Ex) Article Title, Author, Keywords
Ex) Article Title, Author, Keywords
Korean Journal of Medical Physics 2013; 24(4): 237-242
Published online December 30, 2013
Copyright © Korean Society of Medical Physics.
Shin-Wook Kim*, Hun-Joo Shin*, Young-Kyu Lee†, Jae-Hyuk Seo‡, Gi-Woong Lee§,
Hyeong-Wook Park§, Jae-Choon Lee§, Ae-Ran Kim∥, Ji-Na Kim∥, Myong-Ho Kim*,
Chul-Seung Kay*, Hong-Seok Jang†, Young-Nam Kang†
김신욱*ㆍ신헌주*ㆍ이영규†ㆍ서재혁‡ㆍ이기웅§ㆍ박형욱§ㆍ이재춘§, 김애란∥ㆍ김지나∥ㆍ김명호*ㆍ계철승*ㆍ장홍석†ㆍ강영남†
In the intracranial regions, an accurate delineation of the target volume has been difficult with only the CT data due to poor soft tissue contrast of CT images. Therefore, the magnetic resonance images (MRI) for the delineation of the target volumes were widely used. To calculate dose distributions with MRI-based RTP, the electron density (ED) mapping concept from the diagnostic CT images and the pseudo CT concept from the MRI were introduced. In this study, the look up table (LUT) from the fifteen patients’ diagnostic brain MRI images was created to verify the feasibility of MRI-based RTP. The dose distributions from the MRI-based calculations were compared to the original CT-based calculation. One MRI set has ED information from LUT (lMRI). Another set was generated with voxel values assigned with a homogeneous density of water (wMRI). A simple plan with a single anterior 6MV one portal was applied to the CT, lMRI, and wMRI. Depending on the patient’s target geometry for the 3D conformal plan, 6MV photon beams and from two to five gantry portals were used. The differences of the dose distribution and DVH between the lMRI based and CT-based plan were smaller than the wMRI-based plan. The dose difference of wMRI vs. lMRI was measured as 91 cGy vs. 57 cGy at maximum dose, 74 cGt vs. 42 cGy at mean dose, and 94 cGy vs. 53 at minimum dose. The differences of maximum dose, minimum dose, and mean dose of the wMRI-based plan were lower than the lMRI-based plan, because the air cavity was not calculated in the wMRI-based plan. These results prove the feasibility of the lMRI-based planning for brain tumor radiation therapy.
KeywordsMRI-based RTP, Look up table, Electron density
pISSN 2508-4445
eISSN 2508-4453
Formerly ISSN 1226-5829
Frequency: Quarterly