Browsing by Author "Dimmock, MR"
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- ItemEffect of x-ray energy on the radiological image quality in propagation-based phase-contrast computed tomography of the breast(Society of Photo-Optical Instrumentation Engineers (SPIE), 2021-07-12) Wan, S; Arhatari, BD; Nesterets, YI; Mayo, SC; Thompson, D; Fox, J; Kumar, B; Prodanovic, Z; Häusermann, D; Maksimenko, A; Hall, CJ; Dimmock, MR; Pavlov, KM; Lockie, D; Rickard, M; Gadomkar, Z; Alaleh, A; Vafa, E; Peele, AG; Quiney, HM; Lewis, SJ; Gureyev, TE; Brennan, PC; Taba, STPurpose: Breast cancer is the most common cancer in women in developing and developed countries and is responsible for 15% of women’s cancer deaths worldwide. Conventional absorption-based breast imaging techniques lack sufficient contrast for comprehensive diagnosis. Propagation-based phase-contrast computed tomography (PB-CT) is a developing technique that exploits a more contrast-sensitive property of x-rays: x-ray refraction. X-ray absorption, refraction, and contrast-to-noise in the corresponding images depend on the x-ray energy used, for the same/fixed radiation dose. The aim of this paper is to explore the relationship between x-ray energy and radiological image quality in PB-CT imaging. Approach: Thirty-nine mastectomy samples were scanned at the imaging and medical beamline at the Australian Synchrotron. Samples were scanned at various x-ray energies of 26, 28, 30, 32, 34, and 60 keV using a Hamamatsu Flat Panel detector at the same object-to-detector distance of 6 m and mean glandular dose of 4 mGy. A total of 132 image sets were produced for analysis. Seven observers rated PB-CT images against absorption-based CT (AB-CT) images of the same samples on a five-point scale. A visual grading characteristics (VGC) study was used to determine the difference in image quality. Results: PB-CT images produced at 28, 30, 32, and 34 keV x-ray energies demonstrated statistically significant higher image quality than reference AB-CT images. The optimum x-ray energy, 30 keV, displayed the largest area under the curve ( AUCVGC ) of 0.754 (p = 0.009). This was followed by 32 keV (AUCVGC = 0.731, p ≤ 0.001), 34 keV (AUCVGC = 0.723, p ≤ 0.001), and 28 keV (AUCVGC = 0.654, p = 0.015). Conclusions: An optimum energy range (around 30 keV) in the PB-CT technique allows for higher image quality at a dose comparable to conventional mammographic techniques. This results in improved radiological image quality compared with conventional techniques, which may ultimately lead to higher diagnostic efficacy and a reduction in breast cancer mortalities.. © 2021 Society of Photo-Optical Instrumentation Engineers (SPIE).
- ItemImaging breast microcalcifications using dark-field signal in propagation-based phase-contrast tomography(IEEE, 2022-05-18) Aminzadeh, A; Arhatari, BD; Maksimenko, A; Hall, CJ; Häusermann, D; Peele, AG; Fox, J; Kumar, B; Prodanovic, Z; Dimmock, MR; Lockie, D; Pavlov, KM; Nesterets, YI; Thompson, D; Mayo, SC; Paganin, DM; Taba, ST; Lewis, SJ; Brennan, PC; Quiney, HM; Gureyev, TEBreast microcalcifications are an important primary radiological indicator of breast cancer. However, microcalcification classification and diagnosis may be still challenging for radiologists due to limitations of the standard 2D mammography technique, including spatial and contrast resolution. In this study, we propose an approach to improve the detection of microcalcifications in propagation-based phase-contrast X-ray computed tomography of breast tissues. Five fresh mastectomies containing microcalcifications were scanned at different X-ray energies and radiation doses using synchrotron radiation. Both bright-field (i.e. conventional phase-retrieved images) and dark-field images were extracted from the same data sets using different image processing methods. A quantitative analysis was performed in terms of visibility and contrast-to-noise ratio of microcalcifications. The results show that while the signal-to-noise and the contrast-to-noise ratios are lower, the visibility of the microcalcifications is more than two times higher in the dark-field images compared to the bright-field images. Dark-field images have also provided more accurate information about the size and shape of the microcalcifications. © 2023 IEEE
- ItemImaging breast microcalcifications using dark-field signal in propagation-based phase-contrast tomography(Australian Nuclear Science and Technology Organisation, 2021-11-24) Aminzadeh, A; Arhatari, BD; Maksimenko, A; Hall, CJ; Häusermann, D; Peele, AG; Fox, J; Kumar, B; Prodanovic, Z; Dimmock, MR; Lockie, D; Pavlov, KM; Thompson, D; Mayo, SC; Paganin, DM; Tavakoli, A; Lewis, SJ; Brennan, PC; Quiney, HM; Gureyev, TEBreast microcalcifications are an important primary radiological indicator of breast cancer. However, microcalcification classification and diagnosis can be still challenging for radiologists due to limitations of the standard 2D mammography technique, including spatial and contrast resolution. In this study, we propose an approach to improve the detection of microcalcifications in propagation-based phase-contrast X-ray tomography (PB-CT) of breast tissues. Five fresh mastectomies containing microcalcifications were scanned at the Imaging and Medical beamline of the Australian Synchrotron at different X-ray energies and radiation doses. Both bright-field and dark-field images were extracted from the same data sets using different image processing methods [1]. A quantitative analysis was performed in terms of visibility and contrast-to-noise ratio of microcalcifications. The results show that the visibility of the microcalcifications in the dark-field images is more than two times higher compared to the bright-field images. Dark-field images have also provided more accurate information about the size and shape of the microcalcifications [2]. Therefore, dark-field PB-CT images are likely to help radiologists evaluate the probability of breast cancer more effectively. This work has been conducted in the course of developing a medical imaging facility at the Australian Synchrotron for advanced breast cancer imaging. © The Authors
- ItemPropagation-based phase-contrast CT of the breast demonstrates higher quality than conventional absorption-based CT even at lower radiation dose(Elsevier B. V., 2021-01) Taba, ST; Arhatari, BD; Nesterets, YI; Gadomkar, Z; Mayo, SC; Thompson, D; Fox, J; Kumar, B; Prodanovic, Z; Häusermann, D; Maksimenko, A; Hall, CJ; Dimmock, MR; Pavlov, KM; Lockie, D; Gity, M; Peele, AG; Quiney, HM; Lewis, SJ; Gureyev, TE; Brennan, PCRationale and Objectives Propagation-based phase-contrast CT (PB-CT) is an advanced X-ray imaging technology that exploits both refraction and absorption of the transmitted X-ray beam. This study was aimed at optimizing the experimental conditions of PB-CT for breast cancer imaging and examined its performance relative to conventional absorption-based CT (AB-CT) in terms of image quality and radiation dose. Materials and Methods Surgically excised breast mastectomy specimens (n = 12) were scanned using both PB-CT and AB-CT techniques under varying imaging conditions. To evaluate the radiological image quality, visual grading characteristics (VGC) analysis was used in which 11 breast specialist radiologists compared the overall image quality of PB-CT images with respect to the corresponding AB-CT images. The area under the VGC curve was calculated to measure the differences between PB-CT and AB-CT images. Results The highest radiological quality was obtained for PB-CT images using a 32 keV energy X-ray beam and by applying the Homogeneous Transport of Intensity Equation phase retrieval with the value of its parameter γ set to one-half of the theoretically optimal value for the given materials. Using these optimized conditions, the image quality of PB-CT images obtained at 4 mGy and 2 mGy mean glandular dose was significantly higher than AB-CT images at 4 mGy (AUCVGC = 0.901, p = 0.001 and AUCVGC = 0.819, p = 0.011, respectively). Conclusion PB-CT achieves a higher radiological image quality compared to AB-CT even at a considerably lower mean glandular dose. Successful translation of the PB-CT technique for breast cancer imaging can potentially result in improved breast cancer diagnosis. Crown Copyright © 2020 Published by Elsevier Inc. on behalf of The Association of University Radiologists.
- ItemPropagation-based x-ray phase-contrast tomography of mastectomy samples using synchrotron radiation(American Association of Physicists in Medicine, 2019-10-01) Gureyev, TE; Nesterets, YI; Baran, PM; Taba, ST; Mayo, SC; Thompson, D; Arhatari, BD; Mihocic, A; Abbey, B; Lockie, D; Fox, J; Kumar, B; Prodanovic, Z; Häusermann, D; Maksimenko, A; Hall, CJ; Peele, AG; Dimmock, MR; Pavlov, KM; Cholewa, M; Lewis, SJ; Tromba, G; Quiney, HM; Brennan, PCPurpose Propagation-based phase-contrast computed tomography (PB-CT) is a method for three-dimensional x-ray imaging that utilizes refraction, as well as absorption, of x rays in the tissues to increase the signal-to-noise ratio (SNR) in the resultant images, in comparison with equivalent conventional absorption-only x-ray tomography (CT). Importantly, the higher SNR is achieved without sacrificing spatial resolution or increasing the radiation dose delivered to the imaged tissues. The present work has been carried out in the context of the current development of a breast CT imaging facility at the Australian Synchrotron. Methods Seven unfixed complete mastectomy samples with and without breast cancer lesions have been imaged using absorption-only CT and PB-CT techniques under controlled experimental conditions. The radiation doses delivered to the mastectomy samples during the scans were comparable to those approved for mammographic screening. Physical characteristics of the reconstructed images, such as spatial resolution and SNR, have been measured and compared with the results of the radiological quality assessment of the complete absorption CT and PB-CT image stacks. Results Despite the presence of some image artefacts, the PB-CT images have outperformed comparable absorption CT images collected at the same radiation dose, in terms of both the measured objective image characteristics and the radiological image scores. The outcomes of these experiments are shown to be consistent with predictions of the theory of PB-CT imaging and previous reported experimental studies of this imaging modality. Conclusions The results presented in this paper demonstrate that PB-CT holds a high potential for improving on the quality and diagnostic value of images obtained using existing medical x-ray technologies, such as mammography and digital breast tomosynthesis (DBT). If implemented at suitable synchrotron imaging facilities, PB-CT can be used to complement existing imaging modalities, leading to more accurate breast cancer diagnosis. © 2023 American Association of Physicists in Medicine
- ItemX-ray phase-contrast computed tomography for soft tissue Imaging at the Imaging and Medical Beamline (IMBL) of the Australian Synchrotron(MDPI, 2021-04-30) Arhatari, BD; Stevenson, AW; Abbey, B; Nesterets, YI; Maksimenko, A; Hall, CJ; Thompson, D; Mayo, SC; Fiala, T; Quiney, HM; Taba, ST; Lewis, SJ; Brennan, PC; Dimmock, MR; Häusermann, D; Gureyev, TEThe Imaging and Medical Beamline (IMBL) is a superconducting multipole wiggler-based beamline at the 3 GeV Australian Synchrotron operated by the Australian Nuclear Science and Technology Organisation (ANSTO). The beamline delivers hard X-rays in the 25–120 keV energy range and offers the potential for a range of biomedical X-ray applications, including radiotherapy and medical imaging experiments. One of the imaging modalities available at IMBL is propagation-based X-ray phase-contrast computed tomography (PCT). PCT produces superior results when imaging low-density materials such as soft tissue (e.g., breast mastectomies) and has the potential to be developed into a valuable medical imaging tool. We anticipate that PCT will be utilized for medical breast imaging in the near future with the advantage that it could provide better contrast than conventional X-ray absorption imaging. The unique properties of synchrotron X-ray sources such as high coherence, energy tunability, and high brightness are particularly well-suited for generating PCT data using very short exposure times on the order of less than 1 min. The coherence of synchrotron radiation allows for phase-contrast imaging with superior sensitivity to small differences in soft-tissue density. Here we also compare the results of PCT using two different detectors, as these unique source characteristics need to be complemented with a highly efficient detector. Moreover, the application of phase retrieval for PCT image reconstruction enables the use of noisier images, potentially significantly reducing the total dose received by patients during acquisition. This work is part of ongoing research into innovative tomographic methods aimed at the introduction of 3D X-ray medical imaging at the IMBL to improve the detection and diagnosis of breast cancer. Major progress in this area at the IMBL includes the characterization of a large number of mastectomy samples, both normal and cancerous, which have been scanned at clinically acceptable radiation dose levels and evaluated by expert radiologists with respect to both image quality and cancer diagnosis. © 2021 The Authors, Licensee MDPI, Basel, Switzerland. Open Access Creative Commons Attribution (CC BY).