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Plan Quality and Delivery Efficiency Comparison Between Halcyon 2.0 and Tomotherapy Hi-Art

W Feng1*, C Yang2 , A Chu3 , M Kao1 , M Needham1 , L Zhou1 , D Xu1 , F Zhang4 , H Sha4 , (1) St. Barnabas Medical Center, Livingston, NJ, (2) Monmouth Medical Center, Long Branch, NJ, (3) Stony Brook University, Stony Brook, NY, (4) Bayhealth Medical Center, Dover, DE


(Sunday, 7/14/2019)  

Room: ePoster Forums

Purpose: To compare the Head and Neck plan quality and delivery efficiency between Halcyon 2.0 and Tomotherapy Hi-Art.

Methods: For Head-and-Neck Cancer patients, same CT images and structures are used, treatment planning was performed using 4 full arc VMAT on a Halcyon fast-rotating O-ring linac with Eclipse 15.6 and using single helical arc on a Tomotherapy Hi-Art slipper-ring linac with Tomo-Plan 5.1. The plans include 3 overlapping PTV with 3 dose levels 70,59.4,54Gy respectively. Tomotherapy Hi-Art planning parameters include down-sampled CT 256x256, field width fixed 2.5cm, pitch 0.3, dose grid 0.234cmx0.234cm, modulation factor 2.2 and dose rate 874MU/min. Halcyon Eclipse planning parameters include 512x512, 0.25x0.25cm, collimator angle 11,56,281,326 deg, 800MU/min.The Halcyon version 2.0 used in the study includes updated dual layer MLC, combined resolution is 0.5cm compared to 1.0cm for version 1.0. The study was performed on an older generation TomoTherapy Hi-Art system and older version Tomo-Plan, latest generation Radixact includes Tomo-Edge (dynamic jaws) and latest TPS Precision allows for faster imaging and treatment delivery.All plans passed IMRT QA with SNC ArcCheck, >95% pass rate with 3%/3mm gamma for Tomotherapy Hi-Art; 2%/2mm gamma for Halcyon.

Results: Halcyon plan achieves superior coverage and better critical structure and normal tissue sparing, however the out field dose is higher and overall hotspot is higher for Halcyon plan. Halcyon plan can achieve better conformality and gradient out of target, and Tomotherapy Hi-Art plan can achieve better gradient inside of target.The Total MU is 3566 for Tomotherapy Hi-Art and 625.7 for Halcyon. The total treatment time (06FFF Beam-on time) is 256.1sec for Tomotherapy Hi-Art and 126sec for Halcyon. The total imaging, alignment and treatment time (CBCT acquisition to 06FFF beam off) is 9min Tomotherapy and 5.5min Halcyon.

Conclusion: Halcyon plan quality is comparable with Tomotherapy Hi-Art, delivery is around 2 times efficient.


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