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Dosimetric differences between cesium-131 and iodine-125 brachytherapy for the treatment of resected brain metastases.

TitleDosimetric differences between cesium-131 and iodine-125 brachytherapy for the treatment of resected brain metastases.
Publication TypeJournal Article
Year of Publication2020
AuthorsYondorf MZ, Faraz S, Smith AW, Sabbas A, Parashar B, Schwartz TH, A Wernicke G
JournalJ Contemp Brachytherapy
Volume12
Issue4
Pagination311-316
Date Published2020 Aug
ISSN1689-832X
Abstract

Purpose: To compare treatment plans and evaluate dosimetric characteristics of permanent cesium-131 (Cs) vs. iodine-125 (I) implants used in brain brachytherapy.

Material and methods: Twenty-four patients with Cs implants from a prospective phase I/II trial were re-planned with I implants. In order to evaluate the volume of brain tissue exposed to radiation therapy (RT), the dose volume histogram was generated for both radioisotopes. To evaluate the dosimetric differences of the two radioisotopes we compared homogeneity (HI) and conformity indices (CI), and dose covering 100% (D), 90% (D), 80% (D), and 50% (D) of the clinical target volume (CTV).

Results: At the 100%, 90%, 80%, and 50% isodose lines, the Cs plans exposed less mean volume of brain tissue than the I plans ( < 0.001). The D, D, D, and D were smaller for Cs ( < 0.001). The HI and CI for Cs vs. I were 19.71 vs. 29.04 and 1.31 vs. 1.92, respectively ( < 0.001).

Conclusions: Compared to I, Cs exposed smaller volumes of brain tissue to equivalent doses of radiation and delivered lower radiation doses to equivalent volumes of the CTV. Cs exhibited a higher HI, indicating increased uniformity of doses within the CTV. Lastly, Cs presented a CI closer to 1, indicating that the total volume receiving the prescription dose was closer to the desired CTV volume. These results suggest that Cs is dosimetrically superior to I and may explain the reason for the 0% incidence of radiation necrosis (RN) in our previously published prospective study using Cs.

DOI10.5114/jcb.2020.98109
Alternate JournalJ Contemp Brachytherapy
PubMed ID33293969
PubMed Central IDPMC7690233