Radiation-induced pulmonary pneumonitis and fibrosis

Radiation-induced pulmonary pneumonitis and fibrosis

Radiation pneumonitis

Radiation pneumonitis is a type of lung injury. While pneumonia is caused by bacteria or viruses, pneumonitis is caused by an irritant, similar to an allergy. Radiation pneumonitis happens to some people after they’ve received radiation treatments to their lungs or chest area. Between 5 and 15 percent of people receiving radiation treatment for lung cancer develop pneumonitis. However, anyone receiving radiation therapy to the chest can develop it.

While it tends to happen about 4 to 12 weeks after radiation treatment, it can develop as early as 1 week after treatment. In other cases, it develops very slowly over the course of several months.


Radiation pneumonitis is more likely to happen when high doses of radiation are used or a large area of the lung is treated with radiation. Certain chemotherapy drugs, such as bleomycin (Blenoxane), cyclophosphamide (Procytox), and carmustine (BiCNU, BCNU), can also increase the risk of developing radiation pneumonitis if given along with radiation therapy.

Symptoms and signs

You might feel the following symptoms if you have radiation-induced pulmonary-pneumonitis:

  • dyspnoea
  • non-productive cough
  • low-grade fever
  • excessive fatigue/malaise
  • tachycardia
  • pleuritic chest pain (uncommon)
  • occasionally moist crackles
  • a pleural friction rub or evidence of consolidation in the region corresponding to radiation field (uncommon)


The following tests are used to diagnose radiation-induced pulmonary pneumonitis:

  • Full blood count (FBC), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP).
  • Non-contrast CT scan.
  • Correlate CT findings with radiation plan.
  • Consider CT pulmonary angiography(CTPA) if pulmonary thromboembolism is a differential diagnosis

Radiation-Induced Pulmonary Fibrosis

Pulmonary fibrosis (PF) is part of a larger group of more than 200 interstitial lung diseases (also known as ILDs) that are characterized by inflammation and/or scarring in the lung. In ILDs, the injury, and damage occur in the walls of the air sacs of the lung, as well as in the tissue and space around these air sacs. When an interstitial lung disease includes scar tissue in the lung, we call it pulmonary fibrosis.


Radiation to the chest can sometimes injure the lung and cause pulmonary fibrosis. Conditions that are treated with radiation to the chest include lymphoma; Hodgkin’s disease; or breast, lung, and other cancers.


Early in the disease, people with radiation-induced pulmonary fibrosis may not experience symptoms or might have a bothersome cough. As the disease progresses, the following symptoms become evident:

  • breathlessness during exercise and daily activities
  • Fatigue
  • Depression
  • anxiety 


Although changes in the lung are usually confined to the irradiated field, changes in the remainder of the lung may also occasionally be seen.

  • Plain radiograph
  • CT
  • MRI
  • Nuclear Medicine (PET-CT)

General Rating Formula for Interstitial Lung Disease (diagnostic codes 6825 through 6833): 

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