Count rate characteristics and image distortion in preclinical PET systems during intratherapeutic radiopharmaceutical therapy imaging

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Count rate characteristics and image distortion in preclinical PET systems during intratherapeutic radiopharmaceutical therapy imaging. / Mellhammar, Emma Matilda; Dahlbom, Magnus; Axelsson, Johan; Strand, Sven-Erik.

In: Journal of Nuclear Medicine, Vol. 57, No. 12, 28.07.2016, p. 1964-1970.

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TY - JOUR

T1 - Count rate characteristics and image distortion in preclinical PET systems during intratherapeutic radiopharmaceutical therapy imaging

AU - Mellhammar, Emma Matilda

AU - Dahlbom, Magnus

AU - Axelsson, Johan

AU - Strand, Sven-Erik

N1 - Copyright © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

PY - 2016/7/28

Y1 - 2016/7/28

N2 - Positron emission tomography (PET) may provide important information on the therapeutic response of radiopharmaceutical therapy (RPT) during therapy. The radiation emission from the RPT radionuclide may disturb the coincidence detection and impair the image resolution. In this study we tested the feasibility to perform intratherapeutic PET on three preclinical PET systems.METHODS: Using (22)Na point sources and phantoms filled with (18)F, and a phantom filled with either (99m)Tc or (177)Lu, the coincidence count rate and the spatial resolution when both a PET and a therapeutic radionuclide were present in the PET camera, were evaluated. (99m)Tc was used as a substitute for a generic therapeutic radioisotope, since it has a suitable half-life and is easy obtainable.RESULTS: High activities of (99m)Tc deteriorated the coincidence count rate from the (18)F-filled phantom with a (22)Na point source on all three systems evaluated. One of the systems could to a high degree correct the count rate with its dead time correction. The spatial resolution was degraded at high activities of (99m)Tc for all systems. On one of the systems (177)Lu increased the coincidence count rate and slightly affected the spatial resolution. The results for high activities of (177)Lu were similar to those for (99m)Tc.CONCLUSION: Intratherapeutic imaging might be a feasible method to study RPT treatment response. However, some sensitive preclinical PET systems, unable to handle high count rates, suffer count losses and may also introduce image artifacts.

AB - Positron emission tomography (PET) may provide important information on the therapeutic response of radiopharmaceutical therapy (RPT) during therapy. The radiation emission from the RPT radionuclide may disturb the coincidence detection and impair the image resolution. In this study we tested the feasibility to perform intratherapeutic PET on three preclinical PET systems.METHODS: Using (22)Na point sources and phantoms filled with (18)F, and a phantom filled with either (99m)Tc or (177)Lu, the coincidence count rate and the spatial resolution when both a PET and a therapeutic radionuclide were present in the PET camera, were evaluated. (99m)Tc was used as a substitute for a generic therapeutic radioisotope, since it has a suitable half-life and is easy obtainable.RESULTS: High activities of (99m)Tc deteriorated the coincidence count rate from the (18)F-filled phantom with a (22)Na point source on all three systems evaluated. One of the systems could to a high degree correct the count rate with its dead time correction. The spatial resolution was degraded at high activities of (99m)Tc for all systems. On one of the systems (177)Lu increased the coincidence count rate and slightly affected the spatial resolution. The results for high activities of (177)Lu were similar to those for (99m)Tc.CONCLUSION: Intratherapeutic imaging might be a feasible method to study RPT treatment response. However, some sensitive preclinical PET systems, unable to handle high count rates, suffer count losses and may also introduce image artifacts.

U2 - 10.2967/jnumed.116.175539

DO - 10.2967/jnumed.116.175539

M3 - Article

VL - 57

SP - 1964

EP - 1970

JO - Journal of Nuclear Medicine

JF - Journal of Nuclear Medicine

SN - 0161-5505

IS - 12

ER -