HRCT of the chest is the ideal modality for evaluating Interstitial lung disease. HRCT can demonstrate morphologic feature of both normal and abnormal lung parenchyma and interstitium. So this provides more information than chest radiographs and conventional chest CT. Indications of HRCT includes: 1. Screening patients with repeated pulmonary infection 2. Bronchiectasis 3. Cysticfibrosis 4. Bronchopulmonarydysplasia 5. Severe asthma 6. Bronchiolitis obliterans 7. Interstitial lung disease Ref: Pediatric Chest Imaging: Chest Imaging in Infants and Children By Javier Lucaya, A. L. (FRW) Bae, Janet L. Strife, 2nd Edition, Pages 78, 80; Lung Cancer: A Multidisciplinary Approach By Alison Leary, Pages 28-31; Crofton and Douglas's Respiratory Diseases By Anthony Seaton, Douglas Seaton, A. Gordon Leitch, 2nd Volume, 5th Edition, Page 1026.