Collimators are essential component of Industrial Radiography set up as they provide radiation safety to the operating personnel and general public at large by directing the emerging radiation beam to the useful area of exposure. A collimator with optimum design features also helps in reducing the scattered radiation which is turn results in radiographs with better sensitivity. Considering the above factors, tungsten collimators with light weight and compact design suitable for directional and panoramic type of exposures have been developed by Radiation Equipment Pragramme of BRIT.

The collimators are fabricated using the above tungsten alloy and 304 stainless steel material as cladding. The tungsten alloy sheild for the directional collimator is designed to provide a 50 degree radiation beam and is encased with stainless steel and totally sealed by argon arc welding.

The panoramic collimator is constructed with two shields designed to provide a 30 degree panoramic radiation beam. The shields are encased with stainless steel and totally sealed by argon arc welding. The collimators can be easily attached to the guide tube exposure head of ROLI-1 radiography camera with a thumb screw.
 
 Directional Collimator :
 

  • When an exposure is taken with the directional collimator attached to the exposure head of the guide tube of gamma camera, the radiation beam coming out will have a 50 degree solid angle in the forward direction.
  • The primary radiation beam intensity in all other area except the front side will be reduced to 5% with the collimator.
  • At a source to film distance (SFD) of 50 cm, the beam will cover an area of a circle with 24 cm radius which is sufficient to cover a film size of 37 cm x 30 cm.
  • Overall size : 44 mm dia x 82 mm long.
  • Weight : 1.15kg.
 Panoramic Collimator :
 
  • When an exposure is taken with the collimator attached to the exposure head of the gamma camera guide tube, the radiation beam will have a 30 degree solid angle all around for panoramic exposures.
  • The primary radiation beam intensity in other areas will be reduced to 5% with the collimator.
  • At a source to film distance (SFD) of 50 cm, the beam will cover a width of a 27 cm.
  • Overall size : 44 mm dia x 82 mm long.
  • Weight : 1kg.
 Salient Features:
   Shielding material    Tungsten alloy
   Density    17.2 to 17.6 gm/cc
    Half value layer for Ir.192    3.4 mm
    Tenth value layer for Ir.192    11.22 mm
    Intensity reduction    95% at the shielded areas
   Directional Collimator    For unidirectional exposures
   Panoramic Collimator    For Panoramic exposures

 

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