Dedicated CT Scanner Research Articles

Challenges and issues about organizing a hospital to respond to the COVID-19 outbreak: experience from a French reference centre

Challenges and issues about organizing a hospital to respond to the COVID-19 outbreak: experience from a French reference centre

Homogeneous vs. patient specific breast models for Monte Carlo evaluation of mean glandular dose in mammography

PurposeTo compare, via Monte Carlo simulations, homogeneous and non-homogenous breast models adopted for mean glandular dose (MGD) estimates in mammography vs. patient specific digital breast phantoms. MethodsWe developed a GEANT4 Monte Carlo code simulating four homogenous cylindrical breast models featured as follows: (1) semi-cylindrical section enveloped in a 5-mm adipose layer; (2) semi-elliptical section with a 4-mm thick skin; (3) semi-cylindrical section with a 1.45-mm skin layer; (4) semi-cylindrical section in a 1.45-mm skin layer and 2-mm subcutaneous adipose layer. Twenty patient specific digital breast phantoms produced from a dedicated CT scanner were assumed as reference in the comparison. We simulated two spectra produced from two anode/filter combinations. An additional digital breast phantom was produced via BreastSimulator software. ResultsWith reference to the results for patient-specific breast phantoms and for W/Al spectra, models #1 and #3 showed higher MGD values by about 1% (ranges [–33%; +28%] and [−31%; +30%], respectively), while for model #4 it was 2% lower (range [−34%; +26%]) and for model #2 –11% (range [−39%; +14%]), on average. On the other hand, for W/Rh spectra, models #1 and #4 showed lower MGD values by 2% and 1%, while for model #2 and #3 it was 14% and 8% lower, respectively (ranges [−43%; +13%] and [−41%; +21%]). The simulation with the digital breast phantom produced with BreastSimulator showed a MGD overestimation of +33%. ConclusionsThe homogeneous breast models led to maximum MGD underestimation and overestimation of 43% and 28%, respectively, when compared to patient specific breast phantoms derived from clinical CT scans.

Emergency care capabilities in the Kingdom of Swaziland, Africa.

IntroductionEmergency care is available in many forms in Swaziland, and to our knowledge there has never been a systematic study of emergency centres (ECs) in the country. The purpose of this study was to describe the characteristics, resources and capacity of emergency centres in the Kingdom.MethodsThe National Emergency Department Inventory (NEDI)-International survey instrument (www.emnet-nedi.org) was used to survey all Swaziland ECs accessible to the general public 24/7. EC staff were asked about calendar year 2014. Data were entered directly into Lime Survey, a free, web-based, open-source survey application. Responses were analysed using descriptive statistics, including proportions and medians with interquartile ranges (IQR).ResultsSixteen of 17 ECs participated (94% response rate). Participating ECs were either in hospitals (69%) or health centres (31%). ECs had a median of 53,399 visits per year (IQR 15,000–97,895). Fourteen (88%) ECs had a contiguous layout, and the other two (12%) were non-contiguous. Overall, eight (53%) had access to cardiac monitors and 11 (69%) had a 24/7 clinical laboratory available. Only 1 (6%) EC had a dedicated CT scanner, while 2 (13%) others had limited access through their hospital. The typical EC length-of-stay was between 1 and 6 h (44%). The most commonly available specialists were general surgeons, with 9 (56%) ECs having them available for in-person consultation. No ECs had a plastic surgeon or psychiatrist available. Overall, 75% of ECs reported running at overcapacity.DiscussionSwaziland ECs were predominantly contiguous and running at overcapacity, with high patient volumes and limited resources. The limited access to technology and specialists are major challenges. We believe that these data support greater resource allocation by the Swaziland government to the emergency care sector.

Optimization of CT calcium scoring doses on the General Electric Discovery single-photon emission computed tomography/CT D670, 8-slice scanner.

Manufacturer-recommended exposure mA was typically resulting in 3–5 times greater patient doses for calcium score scans compared with other dedicated CT scanners at Nottingham University Hospitals. Image noise was used as a measure of image quality in phantom and patient data. The noise was quantified from the standard deviation in Hounsfield units within regions of interest in the myocardium. Noise in phantom data was found to vary linearly with the inverse square root of the applied mAs. It was assumed that a linear relationship would also apply to patient data but it was predicted that the linear gradient would vary between patients owing to differing patient size and composition. This noise model was used to calculate the exposure mA required to achieve a target noise level of 25 Hounsfield units in the myocardium for each patient. To maintain the image quality for patients of different sizes, three measures of size, weight, body mass index (BMI) and lateral dimension, were all tested for goodness of fit to the noise model. It was found that BMI correlated best with the noise model for small patients, and therefore, BMI was chosen as a measure of patient size for the revised mA table. Using this methodology, doses to small patients were reduced by a factor of four compared with manufacturer-recommended settings.

Emergency department characteristics and capabilities in Bogotá, Colombia.

BackgroundEmergency departments (EDs) are a critical, yet heterogeneous, part of international emergency care. The National ED Inventories (NEDI) survey has been used in multiple countries as a standardized method to benchmark ED characteristics. We sought to describe the characteristics, resources, capabilities, and capacity of EDs in the densely populated capital city of Bogotá, Colombia.MethodsBogotá EDs accessible to the general public 24/7 were surveyed using the 23-item NEDI survey used in several other countries (www.emnet-nedi.org). ED staff were asked about ED characteristics with reference to calendar year 2011.ResultsSeventy EDs participated (82 % response). Most EDs (87 %) were located in hospitals, and 83 % were independent hospital departments. The median annual ED visit volume was approximately 50,000 visits. Approximately 90 % (95 % confidence interval (CI) 80–96 %) had a contiguous layout, with medical and surgical care provided in one area. Almost all EDs saw both adults and children (91 %), while 6 % saw only adults and 3 % saw only children. Availability of technological and consultant resources in EDs was variable. Nearly every ED had cardiac monitoring (99 %, 95 % CI 92–100 %), but less than half had a dedicated CT scanner (39 %, 95 % CI 28–52 %). While most EDs were able to treat trauma 24/7 (81 %, 95 % CI 69–89 %), few could manage oncological (22 %, 95 % CI 13–34 %) or dental (3 %, 95 % CI 0–11 %) emergencies 24/7. The typical ED length-of-stay was between 1 and 6 h in 59 % of EDs (95 % CI, 46–70 %), while most others reported that patients remained for >6 h (39 %). Almost half of respondents (46 %, 95 % CI 34–59 %) reported their ED was over capacity.ConclusionsBogotá EDs have high annual visit volumes and long length-of-stay, and half are over capacity. To meet the emergency care needs of people in Bogotá and other large cities, Colombia should consider improving urban ED capacity and training more emergency medicine specialists capable of efficiently staffing its large and crowded EDs.Electronic supplementary materialThe online version of this article (doi:10.1186/s12245-015-0079-y) contains supplementary material, which is available to authorized users.

Does Distance Matter? Effect of Having a Dedicated CT Scanner in the Emergency Department on Completion of CT Imaging and Final Patient Disposition Times

PurposeTo evaluate whether presence of a CT scanner in the emergency department (ED) improves ED workflow by decreasing time between imaging requisition and completion, and time to final patient disposition. MethodsInstitutional review board approval was obtained for this retrospective study conducted on 2,142 consecutive, acute thoracic, abdomino- pelvic imaging requests from 2 ED hospital campuses affiliated with the same academic institution, August 1 to October 31, 2012. Of these patients, only 1,696 had complete records and were used for analysis. One hospital had a CT scanner in the ED; the other was in the radiology department, 300 meters from the ED. Patients were stratified based on acuity of CT indication, interpreting radiologist training level, and time of day. Time points were compared between hospitals: (1) time of CT requisition receipt to time of scan initiation (2) time from scan initiation to time of preliminary report by resident or fellow, or verbally by staff to the ED; and (3) time of CT requisition receipt to time of final patient disposition. ResultsDecreases in time, favoring the institution with the ED CT scanner, are 16 min (P < .0001); 15 minutes (P < .0001); and 19 minutes (P < .04) for the 3 times, respectively. Significant differences were seen in morning and overnight shifts and for CT reporting times with higher radiology levels of training (20 min, P = .04; and 18 min, P < .0001 for staff and postgraduate year-5 residents, respectively). ConclusionsPresence of an ED CT scanner is associated with decreases in time to CT scan completion, radiologic interpretation, and patient disposition.

Characteristics and capabilities of emergency departments in Abuja, Nigeria

ObjectivesEmergency departments (ED) are the basic unit of international emergency medicine, but often differ in fundamental features. This study sought to describe and characterise ED in the capital city of...

TU-C(SAM)-BRC-01: Multimodality Image Acquisition, Processing and Display for Guiding and Adapting Radiation Therapy

Acquisition and processing of multimodality image data are now fundamental parts of patient management in radiation therapy.Image data are acquired and analyzed to aid diagnosis and staging, to guide treatment planning and delivery and to help monitor the patient during and after therapy. Most radiotherapy departments have dedicated CT scanners, some with 4D capabilities. Many departments also have or are contemplating dedicated MR and PET/CT scanners. More imaging devices are also appearing in the treatment room, with in‐room, on‐board and integrated imaging devices becoming commonplace. The availability of hybrid MR scanner/treatment units is not far off. Naturally, each imaging modality provides both benefits and challenges towards supporting and improving the radiotherapy process. In order to leverage the information in the various imaging studies, effective processing tools are needed to extract useful information and to combine and present it in a way that promotes a clear and efficient workflow. There are several classes of these tools including image enhancement, visualization, segmentation, registration and quantification. These tools may be used individually or in combination at many points in the radiotherapy process with the overall goal to create a more accurate and complete model of the patient so that an effective course of therapy can be devised and carried out. This course will provide an overview of the different imaging modalities and procedures used in radiotherapy and highlight the benefits and challenges of each. The details of the various image processing tools used to extract, combine and analyze the information from the various imaging studies will also be presented. Finally, the effective use of these tools at each step of the radiotherapy process will be described and elucidated using several clinical examples. Educational Objectives: 1. Understand the basic principles for the different imaging modalities used in radiation therapy. 2. Understand the mechanics of the different classes of image processing tools using in radiotherapy. 3. Understand how different image data and processing tools are used to support and improve the radiotherapy process.

WE‐SAM‐BRB‐01: Image Processing in Radiation Therapy: A Play in Three Acts

Acquisition, processing and analysis of medical image data are now fundamental parts of patient management in radiation therapy. Image data are used to aid diagnosis and staging, to guide treatment planning and delivery and to help monitor the patient during and after therapy. Most radiotherapy departments have dedicated CT scanners, some with 4D capabilities. Many departments also have or are contemplating dedicated MR and PET/CT scanners. More imaging devices are also appearing in the treatment room, with in‐room, on‐board and integrated imaging devices becoming commonplace. The availability of hybrid MR scanner/treatment units is not far off.Naturally, each imaging modality provides both benefits and challenges towards supporting and improving the radiotherapy process. In order to leverage the information in the various imaging studies, effective processing tools are needed to extract useful information and to combine and present it in a way that promotes a clear and efficient workflow. There are several classes of these tools including image enhancement, visualization, segmentation, registration and quantification. These tools may be used individually or in combination at many points in the radiotherapy process with the overall goal to create a more complete and accurate model of the patient so that an effective course of therapy can be devised and carried out.This course provides an overview of the different imaging modalities and procedures used in radiotherapy and highlights the benefits and challenges of each. A detailed description of the various image processing tools used to extract, combine and analyze the information from different imaging studies is also presented. Finally, the effective use of these tools at each step of the radiotherapy process is described and elucidated using numerous clinical examples.Learning Objectives:1. Act 1 Understand the benefits and challenges of the various imaging modalities used in radiation therapy.2. Act 2 Understand the mechanics of the different classes of image processing tools using in radiotherapy.3. Act 3 Understand how image processing tools are used to support and improve the radiotherapy process.

Dedicated CT scanner in an emergency department: quantification of factors that contribute to lack of use.

The purpose of our study was to quantify the factors that contribute to the lack of use of a dedicated CT scanner in the emergency department of our institution and to identify possible changes to reduce scanner idle time. We designed a data collection form to record consecutive periods of patient scanning and periods between patients when the CT scanner was not in use. The contributing factors for each idle period were identified and logged according to an entry system previously decided in consensus. Data were collected continuously for 11 days. The factors we identified for measurement were no request for scanning, preventive maintenance, equipment failure, technologist unavailable, room cleaning and preparation, patient preparation for abdominal CT, patient undergoing other tests, transportation delays, pending laboratory workup, and miscellaneous factors. The time attributed to the most prevalent factors was also grouped into four 6-hr periods corresponding to our department's shifts. The scanner was idle 73% of the total study time. The chief contributing factors to lack of use were having no patients to scan, patient undergoing preparation, and transportation delays, which accounted for 38.5%, 31%, and 11.7% of the aggregate idle time, respectively. The 6-hr periods of least use were the 7:00 A.M.-1:00 P.M. and the 1:00 A.M.-7:00 A.M. shifts, which accounted for 17% and 19% of idle time, respectively. Dedicated emergency department CT scanners can have significant daily periods of consistent lack of use. The idle time can be reduced by identifying patterns of referral time and correcting specific operational delays.

Treatment planning for radiotherapy in northern Italy: a survey by the National AIFB-AIRO Committee on 3D-Treatment Planning

Background and purpose: A survey was performed in 1996 to investigate the structures and the process of radiation therapy treatment planning in clinical practice within northern Italy, with particular emphasis on the current and future implementation of 3D equipment and techniques. Materials and methods: Of 57 existing radiation therapy (RT) centres covering a population of 25 million people (45% of the total population of Italy) and treating over 58 000 cancer patients (70% of the cancer cases in Italy) each year, 46 centres were deemed eligible for the survey; a questionnaire was sent to a medical physicist working in each eligible RT centre, 40 of whom responded, making the basis for this report. Results: A dedicated CT scanner was available in 25% of the responding centres and a total of 49 radiation therapy planning systems (RTPS) were reported; none of the RTPS were able to perform 3D calculations, but 50% of the centres had an advanced 2D or 2.5D system. Connection between CT scan and RTPS was by tape or disk in 62% of centres. Immobilization devices were used frequently for head and neck patients (88% of centres), but not for lung (16%) or prostate cancer (24%) patients; the number of contoured slices was largely variable, exceeding 10 in only about 30% of the responding centres. The average working time per patient seemed to closely reflect the number of slices used and the number of critical organs contoured. Finally, the majority of the responding physicists did not favour the use of more than 20 CT slices for 3D treatment planning, nor did they forecast a general spread of this technique in the next 2–3 years. Conclusions: This survey has shown (1) a heterogeneous picture, with 20% of centres ready to implement 3D techniques and 20% of centres lacking the possibility of planning treatments and (2) a general difficulty in coping with the workload represented by 3D treatment planning.

The structure of radiation oncology in the United States in 1994

Purpose : 1) to measure the basic structural characteristics of radiation oncology facilities for the entire country, providing census data for January 1, 1994; 2) to allow comparisons by facility type, equipment, or patient load; 3) to allow comparisons of the patterns of equipment and personnel to previous surveys; and 4) to make a preliminary assessment of the geographic distribution of facilities. Methods and Materials : A mail survey verified whether each potential facility delivered megavoltage radiation therapy and ected data on treatment machines, other equipment, personnel, new patients, and procedures performed. Responses were obtained from 99% of potential facilities. The census data was summarized for the entire country, by hospital-based, free-standing, or federal category, by single or multiple treatment machine group, and by new patient load category. Geographic analysis compared the center of radiation oncology facilities with the center of cities or towns having a population of more than 25,000 residents in 1990. Results : In the United States in 1994, 1542 facilities delivered megavoltage radiation therapy, with 2744 treatment machines, 2777 FTE radiation oncologists, 1349 FTE physicists, 1314 FTE dosimetrists, and 7167 FTE radiation therapists. They treated 560,262 new patients and reported that 60% were treated with curative intent. Eighty percent of the facilities had a dedicated treatment planning computer and 15% had a time-sharing treatment-planning computer, but 5% had no treatment-planning capability. Ninety-five percent of all facilities reported that patients were simulated at that facility. Fourteen percent of all facilities used hyperthermia, 8% intraoperative radiation therapy, 12% stereotactic radiosurgery, and 19% conformal therapy with 3D planning. Of all facilities 35% reported having a dedicated CT scanner and 12% reported having a CT simulator in the department: The distributions of these measures were reported for hospital-based, free-standing, and federal facilities, for single-treatment machine, and multiple-treatment machines facilities, and for three categories based on patient load. Only 18 cities with a population over 25,000 were more than 25 miles from a radiation oncology facility, of which only eight were more than 50 miles from a facility. Conclusion : The Facilities Surveys continue to provide a unique source of census data on radiation oncology in the United States, allowing comparisons by facility group and over time.

Computed tomography in radiotherapy treatment planning.

ABSTRACTComputed tomography (CT) provides in creased accuracy in tumour localisation, patient ouline data and heterogeneity information. This makes the use of CT highly desirable in 2–dimensional treatment planning. Where 3–dimensional (3–D) planning is used computed tomography (or possibly MRI) is essential. Radiotherapy departments must include dedicated CT scanners if they are to attain acceptable accuracy in simulation and treatment planning. The use of modern accelerators and treatment planning systems will be downgraded in the absence of routine CT imaging in a Radiotherapy Department.

An overview of ct based stereotactic systems for the localization of intracranial lesions

Computed tomography, with its inherent accuracy in identifying and localizing intracranial lesions, has been adapted by several groups for use in stereotactic neurosurgical procedures. The systems range from the use of data obtained on conventional CT scans to installation of a dedicated CT scanner in the operating room equipped for stereotactic surgery. Although the GE-8800 scanner is used most frequently, others are also suitable. Adaptations of standard commercially available stereotactic frames are used by some groups while others designed frames specifically for this purpose. The paper is an overview of systems described in the literature to date.