@article{oai:repo.qst.go.jp:00044334,
 author = {Takahashi, Yutaka and Mori, Shinichiro and Yamashita, Takashi and et.al and 高橋 豊 and 森 慎一郎 and 山下 孝},
 issue = {2},
 journal = {Radiation Medicine},
 month = {Feb},
 note = {Purpose:  We investigated the method to correct CT metal artifacts due to I-125 seeds and evaluate this efficacy for postimplant dosimetry in prostate permanent implant brachytherapy.
Material and methods: The raw projection data was used to reduce metal artifacts due to I-125 seeds. The CT image of only metal parts was separated from original CT images by setting threshold for pixel value which corresponds to I-125 seeds. Using these images, the sinogram of CT images with or without seeds were obtained by inverse Radon transform. The sinogram of metal image was subtracted from that of the original image. Finally the image after metal artifact correction was reconstructed by Radon transform. This technique was applied to a prostate phantom and a patient. 
Results: The metal artifact from I-125 seeds was reduced by our methods both in phantom and patient study. This technique made inner region of seeds dark while the edge of seeds remained white. Thus identification of seed number, orientation and locations could be easier.  
Conclusion: Our method can be used to reduce metal artifacts from I-125 seeds and could be helpful to identify seeds, allowing speeding up and improving accuracy of postimplant dosimetry.},
 pages = {133--138},
 title = {Preliminary study of correction of original metal artifacts due to I-125 seeds in postimplant dosimetry for prostate permanent implant brachytherapy},
 volume = {24},
 year = {2006}
}