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Effects of high photon fluence rate from therapeutic radionuclides on preclinical and clinical PET systems

Dahlbom, Magnus ; Mellhammar, Emma LU ; Axelsson, Johan LU ; Tran, Thuy LU and Strand, Sven Erik LU (2016) IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2014 In 2014 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2014
Abstract

Tumor response in radionuclide therapy can be monitored with PET/CT and/or PET/MR. A high background photon fluence from a therapy radionuclide may influence both image quality and quantification, when imaging is performed intra-therapeutically, i.e. with high activity of the therapeutic radionuclide present. Here, count losses and image distortion have been investigated for preclinical and clinical PET systems with different detector designs. The effect on the spatial resolution was studied with a point source of 22Na in a background of 99mTc, where 99mTc emulated the photon emission from a therapeutic radionuclide. An in-house made mouse phantom with silicon tubes filled with 99mTc with a centrally placed 22Na point source was used.... (More)

Tumor response in radionuclide therapy can be monitored with PET/CT and/or PET/MR. A high background photon fluence from a therapy radionuclide may influence both image quality and quantification, when imaging is performed intra-therapeutically, i.e. with high activity of the therapeutic radionuclide present. Here, count losses and image distortion have been investigated for preclinical and clinical PET systems with different detector designs. The effect on the spatial resolution was studied with a point source of 22Na in a background of 99mTc, where 99mTc emulated the photon emission from a therapeutic radionuclide. An in-house made mouse phantom with silicon tubes filled with 99mTc with a centrally placed 22Na point source was used. For the clinical systems, a 70 cm long NEMA PET Scatter Phantom was used, with a 22Na point source placed at the center whereas the off-center silicon tube was filled with 99mTc. In addition, image quality was also evaluated in the presence of different levels of 99mTc with a 18F-filled NEMA image quality phantom on the preclinical systems and a 18F-filled Jaszczak phantom on the clinical system. Preclinical PET systems with different detector geometries showed that the addition of 99mTc affected the count rate capability considerably, especially those with a low number of read-out channels. The coincidence rate for was significantly reduced when high activities of 99mTc were present. The clinical PET system also showed an effect of reduced coincidence rate with increased photon fluence rate. At high 99mTc activities, the spatial resolution was degraded for both the preclinical and the clinical systems. The quantitative capability of PET systems used intra-therapeutically is significantly affected by the additional high photon fluence rate. The dead-time correction implemented on some of the investigated PET systems, was able to accurately compensate for the coincidence count losses. The reduced spatial resolution at high photon fluence rate, however, remains a potentially limiting factor.

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organization
publishing date
type
Chapter in Book/Report/Conference proceeding
publication status
published
subject
host publication
2014 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2014
series title
2014 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2014
article number
7430875
publisher
IEEE - Institute of Electrical and Electronics Engineers Inc.
conference name
IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2014
conference location
Seattle, United States
conference dates
2014-11-08 - 2014-11-15
external identifiers
  • scopus:84965079418
ISBN
9781479960972
DOI
10.1109/NSSMIC.2014.7430875
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2014 IEEE.
id
f058e35b-d9d6-4167-a00a-6686ee61ce0d
date added to LUP
2022-04-04 08:49:32
date last changed
2023-05-15 08:34:25
@inproceedings{f058e35b-d9d6-4167-a00a-6686ee61ce0d,
  abstract     = {{<p>Tumor response in radionuclide therapy can be monitored with PET/CT and/or PET/MR. A high background photon fluence from a therapy radionuclide may influence both image quality and quantification, when imaging is performed intra-therapeutically, i.e. with high activity of the therapeutic radionuclide present. Here, count losses and image distortion have been investigated for preclinical and clinical PET systems with different detector designs. The effect on the spatial resolution was studied with a point source of 22Na in a background of 99mTc, where 99mTc emulated the photon emission from a therapeutic radionuclide. An in-house made mouse phantom with silicon tubes filled with 99mTc with a centrally placed 22Na point source was used. For the clinical systems, a 70 cm long NEMA PET Scatter Phantom was used, with a 22Na point source placed at the center whereas the off-center silicon tube was filled with 99mTc. In addition, image quality was also evaluated in the presence of different levels of 99mTc with a 18F-filled NEMA image quality phantom on the preclinical systems and a 18F-filled Jaszczak phantom on the clinical system. Preclinical PET systems with different detector geometries showed that the addition of 99mTc affected the count rate capability considerably, especially those with a low number of read-out channels. The coincidence rate for was significantly reduced when high activities of 99mTc were present. The clinical PET system also showed an effect of reduced coincidence rate with increased photon fluence rate. At high 99mTc activities, the spatial resolution was degraded for both the preclinical and the clinical systems. The quantitative capability of PET systems used intra-therapeutically is significantly affected by the additional high photon fluence rate. The dead-time correction implemented on some of the investigated PET systems, was able to accurately compensate for the coincidence count losses. The reduced spatial resolution at high photon fluence rate, however, remains a potentially limiting factor.</p>}},
  author       = {{Dahlbom, Magnus and Mellhammar, Emma and Axelsson, Johan and Tran, Thuy and Strand, Sven Erik}},
  booktitle    = {{2014 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2014}},
  isbn         = {{9781479960972}},
  language     = {{eng}},
  publisher    = {{IEEE - Institute of Electrical and Electronics Engineers Inc.}},
  series       = {{2014 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2014}},
  title        = {{Effects of high photon fluence rate from therapeutic radionuclides on preclinical and clinical PET systems}},
  url          = {{http://dx.doi.org/10.1109/NSSMIC.2014.7430875}},
  doi          = {{10.1109/NSSMIC.2014.7430875}},
  year         = {{2016}},
}