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The antibacterial drug, basic bismuth succinate of the composition Ñ2Í4(ÑÎÎBiO)2 is shown to obtain expediently by the interaction of bismuth oxide α-Bi2O3 with a succinic acid solution. Using the method of electron microscopy the influence of the chemical prehistory of obtaining the precursor, monoclinic modification of α-Bi2O3, on the morphological features of basic bismuth succinate synthesized from it has been investigated. The composition of Ñ2Í4(ÑÎÎBiO)2 was confirmed by the data of X-ray phase and chemical analyses. Based on the data of grain size analysis, the particle size of the obtained samples of basic bismuth succinate was estimated and the conditions for the synthesis of fine-crystalline C2H4(COOBiO)2, which is necessary for medical applications, were selected.

Purpose: SRS MapCHECK (SMC) is a commercially available patient-specific quality assurance (PSQA) tool for stereotactic radiosurgery (SRS) applications. This study investigates the effects of degree of modulation, location off-axis, and low dose threshold (LDT) selection on gamma pass rates (GPRs) between SMC and treatment planning system, Analytical Anisotropic Algorithm (AAA), or Vancouver Island Monte Carlo (VMC++ algorithm) system calculated dose distributions., Methods: Volumetric-modulated arc therapy (VMAT) plans with modulation factors (MFs) ranging from 2.7 to 10.2 MU/cGy were delivered to SMC at isocenter and 6 cm off-axis. SMC measured dose distributions were compared against AAA and VMC++ via gamma analysis (3%/1 mm) with LDT of 10% to 80% using SNC Patient software., Results: Comparing on-axis SMC dose against AAA and VMC++ with LDT of 10%, all AAA-calculated plans met the acceptance criteria of GPR ≥ 90%, and only one VMC++ calculated plan was marginally outside the acceptance criteria with pass rate of 89.1%. Using LDT of 80% revealed decreasing GPR with increasing MF. For AAA, GPRs reduced from 100% at MF of 2.7 MU/cGy to 57% at MF of 10.2 MU/cGy, and for VMC++ calculated plans, the GPRs reduced from 89% to 60% in the same MF range. Comparison of SMC dose off-axis against AAA and VMC++ showed more pronounced reduction of GPR with increasing MF. For LDT of 10%, AAA GPRs reduced from 100% to 83% in the MF range of 2.7 to 9.8 MU/cGy, and VMC++ GPR reduced from 100% to 91% in the same range. With 80% LDT, GPRs dropped from 100% to 42% for both algorithms., Conclusions: MF, dose calculation algorithm, and LDT selections are vital in VMAT-based SRT PSQA. LDT of 80% enhances sensitivity of gamma analysis for detecting dose differences compared to 10% LDT. To achieve better agreement between calculated and SMC dose, it is recommended to limit the MF to 4.6 MU/cGy on-axis and 3.6 MU/cGy off-axis., (© 2024 The Author(s). Journal of Applied Clinical Medical Physics published by Wiley Periodicals LLC on behalf of American Association of Physicists in Medicine.)

Objective . Plastic scintillator detectors (PSDs) have demonstrated ability to meet requirements of small field dosimetry. Medscint developed a 1 mm long, 1 mm diameter cylindrical PSD with effective volume of 0.8 mm 3 . Clinically relevant, small field dosimetric properties of this detector, combined with a novel scintillation dosimetry system-HYPERSCINT RP-200, and HYPERDOSE analysis software were evaluated in this study. Approach . This novel scintillator-based dosimetry system was characterized with 6 MV-WFF and 10 MV-FFF x-ray beams delivered by Varian TrueBeam TM linear accelerator. The detector was characterized for leakage, short-term repeatability, dose response linearity, angular response, dose rate response, and field size dependence for radiation field sizes of 0.25 × 0.25 to 10 × 10 cm 2 . Measured detector specific output ratios were compared with microDiamond output factors to determine small field output correction factors,kQclin,Qmsrfclin,fmsr. Main results . The dosimetry system showed excellent short-term repeatability with standard deviation of only 0.04 ± 0.01%. It demonstrated good dose linearity with variations less than 1.0% for 14.4 cGy and above. The dosimetry system was found to be independent of dose rate and angle of irradiation, with deviations for both below 0.5%. Leakage was found to be comparable to background readings. For 6 MV-WFF energy beams, detector specific output ratios for field sizes down to 1 × 1 cm 2 agreed with output factors measured with PTW TN60019 microDiamond, thus,kQclin,Qmsrfclin,fmsrequates to unity for these field sizes. For 10 MV-FFF energy beams, detector specific output ratios for field sizes down to 2 × 2 cm 2 agreed with PTW TN60019 microDiamond output factors, thus,kQclin,Qmsrfclin,fmsrequates to unity for these field sizes.kQclin,Qmsrfclin,fmsrfor field sizes down to 0.5 × 0.5 cm 2 were determined to be within 6% of unity for both 6 MV-WFF and 10 MV-FFF energy beams. Significance . The HYPERSCINT RP-200 dosimetry system coupled with a 0.8 mm 3 PSD showed excellent dosimetric properties and was found to be clinically relevant for relative dosimetry down to field sizes of 0.5 × 0.5 cm 2 and potentially smaller., (Creative Commons Attribution license.)