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Title: SU-F-J-203: Retrospective Assessment of Delivered Proton Dose in Prostate Cancer Patients Based On Daily In-Room CT Imaging

Abstract

Purpose: Retrospective calculation of the delivered proton dose in prostate cancer patients based on a unique dataset of daily CT images. Methods: Inter-fractional motion in prostate cancer patients treated at our proton facility is counteracted by water-filled endorectal ballon and bladder filling protocol. Typical plans (XiO, Elekta Instruments AB, Stockholm) for 74 Gy(RBE) sequential boost treatment in 37 fractions include two series of opposing lateral double-scattered proton beams covering the respective iCTV. Stability of fiducial markers and anatomy were checked in 12 patients by daily scheduled in-room control CT (cCT) after immobilization and positioning according to bony anatomy utilizing orthogonal X-ray. In RayStation 4.6 (RaySearch Laboritories AB, Stockholm), all cCTs are delineated retrospectively and the treatment plans were recalculated on the planning CT and the registered cCTs. All fraction doses were accumulated on the planning CT after deformable registration. Parameters of delivered dose to iCTV (D98%>95%, D2%<107%), bladder (V75Gy<15%, V70Gy<25%, V65Gy<30%), rectum (V70Gy<10%, V50Gy<40%) and femoral heads (V50Gy<5%) are compared to those in the treatment plan. Intra-therapy variation is represented in DVH bands. Results: No alarming differences were observed between planned and retrospectively accumulated dose: iCTV constraints were met, except for one patient (D98%=94.6% in non-boosted iCTV). Considered bladder andmore » femoral head values were below the limits. Rectum V70Gy was slightly exceeded (<11.3%) in two patients. First intra-therapy variability analysis in 4 patients showed no timedependent parameter drift, revealed strongest variability for bladder dose. In some fractions, iCTV coverage (D98%) and rectum V70Gy was missed. Conclusion: Double scattered proton plans are accurately delivered to prostate cancer patients due to fractionation effects and the applied precise positioning and immobilization protocols. As a result of rare interventions after daily 3D imaging of the first 12 patients, in-room CT frequency for prostate cancer patients was reduced. The presented study supports this decision. The authors acknowledge the German Federal Ministry for Education and Research for funding the High Precision Radiotherapy Group at the OncoRay - National Center for Radiation Research in Oncology (BMBF- 03Z1N51).« less

Authors:
;  [1]; ; ;  [2];  [1];  [3]; ;  [1];  [3];  [3];  [4]
  1. OncoRay - National Center for Radiation Research in Oncology, Medical Faculty and University Hospital Carl Gustav Carus, Technische Universitaet Dresden, Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany)
  2. Department of Radiation Oncology, University Hospital Carl Gustav Carus, Techenische Universitaet Dresden (Germany)
  3. (Germany)
  4. (DKTK), Dresden, Germany and German Cancer Research Center (DKFZ), Heidelberg (Germany)
Publication Date:
OSTI Identifier:
22642231
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 43; Journal Issue: 6; Other Information: (c) 2016 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; 61 RADIATION PROTECTION AND DOSIMETRY; ACCURACY; ANATOMY; BIOMEDICAL RADIOGRAPHY; BLADDER; COMPUTERIZED TOMOGRAPHY; DATASETS; FIDUCIAL MARKERS; HEAD; IMAGE PROCESSING; LIMITING VALUES; NEOPLASMS; PATIENTS; PLANNING; PROSTATE; PROTON BEAMS; RADIATION DOSES; RADIOTHERAPY; RECTUM; TIME DEPENDENCE

Citation Formats

Stuetzer, K, Paessler, T, Valentini, C, Thiele, J, Hoelscher, T, Exner, F, now with: University of Wuerzburg, Department of Radiation Oncology, Wuerzburg, Krause, M, Richter, C, Department of Radiation Oncology, University Hospital Carl Gustav Carus, Techenische Universitaet Dresden, Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiooncology, Dresden, and German Cancer Consortium. SU-F-J-203: Retrospective Assessment of Delivered Proton Dose in Prostate Cancer Patients Based On Daily In-Room CT Imaging. United States: N. p., 2016. Web. doi:10.1118/1.4956111.
Stuetzer, K, Paessler, T, Valentini, C, Thiele, J, Hoelscher, T, Exner, F, now with: University of Wuerzburg, Department of Radiation Oncology, Wuerzburg, Krause, M, Richter, C, Department of Radiation Oncology, University Hospital Carl Gustav Carus, Techenische Universitaet Dresden, Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiooncology, Dresden, & German Cancer Consortium. SU-F-J-203: Retrospective Assessment of Delivered Proton Dose in Prostate Cancer Patients Based On Daily In-Room CT Imaging. United States. doi:10.1118/1.4956111.
Stuetzer, K, Paessler, T, Valentini, C, Thiele, J, Hoelscher, T, Exner, F, now with: University of Wuerzburg, Department of Radiation Oncology, Wuerzburg, Krause, M, Richter, C, Department of Radiation Oncology, University Hospital Carl Gustav Carus, Techenische Universitaet Dresden, Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiooncology, Dresden, and German Cancer Consortium. Wed . "SU-F-J-203: Retrospective Assessment of Delivered Proton Dose in Prostate Cancer Patients Based On Daily In-Room CT Imaging". United States. doi:10.1118/1.4956111.
@article{osti_22642231,
title = {SU-F-J-203: Retrospective Assessment of Delivered Proton Dose in Prostate Cancer Patients Based On Daily In-Room CT Imaging},
author = {Stuetzer, K and Paessler, T and Valentini, C and Thiele, J and Hoelscher, T and Exner, F and now with: University of Wuerzburg, Department of Radiation Oncology, Wuerzburg and Krause, M and Richter, C and Department of Radiation Oncology, University Hospital Carl Gustav Carus, Techenische Universitaet Dresden and Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiooncology, Dresden and German Cancer Consortium},
abstractNote = {Purpose: Retrospective calculation of the delivered proton dose in prostate cancer patients based on a unique dataset of daily CT images. Methods: Inter-fractional motion in prostate cancer patients treated at our proton facility is counteracted by water-filled endorectal ballon and bladder filling protocol. Typical plans (XiO, Elekta Instruments AB, Stockholm) for 74 Gy(RBE) sequential boost treatment in 37 fractions include two series of opposing lateral double-scattered proton beams covering the respective iCTV. Stability of fiducial markers and anatomy were checked in 12 patients by daily scheduled in-room control CT (cCT) after immobilization and positioning according to bony anatomy utilizing orthogonal X-ray. In RayStation 4.6 (RaySearch Laboritories AB, Stockholm), all cCTs are delineated retrospectively and the treatment plans were recalculated on the planning CT and the registered cCTs. All fraction doses were accumulated on the planning CT after deformable registration. Parameters of delivered dose to iCTV (D98%>95%, D2%<107%), bladder (V75Gy<15%, V70Gy<25%, V65Gy<30%), rectum (V70Gy<10%, V50Gy<40%) and femoral heads (V50Gy<5%) are compared to those in the treatment plan. Intra-therapy variation is represented in DVH bands. Results: No alarming differences were observed between planned and retrospectively accumulated dose: iCTV constraints were met, except for one patient (D98%=94.6% in non-boosted iCTV). Considered bladder and femoral head values were below the limits. Rectum V70Gy was slightly exceeded (<11.3%) in two patients. First intra-therapy variability analysis in 4 patients showed no timedependent parameter drift, revealed strongest variability for bladder dose. In some fractions, iCTV coverage (D98%) and rectum V70Gy was missed. Conclusion: Double scattered proton plans are accurately delivered to prostate cancer patients due to fractionation effects and the applied precise positioning and immobilization protocols. As a result of rare interventions after daily 3D imaging of the first 12 patients, in-room CT frequency for prostate cancer patients was reduced. The presented study supports this decision. The authors acknowledge the German Federal Ministry for Education and Research for funding the High Precision Radiotherapy Group at the OncoRay - National Center for Radiation Research in Oncology (BMBF- 03Z1N51).},
doi = {10.1118/1.4956111},
journal = {Medical Physics},
number = 6,
volume = 43,
place = {United States},
year = {Wed Jun 15 00:00:00 EDT 2016},
month = {Wed Jun 15 00:00:00 EDT 2016}
}