X-ray tube construction

Question 1

X-ray tube construction

Answer 1

The x-ray tube has 2 electrodes the cathode(-) and the anode(+). When x-rays are produced, current passes between these 2 electrodes that has opposite charges. These 2 parts work together through energy conversions to produce x-rays. Electrons are released from the cathode. They zoom over to the anode and when they collide with the anode x-rays are produced.

Question 2

Cathode

Answer 2

is the negative(-) charge; it consists of a focusing cup and 2 filaments.

Question 3

Filament

Answer 3

a tiny wire made of tungsten and shaped into a coil. There are usually 2 filaments, larger & smaller; this type of tube is called a dual focus tube.

Question 4

Focusing Cup

Answer 4

surrounds the filament on 3 sides. The cup is made of molybdenum and is negatively(-) charged.

Question 5

Anode

Answer 5

the positive(+) charged electrode. It is a disc made of molybdenum and coated with tungsten which has a little rhenium added to it. The anode is shaped like a saucer.

Question 6

Where X-ray is produced

Answer 6

The edge of the anode that tilts back is where x-rays are produced. The anode rotates while the x-rays are being produced so that the production of x-rays takes place all around the edge of the anode in an area called the Focal Track.

The x-ray beam is produced at the anode and first exits from the tube through this window before it travels towards the patient’s body.

Question 7

Glass Envelope

Answer 7

The inside parts (cathode & anode) are surrounded by a glass housing made of Pyrex. This Pyrex glass has lead added to it. While the X- ray tube is being manufactured it is baked, and this removes the air inside the glass housing creating a vacuum.

The glass housing has a thin spot called a window where x-rays travel through.

Question 8

Metal Housing

Answer 8

A metal housing is built on the outside of the glass envelope. One of its purposes is to protect the glass housing.

The metal housing is what the radiographer sees when looking at the x-ray tube. The inside of the tube and the glass envelope are hidden by the metal housing.

Question 9

Production of the x-ray beam

Answer 9

1) releasing electrons from atoms at the filament,
2) giving the released electrons a high speed,
3) focusing these electrons and then stopping them suddenly at the anode where the x rays are produced.

Question 10

Humans are made up of four distinct tissue types

Answer 10

1. BONE: tissue- most dense or radiopaque. Comes out white (When it attenuates the most it is White)
2. LIQUID: tissue. Comes out grey
3. FAT: or adipose tissue. Comes out grey
4. AIR: tissue-least dense or radiolucent.Comes out black (When it attenuates the most it is Black)

Question 11

Attenuation

Answer 11

the removal of x-rays from the beam by either absorption or scattering

absorption of radiation based on atomic number. The higher the numbrt the higher the absorption.

When it attenuates the most it is White

When it attenuates the least it is Black

Question 12

Radiolucent

Answer 12

low attenuating material (appears darker, or black on radiograph)

Question 13

Radiopaque

Answer 13

Highly attenuating material ( appears lighter, or white on radiograph)