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Preserving Preclinical PET Quality During Intratherapeutic Imaging in Radionuclide Therapy with Rose Metal Shielding Reducing Photon Flux

Mellhammar, Emma LU ; Dahlbom, Magnus; Evans-Axelsson, Susan LU and Strand, Sven Erik LU (2019) In Journal of nuclear medicine : official publication, Society of Nuclear Medicine 60(5). p.710-715
Abstract

Performing PET imaging during ongoing radionuclide therapy can be a promising method to follow tumor response in vivo. However, the high therapeutic activity can interfere with the PET camera performance and degrade both image quality and quantitative capabilities. As a solution, low-energy photon emissions from the therapeutic radionuclide can be highly attenuated, still allowing sufficient detection of annihilation photons in coincidence. Methods: Hollow Rose metal cylinders with walls 2-4 mm thick were used to shield a 22Na point source and a uniform phantom filled with 18F as they were imaged on a preclinical PET camera with increasing activities of 177Lu. A mouse with a subcutaneous tumor was injected with 18F-FDG and imaged with... (More)

Performing PET imaging during ongoing radionuclide therapy can be a promising method to follow tumor response in vivo. However, the high therapeutic activity can interfere with the PET camera performance and degrade both image quality and quantitative capabilities. As a solution, low-energy photon emissions from the therapeutic radionuclide can be highly attenuated, still allowing sufficient detection of annihilation photons in coincidence. Methods: Hollow Rose metal cylinders with walls 2-4 mm thick were used to shield a 22Na point source and a uniform phantom filled with 18F as they were imaged on a preclinical PET camera with increasing activities of 177Lu. A mouse with a subcutaneous tumor was injected with 18F-FDG and imaged with an additional 120 MBq of 177Lu and repeated with shields surrounding the animal. Results: The addition of 177Lu to the volume imaged continuously degraded the image quality with increasing activity. The image quality was improved when shielding was introduced. The shields showed a high ability to produce stable and reproducible results for both spatial resolution and quantification of up to 120 MBq of 177Lu activity (maximum activity tested). Conclusion: Without shielding, the activity quantification will be inaccurate for time points at which therapeutic activities are high. The suggested method shows that the shields reduce the noise induced by the 177Lu and therefore enable longitudinal quantitative intratherapeutic imaging studies.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
count losses, PET, radionuclide therapy, shielding, small-animal imaging
in
Journal of nuclear medicine : official publication, Society of Nuclear Medicine
volume
60
issue
5
pages
6 pages
publisher
Society of Nuclear Medicine
external identifiers
  • scopus:85065521503
ISSN
0161-5505
DOI
10.2967/jnumed.118.217117
language
English
LU publication?
yes
id
60c6bea2-0f04-49b2-baf5-e6088f5fd034
date added to LUP
2019-05-22 14:46:01
date last changed
2019-06-19 04:13:11
@article{60c6bea2-0f04-49b2-baf5-e6088f5fd034,
  abstract     = {<p>Performing PET imaging during ongoing radionuclide therapy can be a promising method to follow tumor response in vivo. However, the high therapeutic activity can interfere with the PET camera performance and degrade both image quality and quantitative capabilities. As a solution, low-energy photon emissions from the therapeutic radionuclide can be highly attenuated, still allowing sufficient detection of annihilation photons in coincidence. Methods: Hollow Rose metal cylinders with walls 2-4 mm thick were used to shield a 22Na point source and a uniform phantom filled with 18F as they were imaged on a preclinical PET camera with increasing activities of 177Lu. A mouse with a subcutaneous tumor was injected with 18F-FDG and imaged with an additional 120 MBq of 177Lu and repeated with shields surrounding the animal. Results: The addition of 177Lu to the volume imaged continuously degraded the image quality with increasing activity. The image quality was improved when shielding was introduced. The shields showed a high ability to produce stable and reproducible results for both spatial resolution and quantification of up to 120 MBq of 177Lu activity (maximum activity tested). Conclusion: Without shielding, the activity quantification will be inaccurate for time points at which therapeutic activities are high. The suggested method shows that the shields reduce the noise induced by the 177Lu and therefore enable longitudinal quantitative intratherapeutic imaging studies.</p>},
  author       = {Mellhammar, Emma and Dahlbom, Magnus and Evans-Axelsson, Susan and Strand, Sven Erik},
  issn         = {0161-5505},
  keyword      = {count losses,PET,radionuclide therapy,shielding,small-animal imaging},
  language     = {eng},
  number       = {5},
  pages        = {710--715},
  publisher    = {Society of Nuclear Medicine},
  series       = {Journal of nuclear medicine : official publication, Society of Nuclear Medicine},
  title        = {Preserving Preclinical PET Quality During Intratherapeutic Imaging in Radionuclide Therapy with Rose Metal Shielding Reducing Photon Flux},
  url          = {http://dx.doi.org/10.2967/jnumed.118.217117},
  volume       = {60},
  year         = {2019},
}