7 . Photon starvation can be diminished by increasing the tube current in order to augment the number of photons in the X-ray beam.…”

Section: Introductionmentioning

confidence: 99%

Metal artifact reduction in ultra-high-resolution cone-beam CT imaging with a twin robotic X-ray system

Kunz

Patzer

Grunz

et al. 2022

Sci Rep

View full text Add to dashboard Cite

Cone-beam computed tomography (CBCT) has been shown to be a powerful tool for 3D imaging of the appendicular skeleton, allowing for detailed visualization of bone microarchitecture. This study was designed to compare artifacts in the presence of osteosynthetic implants between CBCT and multidetector computed tomography (MDCT) in cadaveric wrist scans. A total of 32 scan protocols with varying tube potential and current were employed: both conventional CBCT and MDCT studies were included with tube voltage ranging from 60 to 140 kVp as well as additional MDCT protocols with dedicated spectral shaping via tin prefiltration. Irrespective of scanner type, all examinations were conducted in ultra-high-resolution (UHR) scan mode. For reconstruction of UHR-CBCT scans an additional iterative metal artifact reduction algorithm was employed, an image correction tool which cannot be used in combination with UHR-MDCT. To compare applied radiation doses between both scanners, the volume computed tomography dose index for a 16 cm phantom (CTDIvol) was evaluated. Images were assessed regarding subjective and objective image quality. Without automatic tube current modulation or tube potential control, radiation doses ranged between 1.3 mGy (with 70 kVp and 50.0 effective mAs) and 75.2 mGy (with 140 kVp and 383.0 effective mAs) in UHR-MDCT. Using the pulsed image acquisition method of the CBCT scanner, CTDIvol ranged between 2.3 mGy (with 60 kVp and 0.6 mean mAs per pulse) and 61.0 mGy (with 133 kVp and 2.5 mean mAs per pulse). In essence, all UHR-CBCT protocols employing a tube potential of 80 kVp or more were found to provide superior overall image quality and artifact reduction compared to UHR-MDCT (all p < .050). Interrater reliability of seven radiologists regarding image quality was substantial for tissue assessment and moderate for artifact assessment with Fleiss kappa of 0.652 (95% confidence interval 0.618–0.686; p < 0.001) and 0.570 (95% confidence interval 0.535–0.606; p < 0.001), respectively. Our results demonstrate that the UHR-CBCT scan mode of a twin robotic X-ray system facilitates excellent visualization of the appendicular skeleton in the presence of metal implants. Achievable image quality and artifact reduction are superior to dose-comparable UHR-MDCT and even MDCT protocols employing spectral shaping with tin prefiltration do not achieve the same level of artifact reduction in adjacent soft tissue.

show abstract

Dose Reduction in Dental CT: A Phantom Study With Special Focus on Tin Filter Technique

Cited by 16 publications

References 10 publications

Low-Dose CT Imaging of the Pelvis in Follow-up Examinations—Significant Dose Reduction and Impact of Tin Filtration

Low-Dose CT Imaging of the Pelvis in Follow-up Examinations—Significant Dose Reduction and Impact of Tin Filtration

Metal Artifact Reduction With Tin Prefiltration in Computed Tomography

Metal artifact reduction in ultra-high-resolution cone-beam CT imaging with a twin robotic X-ray system

Contact Info

Product

Resources

About