Program Information
Evaluation of Multiple Brain Metastases Stereotactic Treatment Planning in Cyberknife Versus Linac
S Vikraman1*, D Manigandan2 , Thiyagarajan Rajesh1 , Kp Karrthick1 , R Sambasivaselli1 , V Senniandavar1 , M Ramu1 , S Maragathaveni1 , N Dhivya1 , M Muthukumaran3 ,T Kataria1 , (1) Medanta The Medicity, Gurgaon, (2) Fortis Hospital, Mohali, Punjab, (3) Apollo Speciality Hospitals, Chennai, TN, India
Presentations
SU-E-T-395 (Sunday, July 12, 2015) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose:
The purpose of this study was to evaluate multiple brain metastases stereotactic treatment planning of Cyberknife versus linac using dose volume based indices.
Methods:
Fifteen multiple brain metastases patients were taken for this study from Cyberknife Multiplan TPSv4.6.0. All these patients underwent stereotactic treatment in Cyberknife. For each patient VMAT stereotactic treatment plan was generated in MONACO TPSv5.0 using Elekta beam modulator MLC and matched the delivered plan. A median dose of 8.5Gy(range 7-12Gy) per fraction was prescribed. Tumor volume was in the range of 0.06-4.33cc. Treatment plan quality was critically evaluated by comparing DVH indices such as D98, D95, CI, and HI for target volumes. Maximum point doses and volume doses were evaluated for critical organs
Results:
For each case, target coverage of D98 was achieved with 100% prescription dose with SD of 0.29% and 0.41% in Linac and Cyberknife respectively. The average conformity index(CI) of 1.26±0.0796 SD for Cyberknife and 1.92±0.60SD for linac were observed. Better homogeneity Index (HI) of 1.17±0.09SD was observed in linac as compared to Cyberknife HI of 1.24±0.05SD.All the critical organ doses were well within tolerance limit in both linac and Cyberknife plans. There is no significant difference of maximum point doses for brainstem and optic chiasm. Treatment time and number of monitor units are more in Cyberknife compared to linac. The average volume receiving 12Gy in whole brain was 6% and 12% for Cyberknife and linac respectively. 1000cc of whole brain received 60% lesser dose in Linac compared to Cyberknife in all cases.
Conclusion:
The study shows that dosimetrically comparable plans are achievable Cyberknife and Linac. However, a better conformity, target coverage, lesser OAR dose is achieved with Cyberknife due to greater degrees of freedom with robotic gantry and smaller collimator for multiple targets.
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