Physical dosimetry of volumetric modulated arc therapy (VMAT) using EPID and 2D array for quality assurance

Outline: To address the correspondence of measured and predicted doses for different malignant tumours utilizing various gamma criteria and QA for confirmation of VMAT with an EPID and 2D array detector. Methods: 24 patients with different malignant tumors were treated by VMAT techniques on Varian IX linear accelerator with 6 MV photon beams. Eclipse treatment planning system (TPS) is used to plan Patient’s charts. Gamma Index (GI) variation was compared to the procedure of pre-treatment verification in VMAT plans. Results: The gamma criteria (DD/DTA) of dose difference and distance to agreement for (3%/3 mm), mean ± SD are γ≤1% = 99.42% ± 0.67%, γmax = 2.11 ± 0.56 and γavg = 0.19 ± 0.05 by EPID, and γ%≤1 = 99.36% ± 0.53%, γmax = 1.65 ± 0.45 and γavg = 0.22 ± 0.05 by using 2D array detector. Conclusions: Specific QA of VMAT patient (using EPID or 2D array) display great possibility to spare time and to verify individual IMRT fields. 3%/3 mm is the most appropriate of gamma criteria (DD/DTA) for VMAT plans quality assurance. Control charts are a beneficial method for verification assessment for patient specific quality control

Prevalence of Multidrug-Resistant <i>Pseudomonas aeruginosa</i> Isolated from Dairy Cattle, Milk, Environment, and Workers’ Hands

Pseudomonas aeruginosa is an opportunistic pathogen causing severe infection in animals and humans. This study aimed to determine the ecological distribution and prevalence of multidrug-resistant (MDR) P. aeruginosa isolated from dairy cattle, the environment, and workers’ hand swabs. Samples (n = 440) were collected from farms and households (n = 3, each). Rectal swabs, udder skin swabs, milk, workers’ hand swabs, feed, water, water sources, and beddings were collected. Samples were subjected to the bacterial identification of P. aeruginosa via 16S rRNA. Antimicrobial resistance (AMR) was detected either phenotypically using an antibiotic susceptibility test or genotypically with AMR resistance genes (ARGs) such as drfA, sul1, and ermB. P. aeruginosa was detected on dairy farms and households (10.3–57.5%, respectively), with an average of 23.2%. The resistance of dairy farm strains was observed against sulfamethoxazole, imipenem, cefepime, piperacillin–tazobactam, and gentamycin (100%, 72.7%, 72.7%, 68.8%, and 63.3%, respectively). Meanwhile, the resistance of household strains was observed against sulfamethoxazole, imipenem, amoxicillin, gentamicin, cefepime, and erythromycin by 91.3%, 82.6%, 75.4%, 75.4%, 68.1%, and 63.8%, respectively. The susceptibility of farm strains was detected against norfloxacin, ciprofloxacin, and levofloxacin (90.9%, 84.8%, and 72.7%, respectively). Meanwhile, the susceptibility of household strains was detected against ciprofloxacin, amikacin, and norfloxacin (100%, 84.1%, and 72.5%, respectively). About 81.4% of P. aeruginosa strains were MDR. ARGs (drfA, sul1, and ermB) were detected in farm strains (48.5%, 72.7%, and 24.4%, respectively) and household strains (50.7%, 72.5%, and 47.8%, respectively). Almost all P. aeruginosa had MAR over 0.2, indicating repeated application of antibiotics. P. aeruginosa prevalence was fivefold higher in households than on farms. MDR strains were higher amongst household strains than farm strains