Marcus Oliveira

Dr. Marcus Oliveira

orcid

Research Focus & Metrics

Academic Career Length

15Years (2012-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 September 2022 in Journal of Radiological Protection
Verified
Journal Article
Open access
PDF file
CUCarlos Ubeda
Carlos Ubeda
EVEliseo Vano
Eliseo Vano
MPMaria Del Rosario Perez
Maria Del Rosario Perez
PJPablo Jimenez
Pablo Jimenez
RRRaul Ramirez
Raul Ramirez
PCPedro Chiesa
Pedro Chiesa
The goal of the present study was to propose a set of preliminary regional diagnostic reference levels (DRLs) for pediatric interventional cardiology (IC) procedures in Latin America and the Caribbean countries, classified by age and weight groups. The study was conducted in the framework of the Optimization of Protection in Pediatric Interventional Radiology in Latin America and the Caribbean program coordinated by the World Health Organization and the Pan American Health Organization in cooperation with the International Atomic Energy Agency. The first step of the program was focused on pediatric IC. Dose data from diagnostic and therapeutic procedures were collected between December 2020 and December 2021. Regional DRLs were set as the third quartile of patient dose data (kerma area product) collected in 18 hospitals from 10 countries in an initial sample of 968 procedures. DRLs were set for four age bands and five weight ranges. The values obtained for the four age bands (<1 yr, 1 to <5 yr, 5 to <10 yr and 10 to <16 yr) were 2.9, 6.1, 8.8 and 14.4 Gy cm2 for diagnostic procedures, and 4.0, 5.0, 10.0 and 38.1 Gy cm2 for therapeutic procedures, respectively. The values obtained for the five weight bands (<5 kg, 5 to <15 kg, 15 to <30 kg, 30 to <50 kg and 50 to <80 kg) were 3.0, 4.5, 8.1, 9.2 and 26.8 Gy cm2 for diagnostic procedures and 3.7, 4,3, 7.3, 16.1 and 53.4 Gy cm2 for therapeutic procedures, respectively. While initial data were collected manually as patient dose management systems (DMSs) were not available in most of the hospitals involved in the program, a centralized automatic DMS for the collection and management of patient dose indicators has now been introduced and is envisaged to increase the sample size. The possibility of alerting on high dose values and introducing corrective actions will help in optimization.

1 March 2017 in Dentomaxillofacial Radiology
Verified
Journal Article
Closed access
MOMarcus Oliveira
Marcus Oliveira
AWAnn Wenzel
Ann Wenzel
PCPaulo Sergio Flores Campos
Paulo Sergio Flores Campos
RSRubens Spin-Neto
Rubens Spin-Neto
Objective:To undertake a systematic review on quality assurance phantoms for CBCT imaging, including studies on development and application of the phantoms.Methods:The MEDLINE (PubMed) bibliographic database was searched until May 2016 for studies evaluating the development and use of phantoms in CBCT image quality assurance. The search strategy was restricted to English-language publications using the following combined terms: (Cone Beam CT) OR (Cone Beam Computed Tomography) OR (Cone-Beam Computed Tomography) OR (CBCT) AND (quality OR phantom). It was assessed, which of the six image quality parameters stated by the European Commission could be evaluated with each phantom, and which of them actually were.Results:The search strategy yielded 37 studies, which had developed and used (25) or only used (12) a phantom in CBCT image quality assurance. According to the literature, in seven phantoms it is possible to evaluate four or more image quality parameters, while in 11 phantoms merely one parameter can be...

24 February 2024 in Journal of Medical Imaging and Radiation Sciences
Verified
Journal Article
Open access
MOMarcus Oliveira
Marcus Oliveira
PHPeter Hogg
Peter Hogg
LPLisa Di Prospero
Lisa Di Prospero
SLStephen Lacey
Stephen Lacey
SESamar El-Farra
Samar El-Farra
SJSafora F Johansen
Safora F Johansen
Various national solutions have been considered and implemented to address the factors which limit radiographer engagement in conducting research. Nevertheless, national literature continues to suggest that radiographer engagement in research remains low. The aim of this study was to extend the existing evidence base by conducting an international survey to assess diagnostic radiographers and therapeutic radiographers involvement with, barriers to and support mechanisms for research. Data collection was obtained via an online questionnaire which was distributed by the International Society of Radiographers and Radiologic Technologists (ISRRT). The study population included an international sample of qualified diagnostic radiographers and therapeutic radiographers across clinical and academic contexts in a variety of different roles such as clinical practice, management, education and research. In total, 420 diagnostic radiographers and therapeutic radiographers completed the survey. Multiple reasons were identified that were considered to inhibit respondents from conducting research. 69.3% indicated a combination of reasons for lack of engagement with research, rather than one single issue. Examples of reasons include: lack of time, insufficient research funding, limited research expertise, and lack of a suitable mentorship scheme. A minor segment of survey respondents indicated involvement in research activity. Lack of dedicated time to research, mentors, and funding were among the main barriers to conduct research. Further research is required to explore what solutions are available to overcoming the barriers.

1 January 2017 in Imaging Science in Dentistry
Verified
Journal Article
Open access
PDF file
MOMarcus Oliveira
Marcus Oliveira
ASAntónio Carvalho Santos
António Carvalho Santos
GPGraciano Paulo
Graciano Paulo
PCPaulo Sergio Flores Campos
Paulo Sergio Flores Campos
JSJoana Santos
Joana Santos
The purpose of this study was to apply a newly developed free software program, at low cost and with minimal time, to evaluate the quality of dental and maxillofacial cone-beam computed tomography (CBCT) images. A polymethyl methacrylate (PMMA) phantom, CQP-IFBA, was scanned in 3 CBCT units with 7 protocols. A macro program was developed, using the free software ImageJ, to automatically evaluate the image quality parameters. The image quality evaluation was based on 8 parameters: uniformity, the signal-to-noise ratio (SNR), noise, the contrast-to-noise ratio (CNR), spatial resolution, the artifact index, geometric accuracy, and low-contrast resolution. The image uniformity and noise depended on the protocol that was applied. Regarding the CNR, high-density structures were more sensitive to the effect of scanning parameters. There were no significant differences between SNR and CNR in centered and peripheral objects. The geometric accuracy assessment showed that all the distance measurements were lower than the real values. Low-contrast resolution was influenced by the scanning parameters, and the 1-mm rod present in the phantom was not depicted in any of the 3 CBCT units. Smaller voxel sizes presented higher spatial resolution. There were no significant differences among the protocols regarding artifact presence. This software package provided a fast, low-cost, and feasible method for the evaluation of image quality parameters in CBCT.

28 November 2022 in Journal of Medical Imaging and Radiation Sciences
Verified
Journal Article
Open access
Sibusiso MdletsheSibusiso Mdletshe
Sibusiso Mdletshe
OMOupa Steven Motshweneng
Oupa Steven Motshweneng
MOMarcus Oliveira
Marcus Oliveira
BTBhekisipho Twala
Bhekisipho Twala

5 February 2024 in Children
Verified
Journal Article
Open access
PDF file
VAViviane K. Asfora
Viviane K. Asfora
MFMarcelo Freitas
Marcelo Freitas
RMRegina B. Medeiros
Regina B. Medeiros
HSHugo Reuters Schelin
Hugo Reuters Schelin
AYAkemi Yagui
Akemi Yagui
HKHelen J. Khoury
Helen J. Khoury
Diagnostic reference levels (DRLs) are a pivotal strategy to be implemented since pediatric interventional cardiology procedures are increasing. This work aimed to propose an initial set of Brazilian DRLs for pediatric interventional diagnostic and therapeutic (D&T) procedures. A retrospective study was carried out in four Brazilian states, distributed across the three regions of the country. Data were collected from pediatric patients undergoing cardiac interventional procedures (CIPs), including their age and anthropometric characteristics, and at least four parameters (number of images, exposure time, air kerma–area product—PKA, and cumulative air kerma). Data from 279 patients undergoing CIPs were gathered (147 diagnostic and 132 therapeutic procedures). There were no significant differences in exposure time and the number of images between the D&T procedures. A wide range of PKA was observed when the therapeutic procedures were compared to diagnostics for all age groups. There were significant differences between the D&T procedures, whether grouping data by patient weight or age. In terms of cumulative air kerma, it was noted that no value exceeded the level to trigger a monitoring process for patients. This study shows that it is possible to adopt them as the first proposal to establish national DRLs considering pediatric patient groups.