Dose Constraints in Stereotactic Body Radiation Therapy (SBRT)

Lung Parenchyma Constraints

The American College of Radiology recommends maintaining a mean lung dose (MLD) of ≤8 Gy and lung V20 <10-15% to keep symptomatic radiation pneumonitis below 10-15% for patients with lung tumors 1
For patients with lung tumors, the National Comprehensive Cancer Network suggests keeping V20 (lung volume receiving ≥20 Gy) <10-15% to minimize radiation-induced lung toxicity 1

The American Society for Radiation Oncology recommends that the chest wall volume receiving ≥30 Gy should be <30 cm³ to keep fracture risk below 30% for patients undergoing SBRT 3
For patients undergoing SBRT, the National Comprehensive Cancer Network suggests maintaining a maximum dose to 2 cm³ of any individual rib (D2cc) <27 Gy for 3-fraction regimens, corresponding to approximately 5% fracture risk 3

The American College of Radiology recommends using 50 Gy in 5 fractions for central lung tumors, rather than higher dose-per-fraction regimens that caused lethal toxicity 1, 2
For patients with central lung tumors, the National Comprehensive Cancer Network suggests avoiding SBRT entirely for ultracentral tumors where the PTV overlaps trachea or main bronchi due to unacceptable toxicity risk 1, 2

The American Society for Radiation Oncology recommends using one of the following fractionation schemes to achieve BED ≥50 Gy for approximately 90% local control at 1 year: 16-24 Gy in 1 fraction, 24 Gy in 2 fractions, 24-27 Gy in 3 fractions, or 30-35 Gy in 5 fractions 1
For patients with renal cell carcinoma spinal metastases, the National Comprehensive Cancer Network suggests using 24 Gy in a single fraction to achieve 90% 1-year local control 1

The American College of Radiology recommends keeping the esophagus 5 cc dose <12 Gy for the SBRT component when combining conventional radiotherapy with SBRT boost 1
For patients undergoing conventional concurrent chemoradiotherapy, the National Comprehensive Cancer Network suggests keeping cumulative esophagus dose <10% receiving >50 Gy 2
The American Society for Radiation Oncology recommends keeping spinal cord cumulative dose <33 Gy 1

The National Comprehensive Cancer Network suggests never using conventional low-dose palliative radiation (8 Gy in 1 fraction) for patients with longer expected survival, as this achieves less than 50% 1-year local control for bulky tumors and increases risk of spinal cord compression 1
For patients with central lung tumors, the American College of Radiology recommends avoiding 60-66 Gy in 3 fractions, as this regimen caused lethal toxicity in early studies 1, 2
The American Society for Radiation Oncology recommends ensuring BED10 reaches at least 100 Gy for lung SBRT to optimize outcomes 1, 2

The American Association of Physicists in Medicine recommends using advanced dose calculation algorithms (type B) for thoracic SBRT, as they account for tissue heterogeneity and provide accurate dose distributions 4
The National Comprehensive Cancer Network suggests using planning organ at risk volumes (PRV) with appropriate margins around critical serial organs, especially for centrally located tumors 4, 2