TY - CHAP
T1 - Dose distribution comparison for the treatment of spinal metastases using cyberknife versus IMRT stereotactic body radiotherapy using linac/CT-on-rails unit
AU - Shiu, Almon S.
AU - Wang, He
AU - Ye, Jin Song
AU - Meier, Robert
AU - Metha, Vivek
AU - Vermeulen, Sandra
AU - Chang, Eric L.
N1 - Copyright:
Copyright 2010 Elsevier B.V., All rights reserved.
PY - 2010
Y1 - 2010
N2 - Aims: This study evaluates potential benefits and limitations of two different radiation delivery systems. CyberKnife® radiosurgery and intensity-modulated radiotherapy (IMRT) are assessed using comparative treatment methods on patients with spinal and lung metastases. Methods: The study includes patients with metastatic disease who have undergone CyberKnife® treatment at the Seattle CyberKnife® Center (SCC) since February 2006. Seven CT-image sets from SCC including the contours, and dose-matrix were imported through DICOM-RT into the Pinnacle3 ® treatment-planning system at M.D. Anderson Cancer Center for the purposes of creating a theoretical IMRT treatment plan for the linac. The median volume of 7 lesions was 14.66 (range 0.24-64.11) cm3. The fractional size for each treatment course ranged from 1 to 5 fractions and dose per fraction ranged from 500 to 1,600 cGy. The prescription dose was normalized to 100% of the maximum dose of each plan. Dose-volume histograms were generated for both CyberKnife® and theoretical linac treatment. In addition, the homogeneity index, the new conformity index (NCI), and dose distributions in axial, sagittal, and coronal planes were also used to compare treatment plans. Results: For the target volume, coverage varied from 0.85 to 1.0 with mean of 0.94 for CyberKnife® and from 0.90 to 1.0 with mean of 0.97 for IMRT. The NCI ranged from 1.25 to 4.88 with a mean of 2.08 and from 1.34 to 5.26 with a mean of 2.23. CyberKnife® appears to have a slight advantage over IMRT in dose conformity, however, the prescription isodose line is lower in cases planned with CyberKnife®. It could be observed from the results of the homogeneity index that CyberKnife ® varied from 1.24 to 1.64 with a mean of 1.40 as compared to that of IMRT, which varied from 1.13 to 1.31 with a mean of 1.27. For organs at risk (OARs), both techniques meet their respective planning objectives; however IMRT consistently spared the OAR, anterior to the target, more effectively. This is due to the availability of choosing beam angles from 360° for the IMRT plan while beam angles for CyberKnife® are limited to anterior and anterior oblique arrangements. However, CyberKnife® is better suited for treating small-sized lesion as demonstrated in the study. Conclusion: Dose conformity seems to be comparable between CyberKnife ® and Pinnacle3®-IMRT planning, CyberKnife ® appears to have a slight advantage over IMRT. Dose heterogeneity is greater for patients receiving CyberKnife® treatment compared to IMRT. The use of anterior beam arrangements in CyberKnife® may increase the integral dose to anterior OARs compared to the conventional linac delivery systems.
AB - Aims: This study evaluates potential benefits and limitations of two different radiation delivery systems. CyberKnife® radiosurgery and intensity-modulated radiotherapy (IMRT) are assessed using comparative treatment methods on patients with spinal and lung metastases. Methods: The study includes patients with metastatic disease who have undergone CyberKnife® treatment at the Seattle CyberKnife® Center (SCC) since February 2006. Seven CT-image sets from SCC including the contours, and dose-matrix were imported through DICOM-RT into the Pinnacle3 ® treatment-planning system at M.D. Anderson Cancer Center for the purposes of creating a theoretical IMRT treatment plan for the linac. The median volume of 7 lesions was 14.66 (range 0.24-64.11) cm3. The fractional size for each treatment course ranged from 1 to 5 fractions and dose per fraction ranged from 500 to 1,600 cGy. The prescription dose was normalized to 100% of the maximum dose of each plan. Dose-volume histograms were generated for both CyberKnife® and theoretical linac treatment. In addition, the homogeneity index, the new conformity index (NCI), and dose distributions in axial, sagittal, and coronal planes were also used to compare treatment plans. Results: For the target volume, coverage varied from 0.85 to 1.0 with mean of 0.94 for CyberKnife® and from 0.90 to 1.0 with mean of 0.97 for IMRT. The NCI ranged from 1.25 to 4.88 with a mean of 2.08 and from 1.34 to 5.26 with a mean of 2.23. CyberKnife® appears to have a slight advantage over IMRT in dose conformity, however, the prescription isodose line is lower in cases planned with CyberKnife®. It could be observed from the results of the homogeneity index that CyberKnife ® varied from 1.24 to 1.64 with a mean of 1.40 as compared to that of IMRT, which varied from 1.13 to 1.31 with a mean of 1.27. For organs at risk (OARs), both techniques meet their respective planning objectives; however IMRT consistently spared the OAR, anterior to the target, more effectively. This is due to the availability of choosing beam angles from 360° for the IMRT plan while beam angles for CyberKnife® are limited to anterior and anterior oblique arrangements. However, CyberKnife® is better suited for treating small-sized lesion as demonstrated in the study. Conclusion: Dose conformity seems to be comparable between CyberKnife ® and Pinnacle3®-IMRT planning, CyberKnife ® appears to have a slight advantage over IMRT. Dose heterogeneity is greater for patients receiving CyberKnife® treatment compared to IMRT. The use of anterior beam arrangements in CyberKnife® may increase the integral dose to anterior OARs compared to the conventional linac delivery systems.
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U2 - 10.1159/000288718
DO - 10.1159/000288718
M3 - Chapter
AN - SCOPUS:77949351702
SN - 9783805593649
T3 - Radiosurgery
SP - 56
EP - 65
BT - Radiosurgery
ER -