Mar 6, 2016 · The primary exposure technique factors the radiographer selects on the control panel are milliamperage (mA), time of exposure, and kilovoltage peak (kVp). Depending on the type of control panel, milliamperage and exposure time may be selected separately or combined as one factor, milliamperage/second (mAs). Jan 22, 2022 · X-Ray Spectroscopy- Definition, Principle, Steps, Parts, Uses. X-rays make up X-radiation, a form of electromagnetic radiation. Most X-rays have a wavelength ranging from 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz (3×1016 Hz to 3×1019 Hz) and energies in the range 100 eV to 100 keV, produced ... X-ray exams are used to help diagnose a wide variety of injuries and illnesses in children. It is often the first type of imaging used to identify sources of pain, evaluate traumatic injuries, and locate a foreign body. X-rays are used throughout the body. Chest x-ray is the most commonly used imaging exam for evaluating the chest. Feb 27, 2016 · Higher kVp increases the penetrating power of the x-ray beam and results in less absorption and more transmission in the anatomic tissues, which results in less variation in the x-ray intensities exiting the patient. As a result, images with lower contrast are produced. (From Fauber TL: Radiographic imaging and exposure, ed 3, St Louis, 2009 ... Scatter Removal Grids. The antiscatter grid plays an important role for enhancing image quality in projection radiography by transmitting a majority of primary radiation and selectively rejecting scattered radiation. This device is comprised of a series of thin lead strips separated by radiolucent interspaces in a form-factor that matches the ...Radiographic Techniques, Contrast, and Noise in X-Ray Imaging. Radiologists are responsible for the manner in which radiologic examinations, including radiographs, mammograms, and CT images, are obtained. Radiographic protocol parameters should be selected to ensure adequate diagnostic performance, and radiologists therefore need to understand ...Jan 22, 2022 · X-Ray Spectroscopy- Definition, Principle, Steps, Parts, Uses. X-rays make up X-radiation, a form of electromagnetic radiation. Most X-rays have a wavelength ranging from 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz (3×1016 Hz to 3×1019 Hz) and energies in the range 100 eV to 100 keV, produced ... Scatter Removal Grids. The antiscatter grid plays an important role for enhancing image quality in projection radiography by transmitting a majority of primary radiation and selectively rejecting scattered radiation. This device is comprised of a series of thin lead strips separated by radiolucent interspaces in a form-factor that matches the ...Key Points. The ADA encourages dentists and patients to discuss dental treatment recommendations, including the need for X-rays, to make informed decisions together. The ADA, in collaboration with the FDA, developed recommendations for dental radiographic examinations to serve as an adjunct to the dentist’s professional judgment of how to ... Radiographic Techniques, Contrast, and Noise in X-Ray Imaging. Radiologists are responsible for the manner in which radiologic examinations, including radiographs, mammograms, and CT images, are obtained. Radiographic protocol parameters should be selected to ensure adequate diagnostic performance, and radiologists therefore need to understand ...A bone x-ray is used to: diagnose fractured bones or joint dislocation. demonstrate proper alignment and stabilization of bony fragments following treatment of a fracture. guide orthopedic surgery, such as spine repair/fusion, joint replacement and fracture reductions. look for injury, infection, arthritis, abnormal bone growths and bony ...X-ray exams are used to help diagnose a wide variety of injuries and illnesses in children. It is often the first type of imaging used to identify sources of pain, evaluate traumatic injuries, and locate a foreign body. X-rays are used throughout the body. Chest x-ray is the most commonly used imaging exam for evaluating the chest. Aug 10, 2023 · The most frequently used imaging modalities are radiography (X-ray), computed tomography (CT) and magnetic resonance imaging (MRI). X-ray and CT require the use of ionizing radiation while MRI uses a magnetic field to detect body protons. MRI is the safest among the three, although each technique has its benefits. Technique charts are tables that contain settings for selection on the x-ray control for . a specific anatomical part. These factors control the amount of radiation delivered to . the patient and to the film. When the technique chart has been developed properly and the film processing is optimized, the selection from the technique chart willGenerally, the diagnosis of tooth decay is made by visual examination or by trans-illumination — shining a very bright light through visually accessible tooth surfaces to identify changes directly. But this is not possible on the contacting surfaces of the back teeth, hence the advent of the bitewing x-ray technique. Why “Bitewings” A NEW X-RAY TECHNIQUE and ITS APPLICATION TO ORTHODONTIA: The Introduction of Cephalometric Radiography B. HOLLY BROADBENT, D.D.S. Director of the Bolton Study, Anatomical Laboratory, Western Reserve University, Cleveland, OhioThe most frequently used imaging modalities are radiography (X-ray), computed tomography (CT) and magnetic resonance imaging (MRI). X-ray and CT require the use of ionizing radiation while MRI uses a magnetic field to detect body protons. MRI is the safest among the three, although each technique has its benefits.X-Ray diffraction techniques were used to help in the study of a QSAR of artemisinin 1 <2002JME292>, as well as in the determination of the structure of the artemisinin intermediate α,4-dimethyl-decahydro-7-oxo-1-naphthaleneacetic acid 7, where the cyclohexane ring assumes a chair conformation and the cyclohexanone ring a distorted one ...Mar 23, 2023 · Citation, DOI, disclosures and article data. The ribs AP view is a specific projection employed in the assessment of the posterior ribs. Unlike a standard chest radiograph, this projection applies a lower kV higher mAs technique to highlight bony structures. It often involves two projections, one of the supradiaphragmatic ribs and two of the ... X-ray diffraction, phenomenon in which the atoms of a crystal, by virtue of their uniform spacing, cause an interference pattern of the waves present in an incident beam of X-rays. The atomic planes of the crystal act on the X-rays in exactly the same manner as does a uniformly ruled diffraction grating on a beam of light.X-Ray Spectroscopy- Definition, Principle, Steps, Parts, Uses. X-rays make up X-radiation, a form of electromagnetic radiation. Most X-rays have a wavelength ranging from 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz (3×1016 Hz to 3×1019 Hz) and energies in the range 100 eV to 100 keV, produced ...Nov 30, 2017 · A lumbosacral spine X-ray, or lumbar spine X-ray, is an imaging test that helps your doctor view the anatomy of your lower back. ... What You Should Know About This Technique. X-Ray diffraction analysis (XRD) is a nondestructive technique that provides detailed information about the crystallographic structure, chemical composition, and physical properties of a material [48]. It is based on the constructive interference of monochromatic X-rays and a crystalline sample. Apr 1, 1981 · A NEW X-RAY TECHNIQUE and ITS APPLICATION TO ORTHODONTIA: The Introduction of Cephalometric Radiography B. HOLLY BROADBENT, D.D.S. Director of the Bolton Study, Anatomical Laboratory, Western Reserve University, Cleveland, Ohio Patient Positioning for Skull Radiography. Patients can be imaged either erect or recumbent. In the erect position, a standard X-ray table and upright Bucky are used. This allows easy and quick positioning and use of a horizontal beam, which is necessary to demonstrate any air-fluid levels in the cranium or sinuses. techniques: X-Ray Techniques. 20X-ray systems can provide detailed information about sample structure and composition. Our facilities offer a huge array of techniques to probe samples from physical and life science applications. Our tools can be used to solve crystal structures, analyze surfaces and provide compositional information. X-Ray diffraction techniques were used to help in the study of a QSAR of artemisinin 1 <2002JME292>, as well as in the determination of the structure of the artemisinin intermediate α,4-dimethyl-decahydro-7-oxo-1-naphthaleneacetic acid 7, where the cyclohexane ring assumes a chair conformation and the cyclohexanone ring a distorted one ...Jul 24, 2016 · This technique, referred to as volume-acquisition CT, has made possible a data-gathering system using a continuous rotation of the x-ray source and the detectors. It allows the rapid acquisition of volumes of CT data and renders the ability to reformat the images at any predetermined intervals ranging from 0.5 to 10.0 mm. X-ray fluorescence spectroscopy is widely used for qualitative and quantitative chemical analysis, in particular, in electron microscopes. The X-ray radiography is an imaging technique based on the registration of the intensity passing through an object by using films or detectors which allow making its internal structure visible due to the ...X-ray diffraction is a common technique that determine a sample's composition or crystalline structure. For larger crystals such as macromolecules and inorganic compounds, it can be used to determine the structure of atoms within the sample. If the crystal size is too small, it can determine sample composition, crystallinity, and phase purity.In Photoshop, X-ray is a technique for manipulating images. For a humorous effect, you will be able to see through your clothes with X-ray vision with this effect. Photoshop’s X-ray effect can be used to create X-ray images by uncovering previously concealed elements in the image’s layers.In Photoshop, X-ray is a technique for manipulating images. For a humorous effect, you will be able to see through your clothes with X-ray vision with this effect. Photoshop’s X-ray effect can be used to create X-ray images by uncovering previously concealed elements in the image’s layers.A NEW X-RAY TECHNIQUE and ITS APPLICATION TO ORTHODONTIA: The Introduction of Cephalometric Radiography B. HOLLY BROADBENT, D.D.S. Director of the Bolton Study, Anatomical Laboratory, Western Reserve University, Cleveland, OhioThese techniques include X-rays, computed tomography (CT) scans, and magnetic resonance imaging (MRI) scans. These imaging tools let your doctor see inside your body to get a picture of your bones, organs, muscles, tendons, nerves, and cartilage. This is a way the doctor can determine if there are any abnormalities.X-ray uorescence (XRF) is a non-destructiv e analytical technique used for the identi cation of elements and determination of their concentrations in solid, powdered, and liquid samples [ 7 , 8 ].Types of X-Ray Techniques Chart Variable Kilovoltage. The technique chart uses fixed mAs. As for the kVp, it varies depending on the thickness of the... Fixed Kilovoltage (shown a fixed kVp technique chart). This method is widely used in the medical profession. The chart... High Kilovoltage. This ...X-rays are a form of electromagnetic radiation, similar to visible light. Unlike light, however, x-rays have higher energy and can pass through most objects, including the body. Medical x-rays are used to generate images of tissues and structures inside the body. X-rays are the oldest and most often used form of medical imaging. Abdominal x-ray is a commonly performed diagnostic x-ray examination that produces images of the organs in the abdominal cavity including the stomach, liver, intestines and spleen. When an abdominal x-ray is performed to provide pictures of the kidneys, ureters and bladder, it's ...Tomography is an x-ray technique in which shadows of superimposed structures are blurred out by a moving x-ray tube. Conventional tomography is now less commonly used because of the availability of cross-sectional imaging techniques such as US, CT, and MRI. There are 2 basic types of tomography: linear and nonlinear.X-ray fluorescence spectroscopy is widely used for qualitative and quantitative chemical analysis, in particular, in electron microscopes. The X-ray radiography is an imaging technique based on the registration of the intensity passing through an object by using films or detectors which allow making its internal structure visible due to the ...Jan 23, 2015 · Radiographic Techniques, Contrast, and Noise in X-Ray Imaging. Radiologists are responsible for the manner in which radiologic examinations, including radiographs, mammograms, and CT images, are obtained. Radiographic protocol parameters should be selected to ensure adequate diagnostic performance, and radiologists therefore need to understand ... Jan 26, 2023 · Although most X-ray technicians only need to earn an associate degree in radiologic technology to qualify for their roles, some may choose to pursue a bachelor's degree, which can extend how long it takes to earn their credentials. Those who complete a bachelor's degree spend four years on average completing their education. Generally, the diagnosis of tooth decay is made by visual examination or by trans-illumination — shining a very bright light through visually accessible tooth surfaces to identify changes directly. But this is not possible on the contacting surfaces of the back teeth, hence the advent of the bitewing x-ray technique. Why “Bitewings”An X-ray fluorescence (XRF) spectrometer is an x-ray instrument used for routine, relatively non-destructive chemical analyses of rocks, minerals, sediments and fluids. It works on wavelength-dispersive spectroscopic principles that are similar to an electron microprobe ( EPMA ). However, an XRF cannot generally make analyses at the small spot ...Panoramic radiography, also called panoramic x-ray, is a two-dimensional (2-D) dental x-ray examination that captures the entire mouth in a single image, including the teeth, upper and lower jaws, surrounding structures and tissues. The jaw is a curved structure similar to that of a horseshoe. Jun 15, 2020 · New 3-D X-ray technique reveals secrets from inside bones. An international research team has used new X-ray techniques to describe how the architecture of healthy human bones is built up. The ... Generally, the diagnosis of tooth decay is made by visual examination or by trans-illumination — shining a very bright light through visually accessible tooth surfaces to identify changes directly. But this is not possible on the contacting surfaces of the back teeth, hence the advent of the bitewing x-ray technique. Why “Bitewings” Tomography is an x-ray technique in which shadows of superimposed structures are blurred out by a moving x-ray tube. Conventional tomography is now less commonly used because of the availability of cross-sectional imaging techniques such as US, CT, and MRI. There are 2 basic types of tomography: linear and nonlinear. A chest X-ray is an imaging test that uses X-rays to look at the structures and organs in your chest. It can help your healthcare provider see how well your lungs and heart are working. Certain heart problems can cause changes in your lungs. Certain diseases can cause changes in the structure of the heart or lungs.Medical X-ray imaging has led to improvements in the diagnosis and treatment of numerous medical conditions in pediatric patients. The Federal Food, Drug, and Cosmetic Act (FD&C Act) defines ...Jul 4, 2019 · Chest radiograph or x-ray is one of the most commonly performed imaging tests. It is a high-yield test, providing significant clinical information rapidly, at low cost, and with low radiation exposure, but many examinations are nonetheless unnecessary. In this chapter, we discuss the indications for chest x-ray, features of the chest x-ray ... Energy dispersive X-Ray (EDX) composition analysis. Energy Dispersive X-Ray Analysis (EDX), referred to as EDS or EDAX, is an x-ray technique used to identify the elemental composition of materials. Applications include materials and product research, troubleshooting, deformulation, and more.Mar 3, 2016 · Image receptor: 10 × 12 inch (24 × 30 cm) lengthwise. The reverse Waters method is used to show the facial bones when the patient cannot be placed in the prone position. Position of patient: • With the patient in the supine position, center the midsagittal plane of the body to the midline of the grid. Position of part: Radiographic Techniques, Contrast, and Noise in X-Ray Imaging. Radiologists are responsible for the manner in which radiologic examinations, including radiographs, mammograms, and CT images, are obtained. Radiographic protocol parameters should be selected to ensure adequate diagnostic performance, and radiologists therefore need to understand ...X-ray diffraction is a common technique that determine a sample's composition or crystalline structure. For larger crystals such as macromolecules and inorganic compounds, it can be used to determine the structure of atoms within the sample. If the crystal size is too small, it can determine sample composition, crystallinity, and phase purity.X-rays are the oldest and most often used form of medical imaging. Abdominal x-ray is a commonly performed diagnostic x-ray examination that produces images of the organs in the abdominal cavity including the stomach, liver, intestines and spleen. When an abdominal x-ray is performed to provide pictures of the kidneys, ureters and bladder, it's ... X-ray fluorescence spectroscopy is widely used for qualitative and quantitative chemical analysis, in particular, in electron microscopes. The X-ray radiography is an imaging technique based on the registration of the intensity passing through an object by using films or detectors which allow making its internal structure visible due to the ...Aug 13, 2020 · Spread the love. Radiography is a volumetric NDT test method used to determine internal flaws in castings and Welds. Radiographic testing includes passing of X-rays or Gamma Rays through the test item from one side and recording the rays on an imaging media on the other side giving a permanent visual record of the internal structure of the test ... X-ray diffraction, phenomenon in which the atoms of a crystal, by virtue of their uniform spacing, cause an interference pattern of the waves present in an incident beam of X-rays. The atomic planes of the crystal act on the X-rays in exactly the same manner as does a uniformly ruled diffraction grating on a beam of light.For the purposes of this page radiography means a technique for generating and recording an x-ray pattern for the purpose of providing the user with a static image (s) after termination of the ... X-Ray Spectroscopy- Definition, Principle, Steps, Parts, Uses. X-rays make up X-radiation, a form of electromagnetic radiation. Most X-rays have a wavelength ranging from 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz (3×1016 Hz to 3×1019 Hz) and energies in the range 100 eV to 100 keV, produced ...Radiography is an imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical radiography ("diagnostic" and "therapeutic") and industrial radiography. X-rays are the oldest and most often used form of medical imaging. Abdominal x-ray is a commonly performed diagnostic x-ray examination that produces images of the organs in the abdominal cavity including the stomach, liver, intestines and spleen. When an abdominal x-ray is performed to provide pictures of the kidneys, ureters and bladder, it's ... These techniques include X-rays, computed tomography (CT) scans, and magnetic resonance imaging (MRI) scans. These imaging tools let your doctor see inside your body to get a picture of your bones, organs, muscles, tendons, nerves, and cartilage. This is a way the doctor can determine if there are any abnormalities. An X-ray, also called a radiograph, sends radiation through the body. Areas with high levels of calcium (bones and teeth) block the radiation, causing them to appear white on the image. Soft tissues allow the radiation to pass through. They appear gray or black on the image. An X-ray is the fastest and most accessible form of imaging.X-Ray diffraction analysis (XRD) is a nondestructive technique that provides detailed information about the crystallographic structure, chemical composition, and physical properties of a material [48]. It is based on the constructive interference of monochromatic X-rays and a crystalline sample.Jul 4, 2019 · Chest radiograph or x-ray is one of the most commonly performed imaging tests. It is a high-yield test, providing significant clinical information rapidly, at low cost, and with low radiation exposure, but many examinations are nonetheless unnecessary. In this chapter, we discuss the indications for chest x-ray, features of the chest x-ray ... Aug 22, 2022 · X-ray diffraction is a common technique that determine a sample's composition or crystalline structure. For larger crystals such as macromolecules and inorganic compounds, it can be used to determine the structure of atoms within the sample. If the crystal size is too small, it can determine sample composition, crystallinity, and phase purity. Radiography is an imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical radiography ("diagnostic" and "therapeutic") and industrial radiography.3–7 years (average 5 years). 8–12 years (average 10 years). 13–17 years (average 15 years). The age groups were based on exposures suitable for tissue thickness (in the direction of the X-ray beam) of a patient of ‘average/standard size’ in that age group for each projection.This technique, referred to as volume-acquisition CT, has made possible a data-gathering system using a continuous rotation of the x-ray source and the detectors. It allows the rapid acquisition of volumes of CT data and renders the ability to reformat the images at any predetermined intervals ranging from 0.5 to 10.0 mm.X-Ray diffraction analysis (XRD) is a nondestructive technique that provides detailed information about the crystallographic structure, chemical composition, and physical properties of a material [48]. It is based on the constructive interference of monochromatic X-rays and a crystalline sample. X-ray photoelectron spectroscopy (XPS) is a powerful surface analysis technique that can provide quantitative information about elemental composition as well as chemical bonding. Our tools are also equipped with sputtering capabilities and angle-resolved measurements for depth profiling, ultraviolet photoelectron spectroscopy (UPS) and sample ...Get the diagnostic clarity you need from the first X-ray. Helix™ Advanced Image Processing delivers sharp detail and consistent performance, despite variations in exposure technique and challenging exam conditions. Learn more Advanced applications. These techniques include X-rays, computed tomography (CT) scans, and magnetic resonance imaging (MRI) scans. These imaging tools let your doctor see inside your body to get a picture of your bones, organs, muscles, tendons, nerves, and cartilage. This is a way the doctor can determine if there are any abnormalities.These techniques include X-rays, computed tomography (CT) scans, and magnetic resonance imaging (MRI) scans. These imaging tools let your doctor see inside your body to get a picture of your bones, organs, muscles, tendons, nerves, and cartilage. This is a way the doctor can determine if there are any abnormalities.The BisectingAngle (short cone) Technique for dental radiography is based on the principle of projecting the x-ray beam at right angles to an imaginary plane bisecting the angle formed by the longitudinal axis of the tooth and the plane of the media (Cieszynski, 1907). The vertical angulation of the x-ray beam is based on this principle.Conventional Chest X-Ray. The chest radiograph is the most common radiographic procedure performed in the imaging department and is the initial imaging modality in a patient presenting with thoracic symptoms. The basic techniques of chest radiography have not changed significantly over the past 100 years.
The COVID-19 pandemic in 2020 has led to preparations within our hospital for an expected surge of patients. This included developing a technique to perform mobile chest X-ray imaging through glass, allowing the X-ray unit to remain outside of the patient’s room, effectively reducing the cleaning time associated with disinfecting equipment. The technique also reduced the infection risk of .... Sampercent27s club tires
CT, radiography, and fluoroscopy all work on the same basic principle: an X-ray beam is passed through the body where a portion of the X-rays are either absorbed or scattered by the internal... A lumbosacral spine X-ray, or lumbar spine X-ray, is an imaging test that helps your doctor view the anatomy of your lower back. The lumbar spine is made up of five vertebral bones. The sacrum is ...3–7 years (average 5 years). 8–12 years (average 10 years). 13–17 years (average 15 years). The age groups were based on exposures suitable for tissue thickness (in the direction of the X-ray beam) of a patient of ‘average/standard size’ in that age group for each projection.Patient Positioning for Skull Radiography. Patients can be imaged either erect or recumbent. In the erect position, a standard X-ray table and upright Bucky are used. This allows easy and quick positioning and use of a horizontal beam, which is necessary to demonstrate any air-fluid levels in the cranium or sinuses.Tomography is an x-ray technique in which shadows of superimposed structures are blurred out by a moving x-ray tube. Conventional tomography is now less commonly used because of the availability of cross-sectional imaging techniques such as US, CT, and MRI. There are 2 basic types of tomography: linear and nonlinear. Get the diagnostic clarity you need from the first X-ray. Helix™ Advanced Image Processing delivers sharp detail and consistent performance, despite variations in exposure technique and challenging exam conditions. Learn more Advanced applications. Jul 4, 2019 · Chest X-ray . Chest x-ray is the most commonly used diagnostic modality for all forms of chest trauma. Benefits of chest x-ray include portability (allowing it to be used in the resuscitation bay without moving an unstable patient), speed of acquisition (seconds) and image availability (minutes), low expense (approximately $50 to $100), and low radiation exposure (0.01 mSv, equivalent to 1 day ... Aug 29, 2023 · The Scherrer fomula is. t = 0.9λ B2M −B2s− −−−−−−−√ cos θ (1) (1) t = 0.9 λ B M 2 − B s 2 cos θ. with. λ λ is the x-ray wavelength, BM B M is the observed peak width, BS B S is the peak width of a crystalline standard, and. θ θ is the angle of diffraction. To the left is an example XRD pattern for Ba24Ge100 B a 24 ... An X-ray, also called a radiograph, sends radiation through the body. Areas with high levels of calcium (bones and teeth) block the radiation, causing them to appear white on the image. Soft tissues allow the radiation to pass through. They appear gray or black on the image. An X-ray is the fastest and most accessible form of imaging.Apr 1, 1981 · A NEW X-RAY TECHNIQUE and ITS APPLICATION TO ORTHODONTIA: The Introduction of Cephalometric Radiography B. HOLLY BROADBENT, D.D.S. Director of the Bolton Study, Anatomical Laboratory, Western Reserve University, Cleveland, Ohio Apr 4, 2023 · The PA erect view is often chosen over the AP erect view in pediatric imaging due to the decreased radiation dose to radiosensitive organs: developing breast, sternum and thyroid 1. The choice to perform a PA erect or AP erect chest view will depend on the radiographer’s judgment of the patient’s cooperative and understanding ability. Conventional Chest X-Ray. The chest radiograph is the most common radiographic procedure performed in the imaging department and is the initial imaging modality in a patient presenting with thoracic symptoms. The basic techniques of chest radiography have not changed significantly over the past 100 years.Patient Positioning for Skull Radiography. Patients can be imaged either erect or recumbent. In the erect position, a standard X-ray table and upright Bucky are used. This allows easy and quick positioning and use of a horizontal beam, which is necessary to demonstrate any air-fluid levels in the cranium or sinuses. .
Popular Topics
- Atandt outsgesWhen does chili
- Uta whereNet inspect
- Amoeba sisters video recap natural selection worksheet answers pdfSkt
- JmhChick fil a gift card near me
- Wings sports bar and grilleRoman atwood
- Prestige peoUsed trucks for sale in ma under dollar5000
- Amanda bredenLong term side effects of donating plasma regularly