TFT, CCD, CMOS review questions

Manfufacturers make efforts to maintain a standard of less than _____ to ______ percent defective pixels.

0.1%: 0.2%

What are the 3 layer of flat panel detectors?

1st-x-ray converter 2nd TFT array 3rd glass substrate

A _____ degree drop can reduce dark noise by a factor of ________.

40: 100

Direct conversion uses _____ to turn x-rays into electron

Amorphous selenium

Which material is considered to be a photo conductor?

Amorphous selenium

Which is easier to repair a TFT or CCD?

CCD

what detector uses the bucket brigade?

CCD

Which is more susceptible to noise, a CCD or CMOS?

CMOS

Which type of system uses very little power?

CMOS

Which uses p-type and n-type transistors?

CMOS

Which material is the most common in indirect conversion

Cesium Iodide

What does CCD stand for

Charge-Coupled Device

What does CMOS stand for

Complementary metal oxide semiconductor

The choice of x-ray absorption material determines whether the detector is a direct or indirect _______ system.

Conversion

What does DQE stand for

Detective Quantum efficiency

What applications uses the CCD

Digital flouro stereotactic breast biopsy digital mammography general radiography (full body scanner)

____ _______ is the ratio of the sensitive are of the TFT array to the entire detector area.

Fill Factor

A process known as gain calibration of _______ _________ corrects flaws in the detector, such as dead pixels.

Flat fielding

What material is used in indirect conversion

Gadolinium oxysulfide and cesium iodide

The term image ______ TFT's is similar to double exposure with CR or film screen.

Lag

The _____ and _______ __________ components of a CCD have an effect on spatial resolution and noise.

Lens; fiber optic

A _____ absorbs x-rays and produces electrical charges

Photoconductor

What advantages of CCD over TFT?

Simple and Modular Easy to repair & replace Cheaper

Which detector can have both direct or indirect conversion

TFT

What does TFT stand for

Thin film transistor flat panel

In direct conversion the photons interact with _________

amorphous selenium

A system that uses scintillators that convert x-rays to light, light to electric charge, and store the charge in capacitors is known as a _________ _______ ________.

charge couple device

A system where each pixel or DEL has its own transistor, amplifier, digitization circuit, etc. is called a _________ __________ _________ _____________.

complimentary metal oxide semiconductor

Noise that occurs when there is a rise in temperature of the CCD chip is called ________ noise.

dark

The CCD and CMOS receptors work basically the same up until the read out of the chip for ___________.

digitization

With a CCD, the electrons are moved by ________ down the _______ unitl the readout row is reached. This may be referred to as the ________ __________.

rows; column; bucket brigade

What are the most common noise associated with CCD?

statistical noise Dark or current noise Amplification noise