Radiological Imaging Techniques

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Questions and Answers

What is the primary purpose of the base in radiographic film?

To contribute to image distortion

To act as a medium for color development

To provide a rigid structure for interaction with x-rays or light photons (correct)

To enhance the sensitivity of light reception

What is the thickness of the emulsion layer on radiographic film?

1 to 2 µm

3 to 5 µm (correct)

5 to 7 µm

10 to 15 µm

What is the main function of gelatin in photographic emulsion?

To vary the color sensitivity of the film

To increase the speed of x-ray penetration

To act as a developer for silver halide crystals

To provide mechanical support by holding silver halide crystals in place (correct)

What is the active ingredient of the radiographic emulsion?

Silver halide crystals Signup and view all the answers

What effect does crossover have in radiographic film?

It occurs when light from one screen crosses to expose the emulsion on the opposite side Signup and view all the answers

Darkroom should be adjacent to the_______ room

Examination Room Signup and view all the answers

4 Layers of Intensifying Screen

Protective Coating, Base, Phosphor, Reflective Layer Signup and view all the answers

What condition is essential for the performance of an automatic processor?

Adequate processing conditions Signup and view all the answers

Where should the darkroom be located?

Centrally located Signup and view all the answers

What percentage should the humidity in the darkroom should be?

30-50%. hehehehehe Signup and view all the answers

What is the primary characteristic of fluorescence in phosphors?

It produces light concurrently while being stimulated. Signup and view all the answers

Which statement is true about the thickness of phosphor layers?

Thicker phosphor layers increase x-ray to light conversion. Signup and view all the answers

What is true regarding the crystal size in radiographic screens?

Larger crystals produce more light per interaction. Signup and view all the answers

What does Detective Quantum Efficiency (DQE) measure?

The ability to absorb photons. Signup and view all the answers

What does Conversion Efficiency (CE) refer to?

The amount of light emitted per x-ray. Signup and view all the answers

Which component is NOT a principal part of radiographic film?

Phosphor Signup and view all the answers

safe light handling time

25-40 seconds. hahahaha Signup and view all the answers

4 Types of entrances sa darkroom ( Kapoy english megs )

Single door, Double door, Maze and labyrinth, revolving door Signup and view all the answers

What is the role of the protective coating in an intensifying screen?

To provide a surface for cleaning while protecting the phosphors. Signup and view all the answers

What is the primary substance used as a phosphor in the intensifying screen?

Calcium Tungstate Signup and view all the answers

Which of the following is NOT a rare earth element used in modern screens?

Calcium Signup and view all the answers

What function does the reflective layer serve in an intensifying screen?

It directs emitted light from the phosphor towards the film. Signup and view all the answers

Which layer is farthest from the film in an intensifying screen?

Base Signup and view all the answers

What is luminescence?

Any material that gives off light in response to stimulation. Signup and view all the answers

Which statement about the phosphor in an intensifying screen is correct?

It emits light when stimulated by x-rays. Signup and view all the answers

What is the primary material used to construct the base of an intensifying screen?

Polyester Signup and view all the answers

What is the main role of a darkroom in the film processing environment?

To safely and efficiently handle and process films Signup and view all the answers

What are the components of the silver halide emulsion mentioned?

Silver bromide and silver iodide Signup and view all the answers

Which image type is referred to as the visible image after processing?

Manifest Image Signup and view all the answers

What is the atomic number of bromine (Br)?

35 Signup and view all the answers

What is the primary problem caused by the crossover effect?

Blurring of the image Signup and view all the answers

which is true about direct safelighting?

Light from the safe lamp directly falls on the working surface Signup and view all the answers

What does a latent image refer to in the image formation process?

An invisible image before processing Signup and view all the answers

Which feature is essential for a darkroom to effectively process films?

Complete light proofing Signup and view all the answers

Study Notes

Protective Coating

Transparent to light, protects phosphors from abrasion and handling damage.
Ensures a surface is available for cleaning while preserving phosphor integrity.

Phosphor

Acts as the active layer in intensifying screens, emitting light when exposed to X-rays.
Commonly used phosphor: Calcium Tungstate.
Modern screens utilize rare earth elements like Gadolinium, Lanthanum, and Yttrium for improved performance.

Reflective Layer

Essential for redirecting isotropically emitted light from phosphors to the film.
Without it, only half of the emitted light would interact with the film, decreasing image quality.

Base

The layer farthest from the film, typically made of polyester.
Provides stability and maintains size during use and processing.

Luminescence

Luminescent materials emit light in response to stimuli.
Two types:
- Fluorescence: Emits visible light during stimulation.
- Phosphorescence: Continues emissions post-exposure.

Properties of Screens

Phosphor composition: Rare earth screens enhance X-ray to light conversion.
Phosphor thickness influences light production; thicker layers yield higher light output, suitable for high-speed screens.
Crystal Size: Larger crystals produce more light; detail screens utilize smaller crystals.
Crystal concentration correlates with speed; higher concentrations result in faster screens.

Rare-Earth Screen Materials

Detective Quantum Efficiency (DQE): Measures the ability to absorb photons; higher atomic number indicates better performance (57-71).
Conversion Efficiency (CE): Quantifies light emitted per X-ray exposure.

Radiographic Film

Comprises two main components:
- Base: Provides structural support without distorting images, maintaining size during processing.
- Emulsion: Contains gelatin and silver halide crystals; crucial for interacting with X-rays and light photons.

Gelatin and Silver Halide Crystals

Gelatin supports and evenly distributes silver halide crystals.
Silver halide crystals (98% silver bromide and 2% silver iodide) are the active element for radiation exposure, with bromine, silver, and iodine having atomic numbers 35, 47, and 53, respectively.

Crossover Effect

Results from emulsion exposure caused by light from opposite intensifying screens.
Leads to image blurring, known as crossover effect, compromising image clarity.

Image Formation

X-rays convert to light photons, creating a latent image, which is invisible until processed.
Chemical processing reveals the manifest image, making it visible.

Processing Room Requirements

Centrally located dark room designed for safe film handling and processing without light exposure.
Accessible amenities like power and water supply are essential.
Efficient automatic processors should be in place, and the X-ray apparatus must be appropriately positioned to avoid damage to the darkroom.
Air ventilation and heating are crucial for maintaining satisfactory working conditions in the processing room.

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Description

This quiz explores key concepts related to radiological imaging, including protective coatings, phosphors, reflective layers, and luminescence. Understand the vital roles of these components in enhancing image quality and stability. Dive into the science of how light is emitted and redirected in the context of modern imaging systems.