Dose-intensive thoracic radiation therapy for patients at high risk with early-stage non-small-cell lung cancer.

Recent studies suggest that radiation therapy (RT) dose escalation in early-stage non-small-cell lung cancer (NSCLC) is feasible when 3-dimensional therapy is used. However, the accompanying prolongation of the treatment course when standard fractionation is used could be suboptimal from a practical and biologic standpoint. We report results of a compressed course of RT for patients with pathologically documented clinical stage 1 NSCLC who were unsuitable for curative surgery because of pulmonary dysfunction or other medical comorbidities. Thirty-one lesions were treated with dose-intensive RT (eg, fraction>or=2.25 Gy and nominal total dose>or=60 Gy) and have been followed up for >or=6 months from the completion of treatment. All patients completed therapy without interruption. Three patients developed grade 3 pulmonary toxicity 1-3 months after therapy. The overall tumor response rate was 88% (35% complete response and 53% partial response), whereas in-field tumor progression was documented for 5 of 31 lesions. Actuarial median survival was 38 months and 3-year overall survival was 60%, and most deaths were secondary to intercurrent disease. Moderately accelerated single daily fractionated RT is feasible for high-risk patients with early-stage NSCLC and merits further investigation.

On the use of C-arm fluoroscopy for treatment planning in high dose rate brachytherapy.

Treatment planning for brachytherapy requires the acquisition of geometrical information of the implant applicator and the patient anatomy. This is typically done using a simulator or a computed tomography scanner. In this study, we present a different method by which orthogonal images from a C-arm fluoroscopic machine is used for high dose rate brachytherapy treatment planning. A typical C-arm is not isocentric, and it does not have the mechanical accuracy of a simulator. One solution is to place a reconstruction box with fiducial markers around the patient. However, with the limited clearance of the C-arm this method is very cumbersome to use, and is not suitable for all patients and implant sites. A different approach is adopted in our study. First, the C-arm movements are limited to three directions only between the two orthogonal images: the C-orbital rotation, the vertical column, and the horizontal arm directions. The amounts of the two linear movements and the geometric parameters of the C-arm orbit are used to calculate the location of the crossing point of the two beams and thus the magnification factors of the two images. Second, the fluoroscopic images from the C-arm workstation are transferred in DICOM format to the planning computer through a local area network. Distortions in the fluoroscopic images, with its major component the "pincushion" effect, are numerically removed using a software program developed in house, which employs a seven-parameter polynomial filter. The overall reconstruction accuracy using this method is found to be 2 mm. This filmless process reduces the overall time needed for treatment planning, and greatly improves the workflow for high dose rate brachytherapy procedures. Since its commissioning nearly three years ago, this system has been used extensively at our institution for endobronchial, intracavitary, and interstitial brachytherapy planning with satisfactory results.