Optimal Exposure Technique for Chest AP Semi-erect Radiographs Through Glass Barriers Using Portable X-ray Machine

Abstract

A portable chest x-ray through glass has been used during the COVID-19 pandemic to reduce the risk of infection. This study aimed to determine the optimal exposure technique for chest AP semi-erect x-ray through glass with a 0.5 cm thickness by using a portable x-ray machine and surveying the amount of scattered radiation. An anthropomorphic phantom was used during chest x-ray through the glass and without glass by the same exposure technique during 90-120 kVp with SID 270 cm. A phantom was placed on a wooden wedge with a 45-degree angle. The entrance skin dose (ESD) measurements were performed with an OSL NanoDot dosimeter. The scattered radiation that occurred inside and outside the room was measured with a survey meter. All radiographs were evaluated as a quantitative and qualitative assessment of the image quality. The results showed that the optimal exposure technique for chest AP semi-erect x-ray through glass at SID 270 cm were 100 kVp 5 mAs and 110 kVp 3.2 mAs. When compared with chest x-ray without glass, the amount of entrance skin dose was reduced by 63.16% and 59.76%, respectively. The qualitative assessment from three experienced radiographers, found the image quality score of the chest x-ray through glass image was around 4.47 and 4.33, respectively, meaning that chest film showed a good level of agreement in the interpretation and sufficient for diagnosis. The amount of scattered radiation that occurred at a distance of 1 m to the left side of the phantom inside the room was lowest at a 90-degree angle, and on the left side of the x-ray tube outside the room, the amount of scattered radiation was lowest at a 45-degree angle. However, there is a general recommendation for radiographer to wear a lead apron and standing in an appropriate position during a radiographic examination to prevent the effect of scatter radiation.