Radiation-induced lung injury using a pig model. Evaluation by high-resolution computed tomography.

RATIONALE AND OBJECTIVES: To assess the early phase of radiation-induced lung injury using high-resolution computed tomography (CT) under experimental conditions and to perform precise CT-pathologic correlation. METHODS: Five Yorkshire pigs received a single dose of 12.5 Gy to the right lower lung. Computed tomographic images were obtained at 2-week intervals. The animals were killed after follow-up periods of 4-16 weeks. The lungs were removed, inflated, fixed, dried, and sliced corresponding to the CT sections. Computed tomography, specimen radiography, and histologic findings were correlated. RESULTS: Various CT findings were observed during the first 16 weeks, including ground-glass opacity, discrete consolidation, patchy consolidation, thickened interlobular septum, and bronchovascular bundle. Ground-glass opacity was associated with thickened alveolar wall and scattered tiny fibrotic foci. Thickened interlobular septum and bronchovascular bundle were the results of fibrosis adjacent to these structures. Discrete consolidation correlated with intraalveolar edema with hemorrhage and infiltration of inflammatory cells. CONCLUSIONS: High-resolution CT correlated well with pathology of the lung due to radiation injury as verified by precise radiologic-pathologic correlation.

Sequential morphologic changes of elastase-induced pulmonary emphysema in pig lungs. Evaluation by high-resolution computed tomography.

The authors evaluated the early morphologic changes of elastase-induced pulmonary emphysema in the pig and correlated the findings with high-resolution computed tomography (HRCT). Nine Yorkshire pigs were included in this investigation; in seven, pulmonary emphysema was induced by 2 mg/kg body weight of elastase instilled selectively into the left lower lobe bronchus. Animals were studied by CT at 0, 1, 2, 3, 7, 14, and 21 days. At the completion of the experiment, the lungs were removed, inflated, fixed and dried, and subsequently sliced corresponding to the CT sections. The gross appearance, histologic appearance, and HRCT were correlated. On HRCT, sequential changes from early edema to development of emphysema were noted. Panlobular, centrilobular and paraseptal emphysema were observed. Elastase-induced pulmonary emphysema in the pig is a useful and reproducible animal model, and high-resolution computed tomography depicts the morphologic changes observed both by gross pathologic observations and histologic observations.

Intralobular distribution of oleic acid-induced pulmonary edema in the pig. Evaluation by high-resolution CT.

The objective of this study was to elucidate the features of experimentally induced pulmonary edema at the lobular level, using high-resolution CT (HRCT) with pathological correlation. We selected the pig as the experimental animal because the pig has well-defined pulmonary lobules. Twelve Yorkshire pigs were included in this study. Five animals were used for studying normal anatomy of the pig lung. Pulmonary edema was induced by oleic acid infusion in 7 pigs. All computed tomographic (CT) scans were performed on a GE 9800 scanner, using 1.5 mm slice-thickness, 16 cm field of view with 512 X 512 matrix and bone reconstruction algorithm. The animals were killed after CT scans and the lungs were removed, inflated, fixed and dried, and subsequently sliced in sections which corresponded to the CT sections. Using CT images, specimen radiography, and histology, we studied the intralobular distribution of pulmonary edema in selected lobules of each animal. Oleic acid infusion caused multifocal hemorrhagic pulmonary edema within the pulmonary lobule. The distribution was uneven and areas surrounding the lobular bronchi were less involved. HRCT permits evaluation of morphological changes of oleic acid-induced pulmonary edema at the lobular level. The intralobular distribution of the lesions may provide additional information about the mechanism of permeability pulmonary edema.

Anatomic reconstruction and functional rehabilitation of oromandibular defects with rigid internal fixation.

Fifteen consecutive patients undergoing extensive surgery for head and neck cancer involving the oral cavity and oropharynx were reconstructed using the technique of rigid internal fixation combined with various vascularized flaps. The follow-up ranged from 6 to 18 months. Modifications in various myocutaneous or vascularized free flaps combined with an analysis of the radiation physics necessary to make this procedure a viable alternative for immediate and delayed mandibular reconstruction will be discussed. Consistently satisfactory functional and cosmetic results have been achieved.

Teletherapy beam characteristics: the first second.

The beam characteristics of radiotherapy treatment units are measured and recorded under circumstances in which transient effects are eliminated. Output measurements are done by averaging several readings. Isodose curves are obtained during a period of irradiation which is large compared with that used in patient treatment. When treatments are given, the therapy unit is assumed to deliver radiation beams that match the data acquired during calibration. We have looked at the energy, field uniformity, and output constancy typical of a number of these machines in their initial stages of operation. Although most can provide their "reference" beam characteristics in a short time, there are exceptions. The implications for patient treatment, port filming, and film dosimetry are discussed.