meaning as low as reasonably achievable

- controlling factor of x-ray quality - Increasing this will also INCREASE the AMPLITUDE OF THE SPECTRUM.

____ & _____ supplied to the x-ray tube for formation of x-ray beam

where electrons are gathered

the process where electrons are ejected from filament to the anode

this is called the area of target of what electrons hit - area of the anode to which electrons hit

produced as electrons interact with the target

cloud of electrons, the one that makes it difficult for electrons

called when electrons have difficulty being emitted from the filament or when electrons have difficulty moving

affect the spatial resolution of the radiographic image and heat produced in the anode, determined by filament size

Used when better spatial resolution is required Selected when 300 mA or less is used in the filament size range from 0.1 to 1 mm using this increases heat generated to a smaller area of the anode

Used when larger parts are examined and when other techniques that produce high heat are required. Selected when we use 400 mA and up in the filament sizes range from 0.3 to 2 mm

area on the anode that is EXPOSED TO ELECTRONS from the cathode side

Area projected to the patient Size is controlled by the size of the actual focal spot.

Allows a large area for heating while maintaining a small focal spot. The target is angled to a degree thus making the effective area of the target much smaller than the actual area of electron interaction. When the target angle is made smaller, the effective focal spot size is also made smaller.

Diagnostic x-ray tubes have target angles ranging from 5-20 degrees. Advantage: improves spatial resolution and heat capacity. results in an effective focal spot size much smaller than the actual focal spot size.

An unfortunate consequence of using the line focus principle. Radiation intensity on the cathode side of the x-ray beam is greater than that on the anode side X-rays that constitute the useful beam emitted toward the anode side must traverse a greater thickness of the target material than that on the cathode side. The smaller the anode angle, the larger the heel effect.

important in imaging anatomy with varying thickness.

useful part of the x-ray projected from the x-ray tube window and onto the patient

imaginary line generated by the centermost part of the x-ray beam

- produced when some electrons bounce off the focal spot and then land on other areas of the target, it causes X-rays to be produced outside the focal spot. - Can image patient tissue that was intended to be excluded by the collimators - Undesirable because if extends the size of the focal spot which increases skin dose and reduce Image contrast - X-ray tubes are designed so that the projectile electrons only interact with the target only at the focal spot

Measuring each energy of the useful beam  The number of x-rays emitted is plotted as a function of the energy of each individual x-ray Data of the this is needed to understand how changes in kVp, mA and added filtration affects the image quality of an image.  The minimum wavelength of x-ray emission corresponds to the maximum x-ray energy, and the maximum x-ray energy is numerically equal to the kVp.

The area below the amplitude is the _____ of x-ray photons measured. The area going to the right is the _____ of the x-ray photons.

Characteristic X-ray Spectrum. Contains only specific values.

have precisely fixed energies.

Bremsstrahlung X-ray Spectrum. A spectrum that contains all possible values. If an energy peaks at 90 keV, the spectrum would show all values ranging from 0 to 90 keV.

When ___ is increased, the distribution of the emitted x-ray energy SHIFTS MORE TO THE RIGHT; to a HIGHER AVERAGE ENERGY.

kVp affects both the ____ and ____ of x-rays as to why it also affects both the amplitude and the position of the spectrum

Increase in ______ will result in an INCREASE in the PRODUCTION of BREMSSTRAHLUNG X-RAYS and high-energy x-rays increases in number to a greater extent than lower energy x-rays

- will absorb low energy x-rays than high energy x-rays; therefore the spectrum is reduced more on the left than on the right - reduces contrast due to beam hardening caused by increased in high energy x-rays.

Using power sources with less voltage ripple will result in a ____ increase in x-rays when using the same kVp

- mainly controlled by mAs - The quantity or number of x-rays in the x-ray beam. - Measured in Roentgen or Gray. - Also called Radiation Exposure.

- affects the image optical density. - PROPORTIONAL to the SQUARE OF RATIO of the kVp.

is directly proportional to the mAs.

Increasing ___ will INCREASE the NUMBER OF ELECTRONS striking the target, therefore doubling the x-rays emitted

If the kVp is doubled, x-ray intensity would ____ by a factor of 4.

As the distance increases, x-ray intensity _____ by a factor of 4.

varies INVERSELY with the SQUARE OF DISTANCE from the x-ray tube target

- Reduces low energy x-rays which contribute nothing in image production - lowers patient dose - will reduce beam intensity while increasing the average energy

Ability of x-rays to penetrate deeper in tissue. High energy x-rays penetrate deeper than low energy x-rays. As the x-ray energy is increased, beam penetrability is also increased. Factors affecting the x-ray quality also influences radiographic contrast.

The thickness of the absorbing material necessary to reduce the x-ray intensity to half its original value. It is the best method for specifying x-ray quality.

As the _____ increases, x-ray beam penetrability also increases, therefore HVL is also _________

- material of choice in filtration efficient in removing low-energy x-rays through photoelectric effect and because it is readily available, inexpensive, and easily shaped

- Primary purpose is to remove low energy x-rays that have little chance of getting to the image receptor - Secondary purpose is to reduce patient dose Increasing this increases x-ray beam quality

Located inside the x-ray tube Glass or Metal enclosure of the x-ray tube Usually made with Pyrex glass Equivalent to 0.5 mm Al (General Radiography) Equivalent to 0.1 mm Al (Beryllium material for Mammography)

Thin sheet of Aluminum placed between the x-ray tube and collimator Usually has two sources 1-2 mm Al: Permanently installed between the housing and the collimator 1 mm Al: Silver Surface of the mirror in the collimator

Used when a body part with unequal thickness or tissue composition needs to be examined and produce an image with uniform intensity.

obtained as the voltage across the x-ray tube increases from zero to its peak value, x-ray intensity and energy increase SLOWLY at first, then RAPIDLY

Size of the Effective Focal Spot is controlled by?

Radiation intensity across the useful beam of an x-ray field can vary by as much as what percent

must be positioned on the thicker part of the anatomy to provide a more uniform radiation exposure to the image receptor