(Saturday, 4/7/2018)
Room: Foyer
Purpose: I evaluated the DP-850 phantom as a multi-use tool for the use in the end-to-end testing process to evaluate image quality, treatment planning system (TPS) accuracy and dose delivery accuracy.
Methods: The assessment was conducted out of nine separate clinical facilities, utilizing five different linear accelerators and with two types of TPS software. The end-to-end testing included a CT sim of the DP-850 with an ion chamber in the center, generating test plans in the TPS, and delivering those plans to the phantom. Various image quality factors were verified at the CT simulator and the TPS. Dose accuracy of the TPS was confirmed by use of the ion chamber and the phantom as the patient. The sample plans included: 3D, IMRT, and VMAT. The IMRT/VMAT plans were created with generic optimization values to a contoured target within the phantom, this served to verify the IMRT/VMAT dose algorithms. The procedure was repeated separately for each facility evaluated.
Results: The images were successfully transferred from the CT simulators to the TPS with the correct orientation and image information. The image quality and accuracy verification testing performed on each CT scan was within acceptable limits, with no visible errors or degradation of image quality. The treatment plans were prepared in the record and verify system and were confirmed to be accurate in the treatment delivery system. The dose calculation accuracy of the TPS was confirmed by obtaining the mean dose to the contoured ion chamber volume during treatment delivery. Most results were measured below 5%, with the exception of the 4-field box when utilizing two different energies.
Conclusion: The DP-850 phantom was found to be an acceptable device to perform annual end-to-end testing for all aspects of treatment planning including importing CT data sets, dose calculation, IMRT planning, and exporting treatment data.
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