CLO19: Compare the production of bremsstrahlung and characteristic radiations.

Bremsstrahlung and characteristic radiation are a result of electrons moving rapidly from the cathode to the anode which then proceeds to the target of the x-ray tube. Bremsstrahlung radiation occurs when a projectile electron from the filament comes in contact with the nucleus of the target atom, slows down and then changes direction which leaves it with a decreased kinetic energy. The decreased kinetic energy results in bremsstrahlung x-rays. Characteristic radiation occurs when a projectile electron from the filament ionizes the target atom by removing an inner-shell electron. The projectile electron proceeds to fill the inner-shell vacancy of the target atom. The result being characteristic x-rays.

CLO08: Explain methods used to extend x-ray tube life.

Methods used to extend x-ray tube life:

• using quality control tools such as cooling charts and rating charts (safe and unsafe exposure factors)
• to minimize frequent use of maximum exposure factors
• to minimize use of long exposure factors
• not to overload the filament (excessive heating)

CLO05: Explain the inverse square law.

As the distance between a light source and the subject in question increases, the intensity of the light is decreased. The intensity of the light is decreased because the light area is greatly increased. This same concept also applies to the x-ray tube. The intensity of the light source is inversely proportional to the distance of the subject in question. The inverse square law is as follows:

I1/I2 = (d2)^2/(d1)^2

CLO04: Discuss importance of voltage ripple.

Voltage waveforms are characterized by voltage ripple. Voltage ripple consists of four different types. Single-phase has a one hundred percentage voltage ripple where the voltage ranges from zero to its maximum value. Three phase, six pulse has a fourteen percent voltage ripple with eighty-six being its lowest percent of the maximum value. Three phase, twelve pulse has a four percent voltage ripple with ninety-six being the lowest percent of the maximum value. The high-frequency generator has a one percent voltage ripple. Voltage ripple is absolutely necessary because in order to utilize an x-ray tube, the wavelength cannot be interrupted. The high-frequency generator is the only viable option that is sufficient for x-ray tube production. A voltage waveform with a lesser voltage ripple allows for greater quality as well as quantity in terms of its x-ray production.

CLO01: Describe potential difference, current and resistance.

Potential difference is the difference of potential between two points. Current is a moving charged particle. Resistance is opposition to the flow of a current. The law of Ohm is an example of all three aspects condensed into an equation. Ohm’s law equation is V=IR.

CLO016: Describe conditions that cause quantum mottle in a digital image.

Quantum mottle refers to the amount of exposure that reaches the image receptor. As the amount of photons that reached the image receptor decreased, the grainer the image or a pattern is superimposed upon the image. It can also affect the contrast resolution by concealing differences of the grey scale. To ensure that this doesn’t happen, the mAs or kVp must be increased as it will guarantee that an increased number of photons will reach the image receptor.

CLO15: Describe signal to noise (SNR) as it relates to digital radiography detectors.

Signal to noise (SNR) is designed as a ratio between the desired signals and undesired signals that were used to actually create the image. The desired signal comes from the beams of the volume of interest on the image. The undesired signals otherwise known as noise includes scattering and quantum mottle. An undesired signal meaning an interference of some kind. The desired signals and undesired signals are inversely proportional to each other. As the signal to noise ratio increases so does the desired signals while undesired signals decrease.

CLO12: Differentiate images produced by various modalities.

CT image of Abdomen: Computed tomography produces 3D cross-sectional images of the affected area.

MRI image of the brain: Magnetic Resonance Imaging uses a magnetic field and radio waves to produce cross-sectional images of internal organs and structures. MRI does not use ionizing radiation.

Fetal Ultrasound: Ultrasound uses high frequency sound waves to produce images of soft tissue structures.

CLO03: Describe an effective image analysis method.

Radiographic images need to be dissected segment by segment. First, analyze whether the anatomy is positioned properly. Second, question whether the part is centered to the image receptor both longitudinally and transversely. Third, question whether the central ray from the x-ray tube is directed towards the image receptor longitudinally and transversely. Also, is the central ray from the x-ray tube directed to the body part? Fourth, the exposure indicator should be analyzed as to whether its overexposed, underexposed or properly exposed. If the radiographic image isn’t optimal then a plan should be constructed that ensures that if taken again, the image will be optimal.

CLO08: Discuss the impact of patient preparation on the resulting radiographic image.

Patient preparation is significant during a radiographic exam. The reason being that artifacts may be present. While taking a patient’s history, it is important to ask about any metal or buttons on their clothing near the affected anatomy. If the answer is yes, then the patient needs to change into a gown. Artifacts distort the image and another exposure would have to be taken.