Assessing effective half-life of I-131 in 39 thyroid cancer patients at Dong Nai General Hospital

Nguyen Tan Duoc1, Do Ha Phuong, Tran Pham Ngoc Trinh
1 Nguyen Tat Thanh University

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Radioiodine therapy to kill the residual cells after surgery in thyroid cancer patients is a widespread treatment method nowadays. Despite the therapeutic benefits, the amount of I-131 that remains in the patient's body also causes radiation risks to caregivers and persons in close contact. This study assesses the effective half-life () of I-131 in 39 patients underwent thyroid cancer treatment at Dong Nai General Hospital. Radioactive activity on the patient's body was measured by survey meter GAL20-C (ELSE SOLUTIONS), placed 1.0 meters away from the patient, at 0.5; 2.0; 4.0; 6.0; 24.0 hours; and 7 days after administration. The measurement data was fitted by a mono-exponential function respecting time by the least squares method to figure out the effective half-life. The result function has a good coefficient of determination, R2 ~ 1, Te was 7.89 +- 1.55 h (high-activity group), and 5.83+-1.76 h  (low-activity group). The effective half-life was proved to be different between these two groups of patients.

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[1]. S. Mattsson et al., "ICRP publication 128: radiation dose to patients from radiopharmaceuticals: a compendium of current information related to frequently used substances," Annals of the ICRP, vol. 44, no. 2_suppl, pp. 7-321, 2015.
[2]. IAEA, "," p. 19, 2009.
[3]. F. Paquet et al., "ICRP publication 137: occupational intakes of radionuclides: part 3," Annals of the ICRP, vol. 46, no. 3-4, pp. 1-486, 2017.
[4]. R. Leggett, "An age-specific biokinetic model for iodine," Journal of Radiological Protection, vol. 37, no. 4, p. 864, 2017.
[5]. M. Andersson, L. Johansson, D. Minarik, S. Leide-Svegborn, and S. Mattsson, "Effective dose to adult patients from 338 radiopharmaceuticals estimated using ICRP biokinetic data, ICRP/ICRU computational reference phantoms and ICRP 2007 tissue weighting factors," EJNMMI physics, vol. 1, pp. 1-13, 2014.
[6]. C. Foreman and S. Dewji, "Estimation of external dose rates to hotel workers from bed linens contaminated by 131I patients," Health Physics, vol. 118, no. 6, pp. 615-622, 2020.
[7]. J. T. Bushberg and J. M. Boone, The essential physics of medical imaging. Lippincott Williams & Wilkins, 2011.
[8]. H. Hänscheid et al., "Iodine biokinetics and dosimetry in radioiodine therapy of thyroid cancer: procedures and results of a prospective international controlled study of ablation after rhTSH or hormone withdrawal," Journal of Nuclear Medicine, vol. 47, no. 4, pp. 648-654, 2006.
[9]. F. Tabei, I. Neshandar Asli, Z. Azizmohammadi, H. Javadi, and M. Assadi, "Assessment of radioiodine clearance in patients with differentiated thyroid cancer," Radiation protection dosimetry, vol. 152, no. 4, pp. 323-327, 2012.
[10]. ICRP, ICRP Publication 56: Age-dependent Doses to Members of the Public from Intake of Radionuclides: Part 3. Elsevier Health Sciences, 1990.
[11]. P. Kumar, C. Bal, N. A. Damle, S. Ballal, S. Dwivedi, and S. Agarwala, "Lesion-wise comparison of pre-therapy and post-therapy effective half-life of iodine-131 in pediatric and young adult patients with differentiated thyroid cancer undergoing radioiodine therapy," Nuclear medicine and molecular imaging, vol. 53, pp. 199-207, 2019.
[12]. ICRP, "Radiation Dose to Patients from Radiopharmaceuticals. ICRP Publication 53," Ann. ICRP, vol. 18, no. 1-4, 1988.