ABSTRACT
Thirty consecutive breast cancer patients receiving tangential field radiation therapy underwent clinical examination followed by high resolution CT [HRCT] aiming to evaluate the accuracy of HRCT in diagnosis of radiation-induced parenchymal lung diseases. Thin section 1-mm HRCT images were obtained at identical levels at a 250 - mm filed of view, 120 KV and 200 mA settings. HRCT was performed during 4-12 weeks and 12 months after the completion of radiotherapy. Pathological changes were detected in 10 out of 30 examined patients [33%]. Acute radiation-induced parenchymal lung diseases were detected in 7 [23%] patients. Out of those 7 patients 4 [13%] patients showed ground glass opacity appeared in a period ranged from 4-10 weeks after radiation therapy. Minimal alveolar filling [minimal acinar nodules], septal thickening and parenchymal consolidation each was detected in one patient [3%] for each HRCT pathological pattern. Chronic radiation-induced parenchymal lung diseases were detected in 4 [13%] patients, axial interstitial thickening with fibrotic bands were detected in 2 [6%] patients. Cylindrical brocnh-ciatesis was detected in one patient [3%], it involves peripheral bronchi and associated with bronchial wall thickening. In another one patient [3%] and non septal subpleuaral linear opacity is observed. All above HRCT changes were detected in the territory of the beam boundaries. The study concluded that HRCT yield good quality images of subtle radiation induced injuries. The use of tangential fields limits radiological changes that can be detected only by HRCT examination and may not associated with clinical symptoms