Program Information
Comparison of the Phantom Dose Distribution of Dual-Energy CT Scan and That of Single-Energy CT Scan with Orthopedic Metal Artifact Reduction Algorithm Using Volumetric Arc Therapy in Monaco
K Li*, W Leung , Tuen Mun Hospital, Hong Kong
Presentations
SU-I-GPD-J-9 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose: To compare the phantom dose distribution of dual-energy CT (DECT) scan and that of single-energy CT scan with orthopedic metal artifact reduction (OMAR) algorithm using volumetric arc therapy (VMAT) in Monaco.
Methods: An additional in-house developed water-equivalent slice, which is sandwiched by Rando anthropomorphic head phantom, incorporated with animal’s cervical spine (C-Spine) and one pair of metal screws were used to simulate a patient undergoes stereotactic body radiation therapy (SBRT). The phantom was scanned on Siemens Somatom Definition Flash DECT system and Philips Brilliance Big Bore CT system with OMAR, respectively. The images acquired from DECT were reconstructed to 80keV, 100keV, 120keV, 140keV and 160keV monoenergetic images. The Gammex RMI461A Head/Body phantom was scanned in both CTs to obtain corresponding CT calibration curves at different energies. Treatment plans using VMAT was created in Monaco v5.0 (Elekta AB, Stockholm, Sweden) with Elekta Agility LINAC 6MV photon beams. 24Gy in 3 fractions was prescribed to the C-Spine which is assumed as planning target volume (PTV). Dose-volume-histogram (DVH) statistics to the PTV were compared.
Results: The dose distribution in terms of minimum dose, maximum dose and mean dose to PTV for Siemens dual-energy CT and Philips single-energy CT with OMAR were summarized in Table 1. The dose distribution in terms of DVH statistics for both single-energy CT image with OMAR and dual-energy monoenergetic CT images was very similar.
Conclusion: The dual-energy monoenergetic CT image has the potential to replace single-energy CT image for treatment planning with two good reasons: (1) Dual-energy monoenergetic CT image helps delineating OAR and target volume where severe metal artifacts conceal anatomical structures for treatment planning, such as the area between the two metal implants in our phantom. (2) Dose distribution differences between the two approaches are negligible. More anatomical structures will be included in the future studies.
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