Anisotropy Characterization of I-125 Seed with Attached Encapsulated Cobalt Chloride Complex Contrast Agent Markers for MRI-Based Prostate Brachytherapy

Journal Article · Fri Jul 01 00:00:00 EDT 2011 · Medical Dosimetry

DOI:https://doi.org/10.1016/j.meddos.2010.03.004· OSTI ID:21499794

Tailor, Ramesh C; Kudchadker, Rajat J ^[1]; Martirosyan, Karen S ^[2]; Stafford, R Jason; Elliott, Andrew M ^[3]; Swanson, David A ^[4]; Sing, David; Choi, Jonathan ^[5]; Mourtada, Firas; Ibbott, Geoffrey S ^[1]

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1. Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States)
2. Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX (United States)
3. Department of Imaging Physics, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States)
4. Department of Urology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States)
5. Department of Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States)

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}{sub 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}{sub 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.

• OSTI ID: 21499794
• Journal Information: Medical Dosimetry, Vol. 36, Issue 2; Other Information: DOI: 10.1016/j.meddos.2010.03.004; PII: S0958-3947(10)00031-2; Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0958-3947
• Country of Publication: United States
• Language: English

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62 RADIOLOGY AND NUCLEAR MEDICINE
61 RADIATION PROTECTION AND DOSIMETRY
ANISOTROPY
BRACHYTHERAPY
COBALT CHLORIDES
CONTRAST MEDIA
DOSIMETRY
IODINE 125
NMR IMAGING
PROSTATE
THERMOLUMINESCENT DOSEMETERS
TITANIUM
BETA DECAY RADIOISOTOPES
BODY
CHLORIDES
CHLORINE COMPOUNDS
COBALT COMPOUNDS
DAYS LIVING RADIOISOTOPES
DIAGNOSTIC TECHNIQUES
DOSEMETERS
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTS
GLANDS
HALIDES
HALOGEN COMPOUNDS
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
IODINE ISOTOPES
ISOTOPES
LUMINESCENT DOSEMETERS
MALE GENITALS
MEASURING INSTRUMENTS
MEDICINE
METALS
NUCLEAR MEDICINE
NUCLEI
ODD-EVEN NUCLEI
ORGANS
RADIOISOTOPES
RADIOLOGY
RADIOTHERAPY
THERAPY
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS