Changes in the size and location of kidneys from the supine to standing positions and the implications for block placement during total body irradiation.
OBJECTIVE
The use of total body irradiation (TBI) as a conditioning regimen for bone marrow transplantation often calls for partial transmission kidney blocks. These blocks are frequently designed based on the location of the kidneys during the abdominal computerized tomography (CT) scan. At our institution, TBI patients are treated in the standing position. As the kidneys can shift with different patient positions, a study was undertaken to evaluate the magnitude of the changes in the size and location of the kidneys from the supine CT position to the upright treatment position.


METHODS
Intravenous contrast was administered to 15 patients. The patients were initially positioned supine on a simulator table and then positioned upright immediately in front of the image intensifier. PA radiographs were obtained with the patients in both positions. Changes in the size of the kidneys and their location relative to the vertebral bodies were noted.


RESULTS
In going from the supine to upright position, all the kidneys shifted inferiorly between 0.5 cm and 7.5 cm with an average of 3.6 cm. Most of the kidneys also shifted in the transverse dimension and incurred a change in width. The range of the transverse shift was from 0.9 cm in the lateral direction to 4.9 cm medially. The maximum width broadening was 1.2 cm and the maximum decrease in width was 1.8 cm.


CONCLUSIONS
When compared to the supine position, patients in the upright position show a dramatic inferior shift of the kidneys with other obvious, but less predictable, changes. For TBI treatments delivered in the upright position, kidney blocks should not be designed on the basis of supine abdominal CT scans.
Reiff
J E
JE
Department of Radiation Oncology, Kimmel Cancer Center of Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA.
Werner-Wasik
M
M
Valicenti
R K
RK
Huq
M S
MS
D006801:Humans; D007668:Kidney / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D009068:Movement; D011187:Posture / Q000502:physiology*; D011835:Radiation Protection; D011859:Radiography; D016683:Supine Position; D014916:Whole-Body Irradiation / Q000379:methods*