Four-Dimensional Dose Reconstruction for Scanned Proton Therapy Using Liver 4DCT-MRI

Published:February 23, 2016DOI:


      Four-dimensional computed tomography-magnetic resonance imaging (4DCT-MRI) is an image-processing technique for simulating many 4DCT data sets from a static reference CT and motions extracted from 4DMRI studies performed using either volunteers or patients. In this work, different motion extraction approaches were tested using 6 liver cases, and a detailed comparison between 4DCT-MRI and 4DCT was performed.

      Methods and Materials

      4DCT-MRI has been generated using 2 approaches. The first approach used motion extracted from 4DMRI as being “most similar” to that of 4DCT from the same patient (subject-specific), and the second approach used the most similar motion obtained from a motion library derived from 4DMRI liver studies of 13 healthy volunteers (population-based). The resulting 4DCT-MRI and 4DCTs were compared using scanned proton 4D dose calculations (4DDC).


      Dosimetric analysis showed that 93% ± 8% of points inside the clinical target volume (CTV) agreed between 4DCT and subject-specific 4DCT-MRI (gamma analysis: 3%/3 mm). The population-based approach however showed lower dosimetric agreement with only 79% ± 14% points in the CTV reaching the 3%/3 mm criteria.


      4D CT-MRI extends the capabilities of motion modeling for dose calculations by accounting for realistic and variable motion patterns, which can be directly employed in clinical research studies. We have found that the subject-specific liver modeling appears more accurate than the population-based approach. The former is particularly interesting for clinical applications, such as improved target delineation and 4D dose reconstruction for patient-specific QA to allow for inter- and/or intra-fractional plan corrections.
      To read this article in full you will need to make a payment
      ASTRO Member Login
      ASTRO Members, full access to the journal is a member benefit. Use your society credentials to access all journal content and features.

      Purchase one-time access:

      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Knopf A.
        • Lomax A.J.
        In the context of radiosurgery - pros and cons of rescanning as a solution for treating moving targets with scanned particle beams.
        Phys Med. 2014; 30: 551-554
        • von Siebenthal M.
        • Székely G.
        • Gamper U.
        • et al.
        4D MR imaging of respiratory organ motion and its variability.
        Phys Med Biol. 2007; 52: 1547-1564
        • Boye D.
        • Lomax A.J.
        • Knopf A.
        Mapping motion from 4D-MRI to 3D-CT for use in 4D dose calculations: a technical feasibility study.
        Med Phys. 2013; 40: 061702
        • Zhang Y.
        • Knopf A.
        • Tanner C.
        • et al.
        Deformable motion reconstruction for scanned proton beam therapy using on-line x-ray imaging.
        Phys Med Biol. 2013; 58: 8621-8645
        • Schaffner B.
        • Pedroni E.
        • Lomax A.J.
        Dose calculation models for proton treatment planning using a dynamic beam delivery system: an attempt to include density heterogeneity effects in the analytical dose calculation.
        Phys Med Biol. 1999; 44: 27-41
        • Lomax A.J.
        • Böhringer T.
        • Bolsi A.
        • et al.
        Treatment planning and verification of proton therapy using spot scanning: initial experiences.
        Med Phys. 2004; 31: 3150-3157
        • Pedroni E.
        • Bearpark R.
        • Böhringer T.
        • et al.
        The PSI Gantry 2: a second generation proton scanning gantry.
        Z Med Phys. 2004; 14: 25-34
        • Bernatowicz K.
        • Lomax A.J.
        • Knopf A.
        Comparative study of layered and volumetric rescanning for different scanning speeds of proton beam in liver patients.
        Phys Med Biol. 2013; 58: 7905-7920
        • Perrin R.
        • Peroni M.
        • Bernatowicz K.
        • et al.
        SU-D-BRE-01: A Realistic Breathing Phantom of the Thorax for Testing New Motion Mitigation Techniques with Scanning Proton Therapy.
        Med Phys. 2014; 41
        • Ehrhardt J.
        • Werner R.
        • Schmidt-Richberg A.
        • et al.
        Statistical modeling of 4D respiratory lung motion using diffeomorphic image registration.
        IEEE Trans Med Imaging. 2011; 30: 251-265
        • Eilertsen K.
        • Vestad L.N.
        • Geier O.
        • et al.
        A simulation of MRI based dose calculations on the basis of radiotherapy planning CT images.
        Acta Oncol. 2008; 47: 1294-1302
        • Eley J.G.
        • Newhauser W.D.
        • Lüchtenborg R.
        • et al.
        4D optimization of scanned ion beam tracking therapy for moving tumors.
        Phys Med Biol. 2014; 59: 3431-3452
        • Langner U.W.
        • Keall P.J.
        Prospective displacement and velocity-based cine 4D CT.
        Med Phys. 2008; 35: 4501-4512
        • Marx M.
        • Ehrhardt J.
        • Werner R.
        • et al.
        Simulation of spatiotemporal CT data sets using a 4D MRI-based lung motion model.
        Int J Comput Assist Radiol Surg. 2014; 9: 401-409
        • Mittauer K.E.
        • Deraniyagala R.
        • Li J.G.
        • et al.
        Monitoring ABC-assisted deep inspiration breath hold for left-sided breast radiotherapy with an optical tracking system.
        Med Phys. 2015; 42: 134
        • Mori S.
        • Lu H.M.
        • Wolfgang J.A.
        • et al.
        Effects of interfractional anatomical changes on water-equivalent path length in charged-particle radiotherapy of lung cancer.
        J Radiat Res. 2009; 50: 513-519
        • Paganelli C.
        • Summers P.
        • Bellomi M.
        • et al.
        Liver 4DMRI: A retrospective image-based sorting method.
        Med Phys. 2015; 42: 4814
        • Pan T.
        • Sun X.
        Improvement of the cine-CT based 4D CT imaging.
        Med Phys. 2007; 34: 4499-4503
        • Persson G.
        • Nygaard D.
        • Brink C.
        • et al.
        Deviations in delineated GTV caused by artefacts in 4DCR.
        Radiother Oncol. 2010; 96: 61-66
        • Ravkilde T.
        • Keall P.J.
        • Grau C.
        • et al.
        Fast motion-including dose error reconstruction for VMAT with and without MLC tracking.
        Phys Med Biol. 2014; 59: 7279-7296
        • Shackleford J.A.
        • Kandasamy N.
        • Sharp G.C.
        On developing B-spline registration algorithms for multi-core processors.
        Phys Med Biol. 2010; 55: 6329-6351
        • Shackleford J.A.
        • Yang Q.
        • Lourenço A.M.
        • et al.
        Analytic regularization of uniform cubic B-spline deformation fields.
        Med Image Comput Comput Assist Interv. 2012; 15: 122-129
        • Tyagi N.
        • Yang K.
        • Gersten D.
        • et al.
        A real time dose monitoring and dose reconstruction tool for patient specific VMAT QA and delivery.
        Med Phys. 2012; 39: 7149
        • Yamamoto T.
        • Langner U.
        • Loo B.
        • et al.
        Retrospective analysis of artifacts in four-dimensional CT images of 50 abdominal and thoracic radiotherapy patients.
        Int J Radiat Oncol Biol Phys. 2008; 72: 1250-1258


      Commenting Guidelines

      To submit a comment for a journal article, please use the space above and note the following:

      • We will review submitted comments as soon as possible, striving for within two business days.
      • This forum is intended for constructive dialogue. Comments that are commercial or promotional in nature, pertain to specific medical cases, are not relevant to the article for which they have been submitted, or are otherwise inappropriate will not be posted.
      • We require that commenters identify themselves with names and affiliations.
      • Comments must be in compliance with our Terms & Conditions.
      • Comments are not peer-reviewed.