Computed tomography arthrography of the shoulder with tin filter-based spectral shaping at 100 kV and 140 kV

Background Tin filter-based spectral shaping has been used for low-dose and ultra-low-dose computed tomography (CT) in several body parts. However, studies of shoulder CT arthrography with spectral shaping are limited. Purpose To investigate image quality and radiation dose of shoulder CT arthrography with tin filter-based spectral shaping at 100 kV (Sn 100 kV) and 140 kV (Sn 140 kV) in comparison with the conventional protocol. Material and Methods Ninety-nine shoulder CT arthrographies with protocols of Sn 100 kV (n = 32), Sn 140 kV (n = 25), and conventional 120 kV (n = 42) were retrospectively evaluated. Qualitative image quality, CT attenuations of intra-articular contrast mixture and tissues, background noise, contrast-to-noise ratios (CNRs), and figures of merit were assessed. Radiation doses were compared. Results CT arthrographies with Sn 100 kV and Sn 140 kV yielded approximately 70% and 60% radiation dose reduction, respectively, compared with the conventional 120 kV ( P < 0.001). Qualitative image noise and quantitative background noise of Sn 100 kV and Sn 140 kV were significantly less than those of the conventional protocol. Qualitative image contrast, CT attenuations of intra-articular contrast mixture and tissues, and CNRs for Sn 100 were similar to those of the conventional 120 kV. However, Sn 140 kV showed significantly lower qualitative contrast and CNRs than 120 kV. Sn 100 kV was the most dose efficient among the three protocols. Conclusion Shoulder CT arthrography with Sn 100 kV substantially reduced radiation dose and image noise and maintained image contrast, compared with the conventional protocol.

Third-generation dual-source computed tomography of the abdomen: comparison of radiation dose and image quality of 80kVp and 80/150kVp with tin filter

ObjectiveTo compare the radiation dose, objective and subjective image quality, and diagnostic performances of 80 kVp and 80/150 kVp with tin filter (80/Sn150 kVp) computed tomography (CT) in oncology patients.MethodsOne hundred forty-five consecutive oncology patients who underwent third-generation dual-source dual-energy CT of the abdomen for evaluation of malignant visceral, peritoneal, extraperitoneal, and bone tumor were retrospectively recruited. Two radiologists independently reviewed each observation in 80 kVp CT and 80/Sn150 kVp CT. Modified line-density profile of the tumor and contrast-to-noise ratio (CNR) were measured. Diagnostic confidence, lesion conspicuity, and subjective image quality were calculated and compared between image sets.ResultsModified line-density profile analysis revealed higher attenuation differences between the tumor and the normal tissue in 80 kVp CT than in 80/Sn150 kVp CT (127 vs. 107, P = 0.05). The 80 kVp CT showed increased CNR in the liver (8.0 vs. 7.6) and the aorta (18.9 vs. 16.3) than the 80/Sn150 kVp CT. The 80 kVp CT yielded higher enhancement of organs (4.9 ± 0.2 vs. 4.7 ± 0.4, P < 0.001) and lesion conspicuity (4.9 ± 0.3 vs. 4.8 ± 0.5, P = 0.035) than the 80/Sn150 kVp CT; overall image quality and confidence index were comparable. The effective dose reduced by 45.2% with 80 kVp CT (2.3 mSv ± 0.9) compared to 80/Sn150 kVp CT (4.1 mSv ± 1.5).ConclusionsThe 80 kVp CT performed similar or better than 80/Sn150 kVp CT for abdominal tumor evaluation with 45.2% radiation dose reduction in oncology patients.