Saturday, March 7, 2009

Assessment of image-guided CyberKnife(@) radiosurgery for metastatic spine tumors

Assessment of image-guided CyberKnife(@) radiosurgery for metastatic spine tumors.

Tsai JT, Lin JW, Chiu WT, Chu WC.

Institute of Biomedical Engineering, National Yang-Ming University, No. 155, Sec 2, Li-Nong St., Shih-Pai, Taipei, 112, Taiwan, ROC.

Spinal metastases are associated with significant symptoms. From September 2005 to September 2007, 69 consecutive patients with 127 malignant spine metastatic lesions were treated at Wanfang Hospital with CyberKnife(@) (CK) radiosurgery. The radiosurgery dose ranged from 10 to 30 Gy (mean 15.5 Gy) prescribed to the 75-85% isodose line that encompassed at least 95% of the tumor volume. We used fiducials as tracking landmarks for CK treatment of the thoracic and lumbar spine. A torso anthropomorphic phantom and GafChromic MD-55 films were used to verify the accuracy of CK radiosurgery and 2D dose distribution, demonstrated high targeting accuracy with 2% average deviation of the measured dose from the estimated dose at the set-up center and less than 5% dose deviation in 2D isodose curve. Visual Analogue Scale and Oswestry Disability Index questionnaires were used to monitor functional outcome after radiosurgery. Local tumor control at 10 months was 96.8%. Mean pain scores decreased significantly from 65 to 30 after treatment (P = 0.001). Functional disability was significantly improved after treatment (P = 0.002). The most common treatment toxicities were nausea and fatigue.

In conclusion, CK radiosurgery is a well-tolerated and effective treatment for spine tumors with good local tumor control and a favorable outcome on pain and functional improvement after treatment.

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