How is CTDI calculated?

How is CTDI calculated?

The CTDI calculation assumes that the radiation decreases linearly from the outside to the center and is calculated as CTDI = (1/3) * radiationcenter + (2/3) * radiationperiphery. It is then divided by the length of the scan to give a CTDI per slice.

What does Ctdivol stand for?

All modern computed tomography (CT) scanners display a value called CT dose index-volume (CTDI-vol), in units of milliGray (mGy). CTDI-vol is calculated by the scanner based on the radiation output for the particular scan.

What is Msad in radiology?

One term used to describe this accumulated dose is the multiple scan average dose (MSAD), which as its name implies, is the dose from a multiple scan examination, averaged over one scan interval in the central portion of the multiple-scan dose profile.

What is tube current modulation in CT?

Tube current modulation is a feature of modern CT scanners to alter the strength of the beam by modulating the current of the x-ray tube depending on the signal to noise ratio.

What is CTDI100?

CTDI100 means the accumulated multiple scan dose at the center of a 100-mm scan and underestimates the accumulated dose for longer scan lengths. It is thus smaller than the equilibrium dose. The CTDI100, requires integration of the radiation dose profile from a single axial scan over specific integration limits.

How do you calculate DLP on a CT scan?

Along with the CTDI we need to know the scan length in order to compute the DLP (DLP (mGy*cm) = CTDI (mGy) * Scan Length (cm)). In the dose report the CT scanners will typically output both the CTDI and the DLP.

What does DLP stand for radiation?

Dose length product (DLP) measured in mGy*cm is a measure of CT tube radiation output/exposure. It is related to volume CT dose index (CTDIvol), but CTDIvol represents the dose through a slice of an appropriate phantom. DLP accounts for the length of radiation output along the z-axis (the long axis of the patient).

What is SSDE in CT?

Size specific dose estimate (SSDE) measured in mGy, is a method of estimating CT radiation dose that takes a patient’s size into account. CTDIvol and DLP are common methods to estimate a patient’s radiation exposure from a CT procedure.

What is CT Phantom?

NIST developed phantoms to improve CT scans, which use computer processing to combine multiple X-ray images into three-dimensional (3D) slices of the body that may reveal cancers or disease.

What does Ctdivol mean?

What is ATCM in CT?

Automatic tube current modulation (ATCM) on CT scanners can yield significant reductions in patient doses. Modulation is based on x-ray beam attenuation in body tissues obtained from scan projection radiographs (SPRs) and aims to maintain the same level of image quality throughout a scan.

What is the difference between tube current and filament current?

Filament current is applied across the tungsten cathode filament (10 A) and affects the number of electrons released. Tube current is applied across the x-ray tube from cathode to anode and affects the energy and number of electrons released.

What is rad output CT?

CT dose index (CTDI) (measured in mGy) is a standardized measure of radiation dose output of a CT scanner which allows the user to compare radiation output of different CT scanners.

What is CT pitch?

(p) The pitch (in computed tomography) is the ratio of the patient table increment to the total nominal beam width for the CT scan. The pitch factor relates the volume coverage speed to the thinnest sections that can be reconstructed. In spiral CT, dose is always inversely proportional to pitch.

What is DLP formula?

DLP = (CTDIvol ) * (length of scan, cm) [units: mGy*cm] DLP does not take the size of the patient into account and is not a measure of absorbed dose. If the AP and lateral dimensions of the patient are available, then the size specific dose estimate (SSDE) can be used to estimate the absorbed dose.