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? asked in Education & ReferenceHomework Help · 9 years ago

background radiation includes radiation from...?

1.radioactive materials in the earth

2. medical radiographs

3. outer space

4. dental radiographs


These questions can have more than 1 answer. This is an open book test and I'm having problems finding a few answers, so any answers will help.


Which of the following are principles of ideal projection?

1. The central ray should strike the tooth at 90 degree angle.

2.The source-object distance should be as long as possible.

3.The source size should be as small as possible.

4. The tooth and the film should be parallel to each other.

When inspecting an intensifying screen, what factors indicate that it needs to be replaced?

1. cracks in the screen

2. tears in the flexible cassette

3. unremovable stains

4. smooth white surface

Which of the following aid in protecting the patient from unnecessary radiation exposure?



3. film holders

4. lead aprons

The "digital" in digital imaging comes from the fact that?

1. the usage of numbers is high thechnology is small segments

4. it can be adjusted after the image is acquired

Which of the following cause fogging on radiographs?

1. scattered radiation

2. underexposure

3. improper safelighting

4. processing solutions that are too cold

Thanks in advance to anyone who can help with any of these answers.

1 Answer

  • Dragon
    Lv 6
    9 years ago
    Favorite Answer

    Hopefully the following information and the referenced sources will help "you" answer the questions.

    Background Radiation (according to wikipedia)

    Sources in the earth. These include sources in food and water, which are incorporated in the body.

    Sources from space, Sources in the atmosphere Man-made sources like Self-luminous dials

    Global radioactive contamination due to historical nuclear weapons testing

    Nuclear power station or nuclear fuel reprocessing accidents and so on

    Imaging Principles (according to wikipedia)

    X-ray under examination: Projectional radiography relies on the characteristics of x-ray radiation and knowledge of how it interacts with human tissue to create diagnostic images.

    X-ray attenuation


    Intensifying Screen Needs (according to

    1. Intensifying screens in a flat cassette may come loose and should be re-attached

    immediately. .

    2. The felt pad or foam rubber in the back of the cassette may have become

    insecure or worn.3. Screens which are old or cracked can be seen to have fairly mottled

    appearance and this will be reproduced on radiographs. When this is noticed it is time to

    discard the screens.

    Care of Intensifying Screens

    Screens are easily damaged. Their fluorescent emission will be affected if the active surface is

    soiled even slightly. Screens must thus be kept clean otherwise light photons will be prevented

    from reaching the screen and creating an image and the screen in that area will appear clear.

    Dirt will also create “high” spots which will create wear.

    Patient Protection (according to

    4.1 Beam Filtration A.

    4.2 Achieving ALARA through technique selection. E. Effect of kVp on photon absorption and patient dose.

    F. Effect of kVp on the production of scatter radiation and exit radiation.

    G. Balancing the relationships between PE effect,4.3 Positive Beam Limiting (PBL) and Automatic Exposure Control (AEC) A. PBL standards for x-ray units equipped with positive beam limitation.

    B. The use of AEC to produce uniform radiographs reducing repeat exposure.

    C. Components of an AEC device and their functions.

    D. Understanding the adjustment of the AEC from the console, and use of density settings.

    E. Overcoming overexposure issues caused by the minimum response time (MRT) when imaging small or pediatric patients.

    F. Back-up timer and maximum single exposure limits set by the FDA.

    4.4 Principles of beam restriction and types of beam limiting devices A. Types of beam restrictors and their effectiveness.

    B. Light field-radiation field congruency and FDA standards.

    C. Concepts of contrast enhancement and reduced patient exposure with beam restrictors when their use is appropriate.

    4.5 Patient shielding A. Requirements for shielding the gonads of patients in the childbearing years.

    B. Shielding strategy of patients undergoing stationary and mobile C-arm luoroscopy.

    C. FDA & NCRP standards for maximum closeness of any x-ray source to skin distance during single exposure, stationary fluoroscopy, or mobile C-arm fluoroscopy.

    D. Regulations on managing time of patient exposure during fluoroscopy.

    E. Standard measurements of patient dose.

    F. Understanding the adjustment of the AEC from the console, and use of density settings.

    Digital Imaging (according to wilipedia)

    A digital image is a representation of a two-dimensional image using ones and zeros (binary). Depending on whether or not the image resolution is fixed, it may be of vector or raster type. Without qualifications, the term "digital image" usually refers to raster images also called bitmap images.

    Fogging on Radiographs (according to

    The wide dynamic range and high sensitivity of the imaging

    plate used in computed radiography results in a greater

    susceptibility to fogging . Because the imaging plates

    have such a high sensitivity, extra precautions should be

    taken so that they are not exposed to extraneous radiation.

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