Table 2. The RILI grade in CTCAE-5.0.

Adverse event	Grade 1	Grade 2	Grade 3	Grade 4	Grade 5
Pneumonitis (definition: a disorder characterized by inflammation focally or diffusely affecting the lung parenchyma)	Asymptomatic; clinical or diagnostic observations only; intervention not indicated	Symptomatic; medical intervention indicated; limiting instrumental ADL	Severe symptoms; limiting self-care ADL; oxygen indicated	Life-threatening respiratory compromise; urgent intervention indicated (e.g., tracheotomy or intubation)	Death
Pulmonary fibrosis (definition: a disorder characterized by the replacement of the lung tissue by connective tissue, leading to progressive dyspnea, respiratory failure, or right heart failure)	Radiologic pulmonary fibrosis <25% of lung volume associated hypoxia	Evidence of pulmonary hypertension; radiographic pulmonary fibrosis 25–50% associated with hypoxia	Severe hypoxia; evidence of right-sided heart failure; radiographic pulmonary fibrosis >50–75%	Life-threatening consequences (e.g., hemodynamic/pulmonary complication); intubation with ventilatory support indicated; radiographic pulmonary fibrosis >75% with severe honeycombing	Death

RILI, radiation-induced lung injury; ADL, activities of daily living.