X-ray Phase-Contrast Computed Tomography (PC-CT) increases contrast in weakly attenuating samples, such as soft tissues. In Edge-Illumination (EI) PC-CT, phase effects are accessed from amplitude modulation of the x-ray beam using alternating transmitting and attenuating masks placed prior to the sample and detector. A large field of view PC-CT scanner using this technique was applied to two areas of cancer assessment, namely excised breast and esophageal tissue. For the breast tissue, Wide Local Excisions (WLEs) were studied intra-operatively using PC-CT for the evaluation of tumor removal in breast conservation surgery. Images were acquired in 10 minutes without compromising on image quality, showing this can be used in a clinical setting. Longer, higher resolution PC-CT images were also taken, with analysis showing previously undetected thinning of tumor strands. This would allow a second use of the system for “virtual histopathology”, outside of surgery. For the esophagus samples, tissues were taken from esophagectomy surgery, where the lower part of the esophagus is removed, and the stomach relocated. For the assessment of ongoing therapy, accurate staging of tumors in the removed esophagus is essential, with the current gold standard provided by histopathology. PCCT images were acquired on several samples and compare well with histopathology, with both modalities showing similar features. Examples are shown where staging of tumor penetration is possible with PC-CT images alone, which is hoped will be an important step in performing the imaging and staging intra-operatively.
A preliminary investigation into the use of cycloidal computed tomography for intraoperative specimen imaging is presented. Intraoperative imaging is applied in time-sensitive clinical settings, where obtaining a high-resolution, highquality image within minutes is paramount in evaluating the success of operations and/or the need for additional surgery. As a flexible imaging method that is compatible with x-ray phase contrast imaging, cycloidal computed tomography can provide both high spatial resolution and high image contrast, whilst keeping scan times short thanks to an effective under-sampling approach. To gather early evidence, the method was tested on resected breast and oesophageal tissue. The results, although preliminary, indicate that cycloidal imaging may indeed be beneficial for intraoperative specimen imaging, although further studies are required to confirm this potential.
The design of an X-ray phase contrast tomography system for intra-operative specimen imaging based on edge illumination is presented. The use of edge illumination makes possible working with large focus, polychromatic X-ray sources reducing acquisition times of tomography scans down to values compatible with clinical use, while maintaining phase sensitivity in a compact device. The results collected so far show that application of this technology to breast conservation surgery has great potential to reduce re-operations, thus saving additional costs for healthcare services and stress for patients.