Radiation dose assessment for I-131 therapy of thyroid cancer using I-124 PET imaging Journal Article
| Authors: | Erdi, Y. E.; Macapinlac, H.; Larson, S. M.; Erdi, A. K.; Yeung, H.; Furhang, E. E.; Humm, J. L. |
| Article Title: | Radiation dose assessment for I-131 therapy of thyroid cancer using I-124 PET imaging |
| Abstract: | The goal for this work was to develop a method to determine the feasibility of estimating absorbed dose distribution of I-131 thyroid therapy using I-124 PET images of residual thyroid lesions with the dose constraint of 200 cGy to blood, that is a surrogate for bone marrow toxicity. A dose response study has been carried out on 3 patients with papillary thyroid carcinoma. Those patients were given 15-37 MBq of I-124 along with 74-185 MBq of I-131. PET imaging was performed 2-4 hour and then at 24 hour and either 48 hour, or 72 hour post-infusion. Lesion masses were computed from PET images using an adaptive thresholding technique. The definition of the boundary enabled determination of the iodine activity within the lesion. Time-activity curves were fitted to estimate the cumulated activity and therefore the absorbed dose per MBq administered. Daily blood and total body counts were performed on the patients using a multichannel analyzer with windows set for both I-131 (364 keV) and I-124 (511 keV). Cross-talk corrections from one isotope into the alternate window was determined using a standard of each respective isotope. At maximum-tolerated-activity (MTA) that delivers 200 cGy radiation dose to the blood, the dose to lesions from I-131 varied from 0.04 to 2.44 cGy/MBq (1.57-90.48 rads/mCi) with effective half-lives for I-124 ranging from 0.58 to 1.86 days. The three-dimensional absorbed dose distribution in the thyroid lesions was calculated by convolving the activity values with an I-131 point-source kernel using a Fast Hartley Transform. The calculated mean absorbed dose distribution was displayed as isodose lines on PET images that can be used to refine the amount of administered activity. PET with I-124 may improve the absorbed dose estimates from radioiodine therapy with I-131 in the treatment of thyroid cancer. The capability of estimating I-131 mean absorbed dose distributions from serial I-124 PET images can lead to patient-specific treatment planning for thyroid therapy. Copyright © 1999 Elsevier Science Inc. All rights reserved. |
| Keywords: | treatment planning; thyroid cancer; radioiodine therapy |
| Journal Title: | Clinical Positron Imaging |
| Volume: | 2 |
| Issue: | 1 |
| ISSN: | 1095-0397 |
| Publisher: | Elsevier Inc. |
| Date Published: | 1999-01-01 |
| Start Page: | 41 |
| End Page: | 46 |
| Language: | English |
| DOI: | 10.1016/s1095-0397(99)00004-7 |
| PROVIDER: | scopus |
| PUBMED: | 14516552 |
| DOI/URL: | |
| Notes: | Article -- Export Date: 16 August 2016 -- Source: Scopus |
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