HESI Radiologic Technologist Practice Exam

These questions are part of the practice quiz. Start practicing

• Which device's design, incorporating a heated filament to emit electrons, influenced modern x-ray tube construction?
• How many pixels are present on a 5 megapixel display?
• Which of the following will not affect your exposure indicator value?
• The filament is located on which side of the x-ray tube?
• X-rays transmitted without interaction contribute to which of the following?
• In a dual focus tube, there are two what?
• The cathode side of the tube should be directed toward which part of the patient?
• Projectile electrons travel from which part of the x-ray tube to which part?
• What does NCRP stand for?
• _____ is defined as the ability to image two separate objects and visually detect one from the other.
• How is magnification calculated?
• Characteristic x-rays are produced by _____.
• Total brightness gain in image intensifier imaging is the product of which two gains?
• For lossy compression, the ratio is typically expressed as which option?
• What mostly affects the penetrability of the x-ray beam?
• Which factor most directly contributes to geometric unsharpness in radiography?
• Which statement about fluoroscopy magnification mode is correct?
• Subject contrast is affected by _____.
• Using an image receptor with high DQE can result in lower patient dose.
• The filament is made of _____.
• Which imaging modality uses a superconducting magnet and radiofrequency to visualize soft tissues without ionizing radiation?
• Because of the line focus principle, the effective focal spot size decreases with decreasing _____.
• The smallest quantity of any type of electromagnetic radiation is a(n) _____.
• What term denotes the number of electrons in the outermost shell?
• Starting and maintaining intravenous access as prescribed by a licensed independent practitioner is within a radiographer's scope of practice.
• Differential absorption is dependent on (the) which of the following?
• Which concept describes the combined effect of Compton interactions, photoelectric absorption, and transmitted x-rays on image formation?
• _____ is defined as the ability to image two separate objects and visually detect one from the other.
• The negative side of the x-ray tube holds the _____.
• How many shades of gray can the human visual system distinguish?
• A DR system that directly converts an X-ray signal into an electronic signal is called:
• Using a higher grid ratio improves contrast by reducing scatter but requires an increase in exposure.
• Lossy compression reduces data files _____.
• What computer language is used between the HIS and RIS?
• What is the common lead shielding thickness used for fluoroscopy safety?
• DQE is _____.
• Photon energy and the probability of photoelectric interaction depend primarily on which factor?
• The rate of rise and fall of a sine wave is called its _____.
• Linearity testing in radiography assesses the relationship between which of the following?
• In digital imaging, spatial resolution is ultimately limited by which parameter?
• Patient thickness affects image quality by influencing which of the following?
• Which represents the relationship between SID and recorded detail?
• The abbreviation lp/mm stands for
• When is it not recommended that a pregnant patient receive a radiographic procedure of the abdomen?
• The three primary geometric factors affecting image quality are described as which group?
• Which tissue has the greatest mass density?
• Decreasing the kVp will increase patient dose.
• DR scintillators can be made of III. CsI IV. GdOS.
• Which kVp selection would result in the most scattered x-rays in the image-forming beam?
• Which of the following is the annual dose limit to the lens of the eye for radiation workers?
• If a digital system has a spatial resolution of 3 lp/mm, it can resolve an object as small as _____ mm.
• The positive beam limiting device (PBL) assures that the x-ray beam is collimated to which of the following?
• Which of the following is not one of the three primary geometric factors affecting image quality?
• The three classifications specific to digital imaging artifacts are _____.
• True or False: The ARRT is only concerned about ethics violations related to patient care.
• Bremsstrahlung x-rays are produced by _____ at the target.
• What is the dose limit for a radiologic technologist's hands?
• In the wrist radiograph example, the SID was
• The energy of a photon is directly proportional to its _____.
• Which artifact is caused by incomplete erasure?
• Distortion depends on: I. object thickness II. object position III. object shape IV. object material
• Which energy interaction occurs only at very high energies used in therapy and PET imaging?
• This radiology pioneer wrote about the importance of filtration and collimation.
• Which group enforces the accreditation of a Radiologic Technology program?
• In digital imaging, spatial resolution is ultimately limited by which factor?
• Which material is used for filtration in radiography?
• Which interaction occurs only at the very high energies used in radiation therapy and in nuclear medicine P.E.T. imaging?
• A primary benefit of having a wider dynamic range in digital radiography is which of the following?
• Spatial frequency describes the quality of spatial resolution in terms of what?
• Which two factors are needed to use the Inverse Square Law?
• Valence describes the number of electrons in which shell?
• Dose Area Product takes into account exposure and the size of the lightfield. Which option best reflects this concept?
• The number of gray shades that an imaging system can reproduce is called its which?
• Which energy unit is used to express the energy of characteristic radiation?
• The atomic number of Lead is 82 and the atomic mass number is 207. How many neutrons does it have?
• In an x-ray tube, most of the kinetic energy of the incoming electrons is converted to heat.
• All of the following are types of technique charts except:
• If the SID changes from 40 inches to 60 inches, by what factor must mAs change to maintain exposure?
• As kVp increases, the probability of photoelectric absorption generally
• Focal spot blur can be reduced by using which of the following?
• Anyone in the following professions can order an x-ray except..
• Which of the following is NOT a type of technique chart?
• Radiation protection basics are:
• Which radiology pioneer emphasized filtration and collimation as safety measures?
• A grid ratio is determined by
• The chemical element is determined by the number of _____ in the atom.
• The _____ is the source of radiation in the x-ray tube.
• Which sensor technology is commonly used in digital fluoroscopy to achieve high spatial resolution?
• If an atom has the same number of protons and electrons, its overall electrical charge is zero.
• An order for an x-ray exam must include, at minimum, all of the following except: patient's date of birth.
• In fluoroscopy, the input phosphor converts X-rays to light.
• The lowest energy range of the electromagnetic spectrum is _____.
• A dual focus tube has two _____.
• Detective Quantum Efficiency (DQE) is a measure of which property of an image receptor?
• The quantity of bremsstrahlung radiation increases proportionately with increased _____ .
• Which parameter is not one of the three primary scatter-influencing factors?
• If your modality cannot download a patient worklist, what's the best way to continue on with performing exams and patient care?
• Atoms and molecules are the fundamental building blocks of _____.
• OID primarily affects which aspect of image quality?
• What is the milliampere-seconds value with exposure factors of 27ms, 200 mA and 70 kVp?
• Compton scatter directions can be directed at which angle from the incident beam?
• An incident x-ray interacts with an atom without ionization during _____.
• How often should the exposure timer be measured for accuracy in radiography equipment?
• The scattered x-ray from a Compton interaction usually retains _____ of the energy of the incident photon.
• Which parameter primarily controls the energy of the X-ray photons?
• The energy released when an inner-shell vacancy is filled is called the _____.
• Bremsstrahlung x-rays are produced by what process?
• Filtration is used to _____.
• Increasing object-to-image distance (OID) primarily increases what aspect of the radiographic image?
• The three primary geometric factors affecting image quality are _____.
• Which statement correctly identifies the material used for the X-ray tube filament?
• This modality is fast and extremely sensitive to various tissue density making it the most versatile imaging modality used for all kinds of pathology.
• Subject contrast is affected by
• An image of the wrist is made using 400 mA, 25 ms, 70 kV, a focal spot of 0.4 mm, minimum OID, in a 30 inch SID. Which of the following changes will result in the largest increase in magnification?
• The measurement of the amount of exposure on the digital image receptor describes
• A moving object has _____ energy.
• If the target angle is increased, the effective focal spot size will
• What are the two principal characteristics of a digital medical image?
• Ionizing radiation is capable of removing _____ from atoms as it passes through matter.
• The high voltage generator in an x-ray imaging system is responsible for generating the Kilovoltage Across The Tube.
• Digital radiography offers wide exposure latitude, meaning which statement is true?
• A moving object has which type of energy?
• With narrow detectors and fast helical scanning, this modality is able to produce excellent images of a patient's lung tissue.
• Which statement best describes the function of a collimator in radiography?
• Increasing mAs will increase patient dose.
• Photon energy increases with increasing what?
• Which instrument is used to measure focal spot size in an x-ray tube?
• If the dose at 6 feet is 5 Gy, what is the intensity at 3 feet?
• In digital radiography, the histogram shows the distribution of pixel values; what does the x-axis represent?
• As spatial frequency increases the object size _____ and the spatial resolution _____.
• The quantity of bremsstrahlung radiation increases proportionally with increased what?
• If the source-to-image distance doubles, by what factor must the mAs increase to maintain exposure?
• Barium has an atomic number of 56. How many protons does it have?
• X-ray photons that pass through the patient without interacting contribute to which aspect of radiographic imaging?
• Compton scatter is directed at _____ angle from the incident beam.
• Which of the following has the lowest energy among the listed electromagnetic waves?
• If I want to use a total of 3.2 mAs and I'm using 200 mA, how many seconds should my time be?
• This hot cathode ray tube design led the way to how x-ray tubes are made today.
• Which geometric factor is most directly related to spatial resolution due to the focal spot size?
• mAs is the product of mA and exposure time.
• A higher fill factor indicates that a greater portion of the pixel face is sensitive to x-rays, which most directly increases:
• Image detail is also called _____.
• Increasing which setting increases the rate at which photons are produced in the x-ray tube?
• Which imaging modality captures dynamic images?
• Distortion can be reduced by
• What is the effect on Compton scatter when the mass density of the absorber increases?
• Contrast resolution is improved by which of the following?
• Each sweep of the source-detector around the body during CT is called a _____.
• The device used to measure the luminance response of monitors is called a
• Which parameter primarily controls the quantity of photons produced during exposure?
• What is the minimum source-to-skin distance for a fixed fluoroscopy unit?
• A detector's detective quantum efficiency (DQE) describes its ability to do what?
• Which statement about shielding in fluoroscopy is correct?
• The 3 color filters used on a color active matrix LCD are
• Which material is mentioned as the target for producing characteristic radiation when bombarded by incident electrons?
• When electrons bombard the target, _____% of their kinetic energy is converted to heat.
• The time from the end of CT image scanning to image appearance on the monitor is called the _____ time.
• What is the number assigned to each individual radiology exam called?
• A graph of the frequency of occurrence versus digital value intervals is called a(n) _____.
• Most x-rays produced at the target are _____.
• The three primary geometric factors affecting image quality are which of the following?
• What is the formula for magnification factor?
• The organization that created the registry exam that must be passed in order to practice radiography is:
• Artifacts are an acceptable part of digital imaging.
• When x-rays are transmitted through the patient and reach the image receptor, these photons contribute to which part of the radiographic signal?
• What is the primary function of a Picture Archive and Communication System (PACS) in radiology?
• The number of light photons emitted within the image intensifier is ______ to the amount of x-ray photons exiting the patient.
• Bremsstrahlung radiation is produced when high-energy electrons are decelerated by the atomic nucleus.
• A ghost image can occur in digital imaging because of _____.
• Lossless compression reduces data files by up to which ratio?
• A lead apron using 0.50 mm Pb provides approximately how many HVLs at 100 kVp?
• Total brightness gain of image intensifiers results from which of the following?
• The bit depth of a digital image primarily determines which aspect of image quality?
• Each pixel of information in a CT image contains numerical information based in which units?
• TG 18-QC is a standard test pattern used to evaluate which aspect of imaging systems?
• The smallest discrete unit of electromagnetic radiation is a(n) _____.
• What is the name of the publication that documents dose limits for both radiation workers and members of the public?
• The best way for technologists to reduce occupational exposure is to follow the principles of I ALARA II time and distance III shielding.
• Which statement best describes the relationship between protons and electrons in a neutral atom?
• Flat-field correction in digital imaging is used to compensate for which issue?
• Which organization certifies radiologic technologists in the United States through registry exams?
• Gas typically has a Hounsfield unit value of _______.
• Which unit is used to express occupational dose limits for hands?
• An exposure index of +3 on a digital radiography system indicates which of the following?
• How many pixels does a 3 megapixel monitor have?
• Spatial resolution improves with a decrease in motion blur and a decrease in geometric blur. Which option correctly completes this statement?
• Equivalent dose considers which factors?
• Which type of radiation is the dominant output from the X-ray tube in diagnostic imaging?
• Which of the following is not a property of a photon?
• An atom in a normal state has an electrical charge of _____.
• The contrast on the radiograph that is affected by the patient's size, shape, and tissue composition is called
• Which factor does not contribute to the calculation of effective dose?
• Which approach best minimizes occupational exposure?
• DR scintillators are often made of which material?
• X-rays have a weighting factor (Wr) of what?
• Primary radiation is _____.
• Which option best describes positive beam limitation?
• The standard tool used to measure the effect of focal spot size is the _____.
• Scatter radiation increases as _____ increases.
• The two primary forms of x-ray interaction in the diagnostic range are ____.
• Lowering kVp affects patient dose and image contrast in which way?
• In CT imaging, which material is typically associated with a Hounsfield unit near -1000?
• Which of the following is not a geometric factor affecting image quality?
• Which term describes the whole-body dose used to estimate radiation risk?
• Misalignment between the light field in the x-ray beam must not exceed ____ of the SID.
• Absorbed dose takes into consideration which of the following?
• This modality determines a person's risk for future fractures.
• Viewing the fluoroscopic image in magnification mode increases which aspect?
• An atom that loses or gains one or more electrons is a(n) _____.
• Which term describes adjusting image brightness and contrast to optimize visibility of structures?
• Lossy compression can be used for which type of data?
• Out of the people listed below, who is the best person to assist with holding a child during an x-ray exam?
• Whose hand is in the famous first X-ray image?
• An abdomen decubitus radiograph is performed with 75 kVp at 80 mAs with a source-to-image distance of 80 inches. If the SID is moved to 40 inches while maintaining the same exposure, what should the new mAs be?
• Thermionic emission at the filament creates a _____.
• The three primary factors influencing the intensity of scatter in the image-forming beam are ____.
• Which statement is NOT part of radiation protection basics?
• What controls the exposure factors during a fluoroscopic exam?
• What type of grid error is characterized by decreased density on both sides of the image?
• What is the lead equivalence commonly used for protective aprons in fluoroscopy?
• An outer-shell electron is ejected out and the atom is ionized during _____.
• The innermost electron shell is symbolized by the letter _____.
• With regards to radiation dose, the lens of the eye should never receive more than _____ per year for a person working with radiation.
• Increasing the source-to-image distance (SID) has which effect on magnification?
• The heel effect in radiography is primarily caused by which of the following?
• Characteristic K-shell x-rays have an effective energy of _____ keV.
• The unobservable image stored in the PSP of the image plate is called the
• Which retinal cells are responsible for color vision under bright light?
• Bremsstrahlung x-rays are produced when the incident electron, under the electromagnetic influence of the atom's nucleus, ________.
• Which modality is based on the patient emitting radiation due to administered radioactive tracers?
• An abdomen decubitus is performed with 80 kVp and 32 mAs at a distance of 40 inches. The resulting exposure is 0.24 mGya. If the same technique is used at 80 inches, what will the exposure be?
• Exposure linearity must be within which percentage for adjacent milliampere stations?
• MTF stands for Modulation Transfer Function.
• Fluoroscopy images can be described as which of the following?
• Compute grid ratio: a grid with height 8 mm and interspace 0.8 mm
• The percentage of the pixel face that is sensitive to x-rays is called the
• During an exposure, most of the _____ energy of the projectile electrons is converted to _____.
• Which statement correctly describes the Dose Area Product?
• The most commonly used beam restricting device is the _____.
• DR scintillators can be made from which materials?
• What is the removal of an electron from an atom called?
• Radiographic image quality is improved when the _____ is increased.
• The negative side of the x-ray tube holds the _____.
• Using an air gap technique to improve contrast has the same effect as using a grid with which ratio?
• Which combination correctly lists all three main parts of the x-ray imaging system?
• The four properties of photons are _____, _____, _____ and _____.
• On what date was the x-ray discovered?
• What term describes the percentage of the pixel face that is sensitive to x-rays?
• Approximately _____% of the x-ray beam incident on the patient is transmitted through the patient without interaction to become part of the image-forming beam.
• A 15% increase in kVp is equivalent to which change in mAs?
• Increasing kVp has which effect on x-ray beam?
• Which term best describes the system that handles patient demographics, orders, and scheduling in a radiology department?
• The exposure switch for portable x-ray units must allow the technologist to be at least how far away from the x-ray source?
• Characteristic x-rays are produced by _____.
• Which imaging metric describes the ratio of signal to noise in the resulting image?
• A moving object has which energy?
• The acronym PBL stands for which device?
• If I double the mA while keeping time the same, what happens to exposure?
• Which statement about energy distribution in the x-ray tube during exposure is correct?
• Which combination reduces geometric unsharpness most effectively?
• In the retina, which cells are stimulated by low light, and which by bright light?
• What does RIS stand for?
• Who died from overexposure to x-rays?
• OID affects all of the following except.
• The air gap technique is achieved by placing the patient 10-15 cm away from the image receptor to reduce scatter radiation at the IR. Which technique reduces scatter radiation reaching the image receptor by increasing the distance between the patient and the image receptor by 10-15 cm?
• Which of the following will not result in underexposure of a radiograph?
• Which human tissue is the most radiosensitive?
• Radiology equipment should be inspected by a qualified medical physicist every what period?
• Where is the focal spot located within the x-ray tube?
• Which color channel is NOT part of the RGB color model used by color displays?
• How can you improve image contrast with a heavy patient without increasing patient dose?
• This device discovered by Michael Pupin released a large number of light photons with just a few x-ray photons, thus reducing the dose of x-rays to the patient.
• At 55 kVp, _____ of the x-rays produced are bremsstrahlung.
• The exposure switch on a portable radiography machine should be no shorter than...
• What does equivalent dose take into consideration?
• What is the velocity of all electromagnetic radiation?
• In image intensifier fluoroscopy, brightness increase results from which combination?
• Which statement about ARRT ethics is true?
• How many ethical standards are in the ARRT code of ethics?
• Which is not one of the clinical performance standards found within radiography?
• X-rays transmitted through the patient without interaction contribute to which component of radiographic image formation?
• Most of the x-rays produced at the target are which type?
• Gamma rays are produced in the _____ of the atom.
• Which device reduces patient dose by converting x-ray photons to visible light to brighten images?
• The milliampere-seconds (mAs) is calculated by multiplying which two quantities?
• Which of the following is not a function of the anode in an x-ray tube?
• The effective focal spot size is smaller than the actual focal spot size under which condition?
• Who introduced ALARA in 1950?
• Who discovered the x-ray?
• Which if the following refers to the ability of the imaging system to preserve signal contrast as a function of spatial resolution?
• The _____ of electromagnetic radiation is constant.
• Distortion depends on which of the following? I. object thickness II. object position III. object shape IV. object material?
• What does DQE measure?
• Filtration primarily addresses which type of x-ray photons?
• As mAs is increased the signal to noise ratio is _____.
• Hounsfield units are used to describe radiodensity in which imaging modality?
• TG 18-QC is a standard test pattern used to evaluate which aspect of imaging systems?
• Object artifacts in digital imaging can be caused by errors in histogram selection.
• If HIS, RIS, and PACS are down, as long as a working modality is available, imaging can still be provided.
• Technologists working in fluoroscopy should use shielding whenever possible in addition to the apron and curtain.
• Which statement about increasing the field of view in fluoroscopy is true?
• What is the thickness of lead for the lead curtain hanging from the fluoro carriage?
• The effective focal spot size is _____ the actual focal spot size.
• DICOM is a standard for
• Which organization recommended limiting the amount of x-ray exposure to radiation workers and the general public?
• Air gap technique is equivalent to using a grid with which ratio?
• Digital radiography images should be repeated if there is a problem with _____ .
• ALARA stands for which of the following phrases?
• The three main parts of the x-ray imaging system are the x-ray tube, _____, and _____.
• Which factor directly affects the maximum detectable contrast in a digital radiography system?
• This equipment test looks at consistant x-ray beam intensity from one exposure to the next using a particular technique.
• A feature size of 0.1 mm requires a spatial resolution of at least
• When the structure of a body part prevents use of a short object-to-image distance (OID), which adjustment reduces magnification distortion?
• The bit capacity of each pixel identifies the _____ of a digital imaging system.
• For exposures that are less than 10 ms, the timer should be accurate within what percentage of each exposure?
• Which factor affects x-ray beam quality?
• Which identifier is used to uniquely identify a patient across encounters and generally remains constant?
• Gamma rays are produced in which part of the atom?
• In which interaction is there complete absorption of the incident x-ray photon?
• Radio waves, light, and x-rays are all examples of _____ energy.
• What does PACS stand for?
• Which type of artifact results from poor patient preparation?
• The device that converts scintillator light into a digital signal is called which?
• A graph of the frequency of occurrence versus digital value intervals is called a(n) _____?
• What is the mAs if I use 200 mA with a time of 140 ms?
• In the image intensifier, which component emits electrons when stimulated by light photons?
• Dose Area Product is a measure used to quantify patient dose by combining dose with what parameter?
• Which of the following will result in an increase in patient dose during fluoroscopy?
• Which statement best describes the ion formed when an atom loses electrons?
• Grid use improves contrast by reducing scatter; this typically requires higher exposure.
• Which organization certifies radiologic technologists?
• Attenuation in radiography is caused by which processes?
• Which imaging modality uses X-ray technology to provide real-time moving images during procedures?
• A charge-coupled device used in digital fluoroscopy provides high which property?
• Which statement best describes the effect of increasing patient thickness on image contrast?
• The portion of useful image-forming x-rays is referred to as the _____.
• Lossless data compression in radiology is used to achieve what?
• When atoms of various elements combine, they form _____.
• Which C-Arm mode will give the patient the most dose?
• Which QA term describes the ability of an imaging system to produce the same output for repeated exposures at the same technical factors?
• Artifacts seen after an exposure due to poor patient preparation or poor instruction are called
• The purpose of the lead apron in fluoroscopy is to protect the technologist from radiation caused by which interaction?
• With digital imaging, patient dose can be reduced by using higher _____ techniques.
• The use of which technique improves contrast and reduces patient dose?
• Characteristic x-rays are produced when an electron transitions to fill inner-shell vacancies.
• Which scintillator material is used in digital radiography detectors?
• Object artifacts in digital imaging can occur due to errors in:
• Compton scatter contributes to _____.
• Total brightness gain is the product of which two gains?
• Increasing kilovoltage peak (kVp) generally results in which effect on scatter radiation?
• Which statement describes what happens when characteristic radiation is produced by an incident electron at a tungsten target?
• HL7 is a standard used to exchange information between which types of systems?
• Which imaging modality is described as fast and extremely sensitive to tissue density differences and is widely used for pathology?
• Most of the heat generated at the target is due to _____.
• In the wrist radiograph example, the focal spot size was
• Which component controls the path of electron flow from the photocathode to the output phosphor to maintain image clarity?
• Where is x-ray production primarily located in the tube?
• Which term refers to the standard that enables storage and transfer of medical images and related data?
• Which statement about the air gap technique is true?
• Because of the line focus principal, the effective focal spot size decreases with decreasing _____ .
• Which statement best describes the effective dose in radiology?
• If an image receptor has a high probability of interacting with the x-ray beam, then it has a high _____.
• General-purpose radiographic units must have a minimum total filtration of ____ mm aluminum.
• If a portable chest radiograph uses 110 kVp with 2.0 mAs and an 8:1 grid, what is the mAs required to maintain receptor exposure?
• As an x-ray tube ages, the inside can become coated with tungsten, which can cause _____ in the tube.
• This imaging modality is able to penetrate bone without affecting the image. It also takes high resolution images of soft tissue.
• The best way to minimize magnification is to use a _____.
• What is the removal of an electron from an atom called?
• Why is the intensity of the beam greater on the cathode side than the anode side?
• ___________ should be done on an annual basis by a medical physicist.
• Which of the following is a main component of the x-ray imaging system that houses exposure controls?
• The portion of useful image-forming x-rays is referred to as the ______.
• Which body part has the highest subject contrast?
• The visible light field must be within what percentage of the actual x-ray field?
• Which organization sets radiation dose limits for both workers and the public?
• Which parameter among the following best controls the energy spectrum of the X-ray beam?
• Measuring the relationship between the output intensities of adjacent mA stations is a test of _____.
• When electrons bombard the target, _____% of their kinetic energy is converted to heat.
• What is the primary purpose of beam restricting devices in radiography?
• In a neutral atom, the number of protons equals the number of which particle?
• Which term describes the interval between finishing CT data collection and the images being displayed?
• At energies below 40 keV, the predominant x-ray interaction in soft tissue and bone is _____.
• What does effective dose take into consideration?
• Dynamic fluoroscopy refers to images that __________.
• Which term refers to a system that stores and provides access to radiographic images?
• The software correction that equalizes the response of each pixel to a uniform exposure is called which?
• What is the exposure limit for members of the public receiving a single exposure?
• A cumulative timer is designed to _____ of fluoroscopy beam-on time.
• Photons with the highest frequencies have the _____.
• Which identifier is commonly used to locate a patient’s medical history across visits?