Standardised quantitative radioiodine SPECT/CT imaging for multicentre dosimetry trials in molecular radiotherapy
AffiliationBarts Health NHS Trust, London, United Kingdom
MetadataShow full item record
AbstractThe SEL-I-METRY trial (EudraCT No 2015-002269-47) is the first multicentre trial to investigate the role of 123I and 131I SPECT/CT-based tumour dosimetry to predict response to radioiodine therapy. Standardised dosimetry methodology is essential to provide a robust evidence-base for absorbed dose-response thresholds for molecular radiotherapy (MRT). In this paper a practical standardised protocol is used to establish the first network of centres with consistent methods of radioiodine activity quantification. Nine SPECT/CT systems at eight centres were set-up for quantitative radioiodine imaging. The dead-time of the systems was characterised for up to 2.8 GBq 131I. Volume dependent calibration factors were measured on centrally reconstructed images of 123I and 131I in six (0.8-196?ml) cylinders. Validation of image quantification using these calibration factors was performed on three systems, by imaging a 3D-printed phantom mimicking a patient's activity distribution. The percentage differences between the activities measured in the SPECT/CT image and those measured by the radionuclide calibrator were calculated. Additionally uncertainties on the SPECT/CT-based activities were calculated to indicate the limit on the quantitative accuracy of this method. For systems set-up to image high 131I count rates, the count rate versus activity did not peak below 2.8 GBq and fit a non-paralysable model. The dead-times and volume-dependent calibration factors were comparable between systems of the same model and crystal thickness. Therefore a global calibration curve could be fitted to each. The errors on the validation phantom activities' were comparable to the measurement uncertainties derived from uncertainty analysis, at 10% and 16% on average for 123I and 131I respectively in a 5?cm sphere. In conclusion, the dead-time and calibration factors varied between centres, with different models of system. However, global calibration factors may be applied to the same system model with the same crystal thickness, to simplify set-up of future multi-centre MRT studies.
CitationGregory RA, Murray I, Gear J, Leek F, Chittenden S, Fenwick A, et al. Standardised quantitative radioiodine SPECT/CT Imaging for multicentre dosimetry trials in molecular radiotherapy. Phys Med Biol. 2019;64(24):245013.
JournalPhysics in medicine and biology
- Design and Fabrication of Kidney Phantoms for Internal Radiation Dosimetry Using 3D Printing Technology.
- Authors: Tran-Gia J, Schlögl S, Lassmann M
- Issue date: 2016 Dec
- Whole-remnant and maximum-voxel SPECT/CT dosimetry in <sup>131</sup> I-NaI treatments of differentiated thyroid cancer.
- Authors: Mínguez P, Flux G, Genollá J, Delgado A, Rodeño E, Sjögreen Gleisner K
- Issue date: 2016 Oct
- Impact of missing attenuation and scatter corrections on <sup>99m</sup> Tc-MAA SPECT 3D dosimetry for liver radioembolization using the patient relative calibration methodology: A retrospective investigation on clinical images.
- Authors: Botta F, Ferrari M, Chiesa C, Vitali S, Guerriero F, Nile MC, Mira M, Lorenzon L, Pacilio M, Cremonesi M
- Issue date: 2018 Apr
- Optimizing Image Quantification for <sup>177</sup>Lu SPECT/CT Based on a 3D Printed 2-Compartment Kidney Phantom.
- Authors: Tran-Gia J, Lassmann M
- Issue date: 2018 Apr
- Accurate dosimetry in 131I radionuclide therapy using patient-specific, 3-dimensional methods for SPECT reconstruction and absorbed dose calculation.
- Authors: Dewaraja YK, Wilderman SJ, Ljungberg M, Koral KF, Zasadny K, Kaminiski MS
- Issue date: 2005 May