US researchers have developed a high-resolution, low-dose phase contrast X-ray tomography (PCT) for diagnosis of breast cancers that delivers a 74% reduced radiation dose compared with conventional PCT.
The novel approach, pioneered by Jianwei Miao and colleagues at University of California, Los Angeles, has the potential to address the increased risk for cancer due to repeated mammography, and the high rate of false positives commonly reported with this screening method.
"This new technique can open up the doors to the clinical use of computed tomography in the breast diagnosis, which would be a powerful tool to fight even better and earlier against breast cancer," said Maximilian Reiser (Ludwig Maximilians University, Garching, Germany) in a press statement.
The researchers were able to image a human breast in three dimensions and identify a malignant cancer with a pixel size of 92 µm, by combining PCT with an image reconstruction method know as equally sloped tomography (EST).
Importantly, EST using 512 of the 2000 projections produced by gold-standard filtered back projection (FBP 2000) reduced the radiation dose by approximately 74%, from 7.7 to 2.0 mGy.
Furthermore, blinded evaluation by five radiologists found that, although the overall image quality was lower than that of EST 512 and FBP 2000, EST on 200 projections still outperformed an FBP reconstruction based on 512 projections, with the 3D breast tumor structure remaining visible. The total radiation dose in EST 200 was just 0.8 mGy, which the authors note is about four times lower than that delivered in dual-view screening mammography.
Reiser and colleagues reason that the acquisition time would presumably also be improved by approximately 74% (from 25.1 to 6.6 minutes) with EST 512 versus FBP 2000, while - if the higher noise level could be tolerated - it could be cut to around 2.5 minutes with EST 200, which the researchers say is another critical factor for pursuing in vivo imaging and clinical application of PCT.
"After dramatically reducing the dose delivered during the examination of the breast, our next objective is to develop this technique in the early visualization of other human disease and to work towards its clinical implementation," said co-author Paola Coan, also from Ludwig Maximilians University.
Before this screening method can be implemented in clinics, co-author Emmanuel Brun said an X-ray source small enough to become commonly used for breast cancer screening will be needed: "Many research groups are actively working to develop this device and once this hurdle is cleared, the new X-ray technique is poised to make a big impact on society."
The findings are published in the Proceedings of the National Academy of Sciences.
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