RadPhysics 9

Which is not a unit of x-ray intensity?

• R

• mG_a

• mR

• mGy_a

Other Name: x-ray quantity or radiation exposure

• Exposure Intensity

• Roentgen

• X-ray Radiation

• X-ray Intensity

A measure of the number of ion pairs produced in air by a quantity of x-rays.

• Exposure Intensity

• Roentgen

• X-ray Radiation

• X-ray Intensity

SI Unit: mGy_a

Exposure Rate: mR/s, mR/min or mR/mAs

• Exposure Intensity

• Roentgen

• X-ray Radiation

• X-ray Intensity

Factors that affect x-ray quantity & image receptor

X-ray quantity is increased proportionately

• mAs

• kVp

• Distance

• Filtration

Factors that affect x-ray quantity & image receptor

X-ray quantity is increased by (kVp₁/kVp₂)²

• mAs

• kVp

• Distance

• Filtration

Factors that affect x-ray quantity & image receptor

X-ray quantity is reduced by (d₂/d₁)²

• mAs

• kVp

• Distance

• Filtration

Factors that affect x-ray quantity & image receptor

X-ray quantity is reduced

• mAs

• kVp

• Distance

• Filtration

X-ray Quanity & mAs

X-ray quantity is _________ to the mAs.

Formula: I₁/I₂ = mAs₁/mAs₂

mAs: mA x s = mC/s x s = mC

1 C: 6.25 x 10¹⁸ electrons

• Proportional

• Inversely Proportional

• Directly Proportional

X-ray Quanity & kVp

X-ray quantity is _________ to the kVp².

Formula: I₁/I₂ = (kVp₁/kVp₂)²

40% Increased in kVp: doubling the intensity

15% Increased in kVp: reduction of 1/2 in mAs

• Proportional

• Inversely Proportional

• Directly Proportional