Use of PET for estimation of radiation dose variations within the thyroid from radioiodine therapy in thyrotoxic patients
A series of 22 patients have been studied using a prototype Multiwire Proportional Chamber Positron Camera to determine the accuracy of measurement of thyroid uptake of radioiodine. The patients being treated for thyrotoxicosis were given a solution containing 1.5 mCi of I-131 and 0.7 mCi of I-124. In a few case 0.3 mCi of I-124 was given prior to I-131 therapy. Data acquisition consisted of 8 contiguous views of the thyroid covering the full 360 degrees around the patient. Each study contained approximately 400,000 events. Data analysis consisted of a simple backprojection and 3D deconvolution of the point source response function to produce a 64x64x64 volume matrix using 0.27ml voxels. The volume of the thyroid was obtained using a simple thresholding technique to determine the number of voxels within the thyroid. Phantom measurements show that the functional volume and hence the radiation dose to the thyroid can be estimated to approx. =10%. From conventional imaging with a gamma camera plus pinhole collimator, 18 out of 22 patients were diagnosed as having uniform Graves disease. The high resolution tomographic information provided by PET imaging has shown that the uptake in 5 of these 18 patients was multinodular. In one case the volume of the nodules within the thyroid was estimated to be 45% of the organ volume. This non-uniform uptake of iodine within the thyroid has consequences for the overall management of hyperthyroidism in patients thought to have Graves disease. It may in part explain the cases of unexpected post therapy hypothyroidism.
- Research Organization:
- Royal Marsden Hospital, Sutton, Surrey
- OSTI ID:
- 6791771
- Report Number(s):
- CONF-850611-; TRN: 87-011060
- Journal Information:
- J. Nucl. Med.; (United States), Vol. 26:5; Conference: 32. annual meeting of the Society of Nuclear Medicine, Houston, TX, USA, 2 Jun 1985
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
POSITRON COMPUTED TOMOGRAPHY
CAMERAS
MULTIWIRE PROPORTIONAL CHAMBERS
RADIOPHARMACEUTICALS
UPTAKE
THYROID
DATA ACQUISITION
DIAGNOSIS
HYPERTHYROIDISM
IODINE ISOTOPES
MONITORING
PATIENTS
RADIATION DOSES
RADIOTHERAPY
TISSUE DISTRIBUTION
BODY
COMPUTERIZED TOMOGRAPHY
DIAGNOSTIC TECHNIQUES
DISEASES
DISTRIBUTION
DOSES
DRUGS
EMISSION COMPUTED TOMOGRAPHY
ENDOCRINE DISEASES
ENDOCRINE GLANDS
GLANDS
ISOTOPES
LABELLED COMPOUNDS
MEASURING INSTRUMENTS
MEDICINE
NUCLEAR MEDICINE
ORGANS
PROPORTIONAL COUNTERS
RADIATION DETECTORS
RADIOLOGY
THERAPY
TOMOGRAPHY
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