Rad Science: Mod 2

Front 1

which side is the xray tube located at? high voltage side or low voltage?

Back 1

High voltage.

Front 2

what are the two types of xray tubes?

Back 2

1. stationary anode
2. rotating anode

Front 3

Which end of the x-ray tube is the positive end?

Back 3

Anode

Front 4

what are some problems with early rotating anode disk made only out of one material, tungsten?

Back 4

-limited heat storage capacity
-wobbling
-pitting
-causes early aging of xray tubes

Front 5

RTM anode disk

Back 5

-90% tungsten 10% rhenium

Fewer rotational problems
Resistance to aging
Greater heat storage capacity
Less target roughening
High and uniform dose

Front 6

RTM Anode Disk with Slits

Back 6

-slits angled 20 degrees to the axis of rotation.

-prevent the electrons from passing through the anode and hitting the glass envelope

- Adding the slits to the anode also prevents cracking and helps keep the anode from distorting.

Front 7

Anode Disk with Grooves

Back 7

-alternative to slits
-surface of this disk is composed of tungsten alloyed with rhenium
-base of molybdenum alloyed with tungsten.

Front 8

TZM Anode Disk

Back 8

-pure tungsten sandwiched between a surface layer of tungsten alloyed with rhenium
-base is molybdenum alloyed with titanium and zirconium

Front 9

anode rotation from ball bearings. what do they use now?

Back 9

replaced with a liquid metal lubricant, using hydroplaning principles.

Front 10

as the anode angle increases, the field size?

as the SID increases, the field size?

Back 10

the field size also increases for both

Front 11

what does the protective housing or envelope do?

Back 11

contains the x-rays produced, protects the x-ray tube, insulates the technologist from electrical shock and acts as a thermal conductor to dissipate the heat that is produced in x-ray production.

Front 12

what are the two basic types of envelopes for the x-ray tubes?

Back 12

Metal-glass envelopes
Metal envelopes with ceramic insulators

Front 13

tubes with metal-glass envelopes

Back 13

-two windows, one made of beryllium, and the other aluminum.
-large volume anode disk 100mm diameter + cathode

Functions of metal envelope:
-Encases the electron optical field between the cathode and anode
-Lengthens tube life, as the metal is unaffected by tungsten deposits so there is no arcing

Front 14

Tubes with Metal Envelopes and Ceramic Insulators

Back 14

-better thermal and electrical properties than glass
-more mechanically stable
-direct oil cooling of the spiral groove bearing.
-accommodate a large diameter anode disk (120 mm) with improved cooling and more loadability, allowing the tube to produce more x-rays over a specific time.

functions of metal envelope:
-Encase the electron optical field between cathode and anode and maintain a constant electric potential between electrons and the envelope
-Prevent arcing, as the metal is unaffected by tungsten deposits

Front 15

mammography tubes

Back 15

-tungsten/molybdenum or rhodium target is used
-no aluminum filter

Front 16

grid controlled xray tube

Back 16

-used in digital radiography, digital subtraction angiography and mobile x-ray machines

-designed to turn on and off quickly

Front 17

Special X-ray Tube for Multi-Slice CT Scanning

Back 17

-specially designed for the best heat dissipation
- run for up to 60 seconds continuously

Front 18

The Straton tube

Back 18

-developed to dissipate heat faster
-anode is in direct contact with the cooling oil
-fast heat exchange.

Front 19

What is the main purpose for using a rotating anode?

Back 19

better heat dissipation, longer life.

Front 20

What is the best anode angle for doing barium studies?

Back 20

15 degrees. why? :(

Front 21

What is an advantage of an x-ray tube with a metal envelope with ceramic insulator?

Back 21

better thermal properties, accomodates larger anode

Front 22

What is the best filter for a mammography unit?

Back 22

molybdenum

Front 23

Why is the rhodium target used in a mammography unit?

Back 23

23 kev produced

Front 24

Why is a grid-controlled x-ray tube used for specialized radiography?

Back 24

turns on and off quickly

Front 25

Which x-ray tube has the anode in direct contact with the cooling oil?

Back 25

stranton tube

Front 26

What is the main advantage of the Stranton tube?

Back 26

no wait times for anode to cool

Front 27

What is the purpose of slits in the anode?

Back 27

prevents the anode from cracking

Front 28

What problems are associated with a pure tungsten anode?

Back 28

Limited heat storage capacity
Wobbling
Pitting