Radiography technology
Questions related to Radiography technology: –
1. What are the types of radiation emitted by isotopes?
Answer: –
There are three types of radiation as: –
A. Alpha particle (α– particle).
B. Beta particles (β- particle).
C. Gamma ray (γ- ray).
2. What is the charges on α– particle, β- particle and γ- ray & compare their relative penetration?
Answer: –
Charges on radiation are: –
A. Alpha particle (α– particle) : – Positive charge & less penetrating in comparison to - particle & - Ray. They can be stopped by a thin sheet of paper.
B. Beta particles (β- particle): – Negative charge & have definite range of penetration. Easily absorbed in the matter.
C. Gamma ray (γ- ray) : – No charge & highly penetrating.
3. Name the isotopes, which emits gamma ray?
Answer: –
Gamma ray source are: –
A. Iridium – 192
B. Cobalt – 60
C. Cesium – 137
D. Thulium – 170
4. Name the gamma ray source used for industrial radiography work?
Answer: –
A. Iridium – 192
B. Cobalt – 60
5. What is the depth of penetration in steel by cobalt – 60, cesium – 137, Iridium – 192 & Thulium– 170.
Answer: –
Penetration in steel by: –
A. Cobalt – 60 : – 9 inch.
B. Cesium –137 : – 3 ½ inch.
C. Iridium – 192 : – 3 inch.
D. Thulium–170 : – ½ inch.
6. What do you mean by photographic Density?
Answer: –
7. Name the instrument used for measuring density of photographic or radiographic film?
Answer: –
Densitometer is an instrument for measuring the density of photographic and radiographic film.
8. What are the factors on which the density of radiographic film depends?
Answer: –
The density of radiographic films depends upon the following: –
A. Total amount of radiation emitted by X-ray or gamma ray.
B. Amount of radiation reaching the specimen.
C. The amount of radiation passing through the specimen.
D. Intensifying action of the screen if used.
9. How the intensity of source is related with film distance?
Answer: –
10. What are the governing factors for exposure from particular radioisotopes?
Answer: –
There are three factors for governing the exposure with a given kilovoltage for X- ray or with the gamma ray from particular radioisotopes.
A. Milliamperage (X-ray) or source strength (for Gamma ray).
B. Focal spot to film distance or source to film distance.
C. Time of exposure.
11. What is the relation between Milliamperage (source strength) and film distance?
Answer: –
12. What is the relation between exposure time & film distance?
Answer: –
13. What is the relation between Source strength & exposure time?
Answer: –
14. How the source strength of radiographic isotopes expressed?
Answer: –
The source strength of radiographic isotopes expressed in terms of Curie.
15. What do you mean by exposure?
Answer: –
It is defined as the quantity of X or gamma radiation that produces in air , ions carrying 1 coulomb (C) of charge ( of either sign) per Kg of air. The unit of exposure is C/Kg.
16. What do you mean by Roentgen?
Answer: –
Roentgen is the old unit for exposure. It is defined as the amount of X or gamma radiation which liberates 1e s u of charge of either sign in 1 C. C of air at S T P.
1R = 1e s u / C C of air at STP.
= 2.58 X 104 C/ Kg air.
17. What is Dose equivalent?
Answer: –
Dose Equivalent = Quality factor X absorbed dose.
Quality factor generally considered as:
A. 1 for X, γ or β.
B. 3 for Thermal neutrons.
C. 20 for α – particles.
The unit of dose equivalent is Sievert (SV).
Formerly, the unit of dose equivalent was 1 rem.
1 Sievert = 100rem ( Roentgen).
18. What is the function of radiographic screens?
Answer: –
It intensifies the radiographic images on the film.
19. What are the types of radiographic screens generally used?
Answer: –
Types of radiographic screens generally used are: –
A. Lead screen.
B. Fluorescent screen or salt screens.
20. What are the types of Lead screens?
Answer: –
Types of Lead screens are: –
A. Lead foil screen.
B. Lead oxide screen.
21. What do you mean by intensification factor ( IF)?
Answer: –
Intensification factor = Exposure time required to produce required film density without screen / Exposure time for same density using screen
In the above definition it is assumed that same film and radiation source used for the both the exposure.
22. What are the factors upon which the intensification factor depends?
Answer: –
Intensification factor due to metallic screens depends on the following: –
A. Metal of foil.
B. Thickness of foil.
C. Energy of radiation.
D. Specimen thickness.
23. How the intensification factor depends on metal of foil?
Answer: –
For a given radiation source, the number of electrons produced depends on the nature of the metal foil. Intensification factor increases with atomic number of the metal. For gamma ray radiography generally Lead screen are used.
24. How the intensification factor depends on thickness of foil?
Answer: –
The intensification factor increases with the increase in the thickness of the foil. Intensification increases maximum corresponding to the range of photoelectron in that metal. After further increase it remains practically constant. If the thickness further increased, greater number of gamma photons will be attenuated and this will reduce the produce of photoelectrons.
25. How the intensification factor depends on energy of radiation?
Answer: –
More is the energy of radiation, more is the intensifying action.
26. How the intensification factor depends on thickness of the specimen?
Answer: –
A specimen placed in between the source and film performs following two functions: –
A. It filters the primary radiation.
B. Gives low energy scattered radiation.
The radiographic screen can have different sensitivities for primary radiation and the radiation given by the above two effects. Hence the change in intensification factor with object thickness is expected.
The intensification of low energy scattered radiation is more than the intensification of high energy filtered radiation.
27. Where the fluorescent screen finds its use?
Answer: –
The fluorescent screens are widely used for medical purpose to reduce the exposure time.
28. What are the main constituents of a radiographic film?
Answer: –
The radiographic films consist of the following: –
A. Base material.
B. Subbing layer.
C. Emulsion and
D. Protective layer/ Super coat.
29. What is the different base material tried so far for radiographic film?
Answer: –
The materials so far tried for base is: –
A. Glass.
B. Cellulose Nitrate.
C. Cellulose Acetate.
D. Cellulose Triacetate.
E. Polyester ( Most suitable material to be used as base material).
30. What is the function of Subbing material, Emulsion & protective layer in radiographic film?
Answer: –
Subbing material : – It provides the sticky action to the emulsion, as the emulsion does not adhere directly on the base material.
Emulsion : – It contains silver bromide gelatin ( Generally animal bone marrow)
Protective Layer : – It is coated on emulsion in order to protect the same from physical damage, abrasion and stress mark.
31. How the Radiographic films are classified?
Answer: –
The Radiographic films are classified as: –
A. Class – I : – Highest contrast, Lowest speed.
B. Class – II : – High contrast, Low speed.
C. Class – III : – Medium contrast, Medium speed.
D. Class – IV : – Low contrast, High speed.
32. What is the basis of classification of radiographic film?
Answer: –
Classification of Radiographic film is done on the basis of grain size of Silver Bromide (Silver Bromide Crystals). Finer the grain size of Silver Bromide in emulsion, slower will be the speed. Generally used crystal size is 0.22, 0.52, 0.68, 0.80 and 1 micron.
33. What is speed with reference to Radiography film?
Answer: –
It can be defined as the density records on the film resulting from a given exposure. It is inverse of exposure required to produce on radiograph of particular density under the specified conditions. A film requires less exposure to achieve particular density is called fast film and more exposure called slow film.
34. What type of film is generally used for Radiography?
Answer: –
Class – III type ( D5,D7 – Agfa make) film is generally used for radiography.
35. What type of film is not used for industrial purpose (Used for Medical purpose)?
Answer: –
Class – IV type ( D10 – Agfa make) film is not used for industrial purpose.
36. What do you mean by film processing?
Answer:-W hen the film is exposed to the radiation, creates latent image or invisible image by converting the silver bromide present in the emulsion into metallic silver. The exposed film when processed converts latent image into visible image.
37. What are the main steps in film processing?
Answer: –
Main steps in film processing are: –
A. Developing
B. Stop bath.
C. Fixture.
D. Washing
E. Drying.
38. What are the ingredients of Developer?
Answer: –
A. Developing Agent : – Metol, Hydroquinone and Pencilone.
B. Accelerator : – Sodium carbonate.
C. Restrainer : – Potassium Bromate.
D. Preservative : – Sodium Sulphate.
39. What is the function of Accelerator present in Developer?
Answer: –
It encourages the developer to supply more electrons.
40. What is the function of Restrainer present in Developer?
Answer: –
It opposes to reduce the unexposed silver bromide. It acts as antifogging agent.
41. What is the function of Preservative present in Developer?
Answer: –
It prevents oxidation.
42. What is the affect of temperature on Developer?
Answer: –
The Developer supplies more electrons at high temperature and reduces the developing time. Opposite is the case when the temperature is lower.
43. What is the ideal developing temperature?
Answer: –
Below 18 Degree C and above 24 Degree C, developing is not recommended.
44. What is the developing time generally recommended?
Answer: –
5 to 8 minutes. Larger developing time increases the fog density. The developing time below 3 minutes is not recommended as the required density shall not be achieved and may miss minor discontinuities.
45. What is the ingredient of Stop Bath?
Answer: –
2% Acetic Acid.
46. What is the function of Stop Bath?
Answer: –
Stops the Developing action by neutralizing the alkaline developer.
47. What are the ingredients of Fixer?
Answer: –
Fixing Agent A. Sodium thiosulphate commonly known as Hypo. Commonly used fixing agent.
B. Ammonium thiosulphate. Used as rapid fixing agent.
48. What is the function of Fixer?
Answer: –
It removes all unexposed silver grains and clouded film starts to become clear.
49. What is the recommended time for Fixer?
Answer: –
General recommendation is 5 to 15 minutes.
50. What is Radiographic sensitivity?
Answer: –
It is the combination of Radiographic contrast and Radiographic definition. The Radiographic sensitivity is judged by Image quality Indicator (IQI), also known as penetrometer. Judging the qualitative & quantitative quality of radiograph, a penetrometer is required. The image of IQI on the radiograph is the evidence that the radiographic inspection was conducted under proper condition
and achieved the required sensitivity.
% Sensitivity = (Minimum visible wire diameter / Thickness of the job) X 100
