1,656 research outputs found
Recommended from our members
Implementing a mobile diagnostic unit to increase access to imaging and laboratory services in western Kenya.
Access to basic imaging and laboratory services remains a major challenge in rural, resource-limited settings in sub-Saharan Africa. In 2016, the Academic Model Providing Access to Healthcare programme in western Kenya implemented a mobile diagnostic unit (MDU) outfitted with a generator-powered X-ray machine and basic laboratory tests to address the lack of these services at rural, low-resource, public health facilities. The objective of this paper is to describe the design, implementation, preliminary impact and operational challenges of the MDU in western Kenya. Since implementing the MDU at seven rural health facilities serving a catchment of over half a million people, over 4500 chest radiographs have been performed, with one or more abnormalities detected in approximately 30% of radiographs. We observed favorable feedback and uptake of MDU services by healthcare workers and patients. However, various operational challenges in the design and construction of the MDU and the transmission and reporting of radiographs in remote areas were encountered. Our experience supports the feasibility of deploying an MDU to increase access to basic radiology and laboratory services in rural, resource-limited settings
Implementation of Digital Tomosynthesis in a Real Radiology System
The work included in this thesis is framed on one of the lines of research carried out by the
Biomedical Imaging and Instrumentation Group from the Bioengineering and Aerospace
Department of Universidad Carlos III de Madrid working jointly with the Gregorio Marañón
Hospital. Its goal is to design and develop a new generation of Radiology Systems, valid for
clinical and veterinary applications, through the research and development of innovative
technologies in advanced image processing oriented to increase image quality, to reduce dose
and to incorporate tomographic capabilities. The latter will allow bringing tomography to
situations in which a CT system is not allowable due to cost issues or when the patient cannot
be moved (for instance, during surgery or ICU). It may also be relevant to reduce the radiation
dose delivered to the patient, if we can obtain a tomographic image from fewer projections
than using a CT.
In that context, this thesis deals with incorporating pseudo-tomographic capabilities, through a
tomosynthesis protocol, in a radiology room originally designed for planar images: the NOVA
FA digital radiography system developed by SEDECAL. The room consists of an X-ray generator,
a vertical wall stand system, a mobile elevating table and an automatic ceiling suspension
which allows the X-ray source to cover the whole volume of the room. Images are acquired
using a flat panel detector connected through Wi-Fi to the computer station.
Having evolved from conventional tomography, tomosynthesis produces section images at any
depth from projections obtained at different angles along a linear sweep through the use of a
suitable reconstruction algorithm.
A workflow was established for the incorporation of tomosynthesis protocols to the NOVA FA
system starting from the design of the protocol down to the reconstruction step. This required
the understanding of the system and the development of several software tools.
For the design of new protocols, a tomosynthesis module was incorporated to an in-house X-
ray simulation tool programmed in Matlab and CUDA.
As the X-ray room was built specifically for research, everything is manual and all the software
is open. This system is designed only for planar radiography and, as a consequence, it is very
cumbersome to incorporate a protocol that involves more than one projection. Therefore, a
new software tool was implemented in Matlab that allows the translation of each of the source-detector positions corresponding to the tomosynthesis design to the geometrical
parameters of the NOVA FA system and their automatic addition to its database.
To obtain a tomographic image from the data acquire, a reconstruction tool was developed in
Matlab with the ability to use several reconstruction algorithms including Shift-and-Add and
Backprojection.
Finally, two different evaluations were conducted: a geometric evaluation to assess the
correlation between the simulation tool and the X-ray room and an evaluation of the complete
workflow through the design and implementation of a simple tomosynthesis protocol using a
PBU-50 body phantom developed by Kyoto Kagatu. The results of these evaluation studies
showed the feasibility of the proposal.
It should be noted that the work of this thesis has a clear application in industry, since it is part
of a proof of concept of the new generation of radiology systems which will be commercialised
worldwide by the company SEDECAL.Ingeniería Biomédic
The Empirical Foundations of Teleradiology and Related Applications: A Review of the Evidence
Introduction: Radiology was founded on a technological discovery by Wilhelm Roentgen in 1895. Teleradiology also had its roots in technology dating back to 1947 with the successful transmission of radiographic images through telephone lines. Diagnostic radiology has become the eye of medicine in terms of diagnosing and treating injury and disease. This article documents the empirical foundations of teleradiology. Methods: A selective review of the credible literature during the past decade (2005?2015) was conducted, using robust research design and adequate sample size as criteria for inclusion. Findings: The evidence regarding feasibility of teleradiology and related information technology applications has been well documented for several decades. The majority of studies focused on intermediate outcomes, as indicated by comparability between teleradiology and conventional radiology. A consistent trend of concordance between the two modalities was observed in terms of diagnostic accuracy and reliability. Additional benefits include reductions in patient transfer, rehospitalization, and length of stay.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140295/1/tmj.2016.0149.pd
Technical Note: Phantom study to evaluate the dose and image quality effects of a computed tomography Organ-based Tube Current Modulation Technique
Purpose
This technical note quantifies the dose and image quality performance of a clinically available organ-dose-based tube current modulation (ODM) technique, using experimental and simulation phantom studies. The investigated ODM implementation reduces the tube current for the anterior source positions, without increasing current for posterior positions, although such an approach was also evaluated for comparison.
Methods
Axial CT scans at 120 kV were performed on head and chest phantoms on an ODM-equipped scanner (Optima CT660, GE Healthcare, Chalfont St. Giles, England). Dosimeters quantified dose to breast, lung, heart, spine, eye lens, and brain regions for ODM and 3D-modulation (SmartmA) settings. Monte Carlo simulations, validated with experimental data, were performed on 28 voxelized head phantoms and 10 chest phantoms to quantify organ dose and noise standard deviation. The dose and noise effects of increasing the posterior tube current were also investigated.
Results
ODM reduced the dose for all experimental dosimeters with respect to SmartmA, with average dose reductions across dosimeters of 31% (breast), 21% (lung), 24% (heart), 6% (spine), 19% (eye lens), and 11% (brain), with similar results for the simulation validation study. In the phantom library study, the average dose reduction across all phantoms was 34% (breast), 20% (lung), 8% (spine), 20% (eye lens), and 8% (brain). ODM increased the noise standard deviation in reconstructed images by 6%–20%, with generally greater noise increases in anterior regions. Increasing the posterior tube current provided similar dose reduction as ODM for breast and eye lens, increased dose to the spine, with noise effects ranging from 2% noise reduction to 16% noise increase. At noise equal to SmartmA, ODM increased the estimated effective dose by 4% and 8% for chest and head scans, respectively. Increasing the posterior tube current further increased the effective dose by 15% (chest) and 18% (head) relative to SmartmA.
Conclusions
ODM reduced dose in all experimental and simulation studies over a range of phantoms, while increasing noise. The results suggest a net dose/noise benefit for breast and eye lens for all studied phantoms, negligible lung dose effects for two phantoms, increased lung dose and/or noise for eight phantoms, and increased dose and/or noise for brain and spine for all studied phantoms compared to the reference protocol
The Effects of Organ-based Tube Current Modulation on Radiation Dose and Image Quality in Computed Tomography Imaging
The purpose of this thesis was to quantify dose and noise performance of organ-dose-based tube current modulation (ODM) through experimental studies with an anthropomorphic phantom and simulations with a voxelized phantom library. Tube current modulation is a dose reduction technique that modulates radiation dose in angular and/or slice directions based on patient attenuation. ODM technique proposed by GE Healthcare further reduces tube current for anterior source positions, without increasing current for posterior positions. Axial CT scans at 120 kV were performed on head and chest phantoms (Rando Alderson Research Laboratories, Stanford, CA) on an ODM-equipped scanner (Optima CT660, GE Healthcare, Chalfont St Giles, England). Dosimeters quantified dose to breast, lung, heart, spine, eye lens and brain regions (mobile MOSFET Dosimetry System, Best Medical, Ottawa, Canada) for ODM, AutomA (z-axis modulation), and SmartmA (angular and z-axis modulation) settings. Noise standard deviation was calculated in brain and chest regions of reconstructed images. To study a variety of patient sizes, Monte Carlo dose simulations, validated with experimental data, were performed on voxelized head and chest phantoms. Experimental studies on anthropomorphic chest and head phantoms demonstrated reduction in dose at all dosimeter locations with respect to SmartmA, with dose changes of -31.3% (breast), -20.7% (lung), -24.4% (heart), -5.9% (spine), -18.9% (eye), and -10.1% (brain). Simulation studies using voxelized phantoms indicated average dose changes of -33.4% (breast), -20.2% (lung), -18.6% (spine), -20.0% (eye) and -7.2% (brain). ODM reduced dose to the brain and lung tissues, however these tissues would experience up to 15.2% and 13.1% dose increase respectively at noise standard deviation equal to SmartmA. ODM reduced dose to the eye lens in 22 of 28 phantoms (-1.2% to -12.4%), had no change in dose for one phantom, and increased dose for four phantoms (0.7% to 2.3% ) with respect to SmartmA at equal noise standard deviation. All phantoms demonstrated breast dose reduction (-2.1% to -27.6%) at equal noise standard deviation. Experimental and simulation studies over a range of patient sizes indicate that ODM has the potential to reduce dose to radiosensitive organs by 5 - 38% with a limited increase in image noise
Advanced capabilities for planar X-ray systems
Mención Internacional en el título de doctorThe past decades have seen a rapid evolution towards the use of digital detectors
in radiology and a more flexible robotized movement of the system components,
X-ray tube and detector. This evolution opened the possibility for incorporating
advanced capabilities in these planar X-ray systems, and for providing new valuable
diagnostic information compared to the previous technology. Some of the current
challenges for radiography are to obtain more quantitative images and to reduce the
inherent superposition of tissues because of the 2D nature of the technique.
Dual energy radiography, based on the acquisition of two images at different
source voltages, enables a separate characterization of soft tissue and bone structures.
Its benefits over conventional radiography have been proven in different applications,
since it improves information content without adding significant extra
acquisition time or radiation dose.
In a different direction, a really disruptive advance would be to obtain 3D imaging
with systems designed just for planar images. The incorporation of tomographic
capabilities into these systems would have to deal with the acquisition of a limited
number of projections, with non-standard geometrical configurations.
This thesis presents original contributions in these two directions: dual energy
radiography and 3D imaging with X-ray systems designed for planar imaging. The
work is framed in a line of research of the Biomedical Imaging and Instrumentation
Group from the Bioengineering and Aerospace Department of University Carlos III
de Madrid working jointly with the University Hospital Gregorio Marañón, focused
on the advance of radiology systems. This research line is carried out in collaboration
with the group of Computer Architecture, Communications and Systems (ARCOS),
from the same university, the Imaging Research Laboratory (IRL) of the University
of Washington and the research center CREATIS, France. The research has a clear
focus on technology transfer to the industry through the company Sedecal, a Spanish
multinational among the 10 best world companies in the medical imaging field.
The first contribution of this thesis is a complete novel protocol to incorporate
dual energy capabilities that enable quantitative planar studies. The proposal is
based on the use of a preliminary calibration with a very simple and low-cost phantom
formed by two parts that represent soft tissue and bone equivalent materials.
This calibration is performed automatically with no strict placement requirements.
Compared to current Dual-energy X-ray Absorptiometry (DXA) systems, 1) it provides
real mass-thickness values directly, enabling quantitative planar studies instead
of relative comparisons, and 2) it is based on an automatic preliminary calibration without the need of interaction of an experienced technician.
The second contribution is a novel protocol for the incorporation of tomographic
capabilities into X-ray systems originally intended for planar imaging. For this purpose,
we faced three main challenges.
First, the geometrical trajectory of equipment follows non-standard circular orbits,
thus posing severe difficulties for reconstruction. To handle this, the proposed
protocol comprises a new geometrical calibration procedure that estimates all the
system parameters per-projection.
Second, the reconstruction of a limited number of projections from a reduced angular
span leads to severe artifacts when using conventional reconstruction methods.
To deal with these limited-view data, the protocol includes a novel advanced reconstruction
method that incorporates the surface information of the sample, which
can be extracted with a 3D light surface scanner. These data are introduced as an
imposed constraint following the Split Bregman formulation. The restriction of the
search space by exploiting the surface-based support becomes crucial for a complete
recovery of the external contour of the sample and surroundings when the angular
span is extremely reduced. The modular, efficient and flexible design followed for its
implementation allows for the reconstruction of limited-view data with non-standard
trajectories.
Third, the optimization of the acquisition protocols has not yet explored with
these systems. This thesis includes a study of the optimum acquisition protocols
that allowed us to identify the possibilities and limitations of these planar systems.
Using the surface-constrained method, it is possible to reduce the total number of
projections up to 33% and the angular span down to 60 degrees.
The contributions of this thesis open the way to provide depth and quantitative
information very valuable for the improvement of radiological diagnosis. This could
impact considerably the clinical practice, where conventional radiology is still the
imaging modality most used, accounting for 80-90% of the total medical imaging
exams. These advances open the possibility of new clinical applications in scenarios
where 1) the reduction of the radiation dose is key, such as lung cancer screening or
Pediatrics, according to the ALARA criteria (As Low As Reasonably Achievable),
2) a CT system is not usable due to movement limitations, such as during surgery
or in an ICU and 3) where costs issues complicate the availability of CT systems,
such as rural areas or underdeveloped countries.
The results of this thesis has a clear application in the industry, since it is part
of a proof of concept of the new generation of planar X-ray systems that will be
commercialized worldwide by the company SEDECAL (Madrid, Spain).Los últimos años están viendo un rápido avance de los sistemas de radiología hacia el
uso de detectores digitales y a una mayor flexibilidad de movimientos de los principales
componentes del sistema, el tubo de rayos X y el detector. Esta evolución abre
la posibilidad de incorporar capacidades avanzadas en sistemas de imagen plana por
rayos X proporcionando nueva información valiosa para el diagnóstico. Dos retos en
radiografía son obtener imágenes cuantitativas y reducir la superposición de tejidos
debida a la naturaleza proyectiva de la técnica.
La radiografía de energía dual, basada en la adquisición de dos imágenes a diferente
kilovoltaje, permite obtener imágenes de tejido blando y hueso por separado.
Los beneficios de esta técnica que aumenta la cantidad de información sin añadir
un tiempo de adquisición o de dosis de radiación extra significativos frente al uso de
radiografía convencional, han sido demostrados en diferentes aplicaciones.
En otra dirección, un avance realmente disruptivo sería la obtención de imagen
3D con sistemas diseñados únicamente para imagen plana. La incorporación de capacidades
tomográficas en estos sistemas tendría que lidiar con la adquisición de un
número limitado de proyecciones siguiendo trayectorias no estándar.
Esta tesis presenta contribuciones originales en esas dos direcciones: radiografía
de energía dual e imagen 3D con sistemas de rayos X diseñados para imagen plana.
El trabajo se encuadra en una línea de investigación del grupo de Imagen Biomédica
e Instrumentación del Departamento de Bioingeniería e Ingeniería Aerospacial de
la Universidad Carlos III de Madrid junto con el Hospital Universitario Gregorio
Marañon, centrada en el avance de sistemas de radiología. Esta línea de investigación
se desarollada en colaboración con el grupo Computer Architecture, Communications
and Systems (ARCOS), de la misma universidad, el grupo Imaging Research Laboratory
(IRL) de la Universidad de Washington y el centro de investigación CREATIS,
de Francia. Se trata de una línea de investigación con un claro enfoque de transferencia
tecnológica a la industria a través de la compañía SEDECAL, una multinacional
española de entre las 10 líderes del mundo en el campo de la radiología.
La primera contribución de esta tesis es un protocolo completo para incorporar
capacidades de energía dual que permitan estudios cuantitativos de imagen plana.
La propuesta se basa en una calibración previa con un maniquí simple y de bajo coste
formado por dos materiales equivalentes de tejido blando y hueso respectivamente.
Comparado con los sistemas actuales DXA (Dual-energy X-ray Absorptiometry),
1) proporciona valores reales de tejido atravesado, 2) se basa en una calibración
automática que no requiere la interacción de un técnico con gran experiencia. La segunda contribución es un protocolo nuevo para la incorporación de capacidades
tomográficas en sistemas de rayos X originariamente diseñados para imagen
plana. Para ello, nos enfrentamos a tres principales dificultades.
En primer lugar, las trayectorias que pueden seguir la fuente y el detector en
estos sistemas no constituyen órbitas circulares estándares, lo que plantea retos importantes
en la caracterización geométrica. Para solventarlo, el protocolo propuesto
incluye una calibración geométrica que estima todos los parámetros geométricos del
sistema para cada proyección.
En segundo lugar, la reconstrucción de un número limitado de proyecciones
adquiridas en un rango angular reducido da lugar a artefactos graves cuando se
reconstruye con algoritmos convencionales. Para lidiar con estos datos de ángulo
limitado, el protocolo incluye un nuevo método avanzado de reconstrucción que incorpora
la información de superficie de la muestra, que se puede se obtener con un
escáner 3D. Esta información se impone como una restricción siguiendo la formulación
de Split Bregman, para compensar la falta de datos. La restricción del espacio
de búsqueda a través de la explotación del soporte basado en superficie, es crucial
para una recuperación completa del contorno externo de la muestra cuando el rango
angular es extremadamente pequeño. El diseño modular, eficiente y flexible de la
implementación propuesta permite reconstruir datos de ángulo limitado obtenidos
con posiciones de fuente y detector no estándar.
En tercer lugar, hasta la fecha, no se ha explorado la optimización del protocolo
de adquisición con estos sistemas. Esta tesis incluye un estudio de los protocolos
óptimos de adquisición que permitió identificar las posibilidades y limitaciones de
estos sistemas de imagen plana. Gracias al método de reconstrucción basado en
superficie, es posible reducir el número total de proyecciones hasta el 33% y el rango
angular hasta 60 grados.
Las contribuciones de esta tesis abren la posibilidad de proporcionar información
de profundidad y cuantitativa muy valiosa para la mejora del diagnóstico radiológico.
Esto podría impactar considerablemente en la práctica clínica, donde la radiología
convencional es todavía la modalidad de imagen más utilizada, abarcando el 80-
90% del total de los exámenes de imagen médica. Estos avances abren la posibilidad
de nuevas aplicaciones clínicas en escenarios donde 1) la reducción de la dosis de
radiación es clave, como en screening de cáncer de pulmón, de acuerdo con el criterio
ALARA (As Low As Reasonably Achievable), 2) no se puede usar un sistema
TAC por limitaciones de movimiento como en cirugía o UCI, o 3) el coste limita la
disponibilidad de sistemas TAC, como en zonas rurales o en países subdesarrollados.
Los resultados de esta tesis presentan una clara aplicación industrial, ya que
son parte de un prototipo de la nueva generación de sistemas planos de rayos X que
serán distribuidos mundialmente por la compañía SEDECAL.This thesis has been developed as part of several research projects with public funding:
- DPI2016-79075-R. ”Nuevos escenarios de tomografía por rayos X”, IP: Mónica
Abella García, Ministerio de Economía y Competitividad, 01/01/2017-31/12/2019,
147.620 e.
- ”Nuevos escenarios de tomografía por rayos X (NEXT) DPI2016-79075-R.
Ministerio de Economía”, Industria y Competitividad. (Universidad Carlos
III de Madrid). 30/12/2016-29/12/2019. 147.620 e.
(…)
- FP7-IMI-2012 (GA-115337), ”PreDict-TB: Model-based preclinical development
of anti-tuberculosis drug combinations”. FP7-IMI - Seventh Framework
Programme (EC-EFPIA). Unión Europea. (Universidad Carlos III de Madrid).
01/05/2012-31/10/2017.
(…)
- TEC2013-47270-R, ”Avances en Imagen Radiológica (AIR)”, Ministerio de
Economía y Competitividad”, 01/01/2014-31/12/2016. IP: Mónica Abella Garcia
and Manuel Desco Menéndez. 160.204 e
(…)
- RTC-2014-3028-1, ”Nuevos Escenarios Clínicos con Radiología Avanzada (NECRA)”,
Ministerio de Economía y Competitividad, 01/06/2014-31/12/2016 IP: Mónica
Abella García. 2014-2016. 219.458,96 e
- IDI-20130301, ”Nuevo sistema integral de radiografía (INNPROVE: INNovative
image PROcessing in medicine and VEterinary)”, IP: Mónica Abella García
and Manuel Desco Menéndez. Ministerio de Economía y Competitividad.
Subcontratación CDTI, 14/01/2013-31/03/2015. Total: 1.860.629e (UC3M:
325.000e). (Art. 83)
- IPT-2012-0401-300000 INNPACTO 2012, ”Tecnologías para Procedimientos
Intraoperatorios Seguros y Precisos. XIORT. MINECO. (Universidad Carlos
III de Madrid). 01/01/2013-31/12/2015.Programa Oficial de Doctorado en Ingeniería MatemáticaPresidente: Doménec Ros Puig.- Secretario: Cyril Riddell.- Vocal: Yannick Boursie
Defining the road map to a UK national lung cancer screening programme
Lung cancer screening with low-dose CT was recommended by the UK National Screening Committee (UKNSC) in September, 2022, on the basis of data from trials showing a reduction in lung cancer mortality. These trials provide sufficient evidence to show clinical efficacy, but further work is needed to prove deliverability in preparation for a national roll-out of the first major targeted screening programme. The UK has been world leading in addressing logistical issues with lung cancer screening through clinical trials, implementation pilots, and the National Health Service (NHS) England Targeted Lung Health Check Programme. In this Policy Review, we describe the consensus reached by a multiprofessional group of experts in lung cancer screening on the key requirements and priorities for effective implementation of a programme. We summarise the output from a round-table meeting of clinicians, behavioural scientists, stakeholder organisations, and representatives from NHS England, the UKNSC, and the four UK nations. This Policy Review will be an important tool in the ongoing expansion and evolution of an already successful programme, and provides a summary of UK expert opinion for consideration by those organising and delivering lung cancer screenings in other countries
Prospective in silico evaluation of cone-beam computed tomography-guided stereotactic adaptive radiation therapy (CT-STAR) for the ablative treatment of ultracentral thoracic disease
PURPOSE: We conducted a prospective, in silico study to evaluate the feasibility of cone-beam computed tomography (CBCT)-guided stereotactic adaptive radiation therapy (CT-STAR) for the treatment of ultracentral thoracic cancers (NCT04008537). We hypothesized that CT-STAR would reduce dose to organs at risk (OARs) compared with nonadaptive stereotactic body radiation therapy (SBRT) while maintaining adequate tumor coverage.
METHODS AND MATERIALS: Patients who were already receiving radiation therapy for ultracentral thoracic malignancies underwent 5 additional daily CBCTs on the ETHOS system as part of a prospective imaging study. These were used to simulate CT-STAR, in silico
RESULTS: Seven patients were accrued, 6 with intraparenchymal tumors and 1 with a subcarinal lymph node. CT-STAR was feasible in 34 of 35 simulated fractions. In total, 32 dose constraint violations occurred when the P
CONCLUSIONS: CT-STAR widened the dosimetric therapeutic index of ultracentral thorax SBRT compared with nonadaptive SBRT. A phase 1 protocol is underway to evaluate the safety of this paradigm for patients with ultracentral early-stage NSCLC
- …