In a study of KUB, it is essential to document the size and number of stones in the urinary system. The approximate Hounsfield units provide information for the urologist on what type of management to go ahead with. Documentation of obstruction is mandatory as it can far reaching consequences on the functioning of the afflicted kidney. 

In this case the larger right renal pelvic stone is exhibiting features of obstruction. The secondary urinary stasis has resulted in inflammatory changes in the renal pelvis resulting in pyelitis.