RT Journal Article
SR Electronic
T1 Optimizing Y-90 imaging for a digital PET/CT system
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 1282
OP 1282
VO 56
IS supplement 3
A1 Yu-Lung Hsieh
A1 Sharon Wang
A1 Jinghan Ye
A1 Jun Zhang
A1 Katherine Binzel
A1 Chadwick Wright
A1 Michael Knopp
A1 Zhiqiang Hu
YR 2015
UL http://jnm.snmjournals.org/content/56/supplement_3/1282.abstract
AB 1282 Objectives Y-90 radioembolization becomes a common treatment for inoperable hepatocellular carcinoma (HCC). However, Y-90 has very low positron branching ratio of 3.187 x 10-5 along with high cascade gamma rays at energy of 628 keV. The cascade gamma rays can reduce the prompts sensitivity (prompts/(prompts+delays)) to below 30%. Low branching ratio and cascade gamma rays make it challenging to generate quantitative PET images from Y-90. This study aims at a method for optimizing the Y-90 images.Methods Instead of correcting the cascade gamma rays with modeling [1], a new method is proposed to reduce the cascade gamma rays and improve the prompts sensitivity by selecting an optimized upper energy window at 552 keV, which represents the valley between the 511 keV gamma rays and the cascade gamma rays in the energy spectrum. In addition, due to the low count statistics, a system modeling of random and scatter events is applied to the reconstruction algorithm to improve the intermediate image quality for estimating the scatter distribution. A time-of-flight based PET reconstruction algorithm has been implemented in the Philips digital PET/CT system (Vereos) using blobs as basis function. The selection of blob parameters, number of iterations, and number of subsets were optimized to improve the Y-90 image quality.Results With the optimized energy window the prompts sensitivity for Y-90 was raised from 26.4% to 52.5% and improved the NAC (with no attenuation or scatter correction) images with much cleaner background than the images from the original energy window. The optimization in reconstruction process and parameter tuning yielded better CTAC (with attenuation and scatter correction) images showing more realistic Y-90 distribution.Conclusions A new method is proposed to optimize the data and reconstruction processes for improving the Y-90 image quality on the Philips digital PET/CT system (Vereos). It is demonstrated that this new method shows promise to advance clinically feasible image quality and quantification accuracy.