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Alber M. CLASSICAL NORMAL TISSUE VOLUME EFFECT MODELS FOR DOSE OPTIMIZATION. Radiother Oncol 2009. [DOI: 10.1016/s0167-8140(12)72590-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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77
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Dohm O, Alber M, Paulsen F. CERVICAL SPINE POSITIONING ACCURACY FOR THE MEDICAL INTELLIGENCE HEADSTEP MASK SYSTEM. Radiother Oncol 2009. [DOI: 10.1016/s0167-8140(12)73194-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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78
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Mihaljevic J, Soukup M, Dohm O, Alber M. MONTE CARLO BEAM COMMISSIONING OF PMLC SHAPED ELECTRON FIELDS WITH LARGE AIR GAPS FOR COMBINED IMRT/MERT. Radiother Oncol 2009. [DOI: 10.1016/s0167-8140(12)73188-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Sobotta B, Söhn M, Pütz M, Alber M. Tools for the analysis of dose optimization: III. Pointwise sensitivity and perturbation analysis. Phys Med Biol 2008; 53:6337-43. [DOI: 10.1088/0031-9155/53/22/005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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80
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Alber M. SU-GG-T-533: Rotational Intensity-Modulated Therapies: Can Conventional Arcs Match Tomotherapy? Med Phys 2008. [DOI: 10.1118/1.2962282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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81
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Gröger A, Schlemmer HP, Lichy M, Schick F, Blank M, Belka C, Alber M. 3D MR spectroscopic and diffusion-weighted imaging of prostate cancer with phased-array surface coil at 3 T for tumor definition in the intensity-modulated radiation therapy. ROFO-FORTSCHR RONTG 2008. [DOI: 10.1055/s-2008-1052580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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82
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Widesott L, Pierelli A, Fiorino C, Dell'Oca I, Cattaneo G, Alber M, Soukup M, Fazio F, Calandrino R, Schwarz M. Intensity Modulated Proton Therapy (IMPT) vs. Helicoidal Tomotherapy (HT) in the Treatment of Nasopharynx Cancer: A Planning Comparison. Int J Radiat Oncol Biol Phys 2007. [DOI: 10.1016/j.ijrobp.2007.07.2016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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83
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Ganswindt U, Paulsen F, Alber M, Bares R, Stenzl A, Bamberg M, Belka C. 4024 POSTER IMRT for high risk prostate cancer based on sentinel node optimised target volume definition – first clinical results. EJC Suppl 2007. [DOI: 10.1016/s1359-6349(07)71092-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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84
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Pütz M, Paulsen F, Ganswindt U, Bamberg M, Alber M, Belka C. 943 POSTER IMRT based radiosurgery – a planning study. EJC Suppl 2007. [DOI: 10.1016/s1359-6349(07)70582-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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85
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Sikora M, Dohm O, Alber M. A virtual photon source model of an Elekta linear accelerator with integrated mini MLC for Monte Carlo based IMRT dose calculation. Phys Med Biol 2007; 52:4449-63. [PMID: 17634643 DOI: 10.1088/0031-9155/52/15/006] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A dedicated, efficient Monte Carlo (MC) accelerator head model for intensity modulated stereotactic radiosurgery treatment planning is needed to afford a highly accurate simulation of tiny IMRT fields. A virtual source model (VSM) of a mini multi-leaf collimator (MLC) (the Elekta Beam Modulator (EBM)) is presented, allowing efficient generation of particles even for small fields. The VSM of the EBM is based on a previously published virtual photon energy fluence model (VEF) (Fippel et al 2003 Med. Phys. 30 301) commissioned with large field measurements in air and in water. The original commissioning procedure of the VEF, based on large field measurements only, leads to inaccuracies for small fields. In order to improve the VSM, it was necessary to change the VEF model by developing (1) a method to determine the primary photon source diameter, relevant for output factor calculations, (2) a model of the influence of the flattening filter on the secondary photon spectrum and (3) a more realistic primary photon spectrum. The VSM model is used to generate the source phase space data above the mini-MLC. Later the particles are transmitted through the mini-MLC by a passive filter function which significantly speeds up the time of generation of the phase space data after the mini-MLC, used for calculation of the dose distribution in the patient. The improved VSM model was commissioned for 6 and 15 MV beams. The results of MC simulation are in very good agreement with measurements. Less than 2% of local difference between the MC simulation and the diamond detector measurement of the output factors in water was achieved. The X, Y and Z profiles measured in water with an ion chamber (V = 0.125 cm(3)) and a diamond detector were used to validate the models. An overall agreement of 2%/2 mm for high dose regions and 3%/2 mm in low dose regions between measurement and MC simulation for field sizes from 0.8 x 0.8 cm(2) to 16 x 21 cm(2) was achieved. An IMRT plan film verification was performed for two cases: 6 MV head&neck and 15 MV prostate. The simulation is in agreement with film measurements within 2%/2 mm in the high dose regions (> or = 0.1 Gy = 5% D(max)) and 5%/2 mm in low dose regions (<0.1 Gy).
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Linton N, Pencea S, Krivosheev O, Napolitano M, Alber M. SU-FF-T-298: Monte Carlo Based Dose Calculations for Quality Assurance in the Electronic Medical Record. Med Phys 2007. [DOI: 10.1118/1.2760960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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87
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Sikora M, Dohm O, Tung Z, Alber M. WE-C-AUD-09: Dose Accuracy Gains by Use of Monte Carlo in Routine IMRT Treatment Optimization. Med Phys 2007. [DOI: 10.1118/1.2761517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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88
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Alber M. SU-FF-T-303: Monte Carlo in the Optimization of Intensity Modulated Proton Therapy. Med Phys 2007. [DOI: 10.1118/1.2760965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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89
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Alber M. MO-E-BRA-04: Application of Robust Optimization in Prostate Cancer. Med Phys 2007. [DOI: 10.1118/1.2761297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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90
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Muzik J, Soukup M, Alber M. TU-FF-A2-02: Comparison of Fixed-Beam IMRT, Helical Tomotherapy and IMPT for Selected Cases. Med Phys 2007. [DOI: 10.1118/1.2761456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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91
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Jeleń U, Alber M. A finite size pencil beam algorithm for IMRT dose optimization: density corrections. Phys Med Biol 2007; 52:617-33. [PMID: 17228109 DOI: 10.1088/0031-9155/52/3/006] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
For beamlet-based IMRT optimization, fast and less accurate dose computation algorithms are frequently used, while more accurate algorithms are needed to recompute the final dose for verification. In order to speed up the optimization process and ensure close proximity between dose in optimization and verification, proper consideration of dose gradients and tissue inhomogeneity effects should be ensured at every stage of the optimization. Due to their speed, pencil beam algorithms are often used for precalculation of beamlet dose distributions in IMRT treatment planning systems. However, accounting for tissue heterogeneities with these models requires the use of approximate rescaling methods. Recently, a finite size pencil beam (fsPB) algorithm, based on a simple and small set of data, was proposed which was specifically designed for the purpose of dose pre-computation in beamlet-based IMRT. The present work describes the incorporation of 3D density corrections, based on Monte Carlo simulations in heterogeneous phantoms, into this method improving the algorithm accuracy in inhomogeneous geometries while keeping its original speed and simplicity of commissioning. The algorithm affords the full accuracy of 3D density corrections at every stage of the optimization, hence providing the means for density related fluence modulation like penumbra shaping at field edges.
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Kleshneva T, Muzik J, Alber M. An algorithm for automatic determination of the respiratory phases in four-dimensional computed tomography. Phys Med Biol 2006; 51:N269-76. [PMID: 16885609 DOI: 10.1088/0031-9155/51/16/n01] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Recently, several techniques have been developed to improve the quality of computed tomography (CT) images of the thoracic and abdominal region that are degraded by the interference of the scanning process and respiration. Several devices for respiratory-correlated CT are available for clinical usage. They are based on the synchronization of the acquired CT image data with the respiratory motion using a signal from an external respiratory monitoring system. In this work, some practical aspects of clinical implementation of the multi-slice 4D CT scanner Somatom Sensation Open (Siemens Medical Solutions, Erlangen, Germany) equipped with a respiratory gating system (RGS) AZ-733V (Anzai Medical, Tokyo, Japan) are discussed. A new algorithm developed for automatic respiratory phase determination needed for the reconstruction of the 4D CT images is presented.
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Witte M, van der Geer J, Schneider C, Lebesque J, Alber M, van Herk M. TU-C-ValB-04: Margin-Less Prostate IMRT Plans, Directly Optimized for TCP and NTCP Including Geometric Uncertainties. Med Phys 2006. [DOI: 10.1118/1.2241516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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94
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Thorwarth D, Alber M. 165 A study of pre-treatment hypoxia and reoxygenation with functional FDG and FMISO pet imaging and its correlation to radiotherapy outcome. Radiother Oncol 2006. [DOI: 10.1016/s0167-8140(06)80644-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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95
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Alber M, Ganswindt U, Belka C. 71 IGRT of the prostate with mr spectroscopy, 11C-choline and sentinel node imaging. Radiother Oncol 2006. [DOI: 10.1016/s0167-8140(06)80565-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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96
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Ganswindt U, Paulsen F, Glockerl S, Alber M, Corvin S, Hundt I, Bamberg M, Belka C. 126 Intensity modulated radiotherapy for high risk prostate cancer based on sentinel node optimized target volume definition. Radiother Oncol 2006. [DOI: 10.1016/s0167-8140(06)80605-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Söhn M, Birkner M, Yan D, Alber M. Modelling individual geometric variation based on dominant eigenmodes of organ deformation: implementation and evaluation. Phys Med Biol 2005; 50:5893-908. [PMID: 16333162 DOI: 10.1088/0031-9155/50/24/009] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We present a method of modelling inter-fractional organ deformation and correlated motion of adjacent organ structures in terms of so-called eigenmodes. The method is based on a principal component analysis (PCA) of organ shapes and allows for reducing the large dimensionality of geometry information from multiple CT studies to a few-parametric statistical model of organ motion and deformation. Eigenmodes are 3D vectorfields of correlated displacements of the organ surface points and can be seen as fundamental 'modes' of the patient's geometric variability. The amount of variability represented by the eigenmodes is quantified in terms of corresponding eigenvalues. Weighted sums of eigenmodes describe organ displacements/deformations and can be used to generate new organ geometries. We applied the method to four patient datasets of prostate/rectum/bladder with N = 15-18 CTs to assess interfractional geometric variation. The spectrum of eigenvalues was found to be dominated by only few values, indicating that the geometric variability of prostate/bladder/rectum is governed by only few patient specific eigenmodes. We evaluated the capability of this approach to represent the measured organ samples by calculating the residual errors for the organ surface points, using a varying number of eigenmodes. The distribution of residual errors shows fast convergence with the number of eigenmodes. Using 4 dominating modes, the range of residual errors for the four patients was 1.3-2.0 mm (prostate), 1.4-1.9 mm (rectum) and 1.5-1.9 mm (bladder). Thus, individual geometric variation taken from multiple imaging data can be described accurately by few dominating eigenmodes, thereby providing the most important factors to characterize deformable organ motion, which can assist adaptive radiotherapy planning.
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Ganswindt U, Paulsen F, Glocker S, Birkner M, Alber M, Corvin S, Anastasiadis A, Eichhorn K, Bares R, Bamberg M, Budach W, Belka C. Intensity Modulated Radiotherapy for High Risk Prostate Cancer Based on Sentinel Node Optimized Target Volume Definition. Int J Radiat Oncol Biol Phys 2005. [DOI: 10.1016/j.ijrobp.2005.07.548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Fogliata A, Nicolini G, Alber M, Asell M, Dobler B, El-Haddad M, Hårdemark B, Jelen U, Kania A, Larsson M, Lohr F, Munger T, Negri E, Rodrigues C, Cozzi L. IMRT for breast. A planning study. Radiother Oncol 2005; 76:300-10. [PMID: 16153730 DOI: 10.1016/j.radonc.2005.08.004] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2004] [Revised: 04/13/2005] [Accepted: 08/10/2005] [Indexed: 11/19/2022]
Abstract
BACKGROUND AND PURPOSE To evaluate the performance of ten different treatment-planning systems when intensity modulated (IMRT) plans are designed for breast treatments that include the irradiation of the internal mammary chain. PATIENTS AND METHODS A dataset of five patients (CT images and volumes of interest) was distributed to design IMRT plans on the ten systems. To minimise biases, the same geometry and clinical planning aims were imposed on the individual plans. Results were analysed in terms of dose distributions and dose volume histograms. RESULTS AND CONCLUSIONS For target coverage, the volume receiving more than 95% of the prescribed dose ranged from 77% (OTP) to 91% (Eclipse and Pinnacle), the volume receiving more than 107% ranged from 3.3% (Hyperion) to 23.2% (OTP). The mean dose to ipsilateral lung ranged from 13 Gy (Eclipse) to 18 Gy (OTP). The volume of the contralateral breast receiving more than 10 Gy ranged from 3% (Pinnacle) to 26% (Precise). The volume of heart receiving more than 20 Gy ranged from 7% (Eclipse) to 47% (Precise), the maximum significant dose to heart ranged from approximately 27 Gy (XiO) to approximately 49 Gy (Precise). The maximum significant dose to healthy tissue ranged from approximately 51 Gy (Eclipse) to approximately 62 Gy (OTP). It was also possible to show that the treatment geometry proposed here enables to minimise contralateral breast irradiation while keeping minimal ipsilateral lung (or heart) involvement and satisfactory target coverage.
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Soukup M, Fippel M, Alber M. 124 A pencil beam algorithm for intensity modulated proton therapy and its validation with Monte Carlo. Radiother Oncol 2005. [DOI: 10.1016/s0167-8140(05)81101-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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