RT Journal Article
SR Electronic
T1 The study of beam hardening effect using additional copper filter on low dose CT
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 2008
OP 2008
VO 52
IS supplement 1
A1 Subhash Kheruka
A1 U. Naithani
A1 Anil Maurya
A1 Nirmal Painuly
A1 Lalit Aggarwal
A1 Sanjay Gambhir
YR 2011
UL http://jnm.snmjournals.org/content/52/supplement_1/2008.abstract
AB 2008 Objectives To minimize the beam hardening effects using additional copper filter in the x- ray beam Methods This study was performed SPECT/CT (HAWKEYE 4, GE Medical). For the evaluation of image quality CT QA Phantom (PHILIPS) and Jaszak’s SPECT phantom with contrast materials of iodine & bismuth were used. The axial images were acquired using various thicknesses of copper filters ranging from 1mm to 5 mm in steps of 1 mm. First set of images were acquired without putting any filter into the beam. Then successively filters of different thicknesses were placed into the beam and calibration of the CT scanner was performed before acquiring the images. The x - ray tube parameters were kept same as with unfiltered x- ray beam. Images were analysed for visibility, spatial resolution and contrast. Results Successive improvement in the image quality was noticed when we increased the filter thickness from 1 mm to 3 mm. The images acquired with 3 mm filter appeared almost with no artefacts and visibly sharper. Degradation in the image quality was noticed when we increased the filter thickness further 4 & 5 mm. The spatial resolution for image matrix of 512 x 512 was found 1.29 mm, 1.07 mm, 0.64 mm and 0.54 mm for without filter, 1mm, 2mm & 3 mm filter respectively. The image quality was further analysed for signal-to-noise ratio (SNR). It was found to be 1.72, 1.78, 1.98 & 1.99 for open, with 1, 2 & 3 mm filters respectively. This shows that 3 mm filter results an improvement of 15.7% in SNR. Conclusions Use of 3 mm copper filter in the x - ray beam is optimal for removing the artefacts without causing any significant reduction in the photon flux of the resulting x - ray beamContrast - to - Noise Ratio Estimated from PHILIPS CT Phantom