TU‐A‐9A‐07: X‐Ray Acoustic Computed Tomography (XACT): 100% Sensitivity to X‐Ray Absorption

Purpose: To assess whether X‐ray acoustic computed tomography (XACT) is more sensitive to X‐ray absorption than that of the conventional X‐ray imaging. Methods: First, a theoretical model was built to analyze the X‐ray absorption sensitivity of XACT imaging and conventional X‐ray imaging. Second, an XACT imaging system was developed to evaluate the X‐ray induced acoustic signal generation as well as the sensitivity improvement over transmission x‐ray imaging. Ultra‐short x‐ray pulses (60‐nanosecond) were generated from an X‐ray source operated at the energy of 150 kVp with a 10‐Hz repetition rate. The X‐ray pulse was synchronized with the acoustic detection via a x‐ray scintillation triggering to acquire the X‐ray induced acoustic signal. Results: Theoretical analysis shows that X‐ray induced acoustic signal is sensitive only to the X‐ray absorption, while completely insensitive to out the X‐ray scattering and fluorescence. XACT has reduced background and increased contrast‐to‐noise ratio, and therefore has increased sensitivity compared to transmission x‐ray imaging. For a 50‐μm size, gadolinium insertion in tissue exposed to 40 keV X‐rays; the sensitivity of XACT imaging is about 28.9 times higher than that of conventional X‐ray imaging. Conclusion: X‐ray acoustic computer tomography (XACT) as a new imaging modality combines X‐ray absorption contrast and high ultrasonic resolution in a single modality. It is feasible to improve the imaging sensitivity with XACT imaging compared with conventional X‐ray imaging. Taking advantage of the high ultrasonic resolution, it is possible to perform 3‐D imaging with a single x‐ray pulse with arrays of transducers without any mechanical motion of the imaging system. This single‐shot capability offers the potential of reducing radiation dose by a factor of 1000, and imaging 100 times faster when compared to the conventional X‐ray CT, and thus revolutionizing x‐ray imaging applications in medicine and biology. The authors gratefully acknowledge the Department of Defense Prostate Cancer Research Programs W81XWH‐13‐1‐0481 (LX), the National Institutes of Health 1R01 CA133474 and 1R21 A153587, and SRFDP (20124407120012) for funding.