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Medical Physics / Volume 37 / Issue 6 / FIFTY-SECOND ANNUAL MEETING OF THE AMERICAN ASSOCIATION OF PHYSICISTS IN MEDICINE / JOINT IMAGING‐THERAPY: ROOM 204B: SCIENTIFIC SESSION / Nanotechnology

Med. Phys. 37, 3437 (2010); http://dx.doi.org/10.1118/1.3469431 (1 page)

WE‐E‐204B‐01: Development of an X‐Ray/Optical Luminescence Imager for Improved X‐Ray Contrast Sensitivity

CM Carpenter, G Pratx, C Sun, and L Xing

Stanford School of Medicine, Stanford, CA

P Ravilisetty

SRI International, Menlo Park, CA

  • Abstract
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Purpose: A dual‐modality X‐ray/optical imaging system is being developed to enable the imaging of ultra‐low concentrations of contrast agents under X‐ray excitation. This imaging system uses nano‐sized inorganic phosphors to convert X‐ray photons into optical photons, which are then imaged with an optical camera. This work presents initial data on the performance capabilities of this system, and demonstrates a significant improvement in contrast agent sensitivity over X‐ray fluoroscopy. Method and Materials: Nano‐sized phosphors were fabricated from Gadolinium Oxysulfide and doped with Terbium (a green‐emitting dopant) or Europium, (a red emitting dopant). A 2.5×4cm cylindrical optical/X‐ray phantom was constructed from l%Agar:99%Distilled water, india ink (for optical absorption), and titanium oxide (for optical scatter) to match biological tissue optical properties. Phosphors were homogeneously mixed at a concentration of 10mg/ml, and poured into a 1cm plug‐shaped inclusion in the phantom. An X‐ray fluoroscopy scanner was positioned vertically above the setup, with the tube voltage/current at 100keV/10mA. Light output was imaged on a lead‐shielded CCD camera, placed 15cm from the phantom, during sample irradiation. An X‐ray fluoroscopy image was collected for comparison. Images acquired via the optical camera and the X‐ray fluoroscopy system were compared to measure the Weber contrast between the phosphor‐filled inclusion and the background. Results: Analysis performed on the X‐ray fluoroscopy image showed a 0.6% contrast between the inclusion and the background. This slight contrast difference is due to the fact that Gadolinium has relatively high X‐ray stopping power compared to water. In contrast, the X‐ray/optical luminescence image showed a 260% difference. Conclusion: The potential of a hybrid X‐ray/optical imaging system was shown in a tissue‐simulating phantom. This technique showed improved contrast to background; this contrast is expected to increase with the addition of Diffuse Optical Tomographic methods, which take into account photon scatter into the background.

© 2010 American Association of Physicists in Medicine

Digital Object Identifier
http://dx.doi.org/10.1118/1.3469431

PUBLICATION DATA

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0094-2405 (print)  

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$abstract.society.value is a Member of CrossRef American Association of Physicists in Medicine

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