Week 1

Question 1

In what year were X-rays discovered and by whom?

Answer 1

1895 by Wilhelm Roentgen

Question 2

What was the first radiograph?

Answer 2

Roentgen’s wife’s hand showing her wedding ring

Question 3

What is the first Nobel Prize in Physics related to X-rays?

Answer 3

Awarded to Wilhelm Roentgen in 1901

Question 4

What is the medical branch that initially used X-rays?

Answer 4

Roentgenology

Question 5

X-rays are a form of what type of energy?

Answer 5

Electromagnetic radiation

Question 6

How are wavelength and frequency related?

Answer 6

Inversely related

Question 7

What are the properties of X-rays?

Answer 7

Invisible, electrically neutral, no mass, travel at the speed of light, straight lines, can ionize atoms

Question 8

What is the unit for exposure in air (standard and SI)?

Answer 8

Roentgen (R), Coulomb/kg

Question 9

What is air kerma measured in?

Answer 9

Gray (Gy)

Question 10

What is the conversion between R and Gy?

Answer 10

1 R = 0.01 Gy

Question 11

What is absorbed dose?

Answer 11

Radiation energy transferred to matter (tissues/organs)

Question 12

What is the conversion between rad and gray?

Answer 12

1 Gy = 100 rad

Question 13

What is the unit for occupational radiation dose?

Answer 13

REM or Sievert (Sv)

Question 14

What is the ALARA principle?

Answer 14

As Low As Reasonably Achievable for minimizing radiation

Question 15

What are the three key concepts in radiation protection?

Answer 15

Time, Distance, Shielding

Question 16

What is erythema in relation to X-ray exposure?

Answer 16

Reddening of the skin, early sign of biological damage

Question 17

What determines X-ray beam quantity?

Answer 17

Number of photons in the beam

Question 18

What determines X-ray beam quality?

Answer 18

Penetrating power of the beam

Question 19

What happens when you double the mA?

Answer 19

You double the quantity of X-rays

Question 20

What is thermionic emission?

Answer 20

Release of electrons from heated filament

Question 21

What side of the X-ray tube is the cathode?

Answer 21

Negative, left side

Question 22

What side of the X-ray tube is the anode?

Answer 22

Positive, right side

Question 23

What is the line focus principle?

Answer 23

Relationship between actual and effective focal spot

Question 24

What is the anode heel effect?

Answer 24

X-rays are more intense on the cathode side

Question 25

What is the purpose of beam filtration?

Answer 25

To absorb low-energy photons and reduce patient dose

Question 26

What are the two types of X-ray interactions in the tube?

Answer 26

Bremsstrahlung (85%) and Characteristic (15%)

Question 27

What is the function of compensating filters?

Answer 27

Even out exposure for body parts of varying thickness

Question 28

What is heat unit (HU) calculation used for?

Answer 28

Determining the heat produced in the X-ray tube

Question 29

What does kVp control in x-ray production?

Answer 29

It controls the quality (penetrating power) of the x-ray beam.

Question 30

What does mAs control in x-ray production?

Answer 30

It controls the quantity of x-rays produced.

Question 31

Why use high kVp and low mAs?

Answer 31

To reduce patient dose while maintaining image quality.

Question 32

How can communication reduce repeat x-rays?

Answer 32

By explaining the procedure, verifying patient ID and side, and preparing them properly.

Question 33

How can positioning aids help?

Answer 33

They stabilize anatomy and help reduce motion, improving image quality.

Question 34

What is AEC (Automatic Exposure Control)?

Answer 34

A system that stops exposure when the correct image density is reached.

Question 35

What is the 10 cm rule?

Answer 35

Use a grid for body parts thicker than 10 cm to reduce scatter.

Question 36

What is the current guideline for gonadal shielding?

Answer 36

Not routinely recommended due to potential increased dose and image interference.

Question 37

What is the edge effect in shielding?

Answer 37

Backscatter increases dose near the edges of the lead shield.

Question 38

When is shielding still acceptable?

Answer 38

If requested by the patient or when it doesn't interfere with the image.

Question 39

What are the three cardinal rules of radiation safety?

Answer 39

Time, distance, shielding.

Question 40

What is the inverse square law?

Answer 40

I1/I2 = (D2^2)/(D1^2). Intensity decreases with the square of distance.

Question 41

What is the heat unit formula?

Answer 41

HU = kVp mA time correction factor.

Question 42

What is the correction factor for a 3-phase machine?

Answer 42

1.35.

Question 43

How do you calculate mAs?

Answer 43

mA time (in seconds).

Question 44

If an image is too light, what should you do?

Answer 44

Increase mAs.

Question 45

If an image is too dark, what should you do?

Answer 45

Decrease mAs.

Question 46

How to reduce motion blur in x-rays?

Answer 46

Use higher mA and shorter time.

Question 47

What is the 15% rule?

Answer 47

Increasing kVp by 15% doubles density, so halve mAs. Decreasing by 15% halves density, so double mAs.

Question 48

What is filtration in x-ray?

Answer 48

Absorbing low-energy x-rays to reduce patient dose and improve image quality.

Question 49

What is inherent filtration?

Answer 49

Filtration built into the x-ray tube (e.g., glass, oil).

Question 50

What is added filtration?

Answer 50

Metal sheets added to the beam to filter low-energy x-rays.

Question 51

What are compensating filters used for?

Answer 51

To even out densities in body parts of unequal thickness.

Question 52

Where is the filter placed?

Answer 52

In the collimator, between the tube and the patient.

Question 53

What side of the x-ray tube is more intense?

Answer 53

The cathode side, due to the anode heel effect.