Abstract
BackgroundDifferentiated 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 methodsA 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.ResultsSystem 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.ConclusionsResults 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.
Highlights
Differentiated thyroid cancer has been treated with radioiodine for almost 80 years, controversial questions regarding radiation-related risks and the optimisation of treatment regimens remain unresolved
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
The overall objectives of MEDIRAD Work Package 3 (WP3) are to develop and implement the tools necessary to, for the first time in a multi-centre setting, investigate the range of absorbed doses delivered to healthy organs in patients undergoing thyroid ablation and to establish a threshold absorbed dose required for a successful ablation
Summary
Differentiated thyroid cancer has been treated with radioiodine for almost 80 years, controversial questions regarding radiation-related risks and the optimisation of treatment regimens remain unresolved. A consensus paper [1] developed by experts from the American Thyroid Association (ATA) [2], the European Association of Nuclear Medicine (EANM), the Society of Nuclear Medicine and Molecular Imaging (SNMMI) and the European Thyroid Association (ETA) has established several principles regarding treatment and has highlighted areas in need of investigation. These ‘Martinique principles’ include the need to determine the optimal prescribed activity of radioiodine for adjuvant treatment and for patients at low risk. Multi-centre prospective clinical studies are necessary to resolve the controversies raised in the consensus paper [1] by the ATA, EANM, SNMMI and ETA
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