Endovascular coils as lung tumour markers in real-time tumour tracking stereotactic radiotherapy: preliminary results

Abstract

To evaluate the use of endovascular coils as markers for respiratory motion correction during high-dose stereotactic radiotherapy with the CyberKnife, an image-guided linear accelerator mounted on a robotic arm. Endovascular platinum embolisation coils were used to mark intrapulmonary lesions. The coils were placed in subsegmental pulmonary artery branches in close proximity to the target tumour. This procedure was attempted in 25 patients who were considered unsuitable candidates for standard transthoracic percutaneous insertion. Vascular coils (n = 87) were successfully inserted in 23 of 25 patients. Only minor complications were observed: haemoptysis during the procedure (one patient), development of pleural pain and fever on the day of procedure (one patient), and development of small infiltrative changes distal to the vascular coil (five patients). Fifty-seven coils (66% of total inserted number) could be used as tumour markers for delivery of biologically highly effective radiation doses with automated tracking during CyberKnife radiotherapy. Endovascular markers are safe and allow high-dose radiotherapy of lung tumours with CyberKnife, also in patients who are unsuitable candidates for standard transthoracic percutaneous marker insertion.

Fig. 1

A pulmonary arterial catheter used to place a coil. The inserted coil is indicated by the arrow: 179×179 mm (96×96 DPI)

Fig. 2

Patient with two lung metastases (left and right sided) from a cervical carcinoma. Transthoracic marker insertion in the right cavernous lesion is not feasible. Furthermore, transthoracic placement in both lesions would be related to a major risk for pneumothorax. After endovascular marker placement (coils are indicated by an arrow), both lesions could be treated with CyberKnife. 98×83 mm (96×96 DPI)

Fig. 3

Non-coiling of the coil because of mismatch between the too large coil windings relative to the small vessel diameter. The coil is therefore unsuitable for automated tracking. The arrows indicate two coils that were unsuitable for tracking due to noncoiling: 137×112 mm (96×96 DPI)

Fig. 4

a Patient with a second primary NSCLC in the right lung, after having undergone left pneumonectomy 5 years earlier for early stage NSCLC. Surgical treatment was considered not feasible because of the previous pneumonectomy. Conventional radiotherapy, using large margins to take tumour motion into account, would result in increased risk for lung toxicity. Considering the low forced expiratory volume in 1 s of 1,090 ml (38% of predicted), percutaneous insertion of markers with its risk of pneumothorax was considered potentially life-threatening. Endovascular markers were placed (indicated by the arrow) and the patient was treated with CyberKnife by using a total dose of 45 Gy (administered in three treatment sessions). b Follow-up at 10 weeks. Showed complete tumour response. Arrow indicates the coil without remaining tumour): 84×76 mm (96×96 DPI)