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Gamma camera calibration and validation for quantitative SPECT imaging with (177)Lu.
D'Arienzo, M; Cazzato, M; Cozzella, M L; Cox, M; D'Andrea, M; Fazio, A; Fenwick, A; Iaccarino, G; Johansson, L; Strigari, L; Ungania, S; De Felice, P.
Affiliation
  • D'Arienzo M; National Institute of Ionizing Radiation Metrology, ENEA CR Casaccia, Via Anguillarese 301, I-00123 Rome, Italy.
  • Cazzato M; Istituto Regina Elena, Via Elio Chianesi 53, 00144 Rome, Italy.
  • Cozzella ML; National Institute of Ionizing Radiation Metrology, ENEA CR Casaccia, Via Anguillarese 301, I-00123 Rome, Italy.
  • Cox M; National Physical Laboratory, Teddington TW11 0LW, UK.
  • D'Andrea M; Istituto Regina Elena, Via Elio Chianesi 53, 00144 Rome, Italy.
  • Fazio A; National Institute of Ionizing Radiation Metrology, ENEA CR Casaccia, Via Anguillarese 301, I-00123 Rome, Italy.
  • Fenwick A; National Physical Laboratory, Teddington TW11 0LW, UK.
  • Iaccarino G; Istituto Regina Elena, Via Elio Chianesi 53, 00144 Rome, Italy.
  • Johansson L; National Physical Laboratory, Teddington TW11 0LW, UK.
  • Strigari L; Istituto Regina Elena, Via Elio Chianesi 53, 00144 Rome, Italy.
  • Ungania S; Istituto Regina Elena, Via Elio Chianesi 53, 00144 Rome, Italy.
  • De Felice P; National Institute of Ionizing Radiation Metrology, ENEA CR Casaccia, Via Anguillarese 301, I-00123 Rome, Italy.
Appl Radiat Isot ; 112: 156-64, 2016 06.
Article in En | MEDLINE | ID: mdl-27064195
ABSTRACT
Over the last years (177)Lu has received considerable attention from the clinical nuclear medicine community thanks to its wide range of applications in molecular radiotherapy, especially in peptide-receptor radionuclide therapy (PRRT). In addition to short-range beta particles, (177)Lu emits low energy gamma radiation of 113keV and 208keV that allows gamma camera quantitative imaging. Despite quantitative cancer imaging in molecular radiotherapy having been proven to be a key instrument for the assessment of therapeutic response, at present no general clinically accepted quantitative imaging protocol exists and absolute quantification studies are usually based on individual initiatives. The aim of this work was to develop and evaluate an approach to gamma camera calibration for absolute quantification in tomographic imaging with (177)Lu. We assessed the gamma camera calibration factors for a Philips IRIX and Philips AXIS gamma camera system using various reference geometries, both in air and in water. Images were corrected for the major effects that contribute to image degradation, i.e. attenuation, scatter and dead- time. We validated our method in non-reference geometry using an anthropomorphic torso phantom provided with the liver cavity uniformly filled with (177)LuCl3. Our results showed that calibration factors depend on the particular reference condition. In general, acquisitions performed with the IRIX gamma camera provided good results at 208keV, with agreement within 5% for all geometries. The use of a Jaszczak 16mL hollow sphere in water provided calibration factors capable of recovering the activity in anthropomorphic geometry within 1% for the 208keV peak, for both gamma cameras. The point source provided the poorest results, most likely because scatter and attenuation correction are not incorporated in the calibration factor. However, for both gamma cameras all geometries provided calibration factors capable of recovering the activity in anthropomorphic geometry within about 10% (range -11.6% to +7.3%) for acquisitions at the 208keV photopeak. As a general rule, scatter and attenuation play a much larger role at 113keV compared to 208keV and are likely to hinder an accurate absolute quantification. Acquisitions of only the (177)Lu main photopeak (208keV) are therefore recommended in clinical practice. Preliminary results suggest that the gamma camera calibration factor can be assessed with a standard uncertainty below (or of the order of) 3% if activity is determined with equipment traceable to primary standards, accurate volume measurements are made, and an appropriate chemical carrier is used to allow a homogeneous and stable solution to be used during the measurements.
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Full text: 1 Collection: 01-internacional Database: MEDLINE Main subject: Radioisotopes / Gamma Cameras / Tomography, Emission-Computed, Single-Photon / Lutetium Type of study: Guideline / Prognostic_studies Limits: Humans Language: En Journal: Appl Radiat Isot Year: 2016 Document type: Article

Full text: 1 Collection: 01-internacional Database: MEDLINE Main subject: Radioisotopes / Gamma Cameras / Tomography, Emission-Computed, Single-Photon / Lutetium Type of study: Guideline / Prognostic_studies Limits: Humans Language: En Journal: Appl Radiat Isot Year: 2016 Document type: Article