To improve the quality of cancer treatment with protons, a translation of X-ray Computed Tomography (CT) images into a map of the proton stopping powers needs to be more accurate. Proton stopping powers determined from CT images have systematic uncertainties in the calculated proton range in a patient of typically 3-4\% and even up to 10\% in region containing bone~\cite{USchneider1995,USchneider1996,WSchneider2000,GCirrone2007,HPaganetti2012,TPlautz2014,GLandry2013,JSchuemann2014}. As a consequence, part of a tumor may receive no dose, or a very high dose can be delivered in healthy ti\-ssues and organs at risks~(e.g. brain stem)~\cite{ACKnopf2013}. A transmission radiograph of high-energy protons measuring proton stopping powers directly will allow to reduce these uncertainties, and thus improve the quality of treatment.
The best way to obtain a sufficiently accurate radiograph is by tracking individual protons traversing the phantom (patient)~\cite{GCirrone2007,TPlautz2014,VSipala2013}. In our simulations we have used an ideal position sensitive detectors measuring a single proton before and after a phantom, while the residual energy of a proton was detected by a BaF$_{2}$ crystal. To obtain transmission radiographs, diffe\-rent phantom materials have been irradiated with a 3x3~cm$^{2}$ scattered proton beam, with various beam energies. The simulations were done using the Geant4 simulation package~\cite{SAgostinelli2003}.
In this study we focus on the simulations of the energy loss radiographs for various proton beam energies that are clinically available in proton radiotherapy.
Geant4 software is used to study 10 MeV photon beams and 100 MeV proton beams. Conclusions are drawn as to the advantages and disadvantages of each therapy, with some additional commentary on the secondary effects of radiation damage in treatment.
Verification of patient specific proton stopping powers obtained in the patient treatment position can be used to reduce the distal margins needed in particle beam planning. Proton radiography can be used as a pre-treatment instrument to verify integrated stopping power consistency with the treatment planning CT. Although a proton radiograph is a pixel by pixel representation of integrated stopping powers, the image may also be of high enough quality and contrast to be used for patient alignment. This investigation qualifies the accuracy and image quality of a prototype proton radiography syst…
We propose an innovative method for proton radiography based on nuclear emulsion film detectors, a technique in which images are obtained by measuring the position and the residual range of protons passing through the patient's body. For this purpose, nuclear emulsion films interleaved with tissue equivalent absorbers can be used to reconstruct proton tracks with very high accuracy. This is performed through a fully automated scanning procedure employing optical microscopy, routinely used in neutrino physics experiments. Proton radiography can be used in proton therapy to obtain direct informa…
A survey of physics useful to proton radiotherapy, centered on stopping, scattering and hard scatters: 1. Introduction 2. The fundamental formula dose = fluence x mass stopping power. Practical units, comments on effective stopping power. 3. Range: experimental definition, Beth-Bloch CSDA theory, range-energy tables and approximations, range straggling. 4. Multiple Coulomb Scattering: suggested reading, elements of Moliere theory, the Gaussian approximation, scattering power. 5. Hard scatters (nuclear interactions): contributing reactions, shape and size of the halo, experiment, halo as a Mont…
Usually, Monte Carlo models are validated against experimental data. However, models of multiple Coulomb scattering (MCS) in the Gaussian approximation are exceptional in that we have theories which are probably more accurate than the experiments which have, so far, been done to test them. In problems directly sensitive to the distribution of angles leaving the target, the relevant theory is the Moliere/Fano/Hanson variant of Moliere theory. For transverse spreading of the beam in the target itself, the theory of Preston and Koehler holds. Therefore, in this paper we compare Geant4 simulations…
Purpose: To demonstrate a proton imaging system based on well-established fast scintillator technology to achieve high performance with low cost and complexity, with the potential of a straightforward translation into clinical use. Methods: The system tracks individual protons through one (X, Y) scintillating fiber tracker plane upstream and downstream of the object and into a 13 cm-thick scintillating block residual energy detector. The fibers in the tracker planes are multiplexed into silicon photomultipliers (SiPMs) to reduce the number of electronics channels. The light signal from the res…
Recent developments for the delivery of proton and ion beam therapy have been significant, and a number of technological solutions now exist for the creation and utilisation of these particles for the treatment of cancer. In this paper we review the historical development of particle accelerators used for external beam radiotherapy and discuss the more recent progress towards more capable and cost-effective sources of particles.
Scattering power (T = d/dx of mean squared multiple Coulomb scattering (MCS) angle), as used in proton transport theory, is properly viewed as a differential description of the Gaussian approximation to MCS theories such as Moliere's. That is, we seek a function T which, when integrated over a finite slab, will recover the Moliere/Fano/Hanson angle for that slab. To be accurate, T must include a single scattering correction, which means mathematically it must be nonlocal, depending on how much MCS has taken place as well as the energy and scattering material at the POI. We review five formulas…
Purpose: Variations in proton Relative Biological Effectiveness (RBE) with Linear Energy Transfer (LET) remain one of the largest sources of uncertainty in proton radiotherapy. This work seeks to identify physics-based metrics which can be applied to reduce this biological uncertainty. Materials and Methods: Three different physical metrics - dose, dose $\times$ LET and a complexity-weighted dose (CWD, Dose $\times$ (1+$κLET_D$) ) were compared with in vitro experimental studies of proton RBE and clinical treatment plans analysed using RBE models. The biological effects of protons in each syst…
These are notes for the lecture on Transport Theory in a one-week intensive course, "Techniques of Proton Radiotherapy". Topics are: Phase space diagrams: model beam line-effect of a scatterer-effect of a drift-the beam ellipse-phase space diagrams for the model beam line-emittance change in a drift-emittance change in a scatterer-phase space for a more realistic beam line-summary Miscellaneous topics: review of Gaussians-the Gaussian approximation to multiple Coulomb scattering (MCS)-relativistic single particle kinematics-completing the square-scattering power Fermi-Eyges theory: history-the…
An essential component in proton radiotherapy is the algorithm to calculate the radiation dose to be delivered to the patient. The most common dose algorithms are fast but they are approximate analytical approaches. However their level of accuracy is not always satisfactory, especially for heterogeneous anatomic areas, like the thorax. Monte Carlo techniques provide superior accuracy, however, they often require large computation resources, which render them impractical for routine clinical use. Track-repeating algorithms, for example the Fast Dose Calculator, have shown promise for achieving …
Proton therapy is nowadays becoming a wide spread clinical practice in cancer therapy and sophisticated treatment planning systems are routinely used to exploit at best the ballistic properties of charged particles. The information on the quality of the beams and the range of the protons is a key issue for the optimization of the treatment. For this purpose, proton radiography can be used in proton therapy to obtain direct information on the range of the protons, on the average density of the tissues for treatment planning optimization and to perform imaging with negligible dose to the patient…
This work addresses computing techniques for dose calculations in treatment planning with proton and ion beams, based on an efficient kernel-convolution method referred to as grid-dose spreading (GDS) and accurate heterogeneity-correction method referred to as Gaussian beam splitting. The original GDS algorithm suffered from distortion of dose distribution for beams tilted with respect to the dose-grid axes. Use of intermediate grids normal to the beam field has solved the beam-tilting distortion. Interplay of arrangement between beams and grids was found as another intrinsic source of artifac…
In their article published in Phys. Med. Biol. 59 (2014) 7675-7689, Lin et al studied the dose enhancement of of gold nanoparticles (GNPs) for proton therapy, which they compared with the case of photon irradiation. This comment points out two caveats to the methodlogy used by Lin et al that may not be evident to readers and may contribute to confusion in the literature about the dose enhancement by gold nanoparticles.
A new variant of the pencil-beam (PB) algorithm for dose distribution calculation for radiotherapy with protons and heavier ions, the grid-dose spreading (GDS) algorithm, is proposed. The GDS algorithm is intrinsically faster than conventional PB algorithms due to approximations in convolution integral, where physical calculations are decoupled from simple grid-to-grid energy transfer. It was effortlessly implemented to a carbon-ion radiotherapy treatment planning system to enable realistic beam blurring in the field, which was absent with the broad-beam (BB) algorithm. For a typical prostate …
FLASH is a new treatment modality that requires optimization of dose, dose rate, and LET. Here we validate these three quantities under FLASH conditions, which includes the quantum uncertainty in the time-dependent instantaneous dose rate (IDR) curves and LET spectra that underlie the newly proposed integrated optimization framework. Measurements of dose, IDR, and LET were performed at the Emory Proton Therapy Center using a FLASH proton beam with a nominal energy of 250 MeV and a 3D printed ridge filter. Because 3D printing resin is made from a proprietary chemical formula, we developed a met…
In their article published in Phys. Med. Biol. 60 (2015) 4149-4168, Lin et al studied the radiosensitizing effect of gold nanoparticles (GNPs) using radiation transport simulations and a biological model for the survival of irradiated cells. This comment points out several caveats to the methodlogy used by Lin et al. that may not be evident to readers and may contribute to confusion in the literature about the radiation effects of gold nanoparticles. The two main caveats are the high mass fraction of gold considered and a potential problem with the modified local effect model used to predict c…
We have used an inexpensive 3D printer mounting an inexpensive pre-irradiated silicon diode to measure the 2D dose distribution of a small (approximately 10mm FWHM) proton beam. z was measured with high resolution whereas x was changed on a 2mm grid for a total of 12 scans and 2 repeats in 20 minutes. The peak dose to the diode was approximately 530 cGy/s, and no degradation in diode sensitivity was observed. We present beam profiles and a 2D beam contour derived from these data. Most of the scan time was spent changing x by hand, and a more appropriate 3D printer along with an improved setup …
We are exploring low-dose proton radiography and computed tomography (pCT) as techniques to improve the accuracy of proton treatment planning and to provide artifact-free images for verification and adaptive therapy at the time of treatment. Here we report on comprehensive beam test results with our prototype pCT head scanner. The detector system and data acquisition attain a sustained rate of more than a million protons individually measured per second, allowing a full CT scan to be completed in six minutes or less of beam time. In order to assess the performance of the scanner for proton rad…
Beam monitoring for radiotherapy from conventional to FLASH dose rates using Low Gain Avalanche Silicon detectors
Universidad de Sonora（索诺拉大学）；University of Kansas（堪萨斯大学）；Washington University School of Medicine（华盛顿大学医学院）；Rice University（莱斯大学）；University of Kansas Cancer Center（堪萨斯大学癌症中心）；The University of Texas MD Anderson Cancer Center（德克萨斯大学安德森癌症中心）
A model for beam customization with collimators and a range-compensating filter based on the phase-space theory for beam transport is presented for dose distribution calculation in treatment planning of radiotherapy with protons and heavier ions. Independent handling of pencil beams in conventional pencil-beam algorithms causes unphysical collimator-height dependence in the middle of large fields, which is resolved by the framework comprised of generation, transport, collimation, regeneration, range-compensation, and edge-sharpening processes with a matrix of pencil beams. The model was verifi…
The radiotherapy of malignant diseases has reached much progress during the past decade. Thus, intensity modulated radiation therapy (IMRT) and VMAT (Rapidarc) now belong to the standard modalities of tumor treatment with high energy radiation in clinical practice. In recent time, the particle therapy (protons and partially with heavy carbon ions) has reached an important completion of these modalities with regard to some suitable applications. In spite of this enrichment essential features need further research activities and publications in this field: Nuclear reactions and the role of the r…
Laser acceleration promises innovation in particle beam therapy of cancer where an ultra-compact accelerator system for cancer beam therapy can become affordable to a broad range of patients. This is not feasible without the introduction of a technology that is radically different from the conventional accelerator-based approach. The laser acceleration method provides many enhanced capabilities for the radiation oncologist. It reduces the overall system size and weight by more than one order of magnitude. The characteristics of the particle beams (protons) make them suitable for a class of the…
A combined dose and microdosimetric modeling framework incorporating volume effects correlates with tissue sparing in proton minibeam radiotherapy
University of Trento（特伦托大学）；Trento Institute for Fundamental Physics and Application (TIFPA)（特伦托基础物理与应用研究所）；Istituto Nazionale Fisica Nucleare (INFN), Sezione di Catania（意大利国家核物理研究所（INFN），卡塔尼亚分部）；The Department of Physics & Astronomy at Louisiana State University (LSU)（路易斯安那州立大学物理与天文学系）；Department of Civil, Environmental and Mechanical Engineering, University of Trento（特伦托大学土木、环境与机械工程系）
It has been known for about sixty years that proton and heavy ion therapy is a very powerful radiation procedure for treating tumours. It has an innate ability to irradiate tumours with greater doses and spatial selectivity compared with electron and photon therapy and hence is a tissue sparing procedure. For more than twenty years powerful lasers have generated high energy beams of protons and heavy ions and hence it has been frequently speculated that lasers could be used as an alternative to RF accelerators to produce the particle beams necessary for cancer therapy. The present paper review…
The pencil-beam model is valid only when elementary Gaussian beams are small enough with respect to lateral heterogeneity of a medium, which is not always the case in heavy charged particle radiotherapy. This work addresses a solution for this problem by applying our discovery of self-similar nature of Gaussian distributions. In this method, Gaussian beams split into narrower and deflecting daughter beams when their size has exceeded the lateral heterogeneity limit. They will be automatically arranged with modulated areal density for accurate and efficient dose calculations. The effectiveness …
We present an algorithm for fast and accurate computation of the local dose distribution in MeV beams of protons, carbon ions or other heavy-charged particles. It uses compound Poisson-process modelling of track interaction and succesive convolutions for fast computation. It can handle mixed particle fields over a wide range of fluences. Since the local dose distribution is the essential part of several approaches to model detector efficiency or cellular response it has potential use in ion-beam dosimetry and radiotherapy.
DoseRAD2026 Challenge dataset: AI accelerated photon and proton dose calculation for radiotherapy
Department of Radiation Oncology, LMU University Hospital, LMU Munich, Munich, Germany（路德维希-马克西米利安慕尼黑大学医学院放射肿瘤科，慕尼黑大学医院，慕尼黑，德国）；Division of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany（放射肿瘤学中的医学物理部门，德国癌症研究中心（DKFZ），海德堡，德国）；National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany（肿瘤放射研究国家中心（NCRO），海德堡放射肿瘤学研究所（HIRO），海德堡，德国）；GSI Helmholtzzentrum für Schwerionenforschung, Biophysics Department, Darmstadt, Germany（重离子研究中心GSI，生物物理部门，达姆施塔特，德国）；Department of Physics and Astronomy, Heidelberg University, Heidelberg, Germany（海德堡大学物理与天文学系，海德堡，德国）；Institute of Biomedical Engineering, Karlsruhe Institute of Technology, Baden-Württemberg, Germany（生物医学工程研究所，卡尔斯鲁厄理工学院，巴登-符腾堡，德国）；Department of Radiotherapy, University Medical Center Utrecht, Utrecht, Netherlands（放射治疗科，乌得勒支大学医学中心，乌得勒支，荷兰）；Department of Radiation Oncology, Amsterdam UMC location Vrije Universiteit Amsterdam, Cancer Center Amsterdam, Cancer Treatment and Quality of Life, Amsterdam, Netherlands（放射肿瘤学系，阿姆斯特丹自由大学阿姆斯特丹校区，阿姆斯特丹癌症中心，癌症治疗与生活质量，阿姆斯特丹，荷兰）；Center for Proton Therapy, Paul Scherrer Institute (PSI), Villigen, Switzerland（质子治疗中心，瑞士保罗·谢尔研究所（PSI），维利根，瑞士）；Department of Radiation Oncology, University Hospital Heidelberg, Heidelberg, Germany（放射肿瘤学系，海德堡大学医院，海德堡，德国）；Radiation Physics, Department of Hematology, Oncology, and Radiation Physics, Skåne University Hospital, Lund, Sweden（放射物理，血液学、肿瘤学和放射物理部门，斯德哥尔摩大学医院，吕勒奥，瑞典）；Delft University of Technology, Department of Radiation Science and Technology, Delft, Netherlands（代尔夫特理工大学，辐射科学与技术系，代尔夫特，荷兰）；Radformation Inc., New York, US（Radformation公司，纽约，美国）
Proton radiography combined with X-ray computed tomography (CT) has been proposed to obtain a patient-specific calibration curve and reduce range uncertainties in cancer treatment with charged particles. The main aim of this study was to identify the optimal charged particle for the generation of the radiographies and to determine the optimal number of projections necessary to obtain minimal range errors. Three charged particles were considered to generate the radiographies: proton (p-rad), helium ions (α-rad) and carbon ions (c-rad). The problem formulation was viewed as a least square optimi…
Next generation online and real-time adaptive radiotherapy workflows require precise particle transport simulations in sub-second times, which is unfeasible with current analytical pencil beam algorithms (PBA) or stochastic Monte Carlo (MC) methods. We present a data-driven millisecond speed dose calculation algorithm (DoTA) accurately predicting the dose deposited by mono-energetic proton pencil beams for arbitrary energies and patient geometries. Given the forward-scattering nature of protons, we frame 3D particle transport as modeling a sequence of 2D geometries in the beam's eye view. DoTA…
Proton beam therapy has been developed to irradiate the tumor with higher precision and dose conformity compared to conventional X-ray irradiation. The dose conformity of this treatment modality may be further improved if narrower proton beams are used. Still, this is limited by multiple Coulomb scattering of protons through tissue. The primary aim of this work was to develop techniques to produce narrow proton beams and investigate the resulting dose profiles. We introduced and assessed three different proton beam shaping techniques: 1) metal collimators (100/150~MeV), 2) focusing of conventi…
Purpose: Currently, calculations of proton range in proton therapy patients are based on a conversion of CT Hounsfield Units of patient tissues into proton relative stopping power. Uncertainties in this conversion necessitate larger proximal and distal planned target volume margins. Proton CT can potentially reduce these uncertainties by directly measuring proton stopping power. We aim to demonstrate proton CT imaging with complex porcine samples, to analyze in detail three-dimensional regions of interest, and to compare proton stopping powers directly measured by proton CT to those determined…
This paper describes the optimization of a variable energy degrader design for the Midwest Proton Radiotherapy Institute (MPRI) [1]. To optimize the energy degrader design we investigate the choice of an optimal material for the degrader, the beam emittance growth in the degrader, and the matching of the degraded beam with the acceptance of a medical beam line.
Ionization detail parameters and cluster dose: A mathematical model for selection of nanodosimetric quantities for use in treatment planning in charged particle radiotherapy
A set of physics models and parameters pertaining to the simulation of proton energy deposition in matter are evaluated in the energy range up to approximately 65 MeV, based on their implementations in the Geant4 toolkit. The analysis assesses several features of the models and the impact of their associated epistemic uncertainties, i.e. uncertainties due to lack of knowledge, on the simulation results. Possible systematic effects deriving from uncertainties of this kind are highlighted; their relevance in relation to the application environment and different experimental requirements are disc…
Purpose: In treatment planning of charged-particle radiotherapy, patient heterogeneity is conventionally modeled as variable-density water converted from CT images to best reproduce the stopping power, which may lead to inaccuracies in the handling of multiple scattering and nuclear interactions. Although similar conversions can be defined for these individual interactions, they would be valid only for specific CT systems and would require additional tasks for clinical application. This study aims to improve the practicality of the interaction-specific heterogeneity correction. Methods: We cal…
Proton therapy is a cancer treatment technique currently in growth worldwide. It offers advantages with respect to conventional X-ray and $γ$-ray radiotherapy, in particular, a better control of the dose deposition allowing to reach a higher conformity in the treatments. Therefore, it causes less damage to the surrounding healthy tissue and less secondary effects. However, in order to take full advantage of its potential, improvements in treatment planning and dose verification are required. A new prototype of proton Computed Tomography scanner is proposed to design more accurate and precise t…
For efficient application of protons and light ions in radiotherapy, detailed knowledge and realistic models of the corresponding radiobiological mechanism are necessary. Basic characteristics of this mechanism have been represented within a probabilistic two-stage model. The processes that occur immediately after the traversals of individual particles and the response of cell to the total damage formed by all the particles have been distinguished. The model involves a probabilistic description of DNA damage formation and repair processes, too.
