Abstract/Text: Stereotactic body radiation therapy (SBRT) is a new radiotherapy treatment method that has been applied to the treatment of Stage I lung cancers in medically inoperable patients, with excellent clinical results. SBRT allows the delivery of a very high radiation dose to the target volume, while minimizing the dose to the adjacent normal tissues. As a consequence, CT findings after SBRT have different appearance, geographic extent and progression timeline compared to those following conventional radiation therapy for lung cancer. In particular, SBRT-induced changes are limited to the "shell" of normal tissue outside the tumor and have a complex shape. When SBRT-induced CT changes have a consolidation/mass-like appearance, the differentiation from tumor recurrence can be very difficult. An understanding of SBRT technique as it relates to the development of SBRT-induced lung injury and familiarity with the full spectrum of CT manifestations are important to facilitate diagnosis and management of lung cancer patients treated with this newly emerging radiotherapy method.

Copyright © 2009 Elsevier Ireland Ltd. All rights reserved.

Abstract/Text: Radiation-induced lung disease (RILD) due to radiation therapy is common. Radiologic manifestations are usually confined to the lung tissue within the radiation port and are dependent on the interval after completion of treatment. In the acute phase, RILD typically manifests as ground-glass opacity or attenuation or as consolidation; in the late phase, it typically manifests as traction bronchiectasis, volume loss, and scarring. However, the use of oblique beam angles and the development of newer irradiation techniques such as three-dimensional conformal radiation therapy can result in an unusual distribution of these findings. Awareness of the atypical manifestations of RILD can be useful in preventing confusion with infection, recurrent malignancy, lymphangitic carcinomatosis, and radiation-induced tumors. In addition, knowledge of radiologic findings that are outside the expected pattern for RILD can be useful in diagnosis of infection or recurrent malignancy. Such findings include the late appearance or enlargement of a pleural effusion; development of consolidation, a mass, or cavitation; and occlusion of bronchi within an area of radiation-induced fibrosis. A comprehensive understanding of the full spectrum of these manifestations is important to facilitate diagnosis and management in cancer patients treated with radiation therapy.

Copyright RSNA, 2004

Abstract/Text: PURPOSE: To evaluate the toxicity and efficacy of thoracic stereotactic body radiotherapy (SBRT) in patients with subclinical interstitial lung disease (ILD).
METHODS AND MATERIALS: One hundred patients with 124 lung tumors were treated with SBRT at our institution according to our own protocols; patients with subclinical (untreated and oxygen-free) ILD were treated with SBRT, while those with clinical ILD (post- or under treatment) were not. The administration of 48 Gy in four fractions was used in 103 (83%) of the 124 tumors. The presence of subclinical ILD in the pre-SBRT CT findings was reviewed by two chest radiologists. The relationships between radiation pneumonitis (RP) and clinical factors were investigated.
RESULTS: Subclinical ILD was recognized in 16 (16%) of 100 patients. Grade 2-5 RP was recognized in 13 (13%) of 100 patients. Grade 2-5 RP was observed in three (19%) of 16 patients with subclinical ILD. Subclinical ILD was not found to be a significant factor influencing Grade 2-5 RP; however, extensive RP beyond the irradiated field, including the contralateral lung, was recognized in only three patients with subclinical ILD, and the rate of extensive RP was significantly high in the patients with subclinical ILD. Grade 4 or 5 extensive RP was recognized in only two patients with subclinical ILD. Dosimetric factors of the lungs (V5, V10, V15, V20, V25, MLD) were significantly associated with Grade 2-5 RP. The three-year overall survival and local control rates of all patients were 53% and 86%, respectively. No significant differences were seen in either overall survival or local control rates between the patients with ILD and those without ILD.
CONCLUSIONS: Subclinical ILD was not found to be a significant factor for Grade 2-5 RP or clinical outcomes in the current study; however, uncommon extensive RP can occur in patients with subclinical ILD.

Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.