The Biophotonics/Bioimaging Lab

College of Engineering X-ray Imaging Center

X-ray Computed Tomography

The CENGR x-ray imaging center gives access to a custom designed ex-vivo volumetric CT scanner for samples up to 8" diameter and height, such as agricultural products, soil samples, rock samples, and biological tissue. The CT scanner features dual-energy capability for accurate water content determination or beam-hardening correction.

Technical details of the CT scanner:

X-ray energy: 70 kVp and 140 kVp
Photo of CT scanner (C) AAMI, published in Biomedical Instrumentation & Technology March/April 2014, link to article. Reproduced with permission.
Beam collimation: 2.3mm, 1.2mm and 0.5 mm
Resolution: 0.5 mm in-plane
  0.25mm in-plane interpolated pseudo-resolution
  Minimum 0.5 mm slice distance
Maximum scan width: 8" (20cm)
Maximum axial scan length: 8" (20cm)
Scan modes: Line scan
  2D slice (180 or 360 degrees)
  3D volumetric
  2D projection (scout scan)
Reconstruction: 2D (FBP or SART)
Radiation shield: 800 pounds of lead

 

CT Image Gallery

Cross-sectional images of two different soil samples inside a 4 inch PVC tube. Left: sand, right: gravel. Images taken at 140 kVp.

Two perpendicular cross-sections thorugh an onion, 140kVp.

Surface reconstruction of a 3D
volumetric scan of a denture,
rendered with OpenDX.
Projection image of a hard disk: Left, 140kVp image with detail added from 70kVp,
Right: False-colored image based on removal of aluminum with dual-energy weighting
Projection image of an "enhanced" passport. Left, 70kVp image. The RFID chip (top left) and the large antenna coil are clearly visible. The structure at the bottom is an improvised passport holder. Right: Metallic parts contrast-enhanced with the dual-energy feature. The antenna coil and the wires leading away from the RFID chip become even more prominently visible.
CT scan of a failing UHP (ultrahigh pressure) projector lamp. The 3D rendering was performed with OpenDX: The reflector is shown in gray, metal parts (such as the electrodes and the mounting tab) in red, and the bulb in yellow with a blue clipped view. The expanding and asymmetric gas volume can clearly be seen. The inset shows a cross-sectional cut through the gas discharge bulb. The electrodes can be prominently seen, but the image also shows (a) conspicuous misalignment of the electrodes, and (b) asymmetrical expansion of the bulb with thinning of the glass wall. Failure appears to be imminent.

Small-Sample X-ray Imaging

A converted Faxitron MX-20 is available. The MX-20 allows to take projection images over an area up to 10x10 cm with a custom CMOS sensor. Larger area images are possible by using conventional x-ray film cassettes. This device is perfectly suited for small biological and agricultural samples.

Technical details of the x-ray imaging device:

X-ray source: TruFocus TFX-8050
Target: 8┬Ám focal spot on tungsten
Output window: Beryllium
X-ray energy: 15 to 35 kVp (variable)
Tube current:
 
0.35A maximum
 
Sensor: Teledyne RadEye-1 (4x2 array)
Intensifier: Gd2O2S : Tb (Lanex)
Active area: 100mm x 100mm
Spatial resolution: 50 microns
FWHM: 100 microns

 

X-ray Image Gallery

Absorbance image of a hybrid chip on a 40-pin DIL carrier, taken at 35kVp. The presence of several discrete surface-mounted components and multiple dies, mounted directly on the ceramic carrier is immediately visible, as are the conntecting traces. Projected absorbance ranges from zero (black) to about 5 (white). The image has been reduced by a factor of 2 for the web display, and the green scale bar represents 5mm. The inset shows a small section (blue rectangle) at 1:1 scale and after histogram stretching. Gold bond wires (approximately 50 micron diameter) are prominently visible.