X-Ray Digital Radiography and Computed Tomography applied to Cultural Heritage, Medicine and Industrial applications
 
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Digital Radiography
Computed Tomography
   Intensified Cone Beam CT
   Micro CT
   Multislice Tomography
   Works carried out at the Getty
       Conservation Institute, Los Angeles
   High Energy Tomography
      Old Roman Jug
      Etruscan Fibula
      Bronze Head
   Large Objects
 Neutron Tomography
Iort Project
Autoradiography

High Energy Tomography

THE EXPERIMENTAL SETUP 
The signal is digitized through a 12-bit ADC mounted onboard on the EBCCD camera. The camera provides one digital output provided to the PC. The digital electronics of the EBCCD camera has been developed at Geosphaera Research Center in Moscow and is based on a microprocessor produced by Altera Corporation. The main feature of the presented system is its high spatial resolution, thanks to the pixel size of about 22.5 micrometers, even for large objects (up to 13 cm). 



The high sensitivity of the EBCCD camera allows the use of a low radiation intensity and a significant response also with a short exposure time. In addition, the linear geometry is appropriate for beam collimation and a further reduction in scattered radiation, leading to a better image contrast.
This EBCCD camera consists of a 24 mm photocathode, a high voltage intensifier tube (ranging from 5 to 10 kV) and a CCD chip with 1024×512 useful pixels. The size of the CCD pixels is 13.3×13.1 μm2. The sensitive area of the imaging zone is 13.4×6.7 mm2, whereas the useful area of the photocathode is 20.78×12.0 mm2 (demagnification factor is 0.56). A 12-bit ADC, on the border of the EBCCD electronics, provides the digital output. The sensitivity threshold is about 5×10-5 lux. This characteristic allows detection of low-light images as well as a reduction in exposure time and the irradiated dose.A diagram of the detection system configuration is shown in figure 5. A 30×40 cm2 GOS screen is mounted on the entrance window of a large box that both acts as a support and provides proper shielding for the detection system. By changing the distance between the EBCCD and the scintillating screen and adopting a suitable lens on the photocathode, it is possible to obtain highresolution images of a smaller area and a radiographic zoom of a specific zone. The set-up is similar to that of the micro-CT system, but this intensified system permits investigation of bigger objects with a resolution of about 200 μm (depending on the distance from the detector and screen and the magnification factor). 

 
 
 
 

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