Volume difference between Internal Target Volume (ITV) and Deformable Image Registration (DIR_ITV): A comparative analysis

This study investigates the essential role of Radiation Therapy Quality 
Assurance (RTQA) procedures in modern radiotherapy treatments, particularly 
focusing on Stereotactic Body Radiation Therapy (SBRT) for centrally located 
lung malignancies. This study aims to compare the effectiveness of three 
commonly used metrics DSC (Dice Similarity Coefficient), GMI (Geometric 
Miss Index), and DI (Discordance Index) in assessing patients with specify 
condition/population. We focus on three key aspects: the Initial Tumor Volume 
(ITV) as delineated at 0 of the prescribed dose (ITV_0% P_DIR), 50% of 
the prescribed dose (ITV_50% P_DIR), and Maximum Intensity Projection 
(ITV_MIP). The analysis reveals significant differences among the metrics 
in evaluating tumor characteristics at different dose levels and imaging 
perspectives. Notably, DSC provided distinct insights into tumor perfusion 
dynamics, particularly evident in the delineation of ITV_0 P_DIR and ITV_50% 
P_DIR. GMI exhibited strengths in capturing subtle variations in tumor 
morphology, with ITV_0 P_DIR comparisons showing its utility. DI has turned 
out to be a valuable tool in delineating spatial heterogeneity, with significant 
findings observed between ITV_50% P_DIR and ITV_MIP. These findings 
underscore the importance of selecting appropriate metrics tailored to the 
specific diagnostic or prognostic objectives in patients with specify condition/
population.