Activity‐dependent transit dose assessment in ¹⁹² Ir high‐dose‐rate brachytherapy surface applicator using GafChromic ^TM EBT4 film

This study validates EBT4 film as a reliable tool for transit dose measurement in surface brachytherapy. The observed non-linear relationship between transit dose and source activity reveals the critical influence of experimental setup variables, particularly source guide tube geometry, which affects the source-to-target distance during transit. These findings demonstrate that transit dose is impacted by multiple interdependent factors including source activity, guide tube configuration, and setup geometry. For clinical applications, this highlights the importance of standardized setup protocols and empirical measurement for accurate transit dose assessment.