Purpose: To determine the feasibility of establishing patient radiation dose look-up tables for pediatric X-ray exams by assessing the consistency of performance of 24 radiography X-ray tubes over a period of 5 years.
Methods: Annual quality control testing records were collected over a period of 5 years between 2016 and 2020 for 24 Philips X-ray rooms. The data includes information about each tube’s measured kVp, output/dose, and beam quality (HVL in mm Al). Measurements were taken using either a Raysafe X2 or RTI Piranha solid-state detector under narrow-beam in-air conditions at a source-to-detector distance of 58.5 cm.
Results: The mean measured kVp had an average error of 0.52% over 5 years ranging from -3.8% to 2.48% deviation from the nominal. The mean kVp had an average percent standard deviation of 0.77% between machines over the same time period, where the largest percent standard deviation was 1.25% at 50 kVp in 2016 and 2018. The measured HVL averaged over 5 years was 2.38 mm Al at 60 kVp and 3.11 mm Al at 80 kVp with average percent standard deviations of 2.82% and 2.52% respectively. The maximum percent standard deviation was 3.32% at 60 kVp and occurred in 2016. The measured tube output in mR/mAs had an average percent standard deviation of 6.44% with a maximum deviation of 8.23% at 50 kVp in 2019. The mean standard deviation in average mR/mAs year-to-year was 1.18% with the maximum of 1.25% occurring at 50 kVp. Example look-up tables for pediatric chest and abdomen exams were generated based on average equipment performance data from the previous 5 years.
Conclusion: Machine performance was found to be consistent between machines as well as year-to-year, suggesting that the creation of exam dose look-up tables is feasible.