@misc{oai:repo.qst.go.jp:00067404,
 author = {Yamakawa, Keisuke and Kitamura, Keishi and Uemura, Koji and Toyama, Hinako and Haneishi, Hideaki and Murayama, Hideo and Uchiyama, Akihiko and 山川 恵介 and 北村 圭司 and 上村 幸司 and 外山 比南子 and 羽石 秀昭 and 村山 秀雄},
 month = {Jul},
 note = {The in-plane resolution is known to decrease depending on the distance from the center in a PET image. Many methods to improve the spatial resolution have been proposed by many authors with hardware or software. The purpose of this work was to improve the in-plane resolution of PET images without complex calculation and special hardware. We have adopted the detector response function (DRF) changing in the width at the distance from the center to reconstruct PET images. We have evaluated our method for the computer simulated phantom images by a Monte Carlo simulation method.
 The image reconstruction was performed by means of the proposed two methods, in which OS-EM algorithm is modified with the estimated DRF. Method-1 is the OS-EM algorithm incorporating DRF into forward projection. Method-2 is the OS-EM algorithm incorporating DRF into forward and back projection. The DRF is estimated from projection data of eight point sources at different distance from the center. We have evaluated quantitatively our methods for point sources and the brain phantom generated by using a Monte Carlo simulation method. 
 Applying our methods to the simulation studies for point sources and the brain phantom, the in-plane resolution at the point far from the center found to be improved without complex calculation and special hardware., BrainPET'03},
 title = {Evaluation of image reconstruction methods for improving resolution in radial direction with PET},
 year = {2003}
}