As the efficacy of brachytherapy prostate treatment is becoming realized, new models of 125I seeds are being introduced. In this article we present thermoluminescent dosimetry (TLD) in a solid water phantom for a new design of 125I seed (UroMed/Bebig Symmetra, Model I25.S06). TLD cubes, LiF TLD-100, from Bicron (Solon, OH) with dimension 1 x 1 x 1 mm3 were irradiated at various distances from the seed at angles ranging from 0 degrees to 90 degrees in 10 degrees increments. The TLD detectors were calibrated by irradiation in a 60Co teletherapy beam. Monte Carlo simulation was used to account for TLD energy dependence and the deviation of solid water composition (as determined by chemical analysis of a sample) from liquid water. Dose rates per unit air kerma strength were determined based on calibrations traceable to the 1999 NIST standard (corrected for NIST measurement errors made in 1999) for the Symmetra seed. Dose data is presented in TG-43 format as a function of distance and angle. Values for lambda, F(r, theta), g(r), and the anisotropy constant are obtained for use in radiation treatment planning (RTP) software. The dose rate constant was determined to be 1.033+/-6.4% cGy h(-1) U(-1), which is comparable to model 6702 and higher than model 6711. We find the relative dose distributions of the Symmetra seed are similar to model 6702, and less anisotropic than model 6711. After accounting for deviation of measured solid water composition from the manufacturer's specification, good agreement between TLD results and Monte-Carlo-aided values was found.

Objectives

ObjectivesThe aim of this feasibility study was to prospectively explore in a dog model of chronic ischemic renal disease (CIRD) the hypothesis that real-time contrast-enhanced ultrasonography (CEUS) can quantitatively evaluate the early perfusion changes of renal cortex.Materials and MethodsIn this animal care and use committee-approved study, the model of CIRD was carried out in healthy dogs (10.0∼12.0 kg, n = 5), by placing the Ameroid ring constrictors on the distal portion of right renal artery through operation. CEUS monitoring of right kidney perfusion was performed by intravenous bolus injection of 0.6 ml Sulfur hexafluoride filled microbubbles (SonoVue; Bracco S.P.A., Milan, Italy) every week after operation. The slope rate of ascending curve (A) and descending curve (α), area under curve (AUC), derived peak intensity (DPI), and time to peak (TTP) were measured in renal cortex using commercial quantification software (Q-LAB version 6; Philips Medical Systems, Bothell,WA,USA). The sensitivity of CEUS was compared with blood serum urea nitrogen (BUN) and serum creatinine (SCr) level.ResultsWith the progression of CIRD, dogs showed delayed enhancement and perfusion in renal CEUS curve. Earliest significant changes happened 4 weeks after operation on DPI and TTP which changed from 13.04±2.71 to 15.58±4.75 dB and 9.03±2.01 to 10.62±6.04 sec, respectively (P<.05).ConclusionsCEUS can display the perfusion changes of CIRD in the early period.