Radiography Exam Digital Radiography and PACS

Question 1

In computed radiography (CR), the image is captured by a photostimulable phosphor (PSP) plate. To read the image, the PSP plate is exposed to:

Accepted Answer

A laser beam that stimulates the stored energy to emit visible light

Answer

In CR, the PSP plate stores x-ray energy as trapped electrons; a laser beam stimulates these electrons, causing photostimulated luminescence (PSL) that is detected and converted to a digital image.

Question 2

Direct digital radiography (DR) flat panel detectors using amorphous selenium (a-Se) are classified as:

Accepted Answer

Direct conversion detectors (x-rays directly produce electrical charge)

Answer

Amorphous selenium flat panel detectors are direct conversion detectors — x-rays directly ionize the selenium layer, producing electron-hole pairs that are collected as an electrical signal without intermediate light production.

Question 3

In digital radiography, the exposure index (EI) number primarily reflects:

Accepted Answer

The amount of radiation exposure received by the image detector

Answer

The exposure index (EI) is a standardized number that indicates the exposure reaching the image receptor — it reflects the radiation dose to the detector, not the technique factors.

Question 4

PACS (Picture Archiving and Communication System) uses which standard protocol for storing, transmitting, and displaying medical images?

Accepted Answer

DICOM (Digital Imaging and Communications in Medicine)

Answer

DICOM is the universal standard for medical imaging data, defining how images are stored, formatted, transmitted, and displayed — it is the foundation of PACS interoperability.

Question 5

The primary advantage of using indirect conversion flat panel detectors with cesium iodide (CsI:Tl) over gadolinium oxysulfide (GOS) screens is:

Accepted Answer

CsI:Tl has a needle-like crystal structure that channels light to the detector, reducing light spreading and improving spatial resolution

Answer

CsI:Tl's columnar needle-like crystal structure acts as a light guide, channeling emitted light perpendicular to the detector surface, which minimizes lateral light spreading and preserves spatial resolution.

Radiography Exam Practice Test

Radiography Exam Practice Test

Radiography Exam Digital Radiography and PACS