ANISOTROPY CHARACTERIZATION OF I-125 SEED WITH ATTACHED ENCAPSULATED COBALT CHLORIDE COMPLEX CONTRAST AGENT MARKERS FOR MRI-BASED PROSTATE BRACHYTHERAPY

作者：Frank Steven J^*; Tailor Ramesh C; Kudchadker Rajat J; Martirosyan Karen S; Stafford R Jason; Elliott Andrew M; Swanson David A; Sing David; Choi Jonathan; Mourtada Firas; Ibbott Geoffrey S

来源：Medical Dosimetry, 2011, 36(2): 200-205.

DOI：10.1016/j.meddos.2010.03.004

• MRI-based dosimetry
• Fiducial marker
• Post-implant dosimetry
• Prostate brachytherapy

We have developed a novel MRI marker for prostate brachytherapy. The purpose of this study was to evaluate the changes in anisotropy when cobalt chloride complex contrast agent encapsulated contrast agent markers (C4-ECAM) were placed adjacent to an iodine-125 (I-125) titanium seed, and to verify that the C4-ECAMs were visible on magnetic resonance imaging (MRI) after radiation exposure. Two C4-ECAMs were verified to be MRI visible in a phantom before radiation exposure. The C4-ECAMs were then attached to each end of a 12.7-U (10-mCi) I-125 titanium seed in a polymer tube. Anisotropy was measured and analyzed with the seed alone and with attached C4-ECAMs by suspending thermoluminescent dosimeters in a water phantom in 2 circles surrounding the radioactive source with radius of 1 or 2 cm. A T1-weighted MRI evaluation of C4-ECAMs was then performed after exposure to the amount of radiation typically delivered during 1 month of prostate brachytherapy. Measured values of the anisotropy function F(r, theta) for the I-125 seed with and without the C4-ECAMs were mutually statistically indistinguishable (standard error of the mean <4.2%) and agreed well with published TG-43 values for the bare seed. As expected, the anisotropy function phi(an)(r) for the 2 datasets (with and without C4-ECAMs) derived from the measured F(r, theta) did not exhibit statistically measurable difference. Both datasets showed agreement with the published TG-43 phi(an)(r) for the bare seed. The C4-ECAMs were well visualized by MRI after 1 month of radiation exposure. There were no changes in anisotropy when the C4-ECAMs were placed next to an I-125 radioactive seed, and the C4-ECAMs were visualized after radiation exposure.

• 出版日期2011