Chapter 21
Radiologists: Physicians with specialized training in obtaining and interpreting medical images.
Radiographers, radiologic technologists, and radiologic technicians and radiologic assistants help provide radiologists which images.
Sonographers: Operate ultrasound imaging devices to produce images.
Nuclear medicine specialists: Specialists in use of radiopharmaceuticals for purpose of diagnosis, treatment, and research.
Nuclear medicine technologists: administer radiopharmaceuticals
Radiotherapists: physicians who specialize in treatment of disease using xrays and radioactive materials.
Section 21.1 Xray Imagery Production
Wilhelm Conrad Rontgen discovered x-rays in 1895.
X-rays exhibit velocity, invisibility, ionization, and wavelengths.
Velocity: Due to their electromagnetic nature, they would travel at the speed of light if not for substances.
Wavelength: X-Rays have very short wavelength compared to other rays (with gamma being shortest); Radiolucent materials allow X-rays to pass through, while radiopaque materials block them.
Invisibility: X-Rays cannot be detected by sight, sound, or even touch. Professionals must wear a film badge in order to see if they are exposed.
Ionization: X-Rays possess enough energy to displace electrons from atoms, leading to ionization, which can cause cellular damage if exposure is excessive.
Photographic film is used to record xray photos → light → energy from the X-Rays exposes the film, creating a visual representation of the internal structures and allowing for diagnostics.
Patient Alignment
Posteroanterior (PA): Posterior source to anteriorly placed image receiver.
Anteroposterior (PA) Anterior source to posteriorly placed image receiver.
Lateral View: Left source to right receiver and vice versa.
Mediolateral oblique (MLO): Used typically in mammography.
Craniocaudal (CC): Head to foot x-ray.
Oblique: X-Rays travel at angle from perpendicular plane and pass behind heart and lung hilum to show structures hidden in PA/AP views.
Acquisition of Radiologic Imagery
Plain (Projectional) Radiography
Only modality in first 50 years of radiology, x-rays would pass through a patient and create images on film. Film later developed chemically to produce film.
Digital radiography (DR): x-rays strike plate of sensors that convert signals into digital information which projects an image.
Fluoroscopy
Continuous x-ray image shown on monitor like an movie… allowing for real-time imaginary of structures.
Radiocontrast agents (ex: barium sulfate and iodine) can be administered orally, intravenously, rectally, or into an artery to allow for real-time imaging of dynamic processes.
Esophagogastroduodenoscopy (EGD): barium sulfate taken and fluoroscopy used to get direct visual inspection.
Interventional Radiology
Interventional radiology (IR): minimally invasive procedures both for diagnostic purposes (angiogram) and for treatment (ex: angioplasty).
Helps provide a road map for smaller precise instruments to be guided toward area of disease.
Computed Tomography
Computed tomography (CT): Produced in EMI Labs in England in 1972, CT scans use x-rays in conjunction with computer algorithms to produce a cross-sectional image (tomogram) in axial plane.
Computer algorithms can also produce both coronal and sagittal images.
Radiocontrast substances can help delineate anatomy.
Ultrasound
Medica ultrasonography: Ultrasound (US / high-frequency sound waves) used in real-time to visualize soft tissue structures in the body.
Doesn’t use radiation, allowing for use in pregnant patients and children without the associated risks.
Ultrasound helps measure severity of peripheral vascular disease, heart function and integrity of major viscera.
Magnetic Resonance Imaging
Magnetic Resonance Imaging (MRI): uses strong magnetic fields to align atomic nuclei in tissues, then uses radio signals to disrupt the nuclei and observes radio frequency signals as nuclei return to their baseline states.
Can produce axial, coronal, sagittal, and oblique planes and gives the best soft tissue contrast of all imaging modalities.
Noisy, confined and those with artificial surgical hardware can not use it.
Section 21.2 Nuclear Medicine
Radiopharmaceuticals
Radiopharmaceuticals: Combination of radionuclides with pharmaceutical compounds and a radioactive tracer.
Traces used consist of:
Technetium-99m: Used in 85% of bone scans, liver, renal, red blood cells and use as a gas!
Iodine-123: Thyroid Scans!
Iodine-131: Kills thyroid tissue.
Gallium-67: used in positron emission tomography (PET) scans and for localizing infections.
Indium-111: Used to label and identify movements of white blood cells.
Thallium-201: myocardial perfusion scans in stress tests.
18F-FDG or fludeoxyglucose: Staging for cancer.
PET or Positron emission tomography produces two opposite traveling gamma rays to be detected concurrently to improve resolution.
Radiation Therapy
Radiotherapy is treatment of an disorder with x-rays radionuclides.
X-Ray Therapy
Conventional external-beam radiation therapy: Single beam of radiation delivered to tumor from several directions. However very healthful tissues are likely to be harmed… surgical resection, chemotherapy or radiosenitizing drugs (cisplatin and cetuximab) can be used.
Stereotactic radiation: Specialized form of external-beam radiation therapy. It uses detailed imaging scans to precisely target the tumor. Stereotactic radiosurgery (SRS) also applies several separate narrow beams of radiation to the tumor.
Hypofractionation: A treatment method that involves delivering higher doses of radiation per session over fewer overall sessions, which has shown effectiveness in certain types of cancers while reducing the total treatment time.
Intensity-modulated radiation therapy (IMRT): next generation of 3DCRT… if tumor is wrapped around a vulnerable structure such as a spinal cord or organ, allowing for precise dosage distribution while minimizing exposure to surrounding healthy tissues.
3D conformal radiation therapy (3DCRT): delineate tumors ad surrounding normal tissues in 3D using CT or MRI scanners and planning software. Profile of each radiation beam and treatment volume conform to tumor.
Proton beam therapy: Protons only give up energy when it hits the tumor, and does not continue through the tissue and damage healthy tissue. Very high doses of radiation can be used, and is seen often used in prostate cancer.
Nuclear Medicine Therapy
Radioactive Iodine (I-131) therapy: I-131 is taken orally and absorbed into bloodstream from GI Tract and gets concentrated by thyroid gland. It destroys thyroid gland cells in order to help treat thyroid cancer and abnormalities like hyperthryoidism.
Radioimmunotherapy (RIT): Combination of radiation therapy and immunotherapy. Lab-produced molecule called monoclonal antibody is made which binds to surface of cancer cells. In RIT, the monoclonal antibody also has a radioactive material attached, also giving a dangerous dose of radiation to tumor.
Word bank!!!!!!!!
Prefixes!!
medio - middle
tele - distant
brachy - short
hypo - below
mono - one, single
Roots/Combing Form!!!!!
ax - central support
electro/o - electricity
magnet - magnet
coron - crown
radi/o - radiation
angi/o - blood vessel
anter/o - coming before
poster - coming behind
fluor/o - x-ray beam
later - side
crani/o - skull
caud - tall
mammo/o - breast
fibr/o - fiber
glandul - little gland
intervent - to come between
saggit - arrow
tomo/o - section
son/o - sound
photon - particle of light or electromagnetic radiation
positron - subatomic particle equal in mass to in electron but with opposite positive charge.
nucl - nucleus
pharm/a - drug industry
scint/I - spark
immuno/o - immune response
therapy - medical treatment
stere/o - three dimensional
tact - orderly arrangment
Suffix!!!!!!!
ic - pertaining to
al - pertaining to
ar - pertaining to
ial pertaining to
ior - pertaining to
ical - pertaining to
ion - action, process
er - one who records
ide - having a particular quality
logy - study of
lucent - open
paque - shady
gram - a record
plasty - surgical repair
graphy - process of recording
scopy - to examine
contrast - against