A hybrid attenuation correction technique to compensate for lung density in 3-D total body PET
- UCLA School of Medicine, Los Angeles, CA (United States)
The purpose of this investigation was to develop a technique for correcting attenuation in noisy emission images without using standard measured attenuation techniques. Data sets in 3-D total body PET are very noisy. In order to have attenuation correction in this imaging modality, excessive times required for transmission scans, isotope uptake and imaging procedure must be reduced. The technique requires: (1) Short transmission scans (3-9 m total) are taken of thorax just before, or 1 or 2 days before or after emission scans. (2) The subject is injected with 18-FDG, allowed a 30 m uptake period, then placed in the PET system, and a total body data set is collected. (3) The emission and attenuation coefficient images are reconstructed with the same zoom factor. (4) The tissue-lung and tissue-air boundaries are determined in the attenuation coefficient image, forming a 3-D binary image of the thorax. (5) The binary image is used as an overlay on a side by side display of the transverse, coronal and sagittal slices from the uncorrected emission data. Using landmarks, such as the heart, apex and base of the lungs, position and thickness of anterior and posterior chest wall, etc., the user can translate and rotate the binary image to fit within the thorax. The outer edges of the body are estimated with edge finding techniques from the emission image. (6) Attenuation coefficients are assigned each region and the attenuation correction determined by forward projection of the synthetic attenuation coefficient image. The resulting images in volunteers are comparable to those that use the standard attenuation correction technique. The errors caused by subject motion were larger than the errors caused by the approximations introduced in this technique, at least in terms of visible artifacts.
- OSTI ID:
- 198036
- Report Number(s):
- CONF-940605--
- Journal Information:
- Journal of Nuclear Medicine, Journal Name: Journal of Nuclear Medicine Journal Issue: Suppl.5 Vol. 35; ISSN JNMEAQ; ISSN 0161-5505
- Country of Publication:
- United States
- Language:
- English
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