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) Surface In tegral Exposure5

(SIE)

An alternate name that is sometimes

used for this quantity is Exposure

Area Product. When the exposure is not uniformly

distributed over the exposed area ,

like in the fluoroscopic examplecoming up, the SIE is the sum (or

integral) of the individual area and

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) Surface In tegral Exposure5

(SIE)

An alternate name that is sometimes

used for this quantity is Exposure

Area Product. When the exposure is not uniformly

distributed over the exposed area ,

like in the fluoroscopic examplecoming up, the SIE is the sum (or

integral) of the individual area and

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) Surface In tegral Exposure5

(SIE)

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) Dose Area6

)Product (DAP

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Dose Area Product (DAP) is

similar in concept to (SIE)and

exposure area product in that they

all express total radiation delivered

to a patient. The principle difference is in the

units used.

DAP is in dose units, such as Gy-

cm2.

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DAP

For a uniformly exposed area, the

DAP is just the product of the air

kerma , in Gy or mGy, and theexposed area in cm2.

DAP provides a good estimation of

the total radiation energy delivered toa patient during a procedure.

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DAP

Both radiographic and fluoroscopic

machines can be equipped with

devices (DAP meters) or computerprograms that measure or calculate

the DAP for each procedure.

It is the most practical quantity formonitoring the radiation delivered to

patients.

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) Absorbed Dose7

Dose values can be in the traditional unit of

the rad or the SI unit of the gray (Gy).

The rad is equivalent to 100 ergs of

energy absorbed in a gram of tissue andthe gray is one joule of energy absorbed

per kilogram of tissue.1 gray (Gy) = 100 rads

10 mGy = 1 rad

1 mGy = 100 m rad

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ompu e omograp y ose

Index(CTDI)

The Computed Tomography Dose

Index, CTDI, is the special dose

quantity that is used extensively to

express absorbed dose in CT.

CTDI is based on the assumption that

the scatter measured from a single

slice, is a good estimate of the scatterinto a slice from adjacent slices

in a multiple-slice scan.

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(CTDI) This procedure does provide a good

approximation of the actual dose, butsince it is not completely precise, it is

called a dose index.

The CTDI can bemeasured at

points other

than the center

of a slice, if that

information is

needed.

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) In tegral Dose9* Integral dose is the radiation quant i tythat is equal to the to tal energy

abso rbed by the body.

The SI unit for integral dose is the joule(the standard unit

of energy), and

the conventionalunit is the gram-

rad.

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11) EQUIVALENT DOSE

DEFINE EQUIVALENT DOSEAND EFFECTIVE DOSE???

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Equ ivalent Dose (EqD)in the unit ,

s ievert (Sv), is a quantity that

at tempts to take into accoun t the

variation in biologic harm that is

produced by different types of

radiation.

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Dose Equivalent, is a quantity that

expresses the relative biological

impact of the radiation by including a

radiation weighting factor (wR). The

relationship is:

Dose Equ ivalen t (Sv) = Dose (Gy)

x wR

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Effec tive Dose (EfD)

A quantity that attempts to summarize

the overall potential for biologic damage to

a human due to exposure to ionizing

radiation.

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.....

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