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Purpose: The purpose of this study was to develop a predictive model to evaluate pretreatment patient-specific quality assurance (QA) based on treatment planning parameters for stereotactic body radiation therapy (SBRT) for liver carcinoma. Materials and Methods: We retrospectively selected 180 cases of liver SBRT treated using the volumetric modulated arc therapy technique. Numerous parameters defining the plan complexity were calculated from the DICOM-RP (Radiotherapy Plan) file using an in-house program developed in MATLAB. Patient-specific QA was performed with global gamma evaluation criteria of 2%/2 mm and 3%/3 mm in a relative mode using the Octavius two-dimensional detector array. Various statistical tests and multivariate predictive models were evaluated. Results: The leaf speed (MILS) and planning target volume size showed the highest correlation with the gamma criteria of 2%/2 mm and 3%/3 mm (P < 0.05). Degree of modulation (DoM), MCSSPORT, leaf speed (MILS), and gantry speed (MIGS) were predictors of global gamma pass rate (GPR) for 2%/2 mm (G22), whereas DoM, MCSSPORT, leaf speed (MILS) and robust decision making were predictors of the global GPR criterion of 3%/3 mm (G33). The variance inflation factor values of all predictors were <2, indicating that the data were not associated with each other. For the G22 prediction, the sensitivity and specificity of the model were 75.0% and 75.0%, respectively, whereas, for G33 prediction, the sensitivity and specificity of the model were 74.9% and 85.7%%, respectively. Conclusions: The model was potentially beneficial as an easy alternative to pretreatment QA in predicting the uncertainty in plan deliverability at the planning stage and could help reduce resources in busy clinics. [ABSTRACT FROM AUTHOR]

Objective:Visual acuity (VA) testing is crucial for early intervention in cases of visual impairment, especially in rural health care. This study aimed to determine the potential of a web-based VA test (PocDoc) in addressing the unique health care needs of rural areas through the comparison in its effectiveness against the conventional VA test in identifying visual impairment among an Indian rural population. Methods:Prospective comparative study conducted in December 2022 at a tertiary referral eye care center in central India. We evaluated all patients with the PocDoc VA tests using three device types, and the conventional VA test. Bland–Altman plot (BAP) compared PocDoc and conventional VA tests. Fisher's exact tests evaluated associations between categorical parameters. Kruskal–Wallis tests followed by post hoc Dunn's tests identified association between categorical parameters and numerical parameters. Results:We evaluated 428 patients (792 measurements of VA) with mean age 36.7 (±23.3) years. PocDoc resulted in slightly worse VA scores (mean logMAR: 0.345) than conventional (mean logMAR: 0.315). Correlation coefficient between the conventional and PocDoc logMAR VA values was rho = 0.845 and rho2 = 0.7133 (p = 6.617 × 10–215; adjusted p = 2.205 × 10–214). Most data points fell within the interchangeable range of ±0.32 on BAP. Difference between the two methods increased with higher logMAR values, indicating poorer agreement for worse VA scores. Conclusions:Identifying and addressing the unique health care needs of rural populations is critical, including access to appropriate and effective VA testing methods. Validating and improving VA testing methods can ensure early intervention and improve the quality of life for individuals with visual impairment. [ABSTRACT FROM AUTHOR]

The development of a flexible and robust metamaterial absorber is a great motivation for the new generation of microwave absorbers covering any conformal shape. Ceramic–polymer composites with variable dielectric constant within the microwave frequencies are proposed as a flexible middle dielectric spacer (MDS) layer to provide an additional degree of design freedom for metamaterial absorber applications. By varying the dielectric constant of the MDS layer, the resonance band of the metamaterial absorber can be tuned while retaining a low profile in addition to enhancing its electromagnetic performance for transverse magnetic (TM) polarized waves. To formulate these composites, tetragonal structured barium titanate (BaTiO3) powder is selected as an excellent candidate when mixed with elastomer polydimethylsiloxane (PDMS), resulting in high mechanical strength substrates. Experimentally, samples with a range of dielectric permittivity from 2.81 to 5.67 were obtained for a 0%–20% volume fill fraction of BaTiO3 in PDMS. The obtained dielectric permittivities are consistent with the Bruggeman effective medium theory. Utilizing an optimized composition (10% BaTiO3), resulting in ϵ r = 4 substrate, an X-band flexible absorber is designed and fabricated to absorb more than 90% of incident electromagnetic waves within a frequency band of 8.16–12.12 GHz. [ABSTRACT FROM AUTHOR]