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Table 1 Normal tissue dose tolerance limits for 4-fraction stereotactic body radiation therapy

From: Dosimetric feasibility of stereotactic body radiation therapy as an alternative to brachytherapy for definitive treatment of medically inoperable early stage endometrial cancer

Site 4-fraction SBRT Data point Reference Reference limit Reference BED (α/β = 10) Current BED (α/β = 10)
Volume Threshold dose (Gy) per fx
Bladder        
  <1 cc 8.93 1 cc RTOG 0938 <105% Rx 67 67.6
  <2 cc 4.60 2 cc Institutional* 4.8 Gy × 4 -- --
  <15 cc 4.50 15 cc TG-101 5.6 Gy × 3 26.2 26.1
  90% 7.65 D10% RTOG 0938 <90% Rx 53.9 54.0
  50% 4.25 D50% RTOG 0938 <50% Rx 24.7 24.2
Rectum        
  <1 cc 8.93 1 cc RTOG 0938 <105% Rx 67 67.6
  <2 cc 4.60 2 cc Institutional* 4.8 Gy × 4 -- --
  <3 cc 8.08 3 cc RTOG 0938 <95% Rx 58.1 58.4
  <20 cc 6.50 20 cc TG-101 8 Gy × 3 43.2 42.9
  90% 7.65 D10% RTOG 0938 <90% Rx 53.9 54.0
  80% 6.80 D20% RTOG 0938 <80% Rx 45.8 45.7
  50% 4.25 D50% RTOG 0938 <50% Rx 24.7 24.2
Sigmoid colon        
  <2 cc 4.80 2 cc Institutional* 4.8 Gy × 4 -- --
  <20 cc 6.50 20 cc TG-101 8 Gy × 3 43.2 42.9
Other bowel        
Small bowel <5 cc 4.75 5 cc TG-101 5.9 Gy × 3 28.1 28.0
Large bowel <20 cc 6.50 20 cc TG-101 8 Gy × 3 43.2 42.9
Femoral Heads        
  Point 6.89 Max RTOG 0938 <81% Rx 46.6 46.5
  <10 cc 4.59 10 cc RTOG 0938 <54% Rx 27.2 26.8
  1. These are proposed guidelines that were used as constraints in the current study. References for each parameter are listed.
  2. * In accordance with our institutional per-fraction brachytherapy policy.
  3. Abbreviations: SBRT stereotactic body radiation therapy, fx fraction, BED biological effective dose, Rx prescription dose, D(x)% dose to x percent of the volume, RTOG Radiation Therapy Oncology Group, TG-101 stereotactic body radiation therapy Task Group 101.