방사선의학 웹진

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Abstract

Based on the assumption that apparent diffusion coefficients (ADCs) define high-risk clinical target volume (aCTVHR) in high-grade glioma in a cellularity-dependent manner, the dosimetric effects of aCTVHR-targeted dose optimization were evaluated in two intensity-modulated radiation therapy (IMRT) plans. Diffusion-weighted magnetic resonance (MR) images and ADC maps were analyzed qualitatively and quantitatively to determine aCTVHR in a high-grade glioma with high cellularity. After confirming tumor malignancy using the average and minimum ADCs and ADC ratios, the aCTVHR with double- or triple-restricted water diffusion was defined on computed tomography images through image registration. Doses to the aCTVHR and CTV defined on T1-weighted MR images were optimized using a simultaneous integrated boost technique. The dosimetric benefits for CTVs and organs at risk (OARs) were compared using dose volume histograms and various biophysical indices in an ADC map-based IMRT (IMRTADC) plan and a conventional IMRT (IMRTconv) plan. The IMRTADC plan improved dose conformity up to 15 times, compared to the IMRTconv plan. It reduced the equivalent uniform doses in the visual system and brain stem by more than 10% and 16%, respectively. The ADC-based target differentiation and dose optimization may facilitate conformal dose distribution to the aCTVHR and OAR sparing in an IMRT plan. 

Author information

Park JY1, Suh TS2, Lee JW3, Ahn KJ4, Park HJ5, Choe BY2, Hong S3.

1Department of Radiation Oncology, University of Florida, FL, USA.

2Department of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul, Korea. ; Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul, Korea.

3Department of Radiation Oncology, Konkuk University Medical Center, Seoul, Korea.

4Department of Radiology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.

5Department of Radiation Oncology, Ajou University School of Medicine, Suwon, Korea.