Currently, one of the most used procedures in radiology for diagnosing diseases is diagnostic X-ray. This procedure is often applied in various medical examinations, such as medical check-ups, early cancer detection, and brain hemorrhage detection. Therefore, it is important to determine the amount of scattered radiation produced during this procedure to evaluate the radiation dose received by patients, personnel, and the members of the public. This study aims to evaluate how scattered radiation changes with scatter angle and tube voltage using the Monte Carlo method. This study also evaluates the scattered radiation distribution from patients during Trout and Kelly procedures and supine AP chest radiography. The study uses the Monte Carlo simulation using PHITS software to model scattered radiations with variations of position and tube voltage. The controlled variables are tube current (5 mAs), field size (20×20 ðð2 for Trout and Kelly procedures, 35×43 ðð2 for supine AP chest radiography), focus-to-detector distance (100 cm for Trout and Kelly, 180 cm for supine AP chest radiography), and phantom dimensions. The phantoms used are water blocks with tissue-equivalent density, masonite blocks, and water ellipsoids. The independent variables are scatter angle (30° to 135°) and tube voltage (70 kV to 100 kV). The dependent variables are primary kerma and scatter kerma, measured at 1 m from the focal point and the center of the phantom. Scatter fraction curves from the simulation are compared with literature data and measurements for result verification. Study results show that the 30° angle shows the highest increase in scattered radiation, up to a factor of 2.71, while the 135° angle shows the lowest increase, at a factor of 1.21. The simulated scatter fraction curves have a pattern similar to those from literature data and measurements, with the 80° angle most closely matching the reference literature and the 90° angle for measurement verification. Compared to the Trout and Kelly procedures, the supine AP chest radiography procedure produces a greater scatter fraction, up to a factor of 4.27. Secondary radiation shielding calculations need to be improved by changing the focus-to-detector distance to 180 cm and the field size to 35×43 ðð2.
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