Linac SRS/SRT

Question 1

Linac SRS/SRT: Prescription Doses

Answer 1

Benign disease usually treated in single session (SRS)

Malignant tumors usually treated in multiple fractions (SRT)

SRS:

• 12-25 Gy (single fraction)
• Larger lesions typically receive lower doses
• Recommendations of RTOG 90-05:
  
  • 24 Gy (cone diameter 1-2 cm)
  • 18 Gy (cone diameter 2.25 – 3 cm)
  • 15 Gy (cone diameter 3.25 – 4 cm)

SRT:

• 7 Gy/fraction, 6 fractions, treated every other day
• 4 Gy/fraction, 10 fractions, treated daily

Question 2

SBRT: Applications

Answer 2

• Extracranial sites:
• Lung, liver, spinal tumors

Pancreas, prostate (on the horizon

Question 3

SBRT: Patient Setup and Immobilization

Answer 3

Patient Immobilization - Whole body cast