Vladimir A Bashkirov

Vladimir A Bashkirov
Loma Linda University · Department of Basic Sciences

PhD

About

354
Publications
32,719
Reads
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8,197
Citations
Additional affiliations
February 1999 - present
Loma Linda University
Position
  • Professor (Associate)
June 1990 - March 1992
University of Milan
Position
  • Guest Scientist
Description
  • Scintillating detectors at ultra-low temperature
March 1979 - January 2005
Moscow Institute of Physics and Technology
Position
  • Senior Researcher

Publications

Publications (354)
Article
Full-text available
Background FLASH Radiotherapy (RT) is an emergent cancer RT modality where an entire therapeutic dose is delivered at more than 1000 times higher dose rate than conventional RT. For clinical trials to be conducted safely, a precise and fast beam monitor that can generate out‐of‐tolerance beam interrupts is required. This paper describes the overall...
Preprint
Full-text available
FLASH Radiotherapy (RT) is a potentially new cancer radiotherapy technique where an entire therapeutic dose is delivered in about 0.1 s and at ~1000 times higher dose rate than in conventional RT. For clinical trials to be conducted safely, precise and fast beam monitoring that can generate an out-of-tolerance beam interrupt is required. A FLASH Be...
Article
Background FLASH Radiotherapy (RT) is an emergent cancer radiotherapy modality where an entire therapeutic dose is delivered at more than 1000 times higher dose rate than conventional RT. For clinical trials to be conducted safely, a precise and fast beam monitor that can generate out-of-tolerance beam interrupts is required. This paper describes t...
Article
Exposing cancer cells to alternating electric fields of frequency 100-300 kHz and strength 1-4 V/cm has been shown to significantly reduce cancer growth in cell culture and in human patients. This form of anti-cancer therapy is more commonly referred to as tumor treating fields (TTFields), a novel treatment modality that has been approved by the U....
Article
Full-text available
Background Improving the accuracy of relative stopping power (RSP) in proton therapy may allow reducing range margins. Proton computed tomography (pCT) has been shown to provide state‐of‐the‐art RSP accuracy estimation, and various scanner prototypes have recently been built. The different approaches used in scanner design are expected to impact sp...
Article
Full-text available
Proton CT (pCT) is a promising new imaging technique that can reconstruct relative stopping power (RSP) more accurately than x-ray CT in each cubic millimeter voxel of the patient. This, in turn, will result in better proton range accuracy and, therefore, smaller planned tumor volumes (PTV). The hardware description and some reconstructed images ha...
Article
Purpose To reduce imaging artifacts and improve image quality of a specific proton computed tomography (pCT) prototype scanner by combining pCT data acquired at two different incident proton energies to avoid protons stopping in sub-optimal detector sections. Methods Image artifacts of a prototype pCT scanner are linked to protons stopping close t...
Article
Full-text available
Proton computed tomography (pCT) is a promising tomographic imaging modality allowing direct reconstruction of proton relative stopping power (RSP) required for proton therapy dose calculation. In this review article, we aim at highlighting the role of Monte Carlo (MC) simulation in pCT studies. After describing the requirements for performing prot...
Conference Paper
Full-text available
Robust methods, such as Tikhonov regularization and Bounded data uncertainty, have been used extensively in relatively small problems involving dense matrices for many decades, but have not been used in large-scale iterative methods for image reconstruction in particle imaging until recently. In this case, robust methods may allow more accurate rec...
Article
Full-text available
Proton computed tomography (pCT) has been proposed as an alternative to X-ray computed tomography (CT) for acquiring relative to water stopping power (RSP) maps used for proton treatment planning dose calculations. In parallel, it has been shown that dual energy X-ray CT (DECT) improves RSP accuracy when compared to conventional single energy X-ray...
Article
Full-text available
Data filtering is crucial for accurate relative stopping power (RSP) reconstruction in proton CT (pCT). In this work, we assess different filters and their performance in removing nuclear interactions for the US pCT collaboration prototype pCT system in Monte Carlo (MC) simulations. The potential of the recently proposed ΔE-E filter for pCT is inve...
Article
Full-text available
We present a method to accurately predict image noise in proton computed tomography (pCT) using data generated from a Monte Carlo simulation and a patient or object model that may be generated from a prior x-ray CT image. This enables noise prediction for arbitrary beam fluence settings and, therefore, the application of fluence-modulated pCT (FMpC...
Article
Full-text available
Purpose Proton CT (pCT) has the ability to reduce inherent uncertainties in proton treatment by directly measuring the relative proton stopping power with respect to water, thereby avoiding the uncertain conversion of X‐ray CT Hounsfield unit to relative stopping power and the deleterious effect of X‐ ray CT artifacts. The purpose of this work was...
Article
Full-text available
Single-event ion imaging enables the direct reconstruction of the relative stopping power (RSP) information required for ion-beam therapy. Helium ions were recently hypothesized to be the optimal species for such technique. The purpose of this work is to investigate the effect of secondary fragments on the image quality of helium CT (HeCT) and to a...
Article
Full-text available
Low-dose Proton Computed Tomography (pCT) is an evolving imaging modality that is used in proton therapy planning which addresses the range uncertainty problem. The goal of pCT is generating a 3D map of Relative Stopping Power (RSP) measurements with high accuracy within clinically required time frames. Generating accurate RSP values within the sho...
Article
Proton computed tomography (pCT) has recently seen considerable research interest as a means of reducing range uncertainties in proton therapy, by reconstructing directly relative stopping power to water (RSP). Recent detector developments have permitted the development of two list-mode pCT scanner prototypes based on broad (passively scattered) pr...
Article
Full-text available
A precise relative stopping power map of the patient is crucial for accurate particle therapy. Charged particle imaging determines the stopping power either tomographically – particle computed tomography (pCT) – or by combining prior knowledge from particle radiography (pRad) and x-ray CT. Generally, multiple Coulomb scattering limits the spatial r...
Article
Full-text available
This simulation study presents the application of fluence field modulated computed tomography (FFMCT), initially developed for x-ray CT, to proton computed tomography (pCT). By using pencil beam (PB) scanning, fluence modulated pCT (FMpCT) may achieve variable image quality in a pCT image and imaging dose reduction. Three virtual phantoms, a unifo...
Article
Full-text available
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 a...
Preprint
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 a...
Article
Full-text available
Purpose: Proton computed tomography (pCT) is a promising imaging technique to substitute or at least complement x-ray CT for more accurate proton therapy treatment planning as it allows calculating directly proton relative stopping power from proton energy loss measurements. A proton CT scanner with a silicon-based particle tracking system and a 5...
Article
Purpose: To determine the dependence of the accuracy in reconstruction of relative stopping power (RSP) with proton computerized tomography (pCT) scans on the purity of the proton beam and the technological complexity of the pCT scanner using standard phantoms and a digital representation of a pediatric patient. Methods: The Monte Carlo method w...
Article
Full-text available
Purpose: To evaluate the spatial resolution of proton CT using both a prototype proton CT scanner and Monte Carlo simulations. Methods: A custom cylindrical edge phantom containing twelve tissue-equivalent inserts with four different compositions at varying radial displacements from the axis of rotation was developed for measuring the modulation t...
Article
Purpose:The primary objective of this work is to measure the secondary neutron field produced by an uncollimated proton pencil beam impinging on different tissue-equivalent phantom materials using organic scintillation detectors. Additionally, the Monte Carlo code mcnpx-PoliMi was used to simulate the detector response for comparison to the measure...
Article
The track structure of ionizing radiation predominantly determines the biological effects after irradiation. A new detector to register 3D track structure segments in low pressure gas was proposed in a previous work. The device combines the operational principle of thick gas electron multipliers (THGEM), working in reverse polarity, and resistive p...
Article
Purpose:To characterize the modulation transfer function (MTF) of the pre-clinical (phase II) head scanner developed for proton computed tomography (pCT) by the pCT collaboration. To evaluate the spatial resolution achievable by this system. Methods:Our phase II proton CT scanner prototype consists of two silicon telescopes that track individual pr...
Article
Full-text available
We report on the operation and performance tests of a preclinical head scanner developed for proton computed tomography (pCT). After extensive preclinical testing, pCT is intended to be employed in support of proton therapy treatment planning and pre-treatment verification in patients undergoing particle-beam therapy. In order to assess the perform...
Poster
Full-text available
Absorbed dose times the relative biological effect (RBE) is inadequate to describe biological outcomes for proton and ion beams. It was shown that clusters of multiple ionizations within 2 – 3 nm correlate well with the yield of double-strand breaks in DNA [1]. Furthermore, it is assumed that the reason for the higher biological effectiveness of hi...
Article
Full-text available
Purpose: Protoncomputed tomography (pCT) will enable accurate prediction of proton and ion range in a patient while providing the benefit of lower radiation exposure than in x-ray CT. The accuracy of the range prediction is essential for treatment planning in proton or ion therapy and depends upon the detector used to evaluate the water-equivalent...
Article
We report on the design, fabrication, and first tests of a tomographic scanner developed for proton computed tomography (pCT) of head-sized objects. After extensive preclinical testing, pCT is intended to be employed in support of proton therapy treatment planning and pre-treatment verification in patients undergoing particle-beam therapy. The scan...
Article
Full-text available
Radiation therapy with protons and heavier ions is an attractive form of cancer treatment that could enhance local control and survival of cancers that are currently difficult to cure and lead to less side effects due to sparing of normal tissues. However, particle therapy faces a significant technical challenge because one cannot accurately predic...
Conference Paper
Full-text available
Proton CT is currently being explored with Monte Carlo simulation studies as well as first experimental scanner prototypes as a method to improve the planning and delivery accuracy of particle therapy. The existing scanner prototype (Phase II) built by a collaboration of investigators at Loma Linda University (LLU), UC Santa Cruz, and Baylor Univer...
Article
Full-text available
The spatial distribution of radiation-induced ionisations in sub-cellular structures plays an important role in the initial formation of radiation damage to biological tissues. Using the nanodosimetry approach, physical characteristics of the track structure can be measured and correlated to DNA damage. In this work, a novel nanodosimeter is presen...
Article
Purpose: To characterize tissue equivalence of phantom materials in terms of secondary neutron production and dose deposition from neutrons produced in radiation therapy phantom materials in the context of proton therapy using Monte Carlo simulations and measurements. Methods: In order to study the influence of material choice on neutron production...
Article
Purpose To develop the methodology to evaluate the clinical performance of a Phase II Proton CT scanner Methods Range errors on the order of 3%‐5% constitute a major uncertainty in current charged particle treatment planning based on Hounsfield Unit (HU)‐relative stopping power (RSP) calibration curves. Within our proton CT collaboration, we previ...
Article
Clustered DNA damages are considered the critical lesions in the pathways leading from the initial energy deposition by radiation to radiobiological damage. The spatial distribution of the initial DNA damage is mainly determined by radiation track-structure at the nanometer level. In this work, a novel experimental approach to image the three-dimen...
Article
Full-text available
Proton radiography has applications in patient alignment and verification procedures for proton beam radiation therapy. In this paper, we report an experiment which used 200 MeV protons to generate proton energy-loss and scattering radiographs of a hand phantom. The experiment used the first-generation proton computed tomography (CT) scanner protot...
Patent
Full-text available
Disclosed are systems, devices and methodologies relating to an ion induced impact ionization detector and uses thereof. In certain implementations, the detector can include a dielectric layer having one or more wells. An anode layer defining apertures to accommodate the openings of the wells can be disposed on one side of the dielectric layer, and...
Patent
Disclosed are systems and methods for characterizing interactions or proton beams in tissues. In certain embodiments, charged particles emitted during passage of protons, such as those used for therapeutic and/or imaging purposes, can be detected at relatively large angles. In situations where beam intensity is relatively low, such as in certain im...
Patent
Disclosed are systems and methods for characterizing interactions or proton beams in tissues. In certain embodiments, charged particles emitted during passage of protons, such as those used for therapeutic and/or imaging purposes, can be detected at relatively large angles. In situations where beam intensity is relatively low, such as in certain im...
Article
Range errors of the order of 3%-5% constitute a major uncertainty in charged particle treatment planning. The purpose of this ongoing work is to investigate the usefulness of proton CT for the determination of relative proton stopping power of tissues.
Article
Full-text available
This paper discusses the design and operation of the 1st proton CT scanner for 3D imaging. Reduction of proton range uncertainties and improved dose accuracy in the patient for treatment planning are central goals. A central CT slice acquired by reconstruction of 134 million proton tracks through a 14 cm spherical polystyrene phantom with high and...
Article
We describe a new head scanner developed for Proton Computed Tomography (pCT) in support of proton therapy treatment planning, aiming at reconstructing an accurate map of the stopping power (S.P.) in a phantom and, in the future, in patients. The system consists of two silicon telescopes which track the proton before and after the phantom/patient,...
Conference Paper
Full-text available
This paper considers how to determine the boundary of an object by comparing two methods: space carving (SC) and filtered back-projection (FBP). Determination of the boundary is an important first step in proton CT. The boundary is used to set up the large sparse linear system of equations, which are then solved to determine the relative stopping p...
Conference Paper
In support of developing the next phase of a proton computed tomography (pCT) scanner with features making it applicable to clinical situations, much insight can be gained through Monte Carlo simulation using Geant4. Careful simulation of energy/range detectors, as well as silicon strip detectors (SSDs), has offered insights into the physical limit...
Conference Paper
We report on the development of a range counter to be used in a new head scanner developed for proton Computed Tomography (pCT) in support of proton therapy treatment planning. The scanner consists of two silicon telescopes which track the proton before and after the phantom/patient, and an energy detector which measures the residual energy or rang...
Article
The authors present a calibration method for a prototype proton computed tomography (pCT) scanner. The accuracy of these measurements depends upon careful calibration of the energy detector used to measure the residual energy of the protons that passed through the object. A prototype pCT scanner with a cesium iodide (CsI(Tl)) crystal calorimeter wa...
Conference Paper
Full-text available
CONCLUSION Proton CT has the potential to substantially improve the range accuracy of proton beams and to provide a low-dose imaging modality for daily image guidance. Careful evaluation of this novel technique is underway. BACKGROUND Proton CT is a novel tomographic imaging modality, which has become a realistic possibility with the increasing av...
Conference Paper
BACKGROUND Proton CT can provide improved dose accuracy in treatment planning for proton therapy. In addition, lower doses than X-ray CT are theoretically possible and streaking artifacts will be reduced or eliminated. The first proton CT scanner has now been tested in a proton beam and the results are presented. This paper focuses on the detector...
Article
A YAG(Ce) crystal has been characterized with a proton beam up to 100 MeV. Tests were performed to investigate the possibility of using this detector as a proton calorimeter. A crystal size has been chosen that is able to stop up to 200 MeV. Energy resolution and light response have been measured at Laboratori Nazionali del Sud with a proton beam u...
Article
Full-text available
Proton Computed Tomography (pCT) is being developed in support of proton therapy and treatment planning. The aim of pCT, to reconstruct an accurate map of the stopping power (S.P.) in a phantom and, in the future, in patients, is being pursued with a diverse list of detector systems, using the entire arsenal of tracking and energy detectors develop...