Cumulative EQD2 BED for Kidney
The kidney tolerance dose is approximately 15-17 Gy in 2 Gy fractions (EQD2) for uniform external beam irradiation, with systemic radiation delivery (such as total body irradiation) having a lower threshold of approximately 12 Gy EQD2. 1
Kidney Radiation Tolerance Parameters
Standard External Beam Radiation Therapy
- Uniform kidney irradiation tolerance: 15-17 Gy EQD2 for local external beam therapy 1
- Systemic radiation delivery: Approximately 12 Gy EQD2 when delivered as total body irradiation in bone marrow transplant protocols 1
Radiobiological Considerations
- The kidney demonstrates significant radiosensitivity as a dose-limiting organ 1
- The linear-quadratic (LQ) model with an α/β ratio of 1.5-3 Gy adequately describes kidney fractionation sensitivity for doses per fraction down to approximately 1 Gy 1
- For fraction sizes below 1 Gy, the LQ model may underestimate the biological effectiveness 1
Clinical Context for Soft Tissue Sarcoma
Standard Radiation Doses for Sarcoma Treatment
While treating soft tissue sarcoma, the kidney constraint becomes critical when:
- Retroperitoneal/intra-abdominal sarcomas are treated with 45-50 Gy in standard fractionation 2
- Postoperative radiation delivers 50 Gy external beam with potential boost doses of 10-26 Gy depending on margin status 2
- Total cumulative doses can reach 60-76 Gy to the tumor bed with positive margins 3, 4
Critical Pitfall
The kidney tolerance of 15-17 Gy EQD2 is substantially lower than typical sarcoma treatment doses (50-60 Gy), making kidney sparing absolutely essential in retroperitoneal cases. 1, 2 Advanced techniques including IMRT, tomotherapy, or proton therapy should be utilized to maintain kidney doses below tolerance thresholds 2