[Normal tissue tolerance to external beam radiation therapy: lung]

Area of Science:

• Pulmonary Medicine
• Radiation Oncology
• Medical Physics

Context:

• Radiation pneumonitis is a primary dose-limiting toxicity in thoracic radiation therapy.
• It manifests clinically with symptoms like dyspnea and cough, and radiographically with opacifications within the radiation field.
• Understanding its predictors is crucial for optimizing radiation treatment planning and patient care.

Purpose:

• To review and synthesize the known predictive factors for radiation pneumonitis.
• To evaluate the efficacy of various dosimetric parameters, specifically dose-volume histogram (DVH) metrics, in predicting radiation pneumonitis risk.
• To assess the suitability of these parameters for routine clinical practice.

Summary:

• Radiation pneumonitis risk is influenced by cumulative radiation dose to normal lung tissue, patient-specific factors (e.g., pre-existing lung dysfunction, tumor location), and concurrent chemotherapy.
• While mean lung dose, V20, and V30 are commonly studied dosimetric parameters, no single parameter has proven ideal for predicting radiation pneumonitis.
• This review consolidates current knowledge on predictive factors and the clinical utility of DVH parameters.

Impact:

• Improved identification of patients at high risk for radiation pneumonitis.
• Potential for refinement of radiation treatment planning to minimize lung toxicity.
• Enhanced clinical decision-making regarding radiation dose and fractionation for thoracic malignancies.