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Renal cell carcinoma (RCC) has been historically viewed as a radioresistant tumor. However, novel radiation techniques, such as magnetic resonance-guided stereotactic body radiotherapy (MRgSBRT), enable the delivery of ablative doses of radiation while minimizing toxicity to surrounding organs, allowing for further exploration of the role of radiotherapy in RCC. In this study, we evaluated the safety and disease control outcomes of patients with metastatic RCC who underwent metastasis-directed MRgSBRT. We performed a retrospective analysis of 44 patients who underwent MRgSBRT for RCC metastases at a single institution between 2019-2023. Endpoints were local control, freedom from distant progression, time to change in systemic therapy, overall survival, and toxicity. Disease progression was defined using RECIST criteria. Toxicity was graded using CTCAE v5.0. Outcomes were analyzed using the Kaplan-Meier method. Forty-four patients underwent treatment for 64 lesions. All patients had an Eastern Cooperative Oncology Group status of 0-1. The most frequent histology was clear cell RCC (64%). 75% of patients had fewer than 5 metastatic lesions at the time of MRgSBRT. The most common metastatic sites treated were lymph nodes (28%), pancreas (25%), and adrenal glands (19%). Median lesion size prior to treatment was 2.2 cm (IQR 1.6-3.7). 94% of lesions were treated using daily adaptive planning. Radiation dose range was 40-54 Gy delivered in 3-5 fractions with 40 Gy in 5 fractions being the most common regimen (78%). At a median follow-up of 16.0 months (IQR 8.5-23.0), local control was 95.6% (95% CI = 83.5-98.9), freedom from distant progression was 16.6% (95% CI = 7.7-28.5), and overall survival was 78.0% (95% CI = 62.9-87.6). The 2 local failure events observed were both pancreatic lesions, of clear cell and clear cell with rhabdoid histology. The median change in lesion size post-treatment was -0.45 cm (20% decrease from baseline). At median follow-up, 54.9% (95% CI = 39.7-67.7) of patients continued either without systemic therapy or on the same systemic regimen as prior to MRgSBRT. Median time to change of systemic therapy post-MRgSBRT was 11.5 months (IQR 5.5-17.0). Among the 33 patients who did not receive systemic therapy prior to MRgSBRT, 72% remained off systemic therapy following treatment. There was no grade 3+ toxicity observed up to 3 months following treatment. MRgSBRT provides high rates of local control for metastasis-directed treatment of metastatic RCC and may allow for prolonged time without initiating or switching systemic therapy. Further investigations to explore factors that may predict response to radiotherapy are warranted. [ABSTRACT FROM AUTHOR]

This paper reports on the use of solid sampling-electro. thermal vaporization-inductively coupled plasma mass spectrometry (SS-ETV-ICPMS) for the direct and simultaneous determination of methylmercury and inorganic mercury in biological materials. The main advantage of this fast and sensitive method is that no sample preparation is required. In this way, the sample throughput can be considerably increased, problems of contamination and analyte losses are kept to a minimum and, even more important, the original chemical form of the different analyte species in the solid samples is preserved. To achieve this goal, a solid sample is inserted into a graphite furnace of the boat-in-tube type and is subsequently submitted to an appropriate temperature program, leading to the separate vaporization of methylmercury and inorganic mercury, which are transported into the ICP by means of an argon carrier gas. The separation was accomplished within 75 s. For the quantification of the two peaks, species-unspecific isotope dilution was used. For this purpose, a stable flow of argon loaded with gaseous Hg isotopically enriched in [sup.200]Hg was generated using a permeation tube that was constructed in-house. Its emission rate was determined by collecting the mercury released during a given time interval on a gold-coated silica absorber, after which the amount collected was released by heating of the absorber and determined by cold vapor atomic absorption spectrometry (CVAAS) and cold vapor atomic fluorescence spectrometry (CVAFS). A reference material from the Canadian National Research Council (NRC) (TORT-2) was used to assess the accuracy of the method. For the application of the method to samples with diverse mercury contents, the spike/sample ratio can be optimized by varying the emission rate of the permeation tube simply by adapting its temperature. To prove the feasibility of this approach, two reference materials (BCR 463 and DORM-2) with a methylmercury content more than 10 times higher than that of TORT-2 were also analyzed. The detection limits obtained for 1 mg of sample (2 ng [g.sup.-1] and 6 ng [g.sup.-1] for methylmercury and inorganic mercury, respectively) were found to be sufficiently low for this kind of application and are competitive when compared to other techniques.

The purpose of this feasibility study was to investigate the possibilities and limitations of Charged-Particle Activation Analysis (CPAA) as a thin layer characterization method, i.e., the determination of the mass thickness or the composition of a thin layer. Therefore industrially important layers of sputtered Al, AlO(sub x), TiO(sub x) (all three from the packaging industry), YBa(sub 2)Cu(sub 3)O(sub 6+ delta), and Y(sub 2)O(sub 3)-stabilized ZrO(sub 2) (both superconducting industry) on different substrates were analyzed, and thereby the accuracy, the detection limits, and the precision of the method were studied. To test the accuracy, the same materials were also analyzed with neutron activation analysis (NAA) and inductively coupled plasma mass spectrometry (ICPMS). The results of CPAA compared with the results of NAA and ICPMS showed no significant difference at the 95% confidence level. The detection limits expressed as mass thickness were about 10(super -2) (mu)g cm(super -2) or expressed as thickness 0.04 nm for a monatomic layer of Al. The experiments showed that the precision of the method depends only on the counting statistics. Generally we can conclude that CPAA is an absolute method for the characterization of 'thin' layers, with respect to composition and mass thickness determinations.