Chest radiography remains one of the most frequently performed imaging examinations, highlighting the need for optimization of acquisition parameters to balance image quality and radiation dose. This study presents a phantom-based quantitative evaluation of chest radiography acquisition settings using a digital radiography system (AGFA DR 600). Measurements were performed at three tube voltage levels across simulated patient-equivalent thicknesses generated using PMMA slabs, with a Leeds TOR 15FG image quality phantom positioned centrally in the imaging setup. Image quality was quantitatively assessed using signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), which were calculated from mean pixel values obtained from repeated acquisitions. Radiation exposure was evaluated through estimation of entrance surface dose (ESD). The analysis demonstrated that dose-normalized performance metrics favored intermediate tube voltages for slim and average patient-equivalent thicknesses, while higher voltages were required to maintain image quality in obese-equivalent conditions. Overall, image quality and dose were found to be strongly dependent on the combined selection of tube voltage and phantom thickness. These findings indicate that modest adjustments to tube voltage selection may improve the balance between image quality and radiation dose in chest radiography. Nevertheless, as the present work is based on phantom measurements, further validation using clinical images and observer-based studies is required before any modification of routine radiographic practice.

Introduction: Stereotactic radiosurgery is a highly precise radiotherapy technique widely used for the management of brain metastases. While VMAT enables highly conformal dose distributions, it is often associated with increased plan complexity and longer delivery times. Optimized dynamic conformal arc therapy (OptDCA) represents a less complex alternative that may achieve comparable dosimetric performance. In this retrospective study, dosimetric quality, deliverability, and plan complexity of VMAT and OptDCA were compared for single-isocenter SRS of multiple brain metastases. Materials and Methods: Thirty patients previously treated with VMAT were randomly selected and replanned using OptDCA with identical beam arrangements. Plan quality was evaluated using the Paddick conformity index, gradient index, target coverage, MUs, and brain V12Gy and V20Gy. Deliverability was assessed using gamma passing rates, and plan complexity was quantified using multiple complexity metrics. Results: VMAT achieved a slightly higher CI (0.72 vs. 0.71) but required a higher number of MUs (5376 vs. 4820), while no significant differences were observed in GI or target coverage. OptDCA demonstrated significantly higher GPR (median 96.95% vs. 91.1%) and consistently lower plan complexity. Significant correlations were observed between GPR and several complexity metrics for both techniques. Conclusion: Overall, OptDCA provides comparable plan quality to VMAT, while offering improved deliverability and reduced complexity, making it a viable alternative technique.