A prospective study of ultrasound localization for renal shielding

Accurate and reproducible shielding of sensitive tissues is essential in clinical radiotherapy. Renal localization is necessary when the kidneys are to be shielded during upper or whole abdominal radiotherapy. Despite extensive clinical experience with intravenous contrast media for renal localization, ultrasound has been proposed as a safer, more cost-effective alternative. In a prospective study, we assessed the accuracy of renal localization by ultrasound. Results show that ultrasound localization covers only 56.5 +/- 27.0% of the renal outline on average; moreover, the ultrasound designed shield results in 57.2 +/- 20.4% of its area being superfluous. Possible explanations and modifications are discussed. We urge others using ultrasound localization for renal shielding to assess its accuracy before using these shields in clinical practice.