Computed Tomographic (CT) urography is the best imaging modality to evaluate obstructing lesions of urinary tract such as urinary stone, tumor and inflammatory lesion. The purpose of our study is to compare images of CT urography performed by low voltage and low concentrated iodine CT contrast with them of conventional CT urography.

Computed Tomographic (CT) urography is the best imaging modality to evaluate obstructing lesions of urinary tract such as urinary stone, tumor and inflammatory lesion. It is needed that CT urography should have the high contrast between target lesion described as filling defect and adjacent contrast filled urinary tract. For the implementation of high contras, conventional CT urography has been performed with higher voltage and higher concentrated CT contrast than another CT protocols. The higher voltage results in the more radiation exposure. And the intravenous injection of higher concentrated CT contrast results in the increase of the prevalence of contrast induced nephrotoxicity.

The purpose of our study is to compare images of CT urography performed by low voltage and low concentrated iodine CT contrast with them of conventional CT urography.

Inclusion Criteria:

• Patients to perform Computed Tomographic (CT) urography
• Patients without diminish of renal function (serum creatinine: more than 1.4 mg/dl & glomerular filtration rate: more than 34 mL/min/1.73 m2)

Exclusion Criteria:

• patients to have operations and/or injuries of urinary system
• patients to have the histories of anaphylaxis or allergic reaction about intravenous iodine contrast material