Donald H. Baxter

Noninvasive evaluation of mediastinal metastases in bronchogenic carcinoma: A prospective comparison of chest radiography and gallium‐67 scanning

Evaluation of regional node involvement in patients with bronchogenic carcinoma is a crucial step in determining therapy and prognosis. Mediastinoscopy has been recommended for staging all potentially operable cases, but technical limitations and the need for anesthesia make this impractical. Gallium‐67 scanning and chest radiography were prospectively compared as noninvasive means of evaluating spread to regional nodes in 75 patients with bronchogenic carcinoma in whom histologic evaluation of hilar and mediastinal nodes was performed. Gallium scanning was more accurate than chest radiography in assessing regional nodes (overall accuracy 85.3% vs. 56%, P < 0.05). When positive, both procedures correctly indicate malignant involvement of regional nodes (85% vs. 87.3%). A negative gallium scan, however, was significantly more accurate in predicting the absence of such involvement (80% vs. 40%, P < 0.01). Gallium scanning appears to be a reliable, noninvasive means of assessing mediastinal spread of bronchogenic carcinoma and when used in conjunction with radiographic findings, allows selection of appropriate patients for surgical staging procedures.

Regional immunotherapy has a detrimental effect on the response to combined irradiation and chemotherapy in locally advanced non-small cell bronchogenic carcinoma

SummaryTwenty-one patients with stage III M0 non-oat cell bronchogenic carcinoma confined to the thorax were randomized to receive either intrapleural BCG (107 cfu, Tice strain) or intrapleural saline 3 weeks prior to beginning combined irradiation and chemotherapy. Radiation to the primary tumor and regional nodes was given at a dose of 3,000 rad in ten sessions and was followed in 7–14 days by CAMP chemotherapy (cyclophosphamide, adriamycin, methotrexate, and procarbazine) for a planned duration of 6 months. Isoniazid, 300 mg/day, was given to all patients for 3 months starting 1 week after intrapleural therapy. There were no significant differences in pretreatment prognostic factors or in response to radiation therapy. The patients receiving intrapleural BCG in addition to radiation and chemotherapy had a median survival of 18 weeks, significantly shorter than that for the patients receiving intrapleural saline (54 weeks, P=0.017).

Thin lead sheets as tissue compensators for larger field irradiation

Abstract This paper describes the use of a thin lead sheet as a tissue compensating filter when a large field that includes the supraclavicular and mediastinal regions is irradiated. The typical midplane depths between supraclavicular and mediastinal regions may vary between 6 to 12 cm. Flattening of the beam entry surface is necessary for dose uniformity; this is achieved with a thin lead sheet compensating filter on the shadow tray of a 4 MV Unit. The shadow tray also contains lead shielding blocks for lung, cervical spinal cord, and larynx. The advantages of using thin lead sheets include easy maneuverability of shaping and sizing for irregular fields, and the small dimensions that are needed. Dose uniformity is verified by measuring optical densities from the film that is taken with the actual tray containing this compensating filter. This compensating filter may be extended to many situations where there are marked dose variations between different locations within the same large radiation field. The electron contamination produced by the scattering medium being placed in the beam is less for lead than for aluminum and wax. This contamination is also insignificant when the scatterer is more than 20 cm. away from the patients skin surface when Cobalt-60 and 4 NIV units are used.