Pulse coding with complementary Golay sequences for signal to noise ratio improvement in ultrasound mammography (original) (raw)
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Technical advances in breast ultrasound imaging
Seminars in ultrasound, CT, and MR, 2006
Breast sonography plays an integral role in breast imaging. The technical advances in the field have made breast sonography an essential component of the breast imaging evaluation. In its clinical nascence, the role of breast sonography was primarily to differentiate cysts from solid masses. Technical advances such as compound imaging and harmonics have resulted in improved lesion characterization. Other technical advances such as Doppler imaging, extended field-of-view, fremitus imaging, intravenous contrast, computer-aided diagnosis, and elastography have also expanded the clinical applications of breast sonography. While some of these technical advances are still in the research phase, many are available today for clinical use. We will review these technical advances and examine their roles in clinical breast imaging today.
Recent technological advancements in breast ultrasound
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Computed Radiography (CR) is a cost-effective technology for digital mammography. In order to optimize the quality of images obtained using CR Mammography, we characterized the effect on image quality of the electrooptical components of the CR imaging chain. The metrics used to assess the image quality included the Contrast to Noise Ratio (CNR), Modulation Transfer Function (MTF), Noise Power Spectrum (NPS), Detective Quantum Efficiency (DQE) and Contrast Detail Response Phantom (CDMAM 3.4 Artinis Medical Systems). An 18×24 cm high-resolution granular phosphor imaging plate (AGFA MM3.0) was used to acquire the images. Contrast detail was measured using a GUI developed for the CDMAM phantom that was scored by independent observers. The range of theoretically acceptable values measured for the CR laser was (5-36) mW and voltage range for PMT's was (4-8) V. The light detection amplifier was investigated, and the optimal Laser Power and PMT gain used for scanning was measured. The tools that we used (CNR, MTF, NPS, DQE and Contrast-detail phantom) provided an effective means of selecting optimal values for the electro-optical components of the system. The procedure enabled us to obtain good quality CR mammograms that have less noise and improved contrast.
The Role of Various Modalities in Breast Imaging
Biomedical Papers, 2007
Background: Breast cancer is the most common type of cancer in women worldwide. Mammography is considered the "gold standard" in the evaluation of the breast from an imaging perspective. Apart from mammography, ultrasound examination and magnetic resonance imaging are being off ered as adjuncts to the preoperative workup. Recently, other new modalities like positron emission tomography, 99mTc-sestamibi scintimammography, and electrical impedance tomography (EIT) are also being off ered. However, there is still controversy over the most appropriate use of these new modalities. Based on the literature, this review evaluates the role of various modalities used in the screening and diagnosis of breast cancer. Methods and Results: Based on relevant literatures this article gives an overview of the old and new modalities used in the fi eld of breast imaging. A narrative literature review of all the relevant papers known to the authors was conducted. The search of literatures was done using pubmed and ovid search engines. Additional references were found through bibliography reviews of relevant articles. It was clear that though various new technics and methods have emerged, none have substituted mammography and it is still the only proven screening method for the breast as of date. Conclusion: From the literature it is clear that apropos modern radiology's impact on diagnosis, staging and patient follow-up, only one imaging technique has had a signifi cant impact on screening asymptomatic individuals for cancer i.e.; low-dose mammography. Mammography is the only screening test proven in breast imaging. Positron emission tomography (PET) also plays an important role in staging breast cancer and monitoring treatment response. As imaging techniques improve, the role of imaging will continue to evolve with the goal remaining a decrease in breast cancer morbidity and mortality. Progress in the development and commercialisation of EIT breast imaging system will defi nitely help to promote other systems and applications based on the EIT and similar visualization methods. Breast ultrasound and breast magnetic resonance imaging (MRI) are frequently used adjuncts to mammography in today's clinical practice and these techniques enhance the radiologist's ability to detect cancer and assess disease extent, which is crucial in treatment planning and staging.
Can radiation dose in mammography be further reduced by increasing the image quality?
Breast Cancer Research, 2011
Introduction The automated breast volume scanner (ABVS) is the fi rst of its kind and utilises a large, 17 cm × 15 cm high-frequency ultrasound probe which sweeps across the whole breast generating images that can be reformatted into multiple planes and a 3D volume. ABVS will change breast ultrasound practice by: introducing operator standardisation, reproducibility and repeatability of measurement and interpretation; changing who acquires the volume set and how breast ultrasounds are reported; and allowing accurate comparison of previous and current examinations for screening and assessing treatment change. Methods Patients presented to the symptomatic clinic for conventional 2D ultrasound assessment with a variety of conditions. An additional ABVS was performed. Results Cases were classifi ed into: benign-for example, cysts, fi broadenomas, diabetic mastopathy; and malignant. Conclusion We present a review of our initial experience and highlight its advantages over conventional ultrasound, which include: improved mapping of lesions enabling more accurate future assessment and follow-up, and improved assessment of distortion over conventional 2D ultrasound. Further research is required to explore other potential benefi ts.
Effect of area x-ray beam equalization on image quality and dose in digital mammography
Physics in Medicine and Biology, 2004
In mammography, thicker or denser breast regions persistently suffer from reduced contrast-to-noise ratio (CNR) because of degraded contrast from large scatter intensities and relatively high noise. Area x-ray beam equalization can improve image quality by increasing the x-ray exposure to under-penetrated regions without increasing the exposure to over-penetrated regions. The implementation of equalization into digital mammography, however, requires that optimal parameters with respect to image quality and patient dose be determined. Equalization parameters were optimized through computer simulations and validated with experimental observations on a breast equivalent tissue (BR12) step phantom and breast phantom. Three parameters important in equalization digital mammography were considered: attenuator material (Z=13 to 92), kilovoltage (22 to 34 kVp), and equalization level. A Mo/Mo digital mammography system was used for image acquisition. A prototype 16x16 piston driven equalization system and silicon binder material were utilized for the preparation of patient-specific equalization masks. Improvements in contrast, CNR, and figure of merit (FOM = CNR 2 /exposure) due to equalization were quantified, and the enhancement of image quality and microcalcification detectability with equalization was subjectively assessed. Simulation studies showed that a molybdenum attenuator, a tube voltage of approximately 26 to 28 kVp, and an equalization level of 20 were optimal for improving contrast, CNR, and FOM. Experimental measurements using these suggested parameters showed significant improvements in contrast, CNR, and FOM. Moreover, equalized images of a BR12 breast phantom showed improved overall image quality and micro-calcification detectability. These results indicate that area beam equalization can improve image quality in digital mammography.
Development Of A Digital Mammography System
Medical Imaging II
A digital breast imaging system is under development to provide improved detectability of breast cancer. In previous work, the limitations of screen-film mammography were studied using both theoretical and experimental techniques. Important limitations were found in both the acquisition and the display components of imaging. These have been addressed in the design of a scanned-projection digital mammography system. A high resolution x-ray image intensifier (XRII), optically coupled to a self-scanned linear photodiode array, is used to record the image. Preand post-patient collimation virtually eliminates scattered radiation and veiling glare of the XRII with only a 20% increase in dose due to penumbra. Geometric magnification of 1.6 times is employed to achieve limiting spatial resolution of 7 1p /mm. For low-contrast objects as small as 0.1 mm in diameter, the digital system is capable of producing images with higher contrast and signal-to-noise ratio than optimally-exposed conventional film-screen mammography systems. Greater latitude is obtainable on the digital system because of its wide dynamic range and linearity. The slit system is limited due to long image acquisition times, and poor quantum efficiency. This motivated our current work on a slot beam digital mammography system which is based on a fiber-optic x-ray detector. Preliminary results of this system will be presented.