What is electronic collimation?

The use of coincidence with a pair of gammas giving a coincidence event in detectors 180 degrees apart in a PET scanner to define a line of response along which lies the location of the radiation emitting tracer.

What is the term for electronic collimation?

A related problem that has been reported in the literature, is electronic collimation, also referred to as electronic masking, cropping or shuttering.

What is the purpose of a collimation?

Proper collimation is one of the aspects of optimising the radiographic imaging technique. It prevents unnecessary exposure of anatomy outside the area of interest, and it also improves image quality by producing less scatter radiation from these areas.

What does collimation mean in radiology?

1. The making of a bundle of light rays parallel. 2. In radiography, limiting the size of the beam to the required region on the patient, thereby protecting the remainder of the patient from radiation.

What is electronic masking radiography?

Electronic masking: electronic collimation or cropping of the digital radiographic image that occurs during postprocessing of the acquired image and does not alter the size of the irradiated field. Processing: manipulation of the raw data just after acquisition.

What is post exposure collimation called?

Postexposure cropping, also known as masking and shuttering, refers to the postprocessing technique that uses digital shutters to electronically collimate the image after exposure.

What are the best practices in digital imaging?

A best practice in digital imaging is to use the highest kVp within the optimal range for the position and part coupled with the lowest amount of mAs needed to provide an adequate exposure to the image receptor. The AEC for digital radiography systems operates identically to AEC used for film-screen systems.

Why is preprocessing collimation important?

Preprocessing collimation is important because it cone’s in the x-ray beams to the specific area of interest. If there is not enough collimation scatter radiation creates grain in the latent image and reduces the quality of the image.

What does APR stand for in radiology?

Anatomically programmed radiography (APR) is a system of preprogrammed exposure technique set- tings that is organized by position and examination and set through the control panel of the radiography unit. Essentially, an APR system is an electronic technique chart.

What is anatomical programming?

Anatomic Programming Radiography (APR)



Technique by which graphics representing images of normal skeletal anatomy(human/animal) on the console guide the technologist in selection of a desired kVp and mAs by just selecting the particular body part(human/animal) to be examined.

How is digital radiography used?

Digital radiography (DR) is an advanced form of x-ray inspection which produces a digital radiographic image instantly on a computer. This technique uses x-ray sensitive plates to capture data during object examination, which is immediately transferred to a computer without the use of an intermediate cassette.

What are calipers used for in radiology?

The radiographer must measure the body part accurately to select the correct exposure from the technique chart or to obtain the correct exposure with a programmable computerized control. The tool for body part measurement is called a caliper (Fig. 10-1, B).

How does Sid affect image quality?

The source image receptor distance (SID), is the distance of the tube from the image receptor, affecting magnification. The greater the SID, the less magnification the image will suffer.

What is mAs xray?

Milliampere-seconds, also more commonly known as mAs, is a measure of radiation produced (milliamperage) over a set amount of time (seconds) via an x-ray tube. It directly influences the radiographic density, when all other factors are constant.

What happens when Sid increases?

Video quote: Believe the Sid constant. We can see that the image size increases quite a bit and so the way this typically discussed is that Sid / sod ink is a magnification factor so we take the SID. We divide it

What are the 4 image quality factors?

The important components of the radiographic image quality include contrast, dynamic range, spatial resolution, noise, and artifacts. [3] We will discuss these components briefly.

Does collimation affect spatial resolution?

The use of collimation in fluoroscopy does not significantly affect the overall image quality in terms of spatial resolution or scatter when the II input field of view is unchanged.

How does kVp affect image?

Radiation quality or kVp: it has a great effect on subject contrast. A lower kVp will make the x-ray beam less penetrating. This will result in a greater difference in attenuation between the different parts of the subject, leading to higher contrast. A higher kVp will make the x-ray beam more penetrating.

What is quality xray?

Quality & Quantity:  Quality refers to the overall energy of the beam  As the X-ray beam is polyenergetic, any factors that increase or decrease the average energy of photons in the beam affect x-ray beam quality.  Quality is directly affected by, i. Changes in kVP ii.

What is heel effect in radiology?

Anode heel effect refers to the lower field intensity towards the anode in comparison to the cathode due to lower x-ray emissions from the target material at angles perpendicular to the electron beam.

How kVp is measured?

The most direct way of measuring kVp is by using a high voltage divider. This invasive test device is connected between the generator and the x-ray tube and provides isolated low level analog voltage signals proportional to the kilovoltage applied across the tube.

What are the 4 exposure factors?

The quantity and quality of the x-ray beam are controlled by four prime factors. These factors are under the direct control of the limited operator. The prime factors of exposure are milliamperage (mA), exposure time (S), kVp, and SID.

What is kVp and mAs?

* kVp: the power and strength of the x-ray beam (quality of the x-rays). * mAs: the number of x-ray photons produced by the x-ray tube at the setting selected (quantity of x-rays). * time: how long the exposure lasts. Understanding Technique. kVp stands for kilovoltage peak.

What is the 15 percent rule in radiography?

The 15% rule states that changing the kVp by 15% has the same effect as doubling the mAs, or reducing the mAs by 50%; for example, increasing the kVp from 82 to 94 (15%) produces the same exposure to the IR as increasing the mAs from 10 to 20.