Setting up a quantitative SPECT imaging network for a European multi-centre dosimetry study of radioiodine treatment for thyroid cancer as part of the MEDIRAD project

Abstract

Background Differentiated thyroid cancer has been treated with radioiodine for almost 80 years, although controversial questions regarding radiation-related risks and the optimisation of treatment regimens remain unresolved. Multi-centre clinical studies are required to ensure recruitment of sufficient patients to achieve the statistical significance required to address these issues. Optimisation and standardisation of data acquisition and processing are necessary to ensure quantitative imaging and patient-specific dosimetry. Material and methods A European network of centres able to perform standardised quantitative imaging of radioiodine therapy of thyroid cancer patients was set-up within the EU consortium MEDIRAD. This network will support a concurrent series of clinical studies to determine accurately absorbed doses for thyroid cancer patients treated with radioiodine. Five SPECT(/CT) systems at four European centres were characterised with respect to their system volume sensitivity, recovery coefficients and dead time. Results System volume sensitivities of the Siemens Intevo systems (crystal thickness 3/8″) ranged from 62.1 to 73.5 cps/MBq. For a GE Discovery 670 (crystal thickness 5/8″) a system volume sensitivity of 92.2 cps/MBq was measured. Recovery coefficients measured on three Siemens Intevo systems show good agreement. For volumes larger than 10 ml, the maximum observed difference between recovery coefficients was found to be ± 0.02. Furthermore, dead-time coefficients measured on two Siemens Intevo systems agreed well with previously published dead-time values. Conclusions Results presented here provide additional support for the proposal to use global calibration parameters for cameras of the same make and model. This could potentially facilitate the extension of the imaging network for further dosimetry-based studies.

Recommendations for Multicentre Clinical Trials Involving Dosimetry for Molecular Radiotherapy

“…[ 22 ] and Taprogge et al. [ 23 ] established networks of centres able to carry out standardised radioiodine activity quantification.…”

“…Recent examples of multicentre MRT clinical trials that involved standardisation of the acquisition and reconstruction parameters with centralised dosimetry are SEL-I-METRY [ 22 , 26 , 27 ] and MEDIRAD [ 23 ]. SEL-I-METRY (EudraCT no.…”

“…Experience from multicentre MRT clinical trials [ 22 , 23 ] have shown that such measurements may need to be adapted locally based on radiation protection guidance in different countries and centres. It is essential to ensure that the complexity and time required for such measurements are adapted as necessary, particularly for centres with limited resources.…”

“…Initial studies have shown that inter-system variability for a given vendor and camera type is low if acquisition and reconstruction protocols are standardised across centres so that it may be possible to use the same calibration and correction factors [ 19 , 20 , 22 , 23 ]. System parameters including sensitivity, partial-volume effect and dead-time correction could be measured on a number of systems for each vendor and camera type to establish a quantitative imaging database for gamma cameras.…”

Radioimmunotherapy for Brain Metastases: The Potential for Inflammation as a Target of Choice

“…Nevertheless, a substantial effort is being made to individualise patient treatments and to improve the accuracy of dosimetry procedures in the clinic. Important initiatives to standardise dosimetry include the internal dosimetry task force linked to EANM (29,30), the Medical Internal Radiation Dose committee (31), or the EU consortium MEDIRAD (32,33). Dosimetry should play an important role when a new agent for RIT undergoes clinical testing, alongside the assessment of the maximum tolerated dose and side effects, similar to clinical trials of nonradioactive oncological drugs (34).…”