A flexible bronchoscopy should be performed in the beginning to evaluate the location and the character of the endobronchial lesion, such as the anatomic site and the location of the lesion in reference to a fixed landmark (carina), the length of the lesion, and the degree of the airway obstruction. Speiser and his colleagues proposed scoring criteria for the degree and location of the airway obstruction as displayed in Table 36.2. This information should be recorded for dose prescription purposes.

An adequate passage should be visible through the endobronchial lesion to pass the catheter. If the lesion is occluding the lumen, a passage should be created first by using mechanical debridement, laser, or electrocautery. This procedure should be done in a separate session prior to the brachytherapy treatment.

In patients with early stage central lung malignancy, an adequate assessment with EBUS prior to EBB should be conducted for adequate staging. Lesions with cartilage invasion should be treated as stage IA and should undergo surgical evaluation. Lesions without cartilage involvement will be appropriate for any form of local therapy such as EBB, laser, or electrocautery therapy or mechanical removal.

A flexible polyethylene catheter is usually inserted into the airway by using a flexible bronchoscopy with adequate channel size for the catheter delivery. A transnasal approach is used when performing the bronchoscopy (Fig. 36.1). The majority of the cases can be done under conscious sedation, but general anesthesia may be needed in special circumstances. The distal end of the catheter is placed at the site of the endobronchial lesion, and it should be about 2 cm beyond the distal end of the lesion (Figs. 36.2 and 36.3). In the alternative, the catheter may also be placed by wedging the tip of the catheter into a segmental bronchus. This technique helps in minimizing any catheter displacement. It is important to note that the catheter should not be forced when resistance is felt. The bronchoscopy and the guidewire should be removed gently and the catheter marked at the site of its exit from the nostril and secured into position with adhesive tape. The position is verified with fluoroscopy and CXR. A second and third catheter may be placed in similar fashion to more fully surround the tumor.

Nonradioactive (“dummy”) sources are introduced into the catheter to the level of the bronchial obstruction. Radiographic verification is performed to geographically define the eventual position of the radioactive source. Different prescription points (i.e., total dose and number of fractions) have been used. In practice, prescription depths of 0.5–2 cm have been used by numerous investigators. The American Brachytherapy Society suggested two methods:

The treatment margin should include 1–2 cm at the proximal and distal end of the endobronchial lesion. With advanced technologies, three-dimensional brachytherapy treatment planning may provide more effective and accurate targeting of the tissue.

The patient should be taken to the Department of Radiation Oncology for manual or remote loading of the radioactive source. Once the catheter is connected to the treatment unit, a calculated dose is delivered. After completing the treatment session, the catheter is disconnected from the treatment unit and removed (Fig. 36.4). Then, the patient may be discharged home with specific instructions to contact the treating physician if acute dyspnea, cough, or hemoptysis occurs. The American Brachytherapy Society suggests grading the bronchoscopic response to the treatment as excellent, good, fair, and poor.