ARRT Radiography (Sample Exam)

Leakage and scatter radiation are considered secondary radiation. Leakage radiation can be emitted when a defect exists in the tube housing. Scatter radiation is generated within, and emitted from, the patient.

Optically stimulated luminescence (OSL) dosimeters uses aluminum oxide. The method makes use of electrons trapped between the valence and conduction bands in the crystalline structure of certain types of matter (such as quartz, feldspar, and aluminium oxide). The trapping sites are imperfections of the lattice – impurities or defects.

The OSL dosimeter provides a new degree of sensitivity by giving an accurate reading as low as 1 mrem for x-ray and gamma ray photons with energies ranging from 5 keV to greater than 40 MeV. The OSL dosimeter’s maximum equivalent dose measurement for x-ray and gamma ray photons is 1000 rem. For beta particles with energies from 150 keV to in excess of 10 MeV, dose measurement ranges from 10 mrem to 1000 rem. In diagnostic imaging the increased sensitivity of the OSL dosimeter makes it ideal for monitoring employees working in low-radiation environments and for pregnant workers.

The larger the absorbed dose, the greater the effect. Biologic effect is increased as size of the irradiated area is increased. The nature of the effect is influenced by the type of tissue (bone marrow, gonads, etc).

The first step in solving the equation is to:
1). Solve for milliamperage-seconds
2). The lowest kVp and the lowest mAs would cause the lowest patient dose because dose directly increases with mAs and exponentially with kVp. Doubling the mAs would double the dose to the patient. Doubling the kVp would result in four times greater dose to the patient.

Rigid abdomen, extreme thirst, Nausea and vomiting are signs the radiographer must recognize and respond to. Extreme diarrhea, although unpleasant, is NOT a sign of acute abdominal distress but another underlying process potentially related to a disease process or food poisoning.

In a cardiac or respiratory emergency the radiographer must be prepared to call a code and begin CPR, if necessary.  In an adult patient the carotid pulse is the first location to palpate. If the pulse is difficult to feel, the next location is the femoral pulse. In infants, the brachial pulse is the correct location.

Hospital workers such as radiographers, who disclose confidential information to unauthorized individuals may be found guilty of invasion of privacy. Defamation is the action of damaging the good reputation of a patient. Spoken defamation is known as slander; written defamation is known as libel.

Medication is administered parenterally when it cannot be given by mouth. Examples of parenteral route are:  intravenous, intramuscular, or intracardiac. The speed of absorption varies with the route use.

A lumbar puncture can help diagnose serious infections, such as meningitis; disorders of the central nervous system, such as Guillain-Barre syndrome, and multiple sclerosis, or cancers of the brain or spinal cord. Sometimes doctors use lumbar puncture to inject anesthetic medications or chemotherapy drugs into the cerebrospinal fluid. A spinal needle is inserted between the lumbar vertebrae of L3/L4. Other sites may include  L4/L5 or L5/S1.

To demonstrate the apophyseal joints on a oblique projection of the lumbar vertebrae, rotate the patients body 45° towards the side being examined. The 45° angle should demonstrate the lumbar articular facets closer to the image receptor. If the fifth articular facet is in question, an additional view with a 30° rotation should be obtained.

Motion has a negative effect on radiographic detail. Even the slightest movement can cause unsharpness of the radiograph.  Instructing the patient to hold the breath and suspend respiration is an effective means of reducing voluntary motion.

Severe pain and muscle spasms cause involuntary movements. Peristaltic activity of the G.I. tract is also uncontrollable by the patient.

The energy of the x-rays is controlled by the high voltage kVp. When the kVp is increased, the x-ray photons that are produced have a shorter wavelength, and thus have higher energy. This is an inversely proportional relationship.

Bit depth describes that available grayscale for image acquisition and display.

As the matrix size increases, there are more pixels distributed over the area. As a result, the pixels will be smaller, and smaller pixels give better resolution.

The collimator must be accurate to within 2% of the SID.

Advantages of 35mm cine film over 16mm cine film include a larger filming area which results in higher resolution and which permits the recording of more information.

A quality control program is for all instrumentation and equipment. A quality assurance program is addressing patient care problems.

The Cathode is the negative side of the x-ray tube and has two primary parts: a filament and focusing cup. The filament is the part of the Cathode that emits electrons resulting into current, a process known as thermionic emission. The focusing cup is a metal piece that surrounds the filament.