TY - JOUR
T1 - ART for head and neck patients
T2 - On the difference between VMAT and IMPT
AU - Góra, Joanna
AU - Kuess, Peter
AU - Stock, Markus
AU - Andrzejewski, Piotr
AU - Knäusl, Barbara
AU - Paskeviciute, Brigita
AU - Altorjai, Gabriela
AU - Georg, Dietmar
N1 - Funding Information:
The financial support by the Federal Ministry of Science, Research and Economy and the National Foundation for Research, Technology and Development and The European Community’s Seventh Framework Programme (FP7 2007 – 2013) under Grant Agreement No. 215849-2 (Project PARTNER) is gratefully acknowledged.
Publisher Copyright:
© 2015 Informa Healthcare.
PY - 2015/9/14
Y1 - 2015/9/14
N2 - Anatomical changes in the head-and-neck (H&N) region during the course of treatment can cause deteriorated dose distributions. Different replanning strategies were investigated for volumetric modulated arc therapy (VMAT) and intensity-modulated proton therapy (IMPT).Material and methods. For six H&N patients two repeated computed tomography (CT) and magnetic resonance (MR) (CT
1/MR
1 at week 2 and CT
2/MR
2 at week 4) scans were acquired additionally to the initial planning CT/MR. Organs-at-risk (OARs) and three targets (CTV
70Gy, CTV
63Gy, CTV
56Gy) were delineated on MRs and transferred to respective CT data set. Simultaneously integrated boost plans were created using VMAT (two arcs) and IMPT (four beams). To assess the need of replanning the initial VMAT and IMPT plans were recalculated on repeated CTs. Furthermore, VMAT and IMPT plans were replanned on the repeated CTs. A Demon algorithm was used for deformable registration of the repeated CTs with the initial CT and utilized for dose accumulation. Total dose estimations were performed to compare ART versus standard treatment strategies.Results. Dosimetric evaluation of recalculated plans on CT
1 and CT
2 showed increasing OAR doses for both, VMAT and IMPT. The target coverage of recalculated VMAT plans was considered acceptable in three cases, while for all IMPT plans it dropped. Adaptation of the treatment reduced D
2% for brainstem by 6.7 Gy for VMAT and by 8 Gy for IMPT, for particular patients. These D
2% reductions were reaching 9 Gy and 14 Gy for the spinal cord. ART improved target dose homogeneity, especially for protons, i.e. D
2% decreased by up to 8 Gy while D
98% increased by 1.2 Gy.Conclusion. ART showed benefits for both modalities. However, as IMPT is more conformal, the magnitude of dosimetric changes was more pronounced compared to VMAT. Large anatomic variations had a severe impact on treatment plan quality for both VMAT and IMPT. ART is justified in those cases irrespective of treatment modalities.
AB - Anatomical changes in the head-and-neck (H&N) region during the course of treatment can cause deteriorated dose distributions. Different replanning strategies were investigated for volumetric modulated arc therapy (VMAT) and intensity-modulated proton therapy (IMPT).Material and methods. For six H&N patients two repeated computed tomography (CT) and magnetic resonance (MR) (CT
1/MR
1 at week 2 and CT
2/MR
2 at week 4) scans were acquired additionally to the initial planning CT/MR. Organs-at-risk (OARs) and three targets (CTV
70Gy, CTV
63Gy, CTV
56Gy) were delineated on MRs and transferred to respective CT data set. Simultaneously integrated boost plans were created using VMAT (two arcs) and IMPT (four beams). To assess the need of replanning the initial VMAT and IMPT plans were recalculated on repeated CTs. Furthermore, VMAT and IMPT plans were replanned on the repeated CTs. A Demon algorithm was used for deformable registration of the repeated CTs with the initial CT and utilized for dose accumulation. Total dose estimations were performed to compare ART versus standard treatment strategies.Results. Dosimetric evaluation of recalculated plans on CT
1 and CT
2 showed increasing OAR doses for both, VMAT and IMPT. The target coverage of recalculated VMAT plans was considered acceptable in three cases, while for all IMPT plans it dropped. Adaptation of the treatment reduced D
2% for brainstem by 6.7 Gy for VMAT and by 8 Gy for IMPT, for particular patients. These D
2% reductions were reaching 9 Gy and 14 Gy for the spinal cord. ART improved target dose homogeneity, especially for protons, i.e. D
2% decreased by up to 8 Gy while D
98% increased by 1.2 Gy.Conclusion. ART showed benefits for both modalities. However, as IMPT is more conformal, the magnitude of dosimetric changes was more pronounced compared to VMAT. Large anatomic variations had a severe impact on treatment plan quality for both VMAT and IMPT. ART is justified in those cases irrespective of treatment modalities.
KW - Head and Neck Neoplasms/radiotherapy
KW - Humans
KW - Magnetic Resonance Imaging
KW - Multimodal Imaging
KW - Proton Therapy/methods
KW - Radiometry/methods
KW - Radiotherapy Planning, Computer-Assisted/methods
KW - Radiotherapy, Intensity-Modulated/methods
KW - Tomography, X-Ray Computed
UR - http://www.scopus.com/inward/record.url?scp=84940481256&partnerID=8YFLogxK
U2 - 10.3109/0284186X.2015.1028590
DO - 10.3109/0284186X.2015.1028590
M3 - Journal article
C2 - 25850583
SN - 0284-186X
VL - 54
SP - 1166
EP - 1174
JO - Acta Oncologica
JF - Acta Oncologica
IS - 8
ER -