Air Cavity Effects on the Absorbed Dose for 4-, 6- and 10-MV X-ray Beams: Larynx Model / 대한치료방사선과학회지

PURPOSE: When an x-ray beam of small field size is irradiated to target area containing an air cavity, such as larynx, the underdosing effect is observed in the region near the interfaces of air and soft tissue. With a larynx model, air cavity embedded in tissue-equivalent material, this study is intended for examining parameters, such as beam quality, field size, and cavity size, to affect the dose distribution near the air cavity. MATERIALS AND METHODS: Three x-ray beams, 4-, 6- and 10-MV, were employed to perform a measurement using a 2cm (width)xL (length in cm, one side of x-ray field used)x2cm (height) air cavity in the simulated larynx. A thin window parallel-plate chamber connected to an electrometer was used for a dosimetry system. A ratio of the dose at various distances from the cavity-tissue interface to the dose at the same points in a homogeneous phantom (observed/expected ratio, O/E), normalized buildup curves, and ratio of distal surface dose to dose at the maximum buildup depth were examined for various field sizes. Measurement for cavity size effect was performed by varying the height (Z) of the air cavity with the width kept constant for several field sizes. RESULTS: No underdosing effect for 4-MV beam for fields larger than 5cmx5cm was found. For both 6- and 10-MV beams, the underdosing portion of the larynx at the distal surface was seen to occur for small fields, 4cmx4cm and 5cmx5cm. The underdosed tissue was increased in its volume with beam energy even for similar surface doses. The relative distal surface dose to maximum dose was changed to 0.99 from 0.95, 0.92, and 0.91 for 4-, 6-, and 10-MV, respectively, with increasing field size, 4cmx4cm to 8cmx8cm. For 6- and 10-MV beams, the dose at the surface of the cavity ismeasured less than the predicted by about two and three percent, respectively, but decrease was found for 4-MV beam for 5cmx5cm field. For the 4cm x L x Z (height in cm), varying depth from 0.6 to 4.8cm, cavity, O/E > 1.0 was observed regardless of the cavity size for any field larger than about 8cmx8cm. CONCLUSION: The magnitude of underdosing depends on beam energy, field size, and cavity size for the larynx model. Based on the result of the study, caution must be used when a small field of a high quality x-ray beam is irradiated to regions including air cavities, and especially the region where the tumor extends to the surface. Low quality beam, such as, 4-MV x-ray, and larger fields can be used preferably to reduce the risk of underdosing, local failure. In the case of high quality beams such as 6- and 10-MV x-rays, however, an additional boost field is recommended to add for the compensation of the underdosing region when a typically used treatment field, 5cmx5cm, is employed.

Balloon dilatation for bronchial stenosis in Endobronchial Tuberculosis / 결핵

BACKGROUND: To evaluate the effect of the balloon dilatation in tuberculous bronchial stenosis, we performed balloon dilatation in 13 cases which had airway obstruction in main bronchus with the impairment of pulmonary function. MATERIAL AND METHODS: Thirteen women with tuberculous bronchial stenosis(9cases: left main bronchus, 4 cases: right main bronchus) underwent fluoroscopically guided balloon dilatation under the local anesthesia. Among the these patient, 9 cases were active endobronchial tuberculosis, and 4 cases were inactive. Immediate and long term follow-up(average 15.6months) assessments were done focused on change on PFT. The increase of FVC or FEV1 more than 15% after the procedure was considered effective. Complications after dilatation were evaluated in all patients. RESULT: 1) There were an decrease of self-audible wheezing in 75%(6/8), improvement of dyspnea in 62.5%(5/8), improvement of cough and expectoration in 50%(3/6), and improvement of chest discomfort in 50%(l/2). 2) Significant improvement of PFT was noted in 42.9%(3/7) of which respiratory symptoms duration was below 6 months. But, significant improvement of PFT was noted in only 25% (1/4) of which respiratory symptoms duration was above 12 months. 3) Active stage was 69.2%(9/13) and inactive was 30.8%(4/13). There was an significant improvement of PFT in 44.4%(4/9) of active stage, but, only 25%(l/4) of inactive stage was improved. 4) In 61.5%(8/13), FVC and FEV1 were increased to 35.5%, and 22.2% at post-dilatation 7 days. After 1 month later, FVC and FEV1 were increased to 54.7%, and 31.8% in 5 cases(38.5%). 4 cases in which long-term follow-up(average 19.8months) was possible the improvement of FVC, and FEV1 were 30.5%, and 10.1%. . 5) Just after balloon dilatation therapy, transient leukocytosis or fever was noted in 30.8%(4/13), and blood-tinged sputum was noted in 30.8%(4/13). However, serious complication, such as pneumothorax, pneumomediastinum or mediastinitis, was not noted. CONCLUSION: We conclude that tuberculous bronchial stenosis, which is on active stage, and short dulation of respiratory symptoms was more effective on balloon dilatation than inactive stage or long duration of respiratory symptoms. Furthermore, balloon dilatation is easier, much less invasive and expensive than open surgery, and cryotherapy or photoresection. Because of these advantage, we think that balloon dilatation could be the first choice for treating bronchial stenosis and could be done at first in early stage if unresponsiveness with steroid therapy is observed.

Balloon dilatation for bronchial stenosis in Endobronchial Tuberculosis / 결핵

BACKGROUND: To evaluate the effect of the balloon dilatation in tuberculous bronchial stenosis, we performed balloon dilatation in 13 cases which had airway obstruction in main bronchus with the impairment of pulmonary function. MATERIAL AND METHODS: Thirteen women with tuberculous bronchial stenosis(9cases: left main bronchus, 4 cases: right main bronchus) underwent fluoroscopically guided balloon dilatation under the local anesthesia. Among the these patient, 9 cases were active endobronchial tuberculosis, and 4 cases were inactive. Immediate and long term follow-up(average 15.6months) assessments were done focused on change on PFT. The increase of FVC or FEV1 more than 15% after the procedure was considered effective. Complications after dilatation were evaluated in all patients. RESULT: 1) There were an decrease of self-audible wheezing in 75%(6/8), improvement of dyspnea in 62.5%(5/8), improvement of cough and expectoration in 50%(3/6), and improvement of chest discomfort in 50%(l/2). 2) Significant improvement of PFT was noted in 42.9%(3/7) of which respiratory symptoms duration was below 6 months. But, significant improvement of PFT was noted in only 25% (1/4) of which respiratory symptoms duration was above 12 months. 3) Active stage was 69.2%(9/13) and inactive was 30.8%(4/13). There was an significant improvement of PFT in 44.4%(4/9) of active stage, but, only 25%(l/4) of inactive stage was improved. 4) In 61.5%(8/13), FVC and FEV1 were increased to 35.5%, and 22.2% at post-dilatation 7 days. After 1 month later, FVC and FEV1 were increased to 54.7%, and 31.8% in 5 cases(38.5%). 4 cases in which long-term follow-up(average 19.8months) was possible the improvement of FVC, and FEV1 were 30.5%, and 10.1%. . 5) Just after balloon dilatation therapy, transient leukocytosis or fever was noted in 30.8%(4/13), and blood-tinged sputum was noted in 30.8%(4/13). However, serious complication, such as pneumothorax, pneumomediastinum or mediastinitis, was not noted. CONCLUSION: We conclude that tuberculous bronchial stenosis, which is on active stage, and short dulation of respiratory symptoms was more effective on balloon dilatation than inactive stage or long duration of respiratory symptoms. Furthermore, balloon dilatation is easier, much less invasive and expensive than open surgery, and cryotherapy or photoresection. Because of these advantage, we think that balloon dilatation could be the first choice for treating bronchial stenosis and could be done at first in early stage if unresponsiveness with steroid therapy is observed.

A case report of the Pulmonary Malignant Lymphomaof the mucosa-associated lymphoid tissue(MALT) / 결핵

The pulmonary lymphomas were thought to originate in specialized lymphoid tissue that is associated with bronchial mucosa(bronchus-associated lymphoid tissue(BALT)), and they were categorized as mucosa-associated lymphoid tissue(MALT) lymphoma. MALT lymphoma consists of a monoclonal population of cell, in contrast to reactive lymphoid proliferation, which consists of polyclonal cells. Lymphoma arising from MALT(=MALToma) represents a distinct clinicopathologic features. It is usually localized to their original site for a long time and shows much more favorable prognosis than lymphoma at other site. Some MALT lymphoma could arise simultaneously or successively in different organ or that cells from MALT lymphoma might circulate and give rise to another lymphoma by homing in the MALT of another organ, such as breast, salivary gland, stomach etc, and can be multifocally disseminated or recurred. We report a case of low-grade B-cell lymphoma of the mucosa-associated lymphoid tissue(MALT) of the lung, which was confirmed by open lung biopsy, immunohistochemistry and PCR assay.