M. Vijayam

Publications (3)2.83 Total impact

• Article: Direct calibration of a reference standard against the air kerma strength primary standard, at 192Ir HDR energy.

  K N Govinda Rajan, T Palani Selvam, B C Bhatt, M Vijayam, V S Patki, Vinatha, A M Pendse, V Kannan
  [show abstract] [hide abstract]
  ABSTRACT: The primary standard of low air kerma rate sources or beams, maintained at the Radiological Standards Laboratory (RSL) of the Bhabha Atomic Research Centre (BARC), is a 60 cm3 spherical graphite ionization chamber. A 192Ir HDR source was standardized at the hospital site in units of air kerma strength (AKS) using this primary standard. A 400 cm3 bakelite chamber, functioning as a reference standard at the RSL for a long period, at low air kerma rates (compared to external beam dose rates), was calibrated against the primary standard. It was seen that the primary standard and the reference standard, both being of low Z, showed roughly the same scatter response and yielded the same calibration factor for the 400 cm3 reference chamber, with or without room scatter. However, any likelihood of change in the reference chamber calibration factor would necessitate the re-transport of the primary standard to the hospital site for re-calibration. Frequent transport of the primary standard can affect the long-term stability of the primary standard, due to its movement or other extraneous causes. The calibration of the reference standard against the primary standard at the RSL, for an industrial type 192Ir source maintained at the laboratory, showed excellent agreement with the hospital calibration, making it possible to check the reference chamber calibration at RSL itself. Further calibration procedures have been developed to offer traceable calibration of the hospital well ionization chambers.
  Physics in Medicine and Biology 05/2002; 47(7):1047-58. · 2.83 Impact Factor
• Conference Proceeding: Direct calibration of a reference chamber against the low air kermarate primary standard at Ir-192 energy

  K N Govinda Rajan, N. Palaniselvan, B C Bhatt, M. Vijayam, V.S. Patki, Vinatha, Jadhavgaonkar, A M Pendse, V Kannan
  [show abstract] [hide abstract]
  ABSTRACT: Using a 60 cc spherical graphite ionization chamber as the Primary Standard the HDR Ir-192 source was standardized at the hospital site in a minimum scatter geometry, in units of Air Kerma Strength (AKS). A 400 cc bakelite reference chamber was calibrated against the Primary Standard. It was seen that the Primary Standard and the Reference chamber, both being of low Z, showed roughly the same scatter response and yielded the same calibration factor for the 400 cc reference chamber, with or without scatter. The scatter correction, however, is required for the determination of the Air kerma strength. The theoretical Monte Carlo estimates of the scatter corrections, obtained by simulating the source and the room geometry, showed excellent agreement with the experimental values. This reference chamber can now be used at other hospital sites for determining the AKS of the source, by applying proper scatter corrections. However, any likelihood of change in the reference chamber calibration would necessitate the transport of the Primary Standard to the hospital site for recalibration. Frequent transport of the Primary Standard can lead to changes in its response due to movement or other extraneous causes. The calibration of the Reference chamber against the Primary Standard at the Standards Lab., for an industrial type Ir-192 source maintained at the lab., showed excellent agreement with the hospital calibration, making it possible to check the reference chamber calibration at the lab. itself. Further work is in progress
  Engineering in Medicine and Biology Society, 2000. Proceedings of the 22nd Annual International Conference of the IEEE; 02/2000
• Article: Testing of NK and ND,w based IAEA Codes of Practice for clinical photon beams

  K N Govinda Rajan, S. Vandanaa, M. Vijayam, J. B. Shigwan, M R McEwen, S. Duane