Patient factors, including BMI >25 kg/m 2, male sex, age >18 years, and intensive care unit (ICU) location, were associated with significantly higher dose (P < 0.05). CT scanning using third generation dual-source scanner with model-based iterative reconstruction (IR) had significantly lower dose (mean: 4.90 mSv) versus single-source (64-slice. factors, i.e. the design of the scanner with respect to dose efficiency, and application-related factors, i.e. the way in which the radiologist or the radiographer makes use of 3.1 CT Dose Descriptors The dose quantities used in projection radiography are not applicable to CT for three reasons: •First, the dose distribution inside the patient.
The exposure to radiation of patients undergoing computed tomography (CT) examinations is determined by two factors: equipment-related factors, i.e., design of the scanner with respect to dose efficiency, and application-related factors, i.e., the way in which the radiologist or the radiographer makes use of the scanner . In this review, we seek to provide radiologists with The amount of radiation dose a patient receives from a CT scan depends upon two key factors, the design of the scanner and also on the way that the scanner is used. The designs of single slice and multi-slice scanners are similar in most aspects that affect radiation dose, but multi-slice scanning can potentially result in higher radiation risk to the patient due to increased capabilities allowing long scan lengths at high tube currents Scanner Design Factors Affecting CT Radiation Dose Both scanner design factors and clinical protocol factors affect radiation dose to the patient. Some design factors that affect the radiation dose required to achieve a particular image quality have been previously discussed (8). Those are the factors that determine dose efficiency (9)
In CT scanning, image quality has many components and is influenced by many technical parameters. While image quality has always been a concern for the physics community, clinically acceptable image quality has become even more of an issue as strategies to reduce radiation dose - especially to pediatric patients- become a larger focus For the same technique factors, mean section doses in infants are 35% higher than in adults. Energy imparted for adults is 50% higher than for infants, but infant effective doses are four times higher than for adults. CT doses need to take into account patient age, head size, and composition as well as the selected x-ray technique factors protection of patients in diagnostic radiology regulatory guide pakistan nuclear regulatory authority pnra-rg-904.05 december, 2017 (rev. 0
. Consideration must always be taken when balancing patient dose with a required level of quality. Consultation with a Radiologist and Medical Physicist , will best assist the Technologist in producing acceptable image quality at th The dose information provided from CT scans can be confusing. The CT scanner provides the dose-length-product (in mGy-cm) and the CT for the volume (CTDIvol in mGy). Both of these values are based on the output of the CT scanner, not the dose to the patient. The values can be used to estimate an effective dose from each scan Major CT Parameters Affecting Dose -7-8 mSv for standard chest CT •Dose >> females than males (2.4/1.6) Larke et al. AJR Nov 2011; 197:1165-1169 . A Tale of Two Techniques kV Modulation . Major Untapped Potential has been kV ? Distribution of scans in clinical practice
. The cases include chest, abdomen, elbow and brain CT. Pediatric dose reduction is discussed in the context of consistent image quality Procedure. Approximate effective radiation dose. Comparable to natural background radiation for: Computed Tomography (CT)-Abdomen and Pelvis. 7.7 mSv. 2.6 years. Computed Tomography (CT)-Abdomen and Pelvis, repeated with and without contrast material. 15.4 mSv. 5.1 years
Absorbed dose describes the intensity of the energy deposited in any small amount of tissue located anywhere in the body. The unit of measurement for absorbed dose is the milligray (mGy). If you have a CT of your upper abdomen, the absorbed dose to your chest is very low, because it has only been exposed to a small amount of scattered radiation ) around CT scanners can potentially be estimated from the patient dose parameter dose length product (DLP) using an equation of the form: K s = S CT × DLP. Scatter air kerma levels have been measured to determine values of scatter factors (SCT) for head and body CT scans, and to allow shielding provided by the CT gantry to be taken into account The behavior of the HU of any tissue depends on three factors: (a) photon energy, where increasing the photon energy generally increases the likelihood of Compton scatter interactions, and reduces the likelihood of photoelectric interactions; (b) tissue density, which is the principal determinant of x-ray attenuation at high photon energies of. As mentioned already, on the Discovery CT 750 HD, changing the peak kilovoltage did affect the noise-NI relationship, but as Table 2 suggests, that effect was small compared with other factors. One must keep in mind that noise magnitude is only one of several metrics of image quality
. Recognize patient factors that may affect IR exposure. 16. Identify the exposure factors that can affect patient radiation exposure. 17. State exposure technique modifications for the following considerations: body habitus, pediatric patients, projections and positions, soft tissue, casts and splints, and pathologic conditions - In CT, the number of x-ray photons detected per pixel is also often referred to as signal-to-noise ratio (SNR) 26. • Factors Aff ecting Contrast Resolution: 1) mAs/Dose - Doubling the mAs of the study increases the SNR by 40% →↓quantum noise but The dose increases linearly with mAs per scan
CT Dose. Units of Dose. We can think of the different dose measurements as a stepwise algorithm, each time adding an additional variable into the equation. 1) First, we measure the dose to the detectors from a single gantry rotation. Factors affecting dose Dose =. Dose CT Dose Index (CTDI) Average dose Effective dose Dose-length product (DLP) Effective dose, measured in Sieverts (Sv), is a parameter designed to measure the stochastic risk from a radiation-based exam. It is calculated with tissue weighting factors for radiation sensitivity and requires detailed simulation or measurement of dose to each organ Radiation dose to humans is usually expressed in millisieverts (mSv). The radiation dose to a person in Australia from and other biological factors. The risk is lower for older people and higher for children and unborn babies, so extra care is taken CT renal (KUB) / CT abdomen and/or pelvis (single image) / CT thoracic spine / CT lumbar.
Purpose To evaluate the patients' morphologic factors affecting radiation dose in pediatric chest CT. Materials and methods From November 2013 to May 2015, 315 pediatric chest CT scans were obtained using a CT scanner, and classified into 5 groups according to the patients' age. For each age group, the chest CT scans were divided into two subgroups. A cut-off value used was the 75th. Routine ct for adult patients is usually performed at what kvp. List the factors that affect contrast resolution. 1) energy of X-rays - kVp - ↑ kVp ↓ contrast How does a change in slice thickness affect patient dose? If slice thickness increases, less dose. If slice thickness decreases, more dose Consequently, there is true demand to optimize protocols and to become familiar with the factors affecting the CT radiation dose and available dose-reduction options. Several dose-reduction techniques have been successfully implemented and have been shown to reduce radiation exposure, including tube-current modulation, reducing tube voltage.
ED computed using ICRP 103 weight factors was found to be 24% higher than those from ICRP 60 weight factors for chest CT examination and 21% lower for pelvis CT examinations for the same protocols. Tissue weight factors, tube voltage and BMI were the major factors affecting the estimation of ED of obese patients L10 Patient Dose. 1. RADIATION PROTECTION IN DIAGNOSTIC AND INTERVENTIONAL RADIOLOGY L10: Patient dose assessment IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology. 2 Factors affecting dose rates from Radioactive patients; Uptake room calculation; Imaging room calculation; Calculation for rooms above and below the PET facility; Dose levels in controlled areas; Adjacent rooms on the same level in controlled areas; Design considerations; PET/CT installations; Shielding of the PET tomography from ambient radiatio FACTORS AFFECTING RADIATION PROTECTION • Radionuclide - Half life, emissions • Procedure protocol - Administered activity, uptake time, scan time • Dose rate from the patient - Dose constants, patient attenuation, decay, number of patients per week. • Facility layout - Controlled vs uncontrolled areas, occupancy factors, detectio Therefore, patient's absorbed dose and the factors affecting have been studied in this research. This study aims to present and develop an acceptable level of absorbed dose in CT scan examinations.Methods: Diagnostic reference dose level in the adult age group (older than 15 years) has been studied in eleven CT scan centers in Tehran
Technologists should therefore be familiar with all the essential aspects of CT image formation, factors affecting image quality, and methods for reducing exposure factors to reduce patient doses [8,9]. Hence, the knowledge, skills, and practice of the CT technologists should be properly evaluated for assessment and improvement of education plans X-ray CT scan - source of X-rays with energies from ~30 to 120 keV. Accuracy depends on many factors: dose assay, instrument calibration, reconstruction SUV depends on lesion size and image reconstruction parameters. Further reading about factors affecting quantification in FDG PET • Extensive literature on this topic with a multitude of.
Averages and standard deviations for the factors affecting the patients' radiation exposure dose (manufacturer, number of detectors, and CT exam type) and image quality ratings were analysed. Correlations were calculated to define the effects of the number of detectors on the radiation exposure dose in accordance with CT exam type (abdomen. To evaluate the patients' morphologic factors affecting radiation dose in pediatric chest CT.From November 2013 to May 2015, 315 pediatric chest CT scans were obtained using a CT scanner, and classified into 5 groups according to the patients' age. For each age group, the chest CT scans were divided into two subgroups This study derived measures to reduce exposure doses by identifying factors which affect the external radiation dose rate of patients treated with radiopharmaceuticals for PET-CT tests. The external radiation dose rates were measured on three parts of head, thorax and abdomen at a distance of 50cm from the surface of 60 PET-CT patients. It showed there are changes in factors affecting the. FACTORS AFFECTING RADIATION PROTECTION There are several obvious factors that affect the amount of shielding required for PET facilities. These include the num-TABLE II. Effective dose equivalent dose rate constants for commonly used PET radionuclides. Nuclide Dose rate constant 2Svm /MBqh 1 hour integrated dose Svm2/MBq 11C 0.148 0.063 13N 0.
The solid-state detector(SSD) for X-CT consists of photodiode coupled to CdWO 4$(CWO. It is important to maximize the light collection in respect of a patient's dose, radiation effect and X-ray efficiency. The factors affecting the light collection efficiency are analyzed and optimized by using experimental data and appropriate simulation code The hypothesis to be tested by this trial states that:when compared to patients managed with a best practices standard-of-care coumadin dosing regimen, patients randomized to coumadin dosing based on genetically programmed metabolic capacity and other known clinical and environmental factors affecting dose will: 1)show reduced risk of adverse. CT Image Quality. The image quality is mainly determined by 3 factors: Resolution. Noise. Contrast. Resolution. Resolution is the measure of how far two objects must be apart before they can be seen as separate details in the image. For two objects to be seen as separate the detectors must be able to identify a gap between them Factors Affecting Radiation Protection Pb shields 2.5 cm and 5.0 cm thick are available providing dose reduction factors of 40 and 1900, respectively \ Problems Patient may move in relation to gantry • CT uses higher levels of lower energy photons (x-rays
Factors affecting patient adherence to lung cancer screening: A multisite analysis. Justin T Stowell, Anand K Narayan, Gary X Wang, Florian J Fintelmann, Efren J Flores, Amita Sharma, Milena Petranovic, Jo-Anne O Shepard, and Brent P Little Lung cancer screening with low-dose computed tomography in the United States-2010 to 2015 Drinking or smoking addiction ; 22.Other factors affecting drug absorption, distribution, metabolism, excretion Within 48 hours； 23.Active hepatitis B (HBV-DNA≥104 or 2000IU/ml) or C (Hepatitis C antibodies are positive and HCV-RNA is above the detection limit of the analytical method); 24 Only one recent national CCTA radiation dose survey in the United Kingdom provided a broader view of real-world radiation dose data and the factors associated with CT dose. 15 However, the study did not consider some factors that could impact upon dose. In particular, the work did not explore the impact of CSA of the chest and the impact. The main ones are radiation dose rate (when the CT scan was in progress), where you were standing, and the length of the scan in seconds. The dose rate depends on the technique factors that the scanner used (which can vary from one slice of the scan to the next), the distance you were from the scan plane, and the angle from the central scan axis
In the past several years, significant advances in the technology of Computed Tomography (CT) have driven an expansion in the clinical applications and an increase in the number of CT scans performed. Opportunities for CT technologists have grown, however most technologists lack the training necessary to understand the scope and breath of radiation risks in our current CT environments and. Table 3 Factors affecting radiation dose in CT . Full size table. Scan length. Optimization of patient positioning and scan length adjustment avoids radiation to tissues beyond the region of interest and thereby decreases the absorbed dose without any adverse effect on the image quality [40, 41]
The adult effective dose from a CT exam of the abdomen is roughly equivalent to the adult effective dose from roughly 400 chest x-rays. 4 (See Table 1, below, for the range of doses from various. The patient doses were estimated using measurements of CT dose indexes (CTDI), exposure-related parameters, and the ImPACT spreadsheet based on NRPB conversion factors. [ 1 , 7 , 8 ] Data were collected using a sheet for all patients to maintain the consistency of the information displayed during CT examinations CT-Guided Ablation: Why, How, and When to Do It + CT-Guided Biopsy + CT Imaging: Physical Principles and Radiation Dose Considerations Dedicated Breast CT + Dose Reduction - A Conversation with Experts Dose Reduction - The Effect of New Developments in Clinical CT Emergency Imaging Factors Affecting Image Quality & Radiation Dose in MDCT. The right dose is the reasonable balance between applied radiation, image quality and patient care. In order to help customers achieve this balance, Siemens Healthineers has introduced CARE Right.. This holistic approach is based on the belief that after the recent innovations in radiation reduction, a singular focus on low dose only is not sufficient anymore The CT value is calculated as follows: CT = (Chlorine dose, C in mg/L) x (Contact time, Tin minutes) As the formula suggests, even a small chlorine dose, can provide adequate kill of microorganisms if a longer contact time is provided. Conversely, a large chlorine dose, needs only chlorine has a shorter contact time to kill the pathogens
Alimony-6 CASES: Martone v. Martone, 28 Conn. App. 208, 216, 611 A.2d 896, cert. granted in part 224 Conn. 909 (1992). An award of alimony is based primarily on a spouse's continuing duty t Major factors affecting radiation dose during a CT study include tube current, tube rotation time, peak voltage, pitch, and collimation. 13 Changes in all of these parameters have various effects on image quality. Tube current is directly proportional to dose, and reductions in tube current primarily affect image noise without notable effects. The radiation dose from such a scan can be low (e.g. an effective dose of about 7 mSv for a whole body study). However, the effective dose from a high resolution diagnostic scan can be quite high (up to 30 mSv for a whole body CT scan). The effective dose from a PET scan is modest and depends on the activity of the injected FDG ( 18 F-Fluoro.
Factors that Affect Dose. A dose received over a long period of time is less harmful than the same dose received all at once. A dose to a part of the body is less harmful than a dose to the whole body. Children and young adults are more sensitive to the effects of radiation. Learn more about different factors that affect dose Recommended citation ICRP, 2007. Managing Patient Dose in Multi-Detector Computed Tomography (MDCT). ICRP Publication 102. Ann. ICRP 37 (1). Abstract - Computed tomography (CT) technology has changed considerably in recent years with the introduction of increasing numbers of multiple detector arrays. There are several parameters specific to multi-detector computed tomography (MDCT) scanners. Objective To investigate the objective factors that affect the image quality of infant cranial CT using different mAs. Materials and Methods Ninety infants were divided into three groups randomly. The maximum anteroposterior diameter (MAPD) of skull of each infant was measured. Three reference levels, cerebellar, basal ganglia and centrum semiovale levels were selected respectively Bolus timing monitoring scans used for computed tomography angiography (CTA) repetitively expose the same region of the body to radiation with a view to determining the appropriate threshold attenuation level of the contrast material (CM). Therefore, for an effective CT scan, it is necessary to minimize repetitive radiation exposures from bolus timing.This study aims to effectively identify.
trauma facility, or 24 h/day provider of CT), machine factors (eg, machine age, specific manufacturer and model, or use of updated software that permits dose reduction), or regional choices that affect dose optimization or image quality (or both). For example, the European Union collects dose levels in Europe 6 barriers to CT dose optimization By Kate Madden Yee, AuntMinnie.com staff writer. April 13, 2020-- Use of CT has increased significantly over the last few years, raising concerns about radiation exposure for patients and sparking debate over how to reduce it.But even if it's generally agreed that reducing CT doses is a good idea, there are a number of barriers to doing so, according to a. The computed tomography dose index (CTDI) is a measure of the radiation output of a CT scanner (typically in a standard acrylic phantom, but sometimes reported in air). It is important to note that this is NOT a measure of patient dose. It is a measurement of the average radiation output in a standard phantom as a consequence of the selected. Risk Factors and Prevention Small children, the elderly, and unconscious patients are at higher risk for extravasation, partially because of reduced reporting of injection site pain . Other risk factors are use of an injection site other than the antecubital fossa, use of an indwelling venous cannula that has been in place for over 24 hours. For example, the European Union collects dose levels in Europe, but differences in definitions and data collection techniques across member states confound the identification of factors that explain the observed variation.3 To develop optimization activities likely to meaningfully affect CT doses, we must understand the factors that influence them
Therefore, the Dose Ranges Chart has been published in both systems of measure (rem and sievert). Absorbed Dose. As ionizing radiation passes through matter, some or all of its energy is absorbed by the matter. The amount that is absorbed is referred to as the absorbed dose and the measurement of this dose is given in rads or in grays (Gy) A newly adapted low-dose computed tomography (CT) technique called adaptive statistical iterative reconstruction (ASIR) can help radiologists reduce the already low radiation dose delivered during. National Average Radiation Dose Levels for Medical Imaging. A big issue in medical imaging is that no national guidelines on standard doses have ever been established, so dose levels can vary significantly. We saw a wide range in the protocols, Mahesh explained. That can result in the same person who gets a head CT at five different. These factors must be taken into account in setting chest CT radiation dose parameters in CT chest examinations for younger women (<45 y). Breast shields, thyroid shields, 26,27 and x-ray tube current modulation techniques have been used to decrease radiation doses to these superficial and radiosensitive tissues within the chest
Expert Rev Cardiovasc Ther. 2012;10(1):89-104. The period of time for which x-rays are emitted is an important determinant of x-ray exposure. In cardiac CT, aside from simple beam-on and beam-off. Although many of the operations of a CT scanner are automated, a numbe r of technical parameters remain operator dependent and may significantly affect the diagnostic quality of the CT examination. Wherever possible, scanning protocols should be preprogrammed and saved on the CT scanner console to reduce the operator input required. I The use of pediatric CT, which is a valuable imaging tool, has been increasing rapidly. However, because of the potential for increased radiation exposure to children undergoing these scans, pediatric CT is a public health concern. This page discusses the value of CT and the importance of minimizing the radiation dose, especially in children 02. Radiation units and dose quantities 03. Biological effects 04. International system of radiation protection 05. Interaction of radiation with matter 06. X-ray production 07. X-ray beam 08. Factors affecting image quality 09. Medical exposure BSS; 10. Patient dose assessment 11. Quality assurance; 12. Shielding and X-ray facility design 13
Other factors, such as pathology anticipated, degree and extent of opacification required, structure(s) or area to be examined, disease processes affecting the patient, and equipment and technique to be employed, should be considered. The maximum recommended total dose of iodine is 80 grams [11,83,84] This dose includes the radiation exposure associated with CT scanning to assist with attenuation correction algorithms in PET, which is typically <1 mSv per CT attenuation study Even though in CT simulation we are not diagnosing, we are still helping the Radiation Oncologist properly delineate a tumor/treatment volume in the patient's body. The slice thickness on a CT scan can affect the image in multiple ways, but when paired properly with other factors it can enhance the image showing greater detail and spatial. The typical fetal radiation dose for a routine CT of the abdomen and pelvis is 25 mGy. 6 With modern CT scanners that use automated exposure control the dose is about 13 mGy. 7,8 Low-dose CT KUB protocols can result in doses on the order of 10 mGy to 11 mGy 6 (Table 1)
Patient radiation effective doses in use of PET/CT imaging depend on several factors affecting image acquisition. Table 1 Mean, ±SD and range of patient demographic data, age (y) and BMI (kg/m 2 ) AA (MBq) and effective dose (mSv) per procedure components of the scan. Factors affecting the radiation dose associated with PET, using several radiopharmaceuti-cals but particularly for 18F-FDG, will be described. Var-iations in the dosing schemes used in the practice of pediatric nuclear medicine will also be discussed. The dosimetry associated with the CT component will b Accuracy and Factors Affecting the Outcome of Multi-Detector Computerized Tomography Urography for Bladder Tumors in the Clinical Setting Eu Chang Hwang, Jun Seok Kim, Sun-Ouck Kim, Seung Il Jung, Taek Won Kang, Dong Deuk Kwon, Kwangsung Park, Soo Bang Ryu, Jin Woong Kim, 1 and Lu Ji Wan 2: Department of Urology, Chonnam National University Medical School, Gwangju, Korea Therefore, location of lymph nodes is crucial factors that can affect clinical efficacy. One of the main advantages of 125 I brachytherapy is the high local control [16, 21, 35,36,37]. Therefore, we used LTPFS as the primary end point, and used Kaplan-Meier analysis and log-rank test to explore the factors affecting LTPFS
In general, the radiation dose to a patient with CBCT is markedly lower than that of multi-slice CT scanners.3-6 A review of the literature revealed an average effective dose of 2.7-24.3 µSv for periapical images, 43.2-200 µSv for digital full-mouth series, and 13-560 µSv for medium sized FOV CBCT.5-8 As described above, several factors. Exposure factors: tube voltage (kV), tube current (mA) and exposure time (s) affect image quality and patient dose. Increasing exposure increases low contrast resolution by reducing noise but also increases patient dose. Patient size is an important factor in determining the image noise
Social factors affect CT lung screening compliance By Kate Madden Yee, AuntMinnie.com staff writer. December 4, 2020-- Whether individuals undergo CT lung cancer screening can depend not only on social factors such as unreliable transportation and type of insurance but also on a lack of awareness of screening recommendations, according to research presented Thursday at the virtual RSNA 2020. CT Scanner design factors which affect the total scan time are the gantry rotation time and detector array design along the z-axis (scan axis). The maximum scan length is governed by the z-axis detector array design, and the X-ray tube heat characteristics. With the large volumes of data generated with a 64 slice scanner, for example, the total. There is a growing interest in the use of megavoltage cone-beam computed tomography (MV CBCT) data for radiotherapy treatment planning. To calculate accurate dose distributions, knowledge of the electron density (ED) of the tissues being irradiated is required. In the case of MV CBCT, it is necessary to determine a calibration-relating CT number to ED, utilizing the photon beam produced for MV. Total dose, dose per fraction and BED all correlated with local control. The estimated dose range needed for 1-year local control >90% was 46-52 Gy in 3 fractions. We have also seen favorable local control in all metastases treated to a high BED (BED of greater than 120 Gy with an alpha/beta of 10 Gy) Aims: Tacrolimus has extensive pharmacokinetic variability among patients and a narrow therapeutic window. The U.S. Clinical Pharmacogenetics Implementation Consortium recommends a starting dose fo..