The radiation dose to superficial organs may be lower with standing posterior-anterior projection than with standing anterior-posterior projection during chest digital radiography, reports a study.
The study is published in the PLOS One Journal.
Hongrong Xu and colleagues from the Department of Radiology, Children's Hospital of Chongqing Medical University, Chongqing, China, investigated the impact of the use of different imaging units and projections on radiation dose and image quality during chest digital radiography (DR) in 3- and 4-year-old children.
The authors included a total of two hundred forty 3- and 4-year-old participants requiring chest digital radiography; they were divided into three groups: supine anterior-posterior projection (APP), standing APP and standing posterior-anterior projection (PAP).
Each group included 40 participants who were evaluated using the same imaging unit. The dose area product (DAP) and the entrance surface dose (ESD) were recorded after each exposure.
The visual grading analysis score (VGAS) was used to evaluate image quality, and the longitudinal distance (LD) from the apex of the right lung to the apex of the right diaphragm was used to evaluate the inspiration extent.
The results showed that dose area product and entrance surface dose were significantly lower in the standing posterior-anterior projection and anterior-posterior projection groups than in the supine anterior-posterior projection group (P<0.05), but longitudinal distance was significantly higher in the standing posterior-anterior projection and anterior-posterior projection groups than in the supine anterior-posterior projection group (P<0.05).
Additionally, the pulmonary field area was significantly higher for the standing posterior-anterior projection group than for the standing and supine anterior-posterior projection groups (P<0.05). The correlations between entrance surface dose, dose area product, and visual grading analysis score were positive (P<0.001), showing that larger entrance surface dose and dose area product correspond to higher visual grading analysis score.
The correlations between entrance surface dose, dose area product, and body mass index (BMI) were also positive (P<0.05), indicating that higher body mass index corresponds to larger entrance surface dose and dose area product.
Finally, no differences in dose area product, entrance surface dose, visual grading analysis score, longitudinal distance, pulmonary field area, or body mass index were noted between males and females (P>0.05).
Hence, the authors concluded that "the radiation dose to superficial organs may be lower with standing posterior-anterior projection than with standing anterior-posterior projection during chest digital radiography. Standing posterior-anterior projection should be selected for chest digital radiography in 3- and 4-year-old children, as it may decrease the required radiation dose."

https://doi.org/10.1371/journal.pone.0255749