American Registry of Radiologic Technologists Certification (ARRT) Image Production and Evaluation Flashcards

24 sample cards from the Image Production and Evaluation deck

Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.

1. How does increasing kVp affect scatter and image contrast?

   Higher kVp increases the proportion of Compton (scatter) interactions and produces more penetrating scatter that reaches the IR, decreasing image contrast (longer grayscale).

2. Which interaction is responsible for most scatter reaching the image receptor in the diagnostic range?

   The Compton (incoherent) scattering interaction. It produces scattered photons that fog the image and degrade contrast; it is also the main source of occupational exposure.

3. What does PACS stand for and what is its function?

   Picture Archiving and Communication System — a networked system for the acquisition, storage, retrieval, distribution, and display of digital medical images and reports.

4. What is DICOM and what does it standardize?

   Digital Imaging and Communications in Medicine — the universal standard for formatting, storing, transmitting, and exchanging medical images and associated data so equipment from different vendors is interoperable. It defines file format and network communication protocols.

5. What is included in a DICOM file header?

   Patient demographics and metadata (name, ID), exam/study information, acquisition parameters (technique, modality), and image attributes — embedded with the pixel data in the DICOM object.

6. What is the role of the RIS and HL7 relative to PACS/DICOM?

   The RIS (Radiology Information System) manages scheduling, patient tracking, and reporting; HL7 (Health Level 7) is the standard for exchanging textual/administrative data (orders, reports) between the RIS/HIS and PACS, while DICOM handles the images.

7. What luminance and ratio standards apply to diagnostic display monitors?

   Diagnostic monitors should have high maximum luminance (typically >=350-450 cd/m2, often ~500) and the calibration should follow the DICOM GSDF. Primary diagnostic monitors are usually 3-5 megapixel grayscale with controlled ambient lighting.

8. What is the DICOM Grayscale Standard Display Function (GSDF)?

   A standardized calibration curve that maps stored pixel values to luminance so that grayscale appears perceptually consistent (equal perceptual steps) across different calibrated display devices.

9. What test pattern is used to evaluate display monitor quality?

   The SMPTE (Society of Motion Picture and Television Engineers) test pattern, used to assess luminance, contrast (0-5% and 95-100% patches must be distinguishable), spatial resolution, distortion, and grayscale.

10. List common quality control (QC) tests for radiographic equipment.

    kVp accuracy, mR/mAs linearity and reproducibility, timer accuracy, half-value layer (beam quality/filtration), focal spot size, beam (light field)/x-ray field alignment, and collimator/central ray alignment.

11. What is the acceptable tolerance for x-ray beam/light field alignment?

    The light field and x-ray field must align within +/-2% of the SID; central ray perpendicularity within ~1 degree (collimator/beam alignment test).

12. What is the acceptable tolerance for kVp accuracy and exposure reproducibility?

    kVp should be accurate within +/-5% (or +/-4-5 kVp); exposure reproducibility should be within +/-5% for repeated identical settings.

13. What is the half-value layer (HVL) and minimum filtration requirement?

    HVL is the thickness of absorber (mm Al) that reduces beam intensity by half — a measure of beam quality/penetration. Total filtration must be at least 2.5 mm Al equivalent for units operating above 70 kVp.

14. Define a radiographic artifact.

    Any unwanted optical density, signal, or feature on an image that does not represent the patient's anatomy and may obscure or mimic pathology.

15. Name common CR/PSP imaging plate artifacts.

    Light fog/incomplete erasure (ghosting from prior image), dust/scratch lines, phantom/ghost images from delayed reading, light leaks, and quantum mottle from underexposure.

16. What is a Moire (aliasing) artifact in digital imaging and how is it avoided?

    A wavy/grid-line interference pattern that occurs when a stationary grid's frequency is similar to the laser scan/sampling frequency, or the grid lines align with the scan direction. Avoided by using grids with appropriate frequency or orienting grid lines perpendicular to the plate scan direction.

17. What does quantum mottle (noise) look like and what causes it?

    A grainy, mottled appearance caused by insufficient photons reaching the receptor (too few quanta) — i.e., underexposure (low mAs). Corrected by increasing mAs to raise receptor exposure.

18. What is dead pixel/detector drop-out artifact in DR?

    Nonfunctioning detector elements producing missing or constant-value pixels; corrected by detector calibration (flat-field/gain calibration) which maps and interpolates defective DELs.

19. What is repeat/reject analysis and why is it performed?

    A QC process tracking the number and causes of repeated/rejected images to identify problems (positioning errors, exposure errors, equipment faults), reduce patient dose, and improve technologist performance and department efficiency.

20. What is the typical acceptable repeat/reject rate and the most common cause?

    A target repeat rate is generally around 4-8% (often cited as <5%). Positioning errors are the most common cause of repeats.

21. How is repeat (reject) rate calculated?

    Repeat rate (%) = (number of repeated/rejected images / total number of images taken) x 100.

22. What is detective quantum efficiency (DQE) and which systems have higher DQE?

    DQE measures how efficiently a detector converts incident x-ray photons into useful image signal (dose efficiency). Higher DQE means less dose needed for equivalent image quality. DR (especially CsI indirect and a-Se direct flat panels) generally has higher DQE than CR.

23. How does OID influence both spatial resolution and scatter reaching the IR?

    Increasing OID worsens spatial resolution and increases magnification, but it also acts as an air gap, allowing scattered photons to diverge away from the IR, which can reduce scatter and improve contrast.

24. What is exposure latitude in digital radiography, and what is its risk?

    The wide range of exposures over which a digital system produces an acceptable-appearing image (much wider than film). The risk is 'dose creep' — technologists overexposing because images still look good, increasing patient dose unnoticed without monitoring the exposure/deviation index.

What this deck covers

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