Characterization of microMOSFET detectors for in vivo dosimetry in high-dose-rate brachytherapy with 192 Ir.

PURPOSE: The objective of this study was to characterize the Best Medical Canada microMOSFET detectors for their application in in vivo dosimetry for high-dose-rate brachytherapy (HDRBT) with 192 Ir. We also developed a mathematical model to correct dependencies under the measurement conditions of these detectors. METHODS: We analyzed the linearity, reproducibility, and interdetector variability and studied the microMOSFET response dependence on temperature, source-detector distance, and angular orientation of the receptor with respect to the source. The correction model was applied to 19 measurements corresponding to five simulated treatments in a custom phantom specifically designed for this purpose. RESULTS: The detectors (high bias applied in all measurements) showed excellent linearity up to 160 Gy. The response dependence on source-detector distance varied by (8.65 ± 0.06)% (k = 1) for distances between 1 and 7 cm, and the variation with temperature was (2.24 ± 0.05)% (k = 1) between 294 and 310 K. The response difference due to angular dependence can reach (10.3 ± 1.3)% (k = 1). For the set of measurements analyzed, regarding angular dependences, the mean difference between administered and measured doses was -4.17% (standard deviation of 3.4%); after application of the proposed correction model, the mean difference was -0.1% (standard deviation of 2.2%). For the treatments analyzed, the average difference between calculations and measures was 4.7% when only the calibration coefficient was used, but it is reduced to 0.9% when the correction model is applied. CONCLUSION: Important response dependencies of microMOSFET detectors used for in vivo dosimetry in HDRBT treatments, especially the angular dependence, can be adequately characterized by a correction model that increases the accuracy of this system in clinical applications.

Influence of the addition of Lactobacillus acidophilus La-05, Bifidobacterium animalis subsp. lactis Bb-12 and inulin on the technological, physicochemical, microbiological and sensory features of creamy goat cheese.

The effects of the addition of Lactobacillus acidophilus LA-05, Bifidobacterium animalis subsp. lactis BB-12 and inulin on the quality characteristics of creamy goat cheese during refrigerated storage were evaluated. The manufactured cheeses included the addition of starter culture (Lactococcus lactis subsp. lactis and Lactococcus lactis subsp. cremoris - R-704) (CC); starter culture, L. acidophilus LA-05 and inulin (CLA); starter culture, B. lactis BB-12 and inulin (CBB); or starter culture, L. acidophilus LA-05, B. lactis BB-12 and inulin (CLB). In the synbiotic cheeses (CLA, CBB and CLB), the counts of L. acidophilus LA-05 and B. lactis BB-12 were greater than 6log CFU g-1, the amount of inulin was greater than 6 g per 100 g, and the firmness was reduced. The cheeses evaluated had high brightness values (L*), with a predominance of yellow (b*). CC had higher contents of proteins, lipids and minerals compared to the other cheeses. There was a decrease in the amount of short-chain fatty acids (SCFAs) and an increase of medium-chain (MCFAs) and long-chain fatty acids (LCFAs) in the synbiotic cheeses compared to CC. The amount of conjugated linoleic acid increased in CLA, CBB and CLB. The highest depth of proteolysis and the greatest changes in the release of free amino acids were found in CLB. The addition of inulin and probiotics, alone or in co-culture, did not affect the cheese acceptance. Inulin and probiotics can be used together for the production of creamy goat cheese without negatively affecting the general quality characteristics of the product, and to add value because of its synbiotic potential.