SU-E-I-01: Radiation Dose Reduction and Image Quality Evaluation of Coronal Truncated Projections in Cone-Beam Dedicated Breast CT

Konate, Souleymane; Vedantham, Srinivasan; Shi, Linxi; Karellas, Andrew

doi:10.1118/1.4814101

Cited by 2 publications

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“…Also, the reduction in

D g N^{italicCT}

with the offset‐detector geometry was quantified with respect to the clinical system (KBCT 1000, Koning Corp.) with no detector offset. A preliminary study 42 was presented at the annual meeting of the American Association of Physicists in Medicine (AAPM). We followed the reporting guidelines recommended by the Task Group No.…”

Section: Introductionmentioning

confidence: 99%

Radiation dosimetry of a clinical prototype dedicated cone‐beam breast CT system with offset detector

2021

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Purpose A clinical‐prototype, dedicated, cone‐beam breast computed tomography (CBBCT) system with offset detector is undergoing clinical evaluation at our institution. This study is to estimate the normalized glandular dose coefficients (DgNCT) that provide air kerma‐to‐mean glandular dose conversion factors using Monte Carlo simulations. Materials and methods The clinical prototype CBBCT system uses 49 kV x‐ray spectrum with 1.39 mm 1st half‐value layer thickness. Monte Carlo simulations (GATE, version 8) were performed with semi‐ellipsoidal, homogeneous breasts of various fibroglandular weight fractions (fg=0.01,0.15,0.5,1false), chest wall diameters (d=8,10,14,18,20 cm), and chest wall to nipple length (l=0.75d), aligned with the axis of rotation (AOR) located at 65 cm from the focal spot to determine the DgNCT. Three geometries were considered – 40×30‐cm detector with no offset that served as reference and corresponds to a clinical CBBCT system, 30×30‐cm detector with 5 cm offset, and a 30×30‐cm detector with 10 cm offset. Results For 5 cm lateral offset, the DgNCT ranged 0.177‐0.574 mGy/mGy and reduction in DgNCT with respect to reference geometry was observed only for 18 cm (6.4%±0.23%) and 20 cm (9.6%±0.22%) diameter breasts. For the 10 cm lateral offset, the DgNCT ranged 0.221‐0.581 mGy/mGy and reduction in DgNCT was observed for all breast diameters. The reduction in DgNCT was 1.4%±0.48%, 7.1%±0.13%, 17.5%±0.19%, 25.1%±0.15%, and 27.7%±0.08% for 8, 10, 14, 18, and 20 cm diameter breasts, respectively. For a given breast diameter, the reduction in DgNCT with offset‐detector geometries was not dependent on fg. Numerical fits of italicDgNitalicCTd,l,fg were generated for each geometry. Conclusion The DgNCT and the numerical fit, DgNitalicCTd,l,fg would be of benefit for current CBBCT systems using the reference geometry and for future generations using offset‐detector geometry. There exists a potential for radiation dose reduction with offset‐detector geometry, provided the same technique factors as the reference geometry are used, and the image quality is clinically acceptable.

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“…Also, the reduction in

D g N^{italicCT}

Section: Introductionmentioning

confidence: 99%

Radiation dosimetry of a clinical prototype dedicated cone‐beam breast CT system with offset detector

2021

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“…Also, we use the term pixel size for the detector pixel elements and is in projection domain, and the term voxel size for the reconstructed image volume. Preliminary and partial results investigating the potential of laterally-shifted detector CBBCT were reported in conferences (39,40).…”

Section: Introductionmentioning

confidence: 99%

Dedicated cone-beam breast CT using laterally-shifted detector geometry: Quantitative analysis of feasibility for clinical translation

Vedantham

Tseng

Konate

et al. 2020

XST

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Background: High-resolution, low-noise detectors with minimal dead-space at chest-wall could improve posterior coverage and microcalcification visibility in dedicated cone-beam breast CT (CBBCT). However, their smaller field-of-view necessitates laterally-shifted detector geometry to enable optimizing the air-gap for x-ray scatter rejection. Objective: To evaluate laterally-shifted detector geometry for CBBCT with clinical projection datasets that provide for anatomical structures and lesions. Methods: CBBCT projection datasets (n=17 breasts) acquired with a 40x30-cm detector (1024x768-pixels, 0.388-mm pixels) were truncated along the fan-angle to emulate 20.3x30-cm, 22.2x30-cm and 24.1x30-cm detector formats and correspond to 20, 120, 220-pixels overlap in conjugate views, respectively. Feldkamp-Davis-Kress (FDK) algorithm with three different weighting schemes were used for reconstruction. Visual analysis for artifacts and quantitative analysis of root-mean-squared-error (RMSE), absolute difference between truncated and 40x30cm reconstructions (Diff), and its power spectrum (PS Diff) were performed. Results: Artifacts were observed for 20.3x30-cm, but not for other formats. The 24.1x30-cm provided the best quantitative results with RMSE and Diff (both in units of μ, cm-1) of 4.39x10-3 ±1.98x10-3 and 4.95x10-4 ±1.34x10-4 , respectively. The PS Diff (>0.3 cycles/mm) was in the order of 10-14 μ 2 mm 3 and was spatial-frequency independent. Conclusions: Laterally-shifted detector CBBCT with at least 220-pixels overlap in conjugate views (24.1x30-cm detector format), provides quantitatively accurate and artifact-free reconstruction.

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SU-E-I-01: Radiation Dose Reduction and Image Quality Evaluation of Coronal Truncated Projections in Cone-Beam Dedicated Breast CT

Cited by 2 publications

References 0 publications

Radiation dosimetry of a clinical prototype dedicated cone‐beam breast CT system with offset detector

Radiation dosimetry of a clinical prototype dedicated cone‐beam breast CT system with offset detector

Dedicated cone-beam breast CT using laterally-shifted detector geometry: Quantitative analysis of feasibility for clinical translation

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