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[en] A large high-pressure ion-exchange column, which had been designed for the separation of gadolinium from europium, was tested in the laboratory. Good separations were obtained. Subsequently, columns of the same design were installed in a hot cell and have been used successfully for the separation of gadolinium-153 from irradiated natural europium. The gadolinium-153 production achieved using these columns is substantially greater than that achieved using the previous process. Rapid damage of the resin is a problem and frequent resin changes are required
[en] The bone mineral density (BMD) can vary according with color, sex, feed and knowing the miscegenation and nutritional state of the Brazilian people; it is obvious that the fixed values of Caucasian females BMD cannot be employed to the Brazilian women. We have studied 158 Brazilian women with average age of 42 ± 14 years in whom it was settled the BMD over the lumbar vertebral column (L2, L3 and L4) and the femoral neck with a gadolinium-153 source double-photon densitometer and analyzed images in a IBM/PC/AT 286 processor computer. It was determined the linear regression equation corresponding to the variation of the bone mineral density as a function of age. The results were: BMD-lumbar column = 1.405 - 0.0086 x age ± 0.013 g/cm2 and BMD-femoral neck = 0.909 - 0.0034 x age ± 0.11 g/cm2 preferred to the age group between 25 to 80 years old. The results analysis shows that the Brazilian women BMD is lesser than the Caucasian. (author)
[en] The aim of the study was to determine the accuracy of non-rigid nine-parameter image registrations based on 153Gd transmission computed tomography (TCT) images as compared with those based on 99mTc-ethyl cysteinate dimer (ECD) images and to assess whether normalised mutual information (NMI) or count difference (CD) should be used. TCT and ECD data were acquired in 25 randomly selected patients. Emission images were registered to an ECD template with a CD cost function. The same registration parameters were applied to the transmission images to create a TCT template. All TCT images were registered to the TCT template and the same registration parameters were applied to the ECD images. The procedure was repeated with NMI as cost function. Accuracy of both ECD-based and TCT-based registrations was assessed by comparing the normalisation parameter values and regional activities in the spatially normalised ECD images, using a mixed-model analysis of variance (ANOVA). Scheffe post hoc tests were performed. No significant differences were found between ECD/CD, ECD/NMI and TCT/CD, suggesting that ECD registration can be done with either CD or NMI, and that TCT registration using CD is equally as accurate as ECD registration. The accuracy of TCT registration with NMI was lower, with discrepancies occurring in the frontal inferior region and the cerebellum. The analysis of normalisation parameters indicated that z-scaling is underestimated and yz-rotation overestimated with TCT/NMI registration. We conclude that ECD registrations with CD or NMI are as accurate as TCT registrations with CD and that TCT registrations with NMI should be avoided. (orig.)
[en] The electron capture Q values of 153Gd and 175Hf are analysed by using properties of their β decays to different levels belonging to the same rotational family in the daughter atoms. The results are Q = 500sub(-50)sup(+100) keV for 153Gd and Q = 700sub(-50)sup(+100) keV for 175Hf. They agree with data from nuclear reactions but reject smaller values based on K capture probabilities
[en] Purpose: Our purpose is to present a novel multisource rotating shield brachytherapy (RSBT) apparatus for the simultaneous precise angular and linear positioning of partially shielded 153Gd brachytherapy sources in interstitial needles for the treatment of locally advanced prostate cancer. It is designed to lower the dose to nearby healthy tissues, the urethra in particular, relative to conventional high-dose-rate brachytherapy techniques. Methods and Materials: Following needle implantation through the patient template, an angular drive mechanism is docked to the patient template. Each needle is coupled to a multisource afterloader catheter by a connector passing through a shaft. The shafts are rotated about their axes by translating a moving template between 2 stationary templates. The shafts' surfaces and moving template holes are helically threaded with the same pattern such that translation of the moving template causes simultaneous rotation of the shafts. The rotation of each shaft is mechanically transmitted to the catheter-source-shield combination, inside the needles, via several key-keyway pairs. The catheter angles are simultaneously incremented throughout treatment, and only a single 360° rotation of all catheters is needed for a full treatment. For each rotation angle, source depth in each needle is controlled by a multisource afterloader, which is proposed as an array of belt-driven linear actuators, each of which drives a wire that controls catheter depth in a needle. Results: Treatment plans demonstrated that RSBT with the proposed apparatus reduced urethral D0.1cm3 (the minimum dose delivered to the hottest 0.1cm3 of the urethra) below that of conventional high-dose-rate brachytherapy by 31% for urethral dose gradient volume within 3 mm of the urethra surface. Treatment time to deliver 20 Gy with the proposed multisource RSBT apparatus by use of nineteen 62.4-GBq 153Gd sources was 122 minutes. Conclusions: The proposed RSBT delivery apparatus enables a mechanically feasible urethra-sparing treatment technique for prostate cancer in a clinically reasonable time frame.