Double CT imaging can measure the respiratory movement of small pulmonary tumors during stereotactic ablative radiotherapy

Comparing Pulmonary Nodule Location During Electromagnetic Bronchoscopy With Predicted Location on the Basis of Two Virtual Airway Maps at Different Phases of Respiration

BACKGROUND

Electromagnetic navigational bronchoscopy (ENB) is guided bronchoscopy to pulmonary nodules (PN) that relies on a preprocedural chest CT to create a three-dimensional (3D) virtual airway map. The CT is traditionally done at a full inspiratory breath hold (INSP), but the procedure is performed while the patient tidal breaths, when lung volumes are closer to functional residual capacity. Movement of a PN from INSP to expiration (EXP) has been shown to average 17.6 mm. Therefore, the hypothesis of this study is that preprocedural virtual maps built off a CT closer to physiological lung volumes during bronchoscopy may better represent the actual 3D location of a PN.

METHODS

Consecutive patients with a PN needing a histological diagnosis were enrolled. A preprocedure INSP and EXP CT scan were obtained to create two virtual maps. During the airway inspection, the system tracked the sensor probe to collect 3D points that were reconstructed into the lumen registration map. This map is thought to best represent the patient's airways during bronchoscopy. Predicted PN location on an EXP and INSP map was compared with lumen registration.

RESULTS

Twenty consecutive PN underwent ENB. The predicted PN location, compared with lumen registration, was significantly closer on EXP vs INSP (4.5 mm ± 3.3 mm vs 14.8 mm ± 9.7 mm; p < 0.0001).

CONCLUSIONS

Predicted 3D nodule location using an EXP scan for ENB is significantly closer to actual nodule location when compared with an INSP scan, but whether this leads to increased yields needs to be determined.

Safety and efficacy of intensity-modulated stereotactic body radiotherapy using helical tomotherapy for lung cancer and lung metastasis

Stereotactic body radiotherapy (SBRT) proved to be an effective treatment with acceptable toxicity for lung tumors. However, the use of helical intensity-modulated (IM) SBRT is controversial. We investigated the outcome of lung tumor patients treated by IMSBRT using helical tomotherapy with a Japanese standard fractionation schedule of 48 Gy in 4 fractions (n = 37) or modified protocols of 50-60 Gy in 5-8 fractions (n = 35). Median patient's age was 76 years and median follow-up period for living patients was 20 months (range, 6-46). The median PTV was 6.9 cc in the 4-fraction group and 14 cc in the 5- to 8-fraction group (P = 0.001). Grade 2 radiation pneumonitis was seen in 2 of 37 patients in the 4-fraction group and in 2 of 35 patients in the 5- to 8-fraction group (log-rank P = 0.92). Other major complications were not observed. The LC rates at 2 years were 87% in the 4-fraction group and 83% in the 5- to 8-fraction group. Helical IMSBRT for lung tumors is safe and effective. Patients with a high risk of developing severe complications may also be safely treated using 5-8 fractions. The results of the current study warrant further studies of helical IMSBRT.

Stereotactic body radiation therapy for centrally-located lung tumors

The application of high-dose irradiation to centrally-located lung tumors is generally considered to be of high risk in causing bronchial injury. The aim of the present retrospective study was to investigate the safety and efficacy of stereotactic body radiation therapy (SBRT) for patients with centrally-located lung tumors. In total, 28 patients who underwent SBRT for lung tumors within 2 cm of a major bronchus were retrospectively analyzed. The median total dose prescribed was 45 Gy (range, 36.3–52.5 Gy), the median fraction was 12 (range, 10–15) and the median dose per fraction was 3.6 Gy (range, 3–5 Gy). The median follow-up period for the surviving patients was 14 months (range, 10–41 months). The local control rate of SBRT was 100%, with a complete response (CR) rate of 32.1% (9/28); a partial response (PR) rate of 50% (14/28) and a stable disease (SD) rate of 17.9% (5/28). In total, 15 patients survived and 13 patients succumbed; 11 patients succumbed to tumor progression, one to congestive heart failure and one to a brain hemorrhage. The main side-effects included grade 2 esophagitis (17.9%; 5/28) atelectasis (10.7%; 3/28) and grade 2 late radiation pneumonitis (7.1%; 2/28). Severe late toxicity (≥ grade 3) was not observed in any patient. SBRT is an effective and safe therapy for centrally-located lung tumors.