Radoncquestions -

| Scenario | Answer | |----------|--------| | | Used for locally advanced (e.g., H&N, cervical, lung). Most effective but most toxic. | | Neoadjuvant (chemo first) | For bulky disease where RT fields would be too large (e.g., anal cancer, rectal cancer – though often both). | | Adjuvant (RT after chemo) | For high-risk features after surgery (e.g., breast, endometrial). |

| Organ | Constraint (Dmax or Vx) | |-------|------------------------| | Spinal cord | ≤45-50 Gy (absolute max) | | Brainstem | ≤54 Gy | | Parotid (mean) | ≤26 Gy (to avoid xerostomia) | | Lung (V20) | ≤30-35% (pneumonitis risk) | | Heart (mean) | ≤26 Gy (breast cancer) | | Small bowel (V15) | ≤120 cc (avoid obstruction/perf) | Pro tip: For SBRT, constraints are stricter (e.g., spinal cord ≤14 Gy in 1 fx). C. Timing & Sequencing with Systemic Therapy Typical Q: "Should we give chemo before, during, or after radiation?" radoncquestions

❌ – a frail patient gets palliative, not definitive, regardless of stage. | Scenario | Answer | |----------|--------| | |

❌ – always ask, always document cumulative dose. | | Adjuvant (RT after chemo) | For

❌ – they have different time courses, management, and implications for fractionation. 6. Quick Reference: Commonly Asked Doses by Site | Disease Site | Regimen (Standard) | |--------------|--------------------| | Breast (whole breast) | 40-50.4 Gy / 15-28 fx | | Prostate | 78 Gy / 39 fx or 36.25 Gy / 5 fx (SBRT) | | Rectal (neoadjuvant) | 50.4 Gy / 28 fx with capecitabine | | Brain mets (WBRT) | 30 Gy / 10 fx or 20 Gy / 5 fx | | Spine met (palliative) | 8 Gy / 1 fx or 20 Gy / 5 fx | | Lung (definitive SBRT) | 48-54 Gy / 3-5 fx | Final tip for rotations/boards: When you don’t know a specific dose or constraint, say: "I don't have that number memorized, but I would look up the QUANTEC or ASTRO guideline for that OAR before prescribing." That answer is always respected.