Scatter radiation, as described in Chapter 3, is primarily the result of
the Compton interaction
, in which the incoming x-ray photon loses energy and changes direction. Two major factors affect the amount and energy of scatter radiation exiting the patient: kilovoltage peak (kVp) and the volume of tissue irradiated.
What is scatter radiation caused by?
Scatter radiation occurs
when radiation deflects off an object, causing x-rays to be scattered
. It is important to keep in mind that scatter radiation has the ability to travel in all different directions. Most of the exposure your medical staff will endure is from scatter radiation.
What is scatter radiation in radiography?
Radiation that
spreads out in different directions from a radiation beam when the beam interacts with a substance
, such as body tissue. For example, during x-ray mammography, very small amounts of radiation may be scattered to areas away from the breast, such as the head and neck, sternum, and thyroid gland.
What is the most common form of scatter radiation?
In the case of
X-rays
, the most common source of scatter radiation for most humans, the “object” in question is the patient. Even those the X-Rays are specifically focused on a single target, the x-rays will still scatter and those scattered rays can continue to scatter around the room based on various design features.
What is the principal source of scatter radiation in radiography?
Primary scatter is emitted
from the patient in all directions
, which is the major source of hazard to personnel in mobile radiography and fluoroscopy. The patient thus becomes the source of scattered radiation but only during the time of the primary radiation exposure.
What reduces scatter radiation?
To reduce the scattered radiation, possible methods are
smaller fields-of-view (FOV), larger air gap between object and detector, and the use of an anti-scatter grid
. Large air gaps may give rise to geometrical un-sharpness, which must be kept minimal for high-resolution detectors.
How many feet should you stand away from radiation?
Scatter radiation exposure, the most common type of exposure you will receive in diagnostic radiology, is reduced to 1/1000 the exposure the patient is receiving if you stand one meter (approximately
3 feet
) from the patient.
How can you protect a patient from radiation?
- Keeping the time of exposure to a minimum,
- Maintaining distance from the source,
- When appropriate, placing a shield between yourself and the source, and.
- Protecting yourself against radioactive contamination by using proper protective clothing.
Does radiation stay in the room?
The radiation stays in the body for anywhere from
a few minutes to a few days
. Most people receive radiation therapy for just a few minutes. Sometimes, people receive internal radiation therapy for more time. If so, they stay in a private room to limit other people’s exposure to the radiation.
What is the difference between secondary and scatter radiation?
Secondary Radiation
Leakage
Radiation: This is leakage from the x-ray tube housing. … Scattered Radiation: This is a direct result of the Compton effect in the patient and contributes the most to staff radiation dose. The amount (fluence) of scatter depends on: Field size.
How does scatter radiation affect image quality?
Scattered radiation
reduces the level of contrast of a hidden X ray image
, introduces additional quantum noise, and decreases image sharpness and increases background heterogeneity.
Does scatter radiation cause blurring of the image?
Patient scatter also
produces blurring due to the unwanted scattered radiation from the patient falling
on the image receptor. These are suppressed by using grids below the object or by using narrow beams in special x-ray tube motion configurations ( e.g., AMBER x-ray unit).
What is secondary radiation?
Secondary radiation refers
to radiation originating from the absorption of previous radiation in matter
. It may be in the form either of electromagnetic waves or of moving particles.
How far do XRAY scatters travel?
A general rule of thumb is that the amount of scatter radiation at
1 meter (m)
from the side of the patient will be 0.1% of the intensity of the primary x-ray beam.
What is air gap technique?
The air gap technique is a
radiographic technique that improves image contrast resolution through reducing the amount of scattered radiation
that reaches the image detector.
How does collimation reduce scatter radiation?
Actively collimating to the volume of interest reduces the overall integral dose to the patient
and thus minimizes the radiation risk. Less volume irradiated will result in less x-ray scatter incident on the detector. This results in improved subject contrast and image quality.
