RT Journal Article
SR Electronic
T1 Analysis of Residence Time, Effective Half-Life, and Internal Dosimetry Before Radioiodine Therapy
JF Journal of Nuclear Medicine Technology
JO J. Nucl. Med. Technol.
FD Society of Nuclear Medicine
SP 233
OP 239
DO 10.2967/jnmt.121.263502
VO 50
IS 3
A1 Caio Vinicius Oliveira
A1 Tatiane Sabriela Cagol Camozzato
A1 Patricia Fernanda Dorow
A1 Jéssica Pasqueta
YR 2022
UL http://tech.snmjournals.org/content/50/3/233.abstract
AB Radioiodine therapy has been widely used for ablation of remnant tissue after surgical treatment of differentiated thyroid carcinoma (DTC). Internal dosimetry provides a new approach to choosing the administered activity—an approach that considers the distribution and retention of 131I individually per patient. This study used clinical techniques of internal dosimetry to assess the accumulated activity, internal bone marrow dosimetry, and effective half-life in patients undergoing treatment for DTC. Methods: This was a quantitative, retrospective study analyzing diagnostic documents and images. The internal dosimetry method calculated the dose absorbed by the bone marrow per administered activity of 131I. Calculation of the absorbed dose took into account the accumulated activity, which was obtained through measurements of whole-body images acquired at 4 intervals over 5 d. Results: The median dose absorbed by the bone marrow per administered activity was 0.117 mGy/MBq (range, 0.043–0.152 mGy/MBq). The median whole-body residence time was 22.0 h (range, 12.6–39.4 h). The median effective half-life was 15.6 h (range, 7.6–28.2 h). Conclusion: Internal dosimetry provides information relevant to safe dose limits for DTC radioiodine therapy, especially in advanced cases of the disease for which greater activities may be necessary.