LRA 222: COURSE EXAMINATION

LRA 222: COURSE EXAMINATION



1. Scintillators are phosphors that

A. produce light when absorbing x-rays

B. produce x-rays when absorbing light

C. absorb light and produce electrical charges

D. absorb x-rays and produce electrical charges - answers✔✔A. produce light when absorbing x-
rays



2. A device that includes a photosensitive array and small pixels that convert light into electrical
charges is known as a ______ transistor

A. thin-field

B. field-effect

C. thin-film

D. field-energy - answers✔✔C. thin-film



3. In a flat-panel detector, specialized silicon integrated circuits control

A. line scanning sequence

B. readout

C. amplification

D. analog-to-digital conversion - answers✔✔A. line scanning sequence



4. Which of the following is used as a photoconductor?

, A. Gd2O2S

B. a-Se

C. a-Si:H

D. Cesium Iodide (CsI) - answers✔✔B. a-Se



5. Which of the following is not considered a scintillator?

A. Gd2O2S

B. CsI

C. a-Se

D. None of the above - answers✔✔C. a-Se



6. Flat-panel detectors that use indirect conversion technology convert

A. electrical signals to light

B. light to x-rays

C. x-rays to electrical signals

D. x-rays to visible light - answers✔✔D. x-rays to visible light



7. Indirect conversion in flat-panel detectors is a ____-step process

A. One

B. two

C. three

D. four - answers✔✔B. two



8. Detector performance is measured with all of the following except

A. spatial resolution

B. observation of flow contrast objects in a phantom