Current abdominal radiation uses volumetric data from CT based planning to better define targets and organs at risk. One or both of the kidneys often lie in close proximity to target structures. As the kidneys are inherently radiosensitive and renal tolerance limits are often less than prescribed therapeutic doses, the kidneys are major dose limiting structures

in abdominal radiation treatment fields. Progressive renal dysfunction following abdominal radiation Inhibitors,research,lifescience,medical has been reported (1)-(13). Emami et al described the probability of developing normal tissue complications and suggested organ tolerance limits based on volume of organ irradiated to various doses (14). For kidney, the tolerance limits for 5% probability of complications at 5 years (TD 5/5) are 23 Gy for whole organ, 30 Gy for 2/3 volume, and 50 Inhibitors,research,lifescience,medical Gy to 1/3 volume. The Emami tolerances do not specifically address the relative contribution of each kidney to overall renal function. Split renal function Inhibitors,research,lifescience,medical is commonly assessed prior to abdominal radiation. Split renal function can be measured using renal scintigraphy with each kidney’s relative function expressed as a percentage of total function. Assessment of the

relative contribution of each kidney to overall renal function by renogram may guide radiation treatment planning and design of shielding for renal sparing. This study evaluated renal function prior to and following abdominal radiation with concurrent chemotherapy in the treatment of gastrointestinal malignancies. Inhibitors,research,lifescience,medical The association between split function on Technetium99m MAG-3 renal scintigraphy, change in creatinine clearance, and radiation dose volume parameters was analyzed. Methods

and materials Patient selection Patients with gastrointestinal malignancies treated Inhibitors,research,lifescience,medical with abdominal JSH 23 Chemoradiation between 2002 and 2009 were identified. Patients were included in this analysis if they received concurrent chemotherapy and three-dimensional conformal abdominal radiation, had at least one kidney included in the radiation treatment fields, had pre-radiation renal scintigraphy performed, received at least 20 Gy, and had laboratory data and secondly dosimetric parameters available for review. Chemoradiation All patients underwent CT simulation. Three-dimensional conformal radiation treatment planning was performed using Theraplan Plus treatment planning system (MDS Nordion, Ottawa, Ontario, Canada) and Eclipse Treatment Planning System (Varian Medical Services, Palo Alto, CA, USA). Abdominal radiation was delivered on linear accelerators using 6-23 MV photons. Dose and field arrangements varied by primary site. Targets and organs at risk were contoured. Treatment plans were designed to encompass the primary target and areas at risk with margin.