Loma Linda University

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Reinhard Schulte, MD
Professor, Basic Sciences
School of Medicine
Associate Professor, Radiation Technology
School of Allied Health Professions
Publications    Scholarly Journals--Published
  • Penfold S. N., Schulte R. W., Censor Y., and Rosenfeld A. B. Total variation superiorization schemes in proton computed tomography image reconstruction Med. Phys. 37, 5887-5895, 2010. ( 11/2010 )
  • Bug M. U., Gargioni E., Guatelli S., Incerti S., Rabus H., Schulte R., and Rosenfeld A. B. Effect of a magnetic field on the track structure of low-energy electrons: a Monte Carlo study. Eur. Phys. J. D 60, 85–92, 2010 ( 6/2010 )
  • Garty G, Schulte R, Shchemelinin S, Leloup C, Assaf G, Breskin A, Chechik R, Bashkirov V, Milligan J, Grosswendt B. A nanodosimetric model of radiation-induced clustered DNA damage yields. Phys Med Biol. 55:761-81, 2010. ( 6/2010 )
  • Missaghian J., Hurley F., Bashkirov V., Colby B., Rykalin V., Kachigiun S., Fusi D., Schulte R., Martinez Mckinney F., Sadrozinski H. and Penfold S. Beam test results of a CsI calorimeter matrix element. JINST 5 P06001, 2010. ( 5/2010 )
  • Dowdell S., Clasie B., Wroe A., Guatelli S., Metcalfe P., Schulte R., and Rosenfeld A. Tissue equivalency of phantom materials for neutron dosimetry in proton therapy. Med. Phys. 36:5412, 2009. ( 12/2009 )
  • Penfold S.N., Rosenfeld A.B., Schulte R.W., Schubert K.E. A more accurate reconstruction system matrix for quantitative proton computed tomography. Med. Phys. 36:4511-4518, 2009. ( 10/2009 )
  • R W. Schulte, A. J. Wroe, V. A. Bashkirov, G. Y. Garty, A. Breskin, R. Chechik, S. Shchemelinin, E. Gargioni, B. Grosswendt, and A. B. Rosenfeld, “Nanodosimetry-Based Quality Factors for Radiation Protection in Space”, Zeitschrift fur Medizinische Physik 18:286-296, 2008. ( 12/2008 )
  • R. W. Schulte, S. N. Penfold, J. T. Tafas, and K. E. Schubert, “A maximum likelihood proton path formalism for application in proton computed tomography”, Med. Phys., 35, 4849-4856, 2008. ( 11/2008 )
    Abstract The limited spatial resolution in proton computed tomography (pCT) in comparison to X-ray CT is related to multiple Coulomb scattering (MCS) within the imaged object. The current generation pCT design utilizes silicon detectors that measure the position and direction of individual protons prior to and post traversing the patient to maximize the knowledge of the path of the proton within the imaged object. For efficient reconstruction with the proposed pCT system, one needs to develop compact and flexible mathematical formalisms that model the effects of MCS as the proton traverses the imaged object. In this paper, we present a compact, matrix-based most likely path (MLP) formalism employing Bayesian statistics and a Gaussian approximation of MCS. Using GEANT4 simulations in a homogeneous 20 cm water cube, the MLP expression was found to be able to predict the Monte Carlo tracks of 200 MeV protons to within 0.5 mm on average when employing 3s cuts on the relative exit angle and exit energy. These cuts were found to eliminate the majority of events not conforming to the Gaussian model of MCS used in the MLP derivation.
  • Wroe A., Rosenfeld A., Schulte R.. "Measured out-of-field dose equivalents delivered by proton therapy of prostate cancer." Medical Physics 34.9 (2007): 3449-3456. ( 9/2007 )
  • Schulte R.W.. " Proton Treatment Room Concepts for Precision and Efficiency." Technology in Cancer Research and Treatment 6.(Suppl.) (2007): 55-60. ( 8/2007 )
    Proton radiation therapy involves accurate delivery of proton beams to targets inside the body without direct visual control of the internal anatomy. Targeting of the tumor and avoidance of critical structures within the patient have to be both accurate and precise to achieve the desired therapeutic results. Good understanding of proton radiation delivery and patient alignment concepts in the treatment room is essential to achieve this goal. This overview article presents treatment room concepts that will ensure precise proton beam delivery and, at the same time, guarantee an efficient patient throughput. Concepts discussed include effective patient immobilization, image-guided alignment verification, appropriate training of radiotherapists, and the physician''s integrative role in understanding the complex spatial relationships between tumor, organs at risk, treatment beam configuration, and application of proton radiation dose. It will be demonstrated that in addition to the technical armamentarium, now commonplace in modern radiation oncology departments, the interaction between radiation oncologist, medical physicist and radiotherapist is an important for an efficient operation of a proton treatment facility.
  • Reinhard W. Schulte. "Strategies for Image-guided Proton Therapy of Cancer." U.S. Oncological Disease 2007.I (2007): 75-77. ( 5/2007 ) Link...
  • Bruzzi M., Blumenkrantz N., Feldt J., Heimann J., Sadrozinski H. F.-W., Seiden A., Williams D. C., Bashkirov V., Schulte R., et al. "Prototype Tracking Studies for Proton CT." IEEE Trans. Nucl. Sci. 54,140 - 145, 2007. 54.1 (2007): 140-145. ( 1/2007 )
    As part of a program to investigate the feasibility of proton computed tomography, the most likely path (MLP) of protons inside an absorber was measured in a beam experiment using a silicon strip detector set-up with high position and angular resolution. The locations of 200 MeV protons were measured at three different absorber depth of PolyMethylMethAcrylate-PMMA (3.75, 6.25 and 12.5 cm) and binned in terms of the displacement and the exit angle measured behind the absorber. The observed position distributions were compared to theoretical predictions showing that the location of the protons can be predicted with an accuracy of better than 0.5 mm.
  • Garty G., Schulte R., Shchemelinin S. et al. "First attempts at prediction of DNA strand-break yields using nanodosimetric data." Radiat.ion Protection Dosimetry 2006.1-4 (2006): 451-454. ( 12/2006 )
    We present the first results of our attempts to correlate yields of ionisation clusters in a gas model of DNA and corresponding double-strand break (DSB) yields in irradiated plasmids, using a simple statistical model of DNA lesion We present the first results of our attempts to correlate yields of ionisation clusters in a gas model of DNA and corresponding double-strand break (DSB) yields in irradiated plasmids, using a simple statistical model of DNA lesion We present the first results of our attempts to correlate yields of ionisation clusters in a gas model of DNA and corresponding double-strand break (DSB) yields in irradiated plasmids, using a simple statistical model of DNA lesion formation. Based on the same statistical model, we also provide a comparison of simulated nanodosimetric data for electrons and published DSB yields obtained with the PARTRAC code.
  • Garty G, Schulte R, Shchemelinin S, Grosswendt B, Leloup C, Assaf G, Breskin A, Chechik R, Bashkirov V. "First attempts at prediction of DNA strand-break yields using nanodosimetric data." Radiation Protection Dosimetry 122.1-4 (2007): 451-454. ( 12/2006 )
    We present the first results of our attempts to correlate yields of ionisation clusters in a gas model of DNA and corresponding double-strand break (DSB) yields in irradiated plasmids, using a simple statistical model of DNA lesion formation. Based on the same statistical model, we also provide a comparison of simulated nanodosimetric data for electrons and published DSB yields obtained with the PARTRAC code.
  • Bashkirov V, Schulte R, Breskin A, Chechik R, Schemelinin S, Garty G, Wroe A, Sadrozinski H, Grosswendt B. "Ion-counting nanodosemeter with particle tracking capabilities." Radiation Protection Dosimetry 122.1-4 (2007): 415-419. ( 12/2006 )
    An ion-counting nanodosemeter (ND) yielding the distribution of radiation-induced ions in a low-pressure gas within a millimetric, wall-less sensitive volume (SV) was equipped with a silicon microstrip telescope that tracks the primary particles, allowing correlation of nanodosimetric data with particle position relative to the SV. The performance of this tracking ND was tested with a broad 250 MeV proton beam at Loma Linda University Medical Center. The high-resolution tracking capability made it possible to map the ion registration efficiency distribution within the SV, for which only calculated data were available before. It was shown that tracking information combined with nanodosimetric data can map the ionisation pattern of track segments within 150 nm-equivalent long SVs with a longitudinal resolution of approximately 5 tissue-equivalent nanometers. Data acquired in this work were compared with results of Monte Carlo track structure simulations. The good agreement between ''tracking nanodosimetry'' data acquired with the new system and simulated data supports the application of ion-counting nanodosimetry in experimental track-structure studies.
  • A. Wroe, A. Rosenfeld,, I. Cornelius, D. Prokopovich, M. Reinhard,, R. Schulte, and V. Bashkirov. "Silicon Microdosimetry in Heterogeneous Materials: Simulation and Experiment." IEEE Transactions on Nuclear Science 53.6 (2007): 3738-3744. ( 12/2006 )
    Microdosimetry spectra obtained experimentally utilizing a Silicon-On-Insulator (SOI) microdosimeter within biological materials, was used to provide information on secondary radiation spectra at tissue boundaries. Comparative GEANT4 simulations of the experimental conditions were also conducted.
  • Schulte, RW, Li T.. "Innovative Strategies for Image-Guided Proton Treatment of Prostate Cancer." Technology in Cancer Research and Treatment 5.2 (2006): 91-100. ( 4/2006 )
    Proton beam therapy has a proven track record of treating non-metastatic prostate cancer with excellent disease-free survival results when using homogeneous doses between 75 and 82 CGE (Cobalt Gray Equivalent) to the prostate target volume. In clinically organ-confined prostate cancer, it may be possible, in principle, to further improve outcomes by reducing the margins of the high-dose planning target volume to the gross tumor volume and by covering the clinical target volume with a dose sufficient to control microscopic extensions of the tumor. This would allow further dose escalation without increasing the risk of acute and late effects. In this paper, we undertake a careful review of existing histopathological data that support this view and discuss technical possibilities to this approach utilizing the highly conformal characteristics of proton beams and combining them with modern 4D imaging and treatment techniques.
  • Schulte, RW, Bashkirov V, Shchemelinin, S, Breskin, A, Chechik, R, Garty, G, Wroe, A, Grosswendt, B.. "Mapping the sensitive volume of an ion-counting nanodosimeter." Journal of Instrumentation 1. (2006): 1-14. ( 4/2006 ) Link...
    We present two methods of independently mapping the dimensions of the sensitive volume in an ion-counting nanodosimeter. The first method is based on a calculational approach simulating the extraction of ions from the sensitive volume, and the second method on probing the sensitive volume with 250 MeV protons. Sensitive-volume maps obtained with both methods are compared and systematic errors inherent in both methods are quantified.
  • Wroe, AJ, Schulte, RW, Bashkirov, V, Rosenfeld, AB, Keeney, B, Spradlin, P, Sadrozinski, HEW, Grosswendt, B.. "Nanodosimetric cluster size distributions of therapeutic proton bams.." IEEE Transactions on Nuclear Science 53.2 (2006): 532-538. ( 4/2006 )
    As we move into the new millennium, it is important that we improve our understanding of radiation effects on humans and nanoelectronic systems. This understanding is essential in a number of areas including radiation therapy for cancer treatment and extended human presence in outer space. Nanodosimetry in low-pressure gases enables measurement of the energy deposition of ionizing radiation on a scale equivalent to the dimensions of the DNA molecule. This is extremely important for not only biological applications but also electronic applications, as the effect of radiation on nanoelectronics needs to be determined before they are installed and deployed in complex radiation fields. However, before nanodosimetry can be widely applied, further investigation is required to link the output of gas-based nanodosimeters to the actual effect of the radiation on a biological or electronic system. The purpose of this research is to conduct nanodosimetric measurements of proton radiation fields at the proton accelerator of Loma Linda University Medical Center (LLUMC) and to develop a Monte Carlo simulation system to validate and support further developments of experimental nanodosimetry. To achieve this, measured ion cluster size distributions are compared to the output from the Monte Carlo simulation system that simulates the characteristics of the LLUMC beam line and the performance of the nanodosimeter installed on one of LLUMC''s proton research beam lines.
  • Li, T, Liang, Z, Singanallur, JV, Satogata, TJ, Williams, DC, Schulte, RW.. "Reconstruction for proton computed tomography by tracing proton trajectories: a Monte Carlo study." Medical Physics 33.3 (2006): 699-706-. ( 3/2006 )
    Proton computed tomography (pCT) has been explored in the past decades because of its unique imaging characteristics, low radiation dose, and its possible use for treatment planning and on-line target localization in proton therapy. However, reconstruction of pCT images is challenging because the proton path within the object to be imaged is statistically affected by multiple Coulomb scattering. In this paper, we employ GEANT4-based Monte Carlo simulations of the two-dimensional pCT reconstruction of an elliptical phantom to investigate the possible use of the algebraic reconstruction technique (ART) with three different path-estimation methods for pCT reconstruction. The first method assumes a straight-line path (SLP) connecting the proton entry and exit positions, the second method adapts the most-likely path (MLP) theoretically determined for a uniform medium, and the third method employs a cubic spline path (CSP). The ART reconstructions showed progressive improvement of spatial resolution when going from the SLP [2 line pairs (lp) cm(-1)] to the curved CSP and MLP path estimates (5 lp cm(-1)). The MLP-based ART algorithm had the fastest convergence and smallest residual error of all three estimates. This work demonstrates the advantage of tracking curved proton paths in conjunction with the ART algorithm and curved path estimates.
  • Ronson, BB, Schulte, RW, Han KP, Loredo, LN, Slater JM, Slater JD.. "Fractionated proton beam irradiation of pituitary adenomas." International Journal of Radiation Oncology, Biology, Physics 64.2 (2006): 425-434. ( 2/2006 )
    PURPOSE: Various radiation techniques and modalities have been used to treat pituitary adenomas. This report details our experience with proton treatment of these tumors. METHODS AND MATERIALS: Forty-seven patients with pituitary adenomas treated with protons, who had at least 6 months of follow-up, were included in this analysis. Forty-two patients underwent a prior surgical resection; 5 were treated with primary radiation. Approximately half the tumors were functional. The median dose was 54 cobalt-gray equivalent. RESULTS: Tumor stabilization occurred in all 41 patients available for follow-up imaging; 10 patients had no residual tumor, and 3 had greater than 50% reduction in tumor size. Seventeen patients with functional adenomas had normalized or decreased hormone levels; progression occurred in 3 patients. Six patients have died; 2 deaths were attributed to functional progression. Complications included temporal lobe necrosis in 1 patient, new significant visual deficits in 3 patients, and incident hypopituitarism in 11 patients. CONCLUSION: Fractionated conformal proton-beam irradiation achieved effective radiologic, endocrinological, and symptomatic control of pituitary adenomas. Significant morbidity was uncommon, with the exception of postradiation hypopituitarism, which we attribute in part to concomitant risk factors for hypopituitarism present in our patient population.
  • Schulte RW, Bashkirov V, Klock MC, Li T, Wroe AJ, Evseev I, Williams DC, Satogata T. . "Density resolution of proton computed tomography." Med Phys 32. (2005): 1035-1046. ( 1/2005 )
  • Leloup C, Garty G, Assaf G, Cristovão A, Breskin A, Chechik R, Shchemelinin S, Paz-Elizur T, Livneh Z, Schulte RW, Bashkirov V, Milligan JR and Grosswendt B. "Evaluation of lesion clustering in irradiated plasmid DNA." Intl Journal of Radiation Biology 81. (2005): 41-54. ( 1/2005 )
  • Cirio R, Garelli E, Schulte R, Amerio S, Boriano A, Bourhaleb F, Coutrakon G, Donetti M, Giordanengo S, Koss P, Madon E, Marchetto F, Nastasi U, Peroni C, Santuari D, Sardo A, Scielzo G, Stasi M, Trevisiol E. "Two-dimensional and quasi-three-dimensional dosimetry of hadron and photon beams with the Magic Cube and the Pixel Ionization Chamber." Phys Med Biol 49. (2004): 3713-3724. ( 12/2004 )
  • Sadrozinski H.F.-W.; Bashkirov V.; Bruzzi M.; Ebrahimi M.; Feldt J.; Heimann J.; Keeney B.; Martinez-McKinney F.; Menichelli D.; Nelson G.; Nesom G.; Schulte R.W.M.; Seiden, A.; Spencer, E.; Wray, J.; Zhang, L. "The Particle Tracking Silicon Microscope PTSM." IEEE Trans.Nucl. Sci. 51. (2004): 2032-2036. ( 12/2004 )
  Books and Chapters
  • S.N. Penfold, R.W. Schulte, Y. Censor, V. Bashkirov, S. McAllister, K.E. Schubert, A.B. Rosenfeld, “Block-iterative and string-averaging projection algorithms in proton computed tomography image reconstruction”, In: Biomedical Mathematics: Promising Directions in Imaging, Therapy Planning and Inverse Problems, Y. Censor, M. Jiang and G. Wang (Eds), Medical Physics Publishing, Madison, WI, 347-368, 2010. ( 6/2010 )
  • Z. Liang, T. Li, R. Schulte, T. Satogata, D. Williams, and H. Sadrozinski, “Proton Computed Tomography”, in M. A. Hayat, Ed., Cancer Imaging – Instrumentation and Applications, vol.2, 99-120, 2007. ( 1/2008 ) Link...