Radiologic Specialties Final Exam Review Flashcards
(36 cards)
Define CT:
Computed tomography scan. Detailed images of internal organs are obtained by this type of sophisticated X-ray device. CT stands for computed tomography. The CT scan can reveal anatomic details of internal organs that cannot be seen in conventional X-rays.
Differentiate between pixels and voxels:
Pixels: picture elements. 2d element assigned a gray value in the form of a CT #
Voxel: 3d picture element that reps a volume of tissue in reconstructed CT image. voxel size depends on 3 things= slice thickness, matrix size, and FOV. voxel size is determine by multiplying pixel size by slice thickness
What is window width and window level and what does each control?
WW: range of ct numbers displayed in the image represented by gray scale. determines max # of shades of gray display and controls contrast. wide ww-less variation between tissues of similar density.
WL: designates mid point of CT #s and controls brightness. high WL makes image darker.
What are CT numbers aka Houndsfield units and what do they represent?
gray scale number seen on the image, various shades of gray
Explain how the CT image is created:
The tube and the detector array rotate around the patient and thousands of measurements are taken to determine the radiation attenuation value for each tissue volume element. When that has been determined the data is converted into CT #s for display purposes.
What are the components of the CT equipment?
imaging system, computer and operator console
define pitch, how does pitch affect CT dose?
pitch increases=image quality improves=pt dose decreases. the pitch is distance the table travels during one revolution of the xray tube.
Define MRI:
Magnetic resonance imaging (MRI) is a technique that uses a magnetic field and radio waves to create detailed images of the organs and tissues within your body.
atom that provides MRI signal:
hydrogen
contraindications/safety issues with the magnet:
No projectiles, heating, or electrical interferences
differentiate between T1, T2,
in MRI:
The T1 and T2 relaxation times define the way that the protons revert back to their resting states after the initial radiofrequency pulse. The most common effect of flow is loss of signal from rapidly flowing arterial blood. The most common pulse sequences are T1 weighted and T2 weighted spin-echo sequences. T1 weighted sequence uses a short TR and Short TE. T2 weighted sequence uses a long TR and long TE.
define frequency, spin density and signal strength:
F- the location of origin of the mRI signal
SD- the quantity of hydrogen nuclei that are present in a given volume of tissue.
SS- received by an antenna or coil, is used to define the brightness of each point on the image.
How are resonance and precession created?
R-radiowaves affect the nuclei bc of the time varying magnetic field of the radio wave changes at the same rate as the nuclei precess. As the nucleus rotates the magnetic field appears at just the proper time to have maximum effect in pushing the nucleus away from the static magnetic field.
P-When the proton of a hydrogen nucleus spins around its own axis giving it an angular moment. It’s a wobbling motion that occurs when a spinning object is the subject of an external force. It’s is also known as the strength of the magnetic field
define angiography, venography and interventional radiography:
A-The radiographic examination of vessels after the injection of contrast media
IR- Radiologic procedures that intervene in a disease process, providing a therapeutic outcome.
V-Examination that uses an injection of contrast media to show how blood flows through the veins. This procedure helps to find blood clots, identify a vein for use in a bypass procedure or dialysis access
indications for cerebral angiography and venography:
Vascular stenosis (narrowing) and occlusions (blockage)
Aneurysms
Arteriovenous malformations
Neoplastic disease
Confirm brain tumor
Find a clot that may have caused a stroke
explain the process of accessing the arteries
The patient is lying down on an x-ray table
The head is held in place using a strap, tape, or sandbags to prevent movement
A mild sedative is given to help the patient relax
An Electrocardiogram (ECG) is used to monitor heart activity during the test
An area of the body, usually the groin, is cleaned and numbed with a local anesthetic
A thin, hollow tube called a catheter is placed through an artery. The catheter is carefully moved up through the main blood vessels in the abdomen and chest into an artery in the neck:
common carotid artery, internal carotid artery, external carotid artery and vertebral artery
know the steps involved in the Seldinger procedure
Insert compound (Seldinger) needle
- ) Place needle in lumen of vessel
- ) Insert guidewire
- ) Remove the needle
- ) Thread catheter through the vessel to the area of interest
- ) Remove the guidewire
differentiate between catheters and guidewires
Catheters are chosen based on the area of interest, how the catheter will be traveling through the vessel.
Guidewires allow for safe introduction of the catheter through the vessel to the area of interest.
define PICC line, IVC filter, PTA, and embolization
PICC-A peripherally inserted central catheter, a form of intravenous access that can be used for a prolonged period of time (e.g., for long chemotherapy regimens, extended antibiotic therapy, or total parenteral nutrition)
IVC Filter-inferior vena cava filter is a type of vascular filter, a medical device that is implanted by interventional radiologists or vascular surgeons into the inferior vena cava to presumably prevent life-threatening pulmonary emboli
PTA-percutanous trasluminal angioplasty-A vessel is entered through the skin (percutaneous) and the catheter is moved into the blood vessel through the same vessel or one that communicates with it (transluminal)
Embolization- A procedure that utilizes chemical agents or metallic coils to stop bleeding and treat hemorrhage, cranial tumors, and aneurysms
risks associated with angiography
Bleeding at the puncture site: controlled by applying pressure.
Thrombus formation: of a blot clot in the vessel that may disrupt the flow to the distal parts.
Embolus formation: a piece of plaque may be dislodged from a vessel wall by the catheter.
Dissection of a vessel: the catheter may tear the intima of a vessel.
Infection of the puncture site: caused by contamination of the sterile field.
Contrast media reaction: may be mild, moderate, or severe.
What is French number, how does it affect catheter lumen size
Terms used to describe the size of the catheter.
Refers to the measurement of the outside
Diameter of the catheter.
Measures multi- lumen catheters.
define radiation oncology
uses ionizing radiation (such as megavoltage X-rays or radionuclides) in the treatment of cancer.
identify the equipment used and the purpose of the linear accelerator
its the machine most often used in tele therapy which employs electricity to cast a stream of fast moving subatomic particles which produces high energy radiation that can be used in the treatment of cancer
common side effects of the treatment for oncology
early ones are nausea, loss of appetite, fatigue, skin damage. late effects are hair loss, memory loss, fibrosis, damage to bowels, infertility, second cancer, tooth decay, sexual problems, menopause, bladder problems, dry mouth, skin color changes.
