Measurement of Scattered Radiation Dose to Lens of the Eye during Computed Tomography of the Brain in Phantom

Background and  Objective:   Computed Tomography  of  brain (CT brain) is  a   higher   radiation  dose  imaging  technique  than  in  the conventional  radiographic  examination.  Not only the brain but also the orbits may included in the area of scanning. The  radiation  risk  of  CT  brain  to patient was  the effect of  radiation  damage  to  the  lens  of  eye  which  is  the  radiosensitive  organ.  Which may induced  cataracts.  In 2005, the  Multislice CT  was  set  up in Sappasittiprasong  hospital Ubonrajchathani.  The   majority   of   CT  examination  was   CT brain.  There  is no previous study to determine  the  radiation  dose  delivered  to  the  eye  of  the  lens.    The  result  of  scattered  radiation  dosimetry   may  provide to evaluate of  radiation  risk  to  the  patient. This study aim to  measure the  scattered  radiation  dose  to  the  lens  of  the  eyes  in Rado Phantom during scanning CT  brain.Method :   An  experimental   study was performed at Physics Department, Faculty of  Science, Ubonrajchathani  University  and  Sappasit-tiprasong  hospital  Ubonrajchathani. Using  the thermoluminescence  dosimeter (TLD).  The  TLD  discs   model  TLD–100  and  TLD   Reader  in   model   3500   provided   by   Harshaw.   The   TLD–100  discs   were  attached  directly  to  both  eye  of  Head rando  phantom   and   they  were  scanned  to  measure  the  scattered  radiation  dose  to  the  lens  during  procedures. The  protocol  for  brain  examination  was  120 kV   250 mAs.   Result:  The  mean  scattered  radiation  dose  to  lens of head rado phantom was  13.87  mGy .Conclusion: The  measured  dose  was  lower  than  the  reported  threshold  of  lens opacity  and  well  cataract. Keywords:  Scattered  Radiation  Dose, Computed Tomography  of  brain, lens  dose,  thermoluminescence  dosimeter (TLD)