Assessment of cell damages induced by gamma rays and pulsed electron beam at different dose rates

Abstract

The analysis of radiation induced micronuclei frequency in a binucleated cell (MN/BNC) is a standard biological end point to determine the cell damage as well as absorbed dose. In the present study, biological end points such as binucleated cells with micronuclei (BNC with MN) and the number of micronuclei per micro-nucleated binucleated cell (MN/(BNC with MN)) have been used to assess the cell damage. Further, the results of BNC with MN and MN/BNC with MN have been compared with those of previously obtained MN/BNC results. Cell damages have been assessed in human blood lymphocytes, exposed to ⁶⁰Co <span style="font-family:Symbol;mso-ascii-font-family:" times="" new="" roman";="" mso-hansi-font-family:"times="" roman";mso-char-type:symbol;mso-symbol-font-family:="" symbol"="" lang="EN-GB"> <img src='/image/spc_char/gamma2.gif' border=0>-rays at a dose rate of 0.033 Gy s^{<span style="font-family:Symbol;mso-ascii-font-family:" times="" new="" roman";mso-hansi-font-family:="" "times="" roman";mso-char-type:symbol;mso-symbol-font-family:symbol"="" lang="EN-GB">-1</span>} and 8 MeV pulsed electron beam at a mean instantaneous dose rate of 2.6 <span style="font-family:Symbol;mso-ascii-font-family:" times="" new="" roman";mso-hansi-font-family:="" "times="" roman";mso-char-type:symbol;mso-symbol-font-family:symbol"="" lang="EN-GB"><img src='/image/spc_char/cross.gif' border=0> 10⁵ Gy s^{<span style="font-family:Symbol;mso-ascii-font-family:" times="" new="" roman";mso-hansi-font-family:="" "times="" roman";mso-char-type:symbol;mso-symbol-font-family:symbol"="" lang="EN-GB">-1</span>}. The relative biological effectiveness (RBE) for electrons in comparison with <span style="font-family:Symbol;mso-ascii-font-family:" times="" new="" roman";mso-hansi-font-family:="" "times="" roman";mso-char-type:symbol;mso-symbol-font-family:symbol"="" lang="EN-GB"> <img src='/image/spc_char/gamma2.gif' border=0>-rays, has been studied. Dosimeters such as fricke and ferrous ammonium benzoic acid and xylenol orange have been used for the dose measurements. The linear-quadratic dose response curves have been observed for both gamma and electrons. However, the relative effectiveness of 8 MeV electrons with that of gamma radiation for MN yield was found to be more than unity for all the biological endpoints studied at a given dose.<span style="mso-bidi-font-weight:bold"> Present study suggests that the quantification of BNC with MN and MN/(BNC with MN) along with MN/BNC provides additional information, while assessing radiation induced cell damage.

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