Lecture 2 ~~ Notes

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary function of the step-up transformer in an X-ray system?

To decrease voltage from 60-70kV to 240V.

To convert X-ray photons into electron energy.

To increase voltage from 240V to 60-70kV. (correct)

To emit electrons from the cathode.

What percentage of the kinetic energy of electrons is converted to X-ray photons when they hit the tungsten target?

10%

99%

50%

1% (correct)

During Bremsstrahlung radiation, what causes the emission of X-ray photons?

Electrons collide with other electrons in the tungsten.

Photons are created as electrons gain energy.

Electrons are emitted from the tungsten target.

Electrons decelerate and change direction due to the nucleus's attractive force. (correct)

What is produced during characteristic radiation when an incoming electron collides with an electron in the tungsten atom shell?

A characteristic X-ray photon. Signup and view all the answers

Which component of the X-ray system helps in minimizing exposure and controlling beam direction?

Spacer cone Signup and view all the answers

What is the primary role of the surrounding oil in the X-ray tube?

To provide insulation and remove heat from the anode. Signup and view all the answers

What happens to the outer-shell electron after an inner-shell electron is ejected during characteristic radiation?

It drops into the inner shell, emitting a characteristic X-ray. Signup and view all the answers

What material is primarily used for the cathode in an X-ray tube?

Tungsten Signup and view all the answers

What is the primary purpose of filtering low-energy X-rays?

To decrease patient dose Signup and view all the answers

What happens to image contrast when kilovoltage (kVp) is increased?

It decreases due to greater penetration Signup and view all the answers

How does increasing milliampere (mA) affect X-ray production?

It increases the quantity of X-rays produced Signup and view all the answers

What is the effect of a shorter focal spot to skin distance (FSD) on the X-ray beam?

It leads to a wider, more divergent beam Signup and view all the answers

What is a key benefit of using rectangular collimators in X-ray imaging?

They match the shape of the detector Signup and view all the answers

What is the minimum distance that the spacer cone should be to effectively reduce radiation exposure?

200mm Signup and view all the answers

Which characteristic describes the radiation produced by characteristic X-rays?

It is specific to tungsten and defined by energy differences between shells Signup and view all the answers

Which two components directly affect the dose in the mAs equation?

mA and time Signup and view all the answers

Study Notes

X-Ray Production

Characteristic X-rays require unit to operate 70kV or higher
This radiation is a characteristic of tungsten
Produces photons of specific energy (equal to difference in energy between shells)
Filtering of low energy X-ray photons are required as they produce contribute to image formation as they can't penetrate as they produce dose but don't contribute to image formation
An aluminum filter removes low-energy photons from beam
- 1.5mm for X-ray tubes working up to 70kV
- 2.5mm for X-ray tubes working above 70kV
For safety must have audible and visual warning signs that X-ray is taking place

Exposure Factors

Kilovoltage (kVp) - often fixed (60-70)
Milliampere-Seconds (mAs)
- mA - usually fixed
- Time - always controllable
When kVp increases energy of photons increase
- Less contrast in radiographs as more X-rays penetrate through the patient
- Lower dose
Lower kVp used to image soft tissues
When increasing mA the quantity of X-rays produced also increases
- Too high leads to overexposure, too low leads to underexposure
- mA and time are directly proportional to the dose

Collimation

Collimation reduces dose to patient
Rectangular shaped collimator used to match rectangular shaped detector
- If the collimator was removed, and the image was cylindrical, there would be a rectangular-shaped detector to receive the image, and all the additional area would be exposed by the patient
Rectangular collimation will at least half dosage
Other factor affecting dose: Focal spot to skin distance
- Spacer cone short: very divergent X-ray beam
- Spacer cone long: narrows beam reducing anatomy that is irradiated
- Spacer cone should be at least 200mm

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Explore the crucial principles of X-ray production and the factors that influence exposure. Understand the role of kilovoltage and milliampere-seconds in generating high-quality images. This quiz will test your knowledge on safety measures and the effects of varying exposure settings on radiographic images.