What is an S number in radiography?

The S-number is an inverse measure of dose. If a dose larger than 1 mR gets through the patient and to the plate then the S-number is less than 200. For example, for a median dose of 4mR will yield an S-value of 200/4 or 25. A low S-number means that you used too much x-ray!

What is the EI number in radiology?

The exposure index (EI) in digital radiography has been used to indicate the relative speed and sensitivity of the digital receptor to incident X-rays and, ideally, to provide feedback to the technologist regarding the proper radiographic techniques for a specific exam that achieves an optimal image in terms of …

What is the normal value of exposure index in Kodak Carestream?

Carestream recommended that for all examinations, the EI should fall between 1700 and 1900(6). In another literature, Carestream’s recommendation is to achieve an EI range of 1500–1800(8)—this EI range was used for Carestream throughout this study since it was the latest recommendation.

What is a deviation index?

The deviation index quantifies the difference between the actual EI and the Target EI, and this feedback allows the radiographer to track and adjust his or her exposures. When the actual EI is equal to the Target EI, the DI will equal 0.

What is the 15 rule in radiology?

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. A 15% increase in kVp has the same effect as doubling the mAs.

Is exposure index the same as ISO?

ISO Sensitivity (or ISO speed) is a measure of how strongly an image sensor and/or camera responds to light. Exposure Index (EI) is a camera setting derived from one or more of the Sensitivity measurements. It is used to determine the camera’s exposure in response to a light level measurement.

What is overexposure in radiology?

Overexposure. Due to the high dynamic range in digital imaging, overexposure is slightly more challenging to identify. Overexposed images will have a distinct lack of quantum mottle while appearing ‘saturated’ or in extreme cases ‘burnt out’ whereby anatomy is completely obliterated from the radiograph.

What is the target exposure index?

Target Exposure Index (EI. T. ) Reference exposure when image is. “optimally” exposed.

What does kVp and mAs mean?

* 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.