Design of Light Multi-layered Shields for Use in Diagnostic Radiology and Nuclear Medicine via MCNP5 Monte Carlo Code

Document Type: Original Paper

Authors

1 Ray Medical Engineering Department, School of Mechanical Engineering, Shiraz University, Shiraz Iran

2 Radiation Research Center, School of Mechanical Engineering, Shiraz University, Shiraz, Iran

Abstract

Introduction
Lead-based shields are the most widely used attenuators in X-ray and gamma ray fields. The heavy weight, toxicity and corrosion of lead have led researchers towards the development of non-lead shields.
Materials and Methods
The purpose of this study was to design multi-layered shields for protection against X-rays and gamma rays in diagnostic radiology and nuclear medicine. In this study, cubic slabs composed of several materials with high atomic numbers, i.e., lead, barium, bismuth, gadolinium, tin and tungsten, were simulated, using MCNP5 Monte Carlo code. Cubic slabs (30×30×0.05 cm3) were simulated at a 50 cm distance from the point photon source. The X-ray spectra of 80 kVp and 120 kVp were obtained, using IPEM Report 78. The photon flux following the use of each shield was obtained inside cubic tally cells (1×1×0.5 cm3) at a 5 cm distance from the shields. The photon attenuation properties of multi-layered shields (i.e., two, three, four and five layers), composed of non-lead radiation materials, were also obtained via Monte Carlo simulations.
Results
Among different shield designs proposed in this study, the three-layered shield, composed of tungsten, bismuth and gadolinium, showed the most significant attenuation properties in radiology, with acceptable shielding at 140 keV energy in nuclear medicine.
Conclusion
According to the results, materials with k-edges equal to energies common to diagnostic radiology can be proper substitutes for lead shields.

Keywords

Main Subjects



Volume 12, Issue 3
September and October 2015
Pages 223-228
  • Receive Date: 20 December 2014
  • Revise Date: 21 December 2015
  • Accept Date: 19 May 2015