(Sunday, 7/14/2019)
Room: ePoster Forums
Purpose: This work is to investigate what is the optimal treatment time for treating the liver lesions using the CyberKnife Synchrony Respiratory Tracking System (CSRTS) with the purpose of shortening treatment time.
Methods: The CSRTS is a suitable way to treat fast-moving liver lesions with great delivery accuracy. However many patients have difficulty to maintain regular breathing pattern for long time so that more frequent synchrony remodeling occurs and greatly prolongs the treatment, which potentially has to compromise the delivery accuracy to complete the treatment. To reduce the treatment time to the lowest extent possible, we investigated four liver patients to find out what is the optimal (shortest time) treatment time without compromising the plan quality. The treatment plan is optimized to meet the dosimetircal goals without trying to shorten treatment time. Then the time reduction technique, which was the method provided in the CyberKnife planning system, was utilized to reduce the treatment time to the extent the plan quality still is of more or less the same as the initial plan, but the plan quality would deteriorate if we further reduce the treatment time. With the same PTV coverage, we compared the initial and final “optimal� plan in the treatment time and doses to the critical structures.
Results: With the dose difference to the critical structures, mostly less than 1.0% of the prescription dose, the treatment time reduced from the range of 60 to 70 minutes to the range of 40 to 50 minutes for the investigated cases (PTV sizes range from 130 to 240 cc).
Conclusion: For the liver cases with the CSRTS, the optimal treatment time we can achieve ranges from about 40 to 50 minutes, which don’t compromise the initial plan quality that has a longer treatment (60 to 70 minutes).
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