American Brachytherapy Society consensus guidelines for thoracic brachytherapy for lung cancer

[Endoscopic interventions in pulmonology]

Bronchoscopy plays a significant role in the diagnosis and treatment of pulmonary diseases. Hemoptysis, or central airway obstruction, is a common indication for interventional bronchoscopy. In addition, the treatment of early lung cancer is the domain of bronchoscopy in inoperable patients. In recent years, endoscopic techniques have also been established as new therapeutic options in advanced chronic obstructive pulmonary disease and uncontrolled bronchial asthma.

Design and validation of a CT-guided robotic system for lung cancer brachytherapy

PURPOSE

Currently, lung brachytherapy in clinical setting is a complex procedure. Operation accuracy depends on accurate positioning of the template; however, it is difficult to guarantee the positioning accuracy manually. Application of robotic-assisted systems can simplify the procedure and improve the manual positioning accuracy. Therefore, a novel CT-guided robotic system was developed to assist the lung cancer brachytherapy.

METHODS

A four degree-of-freedom (DOF) robot, controlled by a lung brachytherapy treatment planning system (TPS) software, was designed and manufactured to assist the template positioning. Target position of the template can be obtained from the treatment plan, thus the robot is driven to the target position automatically. The robotic system was validated in both the laboratory and the CT environment. In laboratory environment, a 3D laser tracker and an inertial measurement unit (IMU) were used to measure the mechanical accuracy in air, which includes positioning accuracy and position repeatability. Working reliability was also validated in this procedure by observing the response reliability and calculating the position repeatability. Imaging artifacts and accuracy of the robot registration were validated in the CT environment by using an artificial phantom with fiducial markers. CT images were obtained and used to test the image artifact and calculate the registration accuracy. Phantom experiments were conducted to test the accuracy of needle insertion by using a transparent hydrogel phantom with a high imitation artificial phantom. Also, the efficiency was validated in this procedure by comparing time costs in manual positioning with robotic positioning under the same experimental conditions.

RESULTS

The robotic system achieved the positioning accuracy of 0.28 ± 0.25 mm and the position repeatability of 0.09 ± 0.11 mm. Experimental results showed that the robot was CT-compatible and responded reliably to the control commands. The mean registration accuracy of the robotic system was 0.49 ± 0.29 mm. Phantom experiments indicated that the accuracy of needle insertion was 1.5 ± 1.7 mm at a depth ranging from 30 to 80 mm. The time used to adjust the template to the target position was 12 min on average by robotic system automatically. An average of 30 min was saved compared with the manual positioning procedure in phantom experiments.

CONCLUSIONS

This paper describes the design and experimental validation of a novel CT-guided robotic system for lung cancer brachytherapy. The robotic system was validated in a number of aspects which prove that it was capable of locating the template with clinically acceptable accuracy in the CT environment. All experimental results indicated that the system is reliable and ready to be applied to further studies on animals.

Endobronchial brachytherapy for metastasis from extrapulmonary malignancies as an effective treatment for palliation of symptoms

PURPOSE

Endobronchial metastasis (EBM) originating from primary cancers outside the lung is rare. External beam radiotherapy is often attempted for control of symptoms with variable effectiveness and retreatment is challenging if symptoms recur. There is limited documentation of high-dose-rate brachytherapy for EBM in the literature.

METHODS AND MATERIALS

A prospective database was created from 2006 to 2015. Patients with EBM who received high-dose-rate brachytherapy were included. Cough, dyspnea, chest pain, and hemoptysis were assessed and graded (0-4) at the time of initial consult and in followup. Symptom-free survival and re-expansion were assessed.

RESULTS

Thirty-five patients with EBM were identified. Most patients received three fractions of 700 cGy, and 17 patients had prior external beam radiotherapy. Median symptom-free and overall survival were 67 and 117 days. After brachytherapy, improvement in cough was documented in 75.0%, hemoptysis in 76.4%, dyspnea in 60.0% for a median of 3-6 months. Of the 22 patients who had subsequent chest imaging, re-expansion was documented in 32%. There were no significant toxicities reported.

CONCLUSIONS

Brachytherapy appears effective in achieving durable symptom control of cough hemoptysis, and dyspnea in patients with EBM and should be considered routinely for palliation where available. Further studies are required to better characterize expected symptom improvement, lung re-expansion rates, and efficacy in comparison with other local treatments.