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SBRT planning - Coggle Diagram
SBRT planning
RTOG 0813 and RTOG 0915 and RTOG 0236
- below the Lower Bound, constraints are met
- between LB and Upper Bound, minor violation~
Heterogeneity
- Rx IDL must be between 60%-90% dose at center of PTV
High Dose Spillage
Volume outside the PTV receiving >105% Rx dose should not exceed 15% of PTV volume
- Ratio of Volume of Rx IDL to PTV < 1.2
:pencil2: doesnt apply to v small tumors (<2.5 cm axial, <1.5 CC)
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Low Dose Spillage
R50%
- ratio of volume of 50% Rx isodose volume to PTV
- must be lower than a table given value [2.9-5.9]
D2cm
- max dose to any point >2cm outside the PTV.
- must meet constraints provided by table. [50 Gy for small tumors- 77 Gy for large]
- can turn on a PTV + 2cm and a 50% IDL and check to see if there's overlap
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- center mass of PTV
- usually the isocenter, but not always
Rx coverage
- 95% PTV receives 100% of Rx (V100% = 95%)
- 99% PTV receives 90% or more (V90% = 99%)
Dose Constraints 0915 (single fraction)
- Spinal cord: Max point dose of 14 Gy; V10 < 0.35 cc, V7 < 1.2 cc
- Esophagus: Max point dose of 15.4 Gy; V11.9 < 5 cc
- Brachial plexus: Max point dose of 17.5 Gy; V14 < 3 cc
- Heart/pericardium: Max point dose of 22 Gy; V16 < 15 cc
- Great vessels: Max point dose of 37 Gy; V31 < 10 cc
- Trachea/proximal bronchial tree: Max point dose of 20.2 Gy; V10.5 < 4 cc
- Ribs/chest wall: Max point dose 30 Gy; V22 < 1 cc
- Skin: Max point dose of 26 Gy; V23 < 10 cc
- Lungs: V7 < 1500 cc, V7.4 < 1000 cc
RTOG 0813 Dose Constraints for Five Fractions (10 Gy x 5)
- Heart:
- <15 cc receives ≥32 Gy (6.4 Gy/fraction).
- Maximum point dose: ≤52.5 Gy.
- Trachea/Ipsilateral Bronchus (Non-adjacent Wall):
- <4 cc receives ≥18 Gy (3.6 Gy/fraction).
- Maximum point dose: ≤52.5 Gy.
- Great Vessels (Non-adjacent Wall):
- <10 cc receives >47 Gy (9.4 Gy/fraction).
- Maximum point dose: ≤52.5 Gy.
- Ipsilateral Brachial Plexus:
- <3 cc receives ≥30 Gy (6 Gy/fraction).
- Maximum point dose: ≤32 Gy (6.4 Gy/fraction).
- Spinal Cord:
- <0.25 cc receives ≥22.5 Gy (4.5 Gy/fraction).
- <0.5 cc receives ≥13.5 Gy (2.7 Gy/fraction).
- Maximum point dose: ≤30 Gy (6 Gy/fraction).
- Esophagus:
- <5 cc receives ≥27.5 Gy (5.5 Gy/fraction).
- Maximum point dose: ≤52.5 Gy.
- Whole Lung Minus GTV:
- <1500 cc receives ≥12.5 Gy (2.5 Gy/fraction).
- <1000 cc receives ≥13.5 Gy (2.7 Gy/fraction).
- Skin:
- <10 cc receives ≥30 Gy (6 Gy/fraction).
- Maximum point dose: ≤32 Gy (6.4 Gy/fraction).
Coverage
Prescription isodose line should be chosen so that:
95% of PTV is covered by Rx dose
99% of PTV receives 90% of Rx dose
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