Radiological Physics Research Articles

Abstract ID: 210 Using Monte Carlo simulation as an experimental tool for training of medical physicists in a diagnostic radiological physics residency program

The usefulness of Monte Carlo for solving problems in radiation transport has allowed many applications in the medical physics field. Particularly as a teaching aid, Monte Carlo can be used to demonstrate previously the effects of the interaction of radiation with matter, which can be switched on and off to observe its influence under different conditions of irradiation and geometry. Based on that, this study reports an experience with using of Monte Carlo simulation for training of medical physicists during a residency program in diagnostic radiological physics. The approach was implemented in the EGSnrc Monte Carlo code system [1] to an understanding of the factors affecting quality image and to reduction of patient exposure in radiographic examinations performed in various areas of diagnostic radiology. All simulation conditions were based on the cases provided by the Report of AAPM Task Group 195 [2] . Physical characteristics of primary and scattered X-ray spectra, quantities as radiation dose and contrast-to-noise ratio of imaging systems, among others, could be studied under different radiological conditions by changing the input parameters in the simulation. Results obtained with this approach facilitate resident’s experimental learning curve, contributing to anticipate the discussion about practical problems that would be found in clinical environment. The use of Monte Carlo simulations with educational purposes demonstrated be an efficient and flexible tool for training of medical physicists in a residency program.

Intragastric Meal Distribution During Gastric Emptying Scintigraphy for Assessment of Fundic Accommodation: Correlation with Symptoms of Gastroparesis.

Impaired fundic accommodation (FA) limits fundic relaxation and the ability to act as a reservoir for food. Assessing intragastric meal distribution (IMD) during gastric emptying scintigraphy (GES) allows for a simple measure of FA. The 3 goals of this study were to evaluate trained readers' (nuclear medicine and radiology physicians) visual assessments of FA from solid-meal GES; develop software to quantify GES IMD; and correlate symptoms of gastroparesis with IMD and gastric emptying. Methods: After training to achieve a consensus interpretation of GES FA, 4 readers interpreted FA in 148 GES studies from normal volunteers and patients. Mixture distribution and κ-agreement analyses were used to assess reader consistency and agreement of scoring of FA. Semiautomated software was used to quantify IMD (ratio of gastric counts in the proximal stomach to those in the total stomach) at 0, 1, 2, 3, and 4 h after ingestion of a meal. Receiver-operating-characteristic analysis was performed to optimize the diagnosis of abnormal IMD at 0 min (IMD0) with impaired FA. IMD0, GES, water load testing, and symptoms were then compared in 177 patients with symptoms of gastroparesis. Results: Reader pairwise weighted κ-values for the visual assessment of FA averaged 0.43 (moderate agreement) for normal FA versus impaired FA. Readers achieved 84.0% consensus and 85.8% reproducibility in assessing impaired FA. IMD0 based on the division of the stomach into proximal and distal halves averaged 0.809 (SD, 0.083) for normal FA and 0.447 (SD, 0.132) (P < 0.01) for impaired FA. On the basis of receiver-operating-characteristic analysis, the optimal cutoff for IMD0 discrimination of normal FA from impaired FA was 0.568 (sensitivity, 86.7%; specificity, 91.7%). Of 177 patients with symptoms of gastroparesis, 129 (72.9%) had delayed gastric emptying; 25 (14.1%) had abnormal IMD0 Low IMD0 (impaired FA) was associated with increased early satiety (P = 0.02). Conclusion: FA can be assessed visually during routine GES with moderate agreement and high reader consistency. Visual and quantitative assessments of FA during GES can yield additional information on gastric motility to help explain patients' symptoms.

218 Incidental Findings on Pediatric Abdominal Computed Tomography at a Pediatric Trauma Center

The use of computed tomography (CT) in pediatric abdominal trauma has increased due to the availability of CT scans. This has led to increased detection of incidental findings which can be benign, while others may require follow up or urgent evaluation. This study describes the frequency and type of incidental findings on abdominal CT of trauma patients at a pediatric trauma center. This was a retrospective, observational study of pediatric patients ≤ 21 years of age presenting to the emergency department (ED) between January 1, 2004 and July 31, 2016. The study was conducted at Staten Island University Hospital, a 700-bed, tertiary-care teaching hospital in Staten Island, NY. The pediatric ED is a level II trauma center with a census of 25,000 patient visits per year. Information was extracted from a computer database. Prior to review, a consensus panel consisting of board certified emergency, pediatric and radiology physicians determined the appropriate classification of incidental findings. Each record was reviewed by a physician trained in the study protocol and data abstraction and was then reviewed by a second board certified physician to ensure consistency and accuracy. All findings were categorized into three groups; (1) Benign anatomic variants which require no form of intervention, (2a) Benign pathologic findings not requiring further investigation based on the known natural histories of these lesions, (2b) Likely benign pathologic, may require outpatient monitoring and (3) Pathologic findings requiring further workup. Group 3 was subcategorized as follows as (3a) Requiring attention before discharge and (3b) requiring follow-up as outpatient. 1073 trauma patients underwent a CT of the abdomen and pelvis during the study period. The mean age 15.5 years and 707 (66%) were male. 418 incidental findings were identified in 345 subjects. Of these, 290 (69%) were benign, 60 (14%) were likely benign pathologic, requiring possible outpatient monitoring. The most common findings in this category were adnexal and renal cysts. 68 (16%) of incidental findings required some form of further evaluation. The most common pathological findings were hepatic steatosis and hydronephrosis. Inter-rater agreement for classification of incidental findings was 0.96 (95% CI 0.93-0.98). Of those requiring further evaluation, 5 findings (1%) wanted further evaluation prior to discharge (Table 1). Nearly one third of patients had at least one radiographic finding not related to their traumatic injury. Of these, more than two-thirds had injuries not requiring further evaluation, but a significant number of patients required some form of further evaluation. Although the clinical significance of these findings is unclear, systems need to be in place for informing patients of these findings.

Development of a Monte Carlo multiple source model for inclusion in a dose calculation auditing tool.

The Imaging and Radiation Oncology Core Houston (IROC-H) (formerly the Radiological Physics Center) has reported varying levels of agreement in their anthropomorphic phantom audits. There is reason to believe one source of error in this observed disagreement is the accuracy of the dose calculation algorithms and heterogeneity corrections used. To audit this component of the radiotherapy treatment process, an independent dose calculation tool is needed. Monte Carlo multiple source models for Elekta 6MV and 10MV therapeutic x-ray beams were commissioned based on measurement of central axis depth dose data for a 10×10cm2 field size and dose profiles for a 40×40cm2 field size. The models were validated against open field measurements consisting of depth dose data and dose profiles for field sizes ranging from 3×3cm2 to 30×30cm2 . The models were then benchmarked against measurements in IROC-H's anthropomorphic head and neck and lung phantoms. Validation results showed 97.9% and 96.8% of depth dose data passed a ±2% Van Dyk criterion for 6MV and 10MV models respectively. Dose profile comparisons showed an average agreement using a ±2%/2mm criterion of 98.0% and 99.0% for 6MV and 10MV models respectively. Phantom plan comparisons were evaluated using ±3%/2mm gamma criterion, and averaged passing rates between Monte Carlo and measurements were 87.4% and 89.9% for 6MV and 10MV models respectively. Accurate multiple source models for Elekta 6MV and 10MV x-ray beams have been developed for inclusion in an independent dose calculation tool for use in clinical trial audits.

Development of a flattening filter free multiple source model for use as an independent, Monte Carlo, dose calculation, quality assurance tool for clinical trials.

The Imaging and Radiation Oncology Core-Houston (IROC-H) Quality Assurance Center (formerly the Radiological Physics Center) has reported varying levels of compliance from their anthropomorphic phantom auditing program. IROC-H studies have suggested that one source of disagreement between institution submitted calculated doses and measurement is the accuracy of the institution's treatment planning system dose calculations and heterogeneity corrections used. In order to audit this step of the radiation therapy treatment process, an independent dose calculation tool is needed. Monte Carlo multiple source models for Varian flattening filter free (FFF) 6 MV and FFF 10 MV therapeutic x-ray beams were commissioned based on central axis depth dose data from a 10 × 10 cm2 field size and dose profiles for a 40 × 40 cm2 field size. The models were validated against open-field measurements in a water tank for field sizes ranging from 3 × 3 cm2 to 40 × 40 cm2 . The models were then benchmarked against IROC-H's anthropomorphic head and neck phantom and lung phantom measurements. Validation results, assessed with a ±2%/2 mm gamma criterion, showed average agreement of 99.9% and 99.0% for central axis depth dose data for FFF 6 MV and FFF 10 MV models, respectively. Dose profile agreement using the same evaluation technique averaged 97.8% and 97.9% for the respective models. Phantom benchmarking comparisons were evaluated with a ±3%/2 mm gamma criterion, and agreement averaged 90.1% and 90.8% for the respective models. Multiple source models for Varian FFF 6 MV and FFF 10 MV beams have been developed, validated, and benchmarked for inclusion in an independent dose calculation quality assurance tool for use in clinical trial audits.

Needlestick Injuries in Interventional Radiology Are Common and Underreported.

Purpose To determine the prevalence of and risk factors for needlesticks in interventional radiology physicians, as well as the attitudes, behaviors, and conditions that promote or interfere with reporting of these injuries. Materials and Methods A total of 3889 interventional radiologists from academic and private practice in the United States were surveyed by emailing all interventional radiologist members of the Society of Interventional Radiology, including attending-level physicians and trainees (April-August 2016). The institutional review board waived the need for consent. Questions inquired about the nature, frequency, and type of needlestick and sharps injuries and whether and to whom these incidents were reported. Stepwise regression was used to determine variables predicting whether injuries were reported. Results In total, 908 (23%) interventional radiologists completed at least a portion of the survey. Eight hundred fourteen (91%) of 895 respondents reported a prior needlestick injury, 583 (35%) of 895 reported at least one injury while treating an HIV-positive patient, and 626 (71%) of 884 reported prior training regarding needlestick injury. There was, on average, one needlestick for every 5 years of practice. Most needlestick or sharps injuries were self inflicted (711 [87%] of 817) and involved a hollow-bore device (464 [56%] of 824). Only 566 (66%) of 850 injuries were reported. The most common reasons for not reporting included perceived lack of utility of reporting (79 [28%] of 282), perceived low risk for injury (56 [20%] of 282), noncontaminated needle (53 [19%] of 282), too-lengthy reporting process (37 [13%] of 282), and associated stigma (23 [8%] of 282). Only 156 (25%) of 624 respondents informed their significant other. Stepwise regression assessing variables affecting the likelihood of reporting showed that male sex (P = .009), low-risk patient (P < .0001), self injury (P = .010), trainee status (P < .0001), and the total number of prior injuries (P = .019) were independent predictors of not reporting. Conclusion Needlestick injuries are ubiquitous among interventional radiologists and are often not reported. © RSNA, 2017 Online supplemental material is available for this article.

Textbook of Radiology Physics, First Edition. Editors: HariqbalSingh, AmolSasane and RoshanLodha, Jaypee Brothers Medical Publishers (P) Ltd, New Delhi, India, 2016. Paperback 176 pp. Price: $40.00. ISBN 9789385891304.

This hardcover volume is the first edition textbook on radiology physics. It is composed of 25 chapters, starting with a general description about electromagnetic radiation, X-ray production and radiation protection. Then, it continues with topics on specific imaging modalities, such as, ultrasound, magnetic resonance, computed tomography (CT), mammography, positron emission tomography (PET), and single photon emission tomography (SPECT). The next few chapters address the issue of picture archiving and communication systems, contrast media used in CT, and artifacts. There is also a chapter on the planning of a radiology department. At the beginning of the textbook, you will find eight colorful plates of images and figures that are referenced throughout different sections of the book. The textbook provides a brief and simple description of various imaging systems. It is most suitable for residents who wish to perform adequately on examinations without taking the extra effort to understand the fundamental physics principles related to each modality. Since the textbook is written by physicians, it is ideal for radiology residents and technical staff working in imaging departments. It is also idyllic for medical colleges and various medical and hospital libraries. The book is probably not as detailed as some medical physicists in training would prefer, but it could be a good base for the initial understanding of the imaging chain. The 149 pages of the textbook begin with introducing the book contributors. There are 19 contributors in all. After a small preface and the acknowledgments section, the reader is introduced to the table of contents consisting of 25 chapters and a five page index. Although each chapter contains a substantial number of black and white figures and images, the reader can also revisit the eight plates of colored images, which follows the table of contents. Although not strictly necessary, a few references could have been added at the end of every chapter to facilitate further literature for the reader to review. This textbook provides a simple and concise description of the radiological physics of X-rays. It includes the essential information needed to understand how images are created, aspects that impact image quality, and factors that affect radiation risks and protection. Virginia Tsapaki is the Head of the medical physics department in Konstantopoulio General Hospital of Athens, Greece. She has been an IAEA expert in Medical Imaging Physics for over 10 years, IOMP Secretary General and EFOMP Chair of Projects Committee. She is currently the President of Hellenic Association of Medical Physicists (3rd term).

Assessment of Radiographers’ Awareness about Radiation Protection Principles in Hospitals of Bandar Abbas, Iran

Introduction This study was conducted to evaluate the radiographers’ awareness of radiation protection principles in the radiology centers of the hospitals of Bandar Abbas, Iran. Materials and Methods This analytical cross-sectional study was conducted on 50 radiographers of three hospitals affiliated with Hormozgan University of Medical Sciences in 2015. The data were collected using a two-part questionnaire. The first part was related to the demographic information of the radiographers(i.e. age, gender, work experience, workplace, and passing related training courses). The second part consisted of questions related to the radiographers’ awareness in three fields of radiology physics, radiation protection, and hazards of radiation. Results According to the results of the present study, the mean total scores of the radiographers’ awareness about the radiology physics, radiation protection, and hazards of radiation was 18.41±1.14 out of 22. However, the radiographers’ awareness of the three investigated fields had no statistically significant relationships with the work experience (P=0.244) and gender (P=0.386). However, there was a significant relationship between the radiographers’ awareness about the radiation protection and their education level (P=0.034). Moreover, a significant association was found between the radiographers’ awareness and their workplace (P=0.009). Additionally, the participation in the radiation training courses was significantly correlated with the radiographers’ awareness regarding the radiation hazards (P=0.022). Conclusion According to the findings of the present study, the awareness level of the radiographers about the radiation protection principles was relatively good. However, it seems that the education level of the staff should be enhanced through holding regular short-term radiation training courses.

Message from Editor-in-Chief and Deputy Editors: 10th Anniversary of Radiological Physics and Technology

Message from Editor-in-Chief and Deputy Editors: 10th Anniversary of Radiological Physics and Technology

Radiological Physics and Technology (RPT): Current Status and its Future.

Radiological Physics and Technology (RPT): Current Status and its Future.

Radiological Physics and Technology, Introduction of the Award (Doi Prize) and a New Goal of This Journal toward Next Decade

Radiological Physics and Technology, Introduction of the Award (Doi Prize) and a New Goal of This Journal toward Next Decade

Abstract TP367: Decreasing Decision to Transfer Times

Novant Health Greater Charlotte market is comprised of three advanced primary stroke care centers; one providing 24/7 stroke interventional radiology coverage. To expedite the transfer of patients meeting criteria for mechanical thrombectomy, the stroke best practice teams in the two community primary stroke centers collaborated to develop a protocol to improve the decision to transfer time to meet a goal of 120 minutes from door to skin puncture time, regardless of original transport destination. The Novant Health Charlotte market teams realize the benefit of cohesive physician coverage among the Emergency Department, Radiology and Inpatient Neurology physician providers. CTA scans performed in the non-interventional facilities are readily available to Neuro-Endovascular Radiologists, allowing for prompt interpretation and mobilization of the IR team to prepare for patient arrival. Recognizing internal critical care transport resources are limited and may not be available, the process was facilitated by the development of an activase transport protocol implemented by Mecklenburg County EMS in June of 2016. Since actual transport time is affected by traffic patterns in urban areas, the controllable measure selected by the teams was decision to transfer time. Prior to the initiation of the protocol, the median decision to transfer time for ischemic stroke patients requiring tertiary care was 66.5 minutes. Post protocol implementation the median time was reduced 32% to 44.5 minutes. Across the market, median door to skin puncture time in 2016 is 131.5 minutes. Ongoing evaluation of the transfer process, and multidisciplinary IR case review with identification of process variation is key to the success of this initiative. The Emergency Department at the tertiary care facility has been an instrumental partner in identifying issues that are barriers to timely throughput of these patients. A consistent feedback process informs all team members regarding patient outcomes. Individual case feedback is provided to all direct care givers, EMS crews and stroke team leaders, usually within 24 to 48 hours of the intervention. This data is shared monthly with the stroke best practice teams at the transferring facilities.

Abstract No. 361FEATURED ABSTRACT - Geospatial mapping of interventional radiology physician density

Abstract No. 361FEATURED ABSTRACT - Geospatial mapping of interventional radiology physician density

50 Years of the Radiological Research Accelerator Facility (RARAF).

The Radiological Research Accelerator Facility (RARAF) is in its 50th year of operation. It was commissioned on April 1, 1967 as a collaboration between the Radiological Research Laboratory (RRL) of Columbia University, and members of the Medical Research Center of Brookhaven National Laboratory (BNL). It was initially funded as a user facility for radiobiology and radiological physics, concentrating on monoenergetic neutrons. Facilities for irradiation with MeV light charged particles were developed in the mid-1970s. In 1980 the facility was relocated to the Nevis Laboratories of Columbia University. RARAF now has seven beam lines, each having a dedicated irradiation facility: monoenergetic neutrons, charged particle track segments, two charged particle microbeams (one electrostatically focused to <1 μm, one magnetically focused), a 4.5 keV soft X-ray microbeam, a neutron microbeam, and a facility that produces a neutron spectrum similar to that of the atomic bomb dropped at Hiroshima. Biology facilities are available on site within close proximity to the irradiation facilities, making the RARAF very user friendly.

The FC Rad Diag(SA): Stretched, but still in step – Report on a Royal College observership

A delegation of the College of Radiologists of the overarching Colleges of Medicine of South Africa observed the spring sitting of the Part 2B Examination of the Fellowship of the Royal College of Radiologists (FRCR) in London, in April 2016. Although the principal focus of the Observership was the Part 2B examination, the delegates also assessed broader aspects of the FRCR. This report presents an overview of current FRCR practices, including the findings of an independent review of the FRCR, and reflects on the implications for the South African Fellowship examination. The report is based on discussions with key Royal College role players, direct observation of the Part 2B examination and web-based documentation. It allows appreciation of the continued close alignment of the FC Rad Diag(SA) (Fellowship of the College of Radiologists of the Colleges of Medicine of South Africa) with the FRCR and highlights expected trends in the FC Rad Diag(SA). It also documents the increasing human resources required for successful conduct of examinations. It is hoped that the report will be of interest and relevance to the broad South African radiological community and to those contemplating specialist training in the discipline. It is trusted that it will encourage wider involvement of radiological and medical physics colleagues in the various FC Rad Diag(SA) examination processes.

Radiological Physics and Technology (RPT): Current Status and Its Future

Radiological Physics and Technology (RPT): Current Status and Its Future

IR and the Sunshine Act: Two-Year Analysis of the Open Payments Database and Comparison with Related Specialties

PurposeTo characterize medical industry–based payments made to US-based interventional radiology (IR) physicians, identify trends in compensation, and compare their payment profile with those of other related specialties, including vascular surgery (VS) and interventional cardiology (IC). Payments made to orthopedic surgery (OS) physicians are reported as a historical control. Materials and MethodsFor each group, the total payment number, amount, and mean and median numbers and amounts were calculated. The data were then reanalyzed after correcting for statistical outliers. For IR, VS, and IC, leading industry sponsors, payment amount, and differences in payments from 2013 to 2014 were highlighted. Payments to IR were grouped by category and geographic location. The Kruskal–Wallis test was used for statistical analysis. ResultsA total of $26,857,622 went to 1,831 IR physicians, representing 70.9% of active IR physicians, and the corrected mean payment was $597 ± 832.2 (standard deviation). The respective values were $18,861,041, 3,383, 80.6%, and $851.59 for VS; $32,008,213, 7,939, 78.6%, and $417.16 for IC; and $357,528,020, 21,829, 77.8%, and $598.48 for OS. OS had the largest number of payments (295,465 vs 24,246 for IR, 84,635 for VS, and 160,443 for IC) and greatest total payment amount. VS had a significantly higher corrected median payment amount ($463; P < .0001) than IR ($214) and IC ($99). Covidien and Sirtex Medical were the leading industry sponsors to IR, and 64.6% of IR payments were compensation for services other than consulting. There was no significant difference in median payment received per geographic region (P = .32). ConclusionsOS received the largest number and total payment amount, and VS received a significantly greater corrected median payment amount, versus IR and IC. As the Open Payments program continues to be implemented, it remains to be seen how this information will affect relationships among physicians, patients, and industry.

Strategies to Lessen the Radiation Risk from CT: A Multination Perspective

With the substantial rise in utilization of medical imaging, particularly CT, and concerns about radiation risk, further dose reduction has become an essential target for the radiological community represented by radiological societies, radiologists, physicists, and technologists. This review paper discusses the increase in demand for radiological imaging and the effect of radiation at low doses, in addition to providing several strategies that can be applied to reduce radiation dose from CT with special emphasis on newer technologies and solutions. The strategies discussed in this paper can offer significant reduction in radiation dose while maintaining the same diagnostic performance that made imaging an attractive tool in patient’s management in the first place.

Sustainability of the European training and education of the medical physics expert in diagnostic radiology (EUTEMPE-RX)

Introduction EUTEMPE-RX ( http://www.eutempe-rx.eu/ ) is an EU funded project that provides state-of-the-art education for Medical Physicists in diagnostic and interventional radiology at expert level. Its sustainability is crucial for the high level of education and training of Medical Physicists in this specialty hence ensuring radiation safety in Europe and beyond. Purpose To present the plans for a sustained continuation of EUTEMPE-RX under the umbrella of the EUTEMPE Network. Materials and methods The work-out of a business plan for sustainability of the EUTEMPE-RX course modules is a project task. Given the overwhelming level of satisfaction expressed by the present EUTEMPE-RX participants, the quality EUTEMPE-RX manual was considered the best basis for future actions. The present modules will be repeated and parallel programmes will be developed for Nuclear Medicine and Radiation Oncology. Results The major sustainability achievements so far have been the creation of a Memorandum of Understanding for continued efforts among current project partners and the foundation of the EUTEMPE network. The structure, quality manual and terms of reference for the Boards and Committees of the EUTEMPE Network have been established and the population of these is being solicited. The programme for the second round of EUTEMPE-RX modules will be available soon. Conclusion A sustainability business plan for EUTEMPE-RX is being developed. The EUTEMPE-RX modules will be repeated in the near future and possibly expanded to other specialties of medical physics. Demand will decide the sustainability of EUTEMPE Network. Disclosure The authors declare that they have no conflict of interest.

Moving beyond quality control in diagnostic radiology

Quality control (QC), according to ISO definitions, represents the most basic level of quality. It is considered to be the snapshot of the performance or the characteristics of a product or service, in order to verify that it complies with the requirements. Although it is usually believed that “the role of medical physicists in Diagnostic Radiology is QC”, this, not only limits the contribution of medical physicists, but is also no longer adequate to meet the needs of Diagnostic Radiology in terms of Quality. In order to assure quality practices more organized activities and efforts are required in the modern era of diagnostic radiology. The complete system of QC is just one element of a comprehensive quality assurance (QA) program that aims at ensuring that the requirements of quality of a product or service will consistently be fulfilled. A comprehensive QA system, starts even before the procurement of any equipment, as the need analysis and the development of specifications are important components under the QA framework. Further expanding this framework of QA, a comprehensive Quality Management System can provide additional benefits to a Diagnostic Radiology service. Harmonized policy and procedures and elements such as mission statement or job descriptions can provide clarity and consistency in the services provided, enhancing the outcome and representing a solid platform for quality improvement. The IAEA promotes this comprehensive quality approach in diagnostic imaging and especially supports the field of comprehensive clinical audits as a tool for quality improvement.