Visibility of microcalcification in cone beam breast CT: Effects of x‐ray tube voltage and radiation dose

Lai, Chao Jen; Shaw, Chris C.; Chen, Lingyun; Altunbaş, M.; Liu, Xinming; Han, Tao; Wang, Tianpeng; Yang, Wei Tse; Whitman, Gary J.; Tu, Shu-Ju

doi:10.1118/1.2745921

Cited by 74 publications

(61 citation statements)

References 37 publications

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“…The visibility of MCs in cone beam breast CT with a flat panel ͑FP͒ detector has been investigated and reported. 12,[14][15][16] It was reported that the visibility of large MCs ͑ ജ 250 m͒ increased with increasing mean glandular dose, while the small MCs ͑ Ͻ 250 m͒ were invisible probably due to the limited sensitivity of the FP detector and spatial resolution of the imaging system.…”

Section: Introductionmentioning

confidence: 99%

Dual resolution cone beam breast CT: A feasibility study

et al. 2009

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Purpose: In this study, the authors investigated the feasibility of a dual resolution volume-ofinterest ͑VOI͒ cone beam breast CT technique and compared two implementation approaches in terms of dose saving and scatter reduction. Methods: With this technique, a lead VOI mask with an opening is inserted between the x-ray source and the breast to deliver x-ray exposure to the VOI while blocking x rays outside the VOI. A CCD detector is used to collect the high resolution projection data of the VOI. Low resolution cone beam CT ͑CBCT͒ images of the entire breast, acquired with a flat panel ͑FP͒ detector, were used to calculate the projection data outside the VOI with the ray-tracing reprojection method. The Feldkamp-Davis-Kress filtered backprojection algorithm was used to reconstruct the dual resolution 3D images. Breast phantoms with 180 m and smaller microcalcifications ͑MCs͒ were imaged with both FP and FP-CCD dual resolution CBCT systems, respectively. Two approaches of implementing the dual resolution technique, breast-centered approach and VOI-centered approach, were investigated and evaluated for dose saving and scatter reduction with Monte Carlo simulation using a GEANT4 package. Results:The results showed that the breast-centered approach saved more breast absorbed dose than did VOI-centered approach with similar scatter reduction. The MCs in fatty breast phantom, which were invisible with FP CBCT scan, became visible with the FP-CCD dual resolution CBCT scan. Conclusions:These results indicate potential improvement of the image quality inside the VOI with reduced breast dose both inside and outside the VOI.

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Section: Introductionmentioning

confidence: 99%

Dual resolution cone beam breast CT: A feasibility study

et al. 2009

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“…19 Although an early simulation study indicated that MCs as small as 175-200 μm could be visible in flat panel-based breast CT when the mean glandular dose (MGD) is kept at an acceptable level, a later experimental study reported that the minimum detectable MC size was about 308 μm at the 75% visibility level under similar exposure conditions. 18,20,21 Using a high resolution (48 μm pitch) CCD detector, we have demonstrated that MCs as small as 150 μm could be visualized at an elevated x-ray exposure level. 22 However, it is essential to be able to improve the ability of the BCT system to image small MCs with MGDs as low as 6 mGy.…”

Section: Introductionmentioning

confidence: 95%

“…Optimization and selection of the x-ray spectrum for breast CT has been previously investigated with various conclusions. 15,18,[23][24][25][26] Some of these studies suggested that lower kVs would result in better performance in optimizing the calcification contrast. 24,26 Our own study, based on direct evaluation of MC visibility, did not find any statistically significant improvement when using 60 kV x-rays instead of 80 kV xrays.…”

Section: C Image Acquisition and Reconstructionmentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14] The advantages of CBCT include a higher contrast sensitivity as compared to projection imaging and nearly isotropic high spatial resolution, which have led to the development and investigation of dedicated pendant geometry breast CT technique. [12][13][14][15][16][17][18] Although it has been shown that breast CT has many distinctive advantages, it also has some drawbacks with the two major concerns, poor detection of microcalcifications (MCs) and potentially high radiation dose to the breast. Detection and visualization of MCs play an important role in the screening and diagnosis of breast cancers.…”

Section: Introductionmentioning

confidence: 99%

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Cone beam breast CT with a high pitch (75 μm), thick (500 μm) scintillator CMOS flat panel detector: Visibility of simulated microcalcifications

et al. 2013

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Purpose: To measure and investigate the improvement of microcalcification (MC) visibility in cone beam breast CT with a high pitch (75 μm), thick (500 μm) scintillator CMOS/CsI flat panel detector (Dexela 2923, Perkin Elmer). Methods: Aluminum wires and calcium carbonate grains of various sizes were embedded in a paraffin cylinder to simulate imaging of calcifications in a breast. Phantoms were imaged with a benchtop experimental cone beam CT system at various exposure levels. In addition to the Dexela detector, a high pitch (50 μm), thin (150 μm) scintillator CMOS/CsI flat panel detector (C7921CA-09, Hamamatsu Corporation, Hamamatsu City, Japan) and a widely used low pitch (194 μm), thick (600 μm) scintillator aSi/CsI flat panel detector (PaxScan 4030CB, Varian Medical Systems) were also used in scanning for comparison. The images were independently reviewed by six readers (imaging physicists). The MC visibility was quantified as the fraction of visible MCs and measured as a function of the estimated mean glandular dose (MGD) level for various MC sizes and detectors. The modulation transfer functions (MTFs) and detective quantum efficiencies (DQEs) were also measured and compared for the three detectors used. Results:The authors have demonstrated that the use of a high pitch (75 μm) CMOS detector coupled with a thick (500 μm) CsI scintillator helped make the smaller 150-160, 160-180, and 180-200 μm MC groups more visible at MGDs up to 10.8, 9, and 10.8 mGy, respectively. It also made the larger 200-212 and 212-224 μm MC groups more visible at MGDs up to 7.2 mGy. No performance improvement was observed for 224-250 μm or larger size groups. With the higher spatial resolution of the Dexela detector based system, the apparent dimensions and shapes of MCs were more accurately rendered. The results show that with the aforementioned detector, a 73% visibility could be achieved in imaging 160-180 μm MCs as compared to 28% visibility achieved by the low pitch (194 μm) aSi/CsI flat panel detector. The measurements confirm that the Hamamatsu detector has the highest MTF, followed by the Dexel detector, and then the Varian detector. However, the Dexela detector, with its thick (500 μm) CsI scintillator and low noise level, has the highest DQE at all frequencies, followed by the Varian detector, and then the Hamamatsu detector. The findings on the MC visibility correlated well with the differences in MTFs, noise power spectra, and DQEs measured for these three detectors. Conclusions:The authors have demonstrated that the use of the CMOS type Dexela detector with its high pitch (75 μm) and thick (500 μm) CsI scintillator could help improve the MC visibility. However, the improvement depended on the exposure level and the MC size. For imaging larger MCs or scanning at high exposure levels, there was little advantage in using the Dexela detector as compared to the aSi type Varian detector. These findings correlate well with the higher measured DQEs of the Dexela detector, especially at higher frequencies.

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“…Anderson Cancer Center. 40,41 CT image data used in this study were obtained from investigators at the University of California at Davis as part of an IRB approved study using a prototype dedicated breast CT scanner.…”

Section: Iib Breast Ct Data Acquisition and Image Processingmentioning

confidence: 99%

Methodology for generating a 3D computerized breast phantom from empirical data

Li¹,

Segars²,

Tourassi³

et al. 2009

Medical Physics

116

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The initial process for creating a flexible three-dimensional computer-generated breast phantom based on empirical data is described. Dedicated breast computed-tomography data were processed to suppress noise and scatter artifacts in the reconstructed image set. An automated algorithm was developed to classify the breast into its primary components. A preliminary phantom defined using subdivision surfaces was generated from the segmented data. To demonstrate potential applications of the phantom, simulated mammographic image data were acquired of the phantom using a simplistic compression model and an analytic projection algorithm directly on the surface model. The simulated image was generated using a model for a polyenergetic cone-beam projection of the compressed phantom. The methods used to create the breast phantom generate resulting images that have a high level of tissue structure detail available and appear similar to actual mammograms. Fractal dimension measurements of simulated images of the phantom are comparatively similar to measurements from images of real human subjects. A realistic and geometrically defined breast phantom that can accurately simulate imaging data may have many applications in breast imaging research.

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Visibility of microcalcification in cone beam breast CT: Effects of x‐ray tube voltage and radiation dose

Cited by 74 publications

References 37 publications

Dual resolution cone beam breast CT: A feasibility study

Dual resolution cone beam breast CT: A feasibility study

Cone beam breast CT with a high pitch (75 μm), thick (500 μm) scintillator CMOS flat panel detector: Visibility of simulated microcalcifications

Methodology for generating a 3D computerized breast phantom from empirical data

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