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Introduction: This study aims to evaluate the use of CT-based whole kidney parenchyma (WKP) segmentation in 177Lu-DOTATATE dosimetry. Specifically, it investigates whether WKP volumes change during treatment and evaluates the accuracy of applying a single delineated WKP volume for dosimetry. Furthermore, it aims to determine the cause of WKP volume changes—whether caused by radiation or amino acid infusion—by comparing them with spleen volume changes as a marker for radiation-induced alterations. Methods: SPECT/CT images of 18 patients were acquired over the abdomen approximately 4 h (h) (D0), 24 h (D1), 48 h (D2) and 168 h (D7) post-administration of 177Lu-DOTATATE. CT guided WKP volumes were measured before (baseline) and during treatment. Kidney activity concentrations at each time point were derived from CT-segmented WKP overlaid on SPECT scans. The accuracy of using WKP segmentation from a single CT for all time points was assessed against the gold standard of segmenting each WKP individually. Time-integrated activity calculations were based on a tri-exponential curve fit of the kidney activity concentration over time. Kidney absorbed doses were estimated under the assumption of local energy deposition. Additionally, the impact of various partial volume correction methods on dosimetry was evaluated. Results: Whole-kidney parenchyma (WKP) volumes, ranging from 31 to 243 mL, showed a gradual increase from baseline (mean ± SD = 130.6 ± 46.1 mL) at the initial time points D0 (138.5 ± 44.7 mL) and D1 (139.4 ± 41.6 mL), followed by a slight decrease at D2 (132.8 ± 44.5 mL) and a further decrease at D7 (129.2 ± 42.7 mL). The volume increase at D0 and D1 was statistically significant. Spleen volume did not change during treatment, suggesting that amino acid infusion rather than irradiation effects caused WKP volume changes. Bland-Altman analysis revealed WKP volume biases of 8.77% (D0 vs. BL), 10.77% (D1 vs. BL), 1.10% (D2 vs. BL), and 1.10% (D7 vs. BL), with corresponding uncertainties of 24.4%, 23.6%, 25.4%, and 25.4%, respectively. When WKP segmentation from a single CT is applied across all SPECTs, these WKP volume changes could overestimate the activity concentration and mean absorbed doses up to 4.3% and 2.5%, respectively. The absorbed dose uncertainties using a recovery coefficient (RC) of 0.85 for single-time-point WKP delineation increase the absorbed dose uncertainty by 4% compared to the use of patient-specific RCs and time specific segmentation of WKP volumes. Conclusions: Kidney volume exhibited significant variation form D0 to D7, affecting the precision of dosimetry calculation, primarily due to errors in whole-kidney parenchyma (WKP) delineation. Notably, using WKP segmentation from a single CT scan applied to sequential SPECT images introduce further uncertainty and may lead to an overestimation of the absorbed dose. The fluctuations in kidney volume are most likely attributable to amino acid infusion. [ABSTRACT FROM AUTHOR]

The current study focuses on the biodegradation of selected synthetic dye by using a brown rot fungus, Piptoporus betulinus. Response Surface Methodology (RSM) under Central Composite Design (CCD) was employed to optimize the biodegradation of two synthetic dyes named direct flavine 5-G (Direct-1) and reactive red S3B (Reactive-1). The biodegradation process was optimized by study of the effect of pH, temperature, time period and dye concentration. Further, carbon and nitrogen sources were added to enhance the biodegradation process. Ligninolytic enzymes including laccase, lignin peroxidase and manganese peroxidase were also studied during biodegradation experiments to check their role in the biodegradation process. The results showed that there was 81.17% biodegradation of reactive-1 and 75.91% of direct-1 after optimization of parameters i.e. pH, temperature, time period and dye concentration through RSM. The biodegradation of reactive-1 dye was increased up to 97.29% after the addition of various carbon and nitrogen sources during the biodegradation process, while the biodegradation of direct-1 dye increased upto 93.03% after the addition of carbon and nitrogen sources. These readily available nutrients enhance fungal growth and enzyme production that causes more biodegradation. There was positive interaction among most of the parameters studied, for the biodegradation of above two dyes. The ligninolytic enzymes were actively involved in the process with activities 1638.05 IU/mL for LiP, 1443.01 IU/mL for MnP and 258.88 IU/mL for laccase at the optimized conditions. The optimal conditions for biodegradation of both dyes were pH 6, inoculum size 6 mL, incubation period 5 day and dye concentration 0.03% at temperature 32.5 °C. Lip was the most efficient enzyme involved in the biodegradation process. [ABSTRACT FROM AUTHOR]