Periodic Reporting for period 1 - MONOBREAST (Low-dose breast CT with monochromatic x-ray sources)
Reporting period: 2023-09-01 to 2025-02-28
Although breast cancer screening and improvements in treatment have reduced breast cancer mortality by 30%, this disease still kills over 600,000 women yearly worldwide. To further reduce its morbidity and mortality, new and improved imaging modalities that improve the detection, diagnosis, and treatment of breast cancer are needed.
Over the last two decades, advances in digital imaging technology have revolutionized x-ray-based breast imaging. New digital detectors made feasible the introduction of advanced imaging methods, including dedicated breast computed tomography, or breast CT. Breast CT images the breast from all angles, resulting in a 3-dimensional image that shows the internal breast tissue in its true form and distribution. In a separate project, we improved further upon 3D breast CT to create 4D breast CT. The fourth dimension in this case is time. With 4D breast CT, we create a 3D movie, in which not only the breast tissue is shown, but also the movie shows how blood flows in and out of breast tumors. This information may help the physicians design the best treatment for each individual breast cancer patient, increasing the rate of cure and therefore reducing breast cancer mortality.
However, 3D and 4D breast CT involve too much radiation to be used for screening for breast cancer on all women of screening age. The continued use of the x-ray tube as the source of x rays restricts the reduction in dose and the quantitative accuracy achievable with advances in the rest of the system. Very recently, however, a new monochromatic x-ray source has been developed that provides the necessary flux, x-ray energy, field of view, and portability, to be used in x-ray breast imaging devices.
In MONOBREAST, we aimed to lower the radiation used in breast CT by replacing the traditional x-ray source in these systems by a completely new technology. X-ray source technology has remained essentially unchanged for the last 100 years, but only recently a new type of source, that emits x rays all of the same type, has been developed. This new capability, called monochromatic x-ray emission, could allow for reducing the dose in breast CT considerably. A monochromatic breast CT system would be applicable to every stage in the breast cancer chain, from screening with 3D breast CT at doses equivalent to those of current screening imaging, to 4D breast CT for treatment personalization.
Over the last two decades, advances in digital imaging technology have revolutionized x-ray-based breast imaging. New digital detectors made feasible the introduction of advanced imaging methods, including dedicated breast computed tomography, or breast CT. Breast CT images the breast from all angles, resulting in a 3-dimensional image that shows the internal breast tissue in its true form and distribution. In a separate project, we improved further upon 3D breast CT to create 4D breast CT. The fourth dimension in this case is time. With 4D breast CT, we create a 3D movie, in which not only the breast tissue is shown, but also the movie shows how blood flows in and out of breast tumors. This information may help the physicians design the best treatment for each individual breast cancer patient, increasing the rate of cure and therefore reducing breast cancer mortality.
However, 3D and 4D breast CT involve too much radiation to be used for screening for breast cancer on all women of screening age. The continued use of the x-ray tube as the source of x rays restricts the reduction in dose and the quantitative accuracy achievable with advances in the rest of the system. Very recently, however, a new monochromatic x-ray source has been developed that provides the necessary flux, x-ray energy, field of view, and portability, to be used in x-ray breast imaging devices.
In MONOBREAST, we aimed to lower the radiation used in breast CT by replacing the traditional x-ray source in these systems by a completely new technology. X-ray source technology has remained essentially unchanged for the last 100 years, but only recently a new type of source, that emits x rays all of the same type, has been developed. This new capability, called monochromatic x-ray emission, could allow for reducing the dose in breast CT considerably. A monochromatic breast CT system would be applicable to every stage in the breast cancer chain, from screening with 3D breast CT at doses equivalent to those of current screening imaging, to 4D breast CT for treatment personalization.
A prototype monochromatic breast CT system was built, involving one of these new monochromatic x-ray sources. The overall design of the prototype was based on the geometry of an existing standard 3D breast CT system, but in place of the traditional x-ray tube as the source, the new monochromatic source was used. Assembling the system required the building of the housing that holds all the system components, including x-ray generator, x-ray source, digital detector, programmable controller board, and various electrical sources. The housing is shielded with lead for radiation protection purposes. Once the system was assembled, the capabilities of the monochromatic x-ray source were evaluated. This involved several tests to determine radiation output, variation of the x-ray intensity throughout the image, and spatial resolution and noise characteristics. For this, various test objects and measurement devices were used, in addition to special objects that represent patient breasts, called phantoms. The results are being compared to those known for standard 3D breast CT.
To the best of our knowledge, the prototype system built is the first-ever monochromatic breast CT system in the world. Results indicate that this approach to breast CT is feasible, but there are still hurdles to overcome. The capabilities of the system have been characterized in terms of image quality in the individual projections that are used to compose the final 3D image. To be able to compose this final image, further calibration and characterization is needed; steps which are being taken next. This will allow not only a comparison to the individual projections of standard breast CT, but also a comparison in terms of the final image quality. This comparison will also allow to determine more precisely how long a monochromatic breast CT image of clinical-level quality would take to acquire. This, together with other results of the 3D image characterization will allow for identifying the specific aspects of the new source that need to be improved, if any, to make this cutting-edge technology clinically ready.
Once those technical requirements are met, further research in terms of characterization with more complex phantoms is required. Then, clinical demonstration of performance will be needed, which will involve patient studies. If successful, such studies will allow for the current, or other, manufacturers of breast CT to consider incorporating this technology in their systems. Such introduction could allow for the use of breast CT for every step in the breast care chain, from screening to diagnosis to treatment planning and outcome response evaluation.
Once those technical requirements are met, further research in terms of characterization with more complex phantoms is required. Then, clinical demonstration of performance will be needed, which will involve patient studies. If successful, such studies will allow for the current, or other, manufacturers of breast CT to consider incorporating this technology in their systems. Such introduction could allow for the use of breast CT for every step in the breast care chain, from screening to diagnosis to treatment planning and outcome response evaluation.