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Plan Quality Comparison for Cervical Carcinoma Treated with Halcyon and Trilogy Intensity Modulated Radiotherapy

C Li*, J Lu , Y Yin , Department of Radiation Oncology Physics, Shandong Cancer Hospital Affiliated to Shandong University, Jinan


(Sunday, 7/14/2019)  

Room: ePoster Forums

Purpose: To compare the differences in dosimetry and plan parameters of intensity-modulated radiation therapy (IMRT) plans between the Halcyon and Trilogy accelerators.

Methods: A total of 12 IMRT plans from cervical carcinoma patients were retrospectively analyzed on the Trilogy and Eclipse v13.5 treatment planning system (TPS). For each patient, a new plan based on Halcyon was created with the same planning parameters and optimization constraints using Eclipse Version 15.1 TPS. To compare plan qualities, dosimetry parameters regarding planning target volume (PTV), organs at risk (OAR), monitor unit (MU) efficiency, segment size and treatment time were evaluated. Evaluation of the helical diode array system was carried out with gamma-index analysis.

Results: Dose distribution of the target volume showed no significant differences compared to the Trilogy plans (p > 0.05). The mean doses of bladder, rectum and left femoral head for Halcyon plans were significantly reduced compared to those for Trilogy plans (p < 0.05). Compared to Trilogy, Halcyon increased the number of MUs from 1692.5±259.5 MU to 2316.7±209.7 MU (p = 0.00) and decreased the delivery time from 12.38±1.49 min to 3.01±0.28 min (p = 0.00). The average segment areas of Halcyon plans for proximal and distal MLCs were 43.7 ± 32.5 cm2 and 28.8 ± 25.4 cm2, respectively, and that of Trilogy plans was 25.7 ± 16.8 cm2. The mean gamma index (3 mm/3%) results for Halcyon and Trilogy plans were 99.39±0.28 and 99.55±0.31(p > 0.05), respectively.

Conclusion: All Halcyon treatment plans were recognized as clinically acceptable and had statistically better OAR sparing with higher delivery efficiency. The Halcyon system showed fast treatment delivery of IMRT with good dosimetric agreement using ArcCHECK.


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