An approach for the online determination of Entrance Surface Air Kerma (ESAK) from Kerma Area product (P KA ) in digital radiology.

We propose determining the entrance surface air kerma (ESAK) from the kerma area product (P KA ) in digital radiology. ESAK values were derived from the X-ray tube outputs and patient exposure factors across five X-ray departments. Using linear regression between ESAK and P KA values, the slope and intercept coefficients were determined for each X-ray equipment and procedure. The method was examined using the data collected from patients who underwent chest PA/LAT, abdomen, pelvic AP, and lumbar spine AP/LAT X-ray examinations. The results showed a highly significant correlation between ESAK and P KA values and correlation coefficients, ranging from 0.77 to 1 with P-value < 0.001 in most studies. This method can be employed by incorporating dose data and related parameters into the X-ray device's software, similar to other dose-displayed information. The online determination of ESAK from P KA could help with quality assurance and patient dose management in digital radiology.