Shadi Yousefi MD, Presenter: Nothing to Disclose

Ismet Sarikaya MD, Abstract Co-Author: Nothing to Disclose

Saloomeh Vahdat MD, Abstract Co-Author: Nothing to Disclose

Filip Banovac MD, Abstract Co-Author: Nothing to Disclose

Brian Timothy Collins MD, Abstract Co-Author: Consultant, Accuray Incorporated Speakers Bureau, Accuray Incorporated Research grant, Accuray Incorporated

Carlos Jamis-Dow MD, Abstract Co-Author: Nothing to Disclose

To evaluate radiation-induced lung changes following robotic stereotactic radiosurgery with tumor tracking, a novel technology capable of delivering extremely high doses of radiation with tighter margins than previously feasible.

Twenty-four consecutive patients with small (< 4 cm) peripheral stage I lung cancer (n=15) or single lung metastases (n = 9) were evaluated. Fiducial markers (3-5) were placed under CT-guidance in or near tumors, with adequate spacing (1-2 cm). Treatment plans with 5-mm margins were generated. Patients received 42-60 Gy in 3 equal fractions delivered in less than 2 weeks. Tumor response and fiducial migration following radiosurgery were evaluated by chest CT at 3, 6 and 12 months.

At 3 months, 17/24 Patients had a chest CT. Reduction in tumor size was detected in 16/17 (94%). At 6 months, 20/24 Patients had a chest CT. Peritumoral ground glass opacity was present in 13/20 cases (65%). Patchy consolidation was seen in 12/20 cases (60%) and dense consolidation was observed in 5/20 cases (25%). At 12 months, 20/24 Patients had a chest CT. In 12/20 (60%) dense consolidation obscured the tumor. Patchy consolidation near the target was present in 2/20 (10%) and streaky fibrosis was seen in 2/20 (10%). Tumor growth was noted in 1/20 (5%). In all patients, fiducial markers progressively migrated towards the center of the radiation target.  

CT appearance of lung injury after robotic stereotactic radiosurgery is similar to that induced by conventional radiotherapy. Fiducial migration towards the center of the radiation target may be an indicator of radiation fibrosis.

Radiosurgery provides excellent local control. The progressive development of dense peritumoral consolidation and the

Yousefi, S, Sarikaya, I, Vahdat, S, Banovac, F, Collins, B, Jamis-Dow, C, CT Appearances and Fiducial Migration Patterns Following Radical Stereotactic Radiosurgery of Small Peripheral Lung Tumors.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6009324.html