EANM Dosimetry Committee series on standard operational procedures for internal dosimetry for 131I mIBG treatment of neuroendocrine tumours

Abstract

The purpose of the EANM Dosimetry Committee Series on "Standard Operational Procedures for Dosimetry" (SOP) is to provide advice to scientists and clinicians on how to perform patient-specific absorbed dose assessments. This SOP describes image and data acquisition parameters and dosimetry calculations to determine the absorbed doses delivered to whole-body, tumour and normal organs following a therapeutic administration of ¹³¹I mIBG for the treatment of neuroblastoma or adult neuroendocrine tumours. Recommendations are based on evidence in recent literature where available and on expert opinion within the community. This SOP is intended to promote standardisation of practice within the community and as such is based on the facilities and expertise that should be available to any centre able to perform specialised treatments with radiopharmaceuticals and patient-specific dosimetry. A clinical example is given to demonstrate the application of the absorbed dose calculations.

Keywords: Dosimetry; Iodine-131; Molecular radiotherapy; Neuroblastoma; Neuroendocrine; mIBG.

Fig. 1

Example images demonstrating typical artefacts that can appear during high count rate imaging

Fig. 2

Whole-body retention data from first (a) and second (b) adminstration

Fig. 3

a Camera dead time data for increasing activities showing linear fit to low activity data points (solid line) and b dead time curve fitted with the appropriate dead time function (solid line)

Fig. 4

System recovery curve for ¹³¹I derived from different-sized cylindrical inserts

Fig. 5

Example projection data aquired in main window (a), low-energy scatter window (b), high-energy scatter widow (c), and after triple-energy window scatter correction (d). Each image is scaled to the local maxima and minima on a linear grey scale

Fig. 6

Image data depicting SPECT/CT (a), MRI alone (b) and fused SPECT/MRI (c). The lesion can clearly be seen as the volume with intense uptake adjacent to the left kidney (delineated in b and c)

Fig. 7

Time–activity curves for the tumour after the first (a) and the second administration (b). Time–activity curves for the liver after the first (c) and the second administration (d)

Fig. 8

Plot of liver and sphere S values used to determine the patient specific S value used for dose calculation