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Medical physics 2: Nuclear Medicine > NM QC > Flashcards

NM QC Flashcards

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1
Q

What is NM QA?

A

The overarching nuclear medicine system which ensures quality of outcome

Includes:
Education
Medicines / radiopharmacy
Equipment

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2
Q

What is QC?

A

Specification, assessment, optimisation and maintenance of a particular aspect – e.g. equipment

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3
Q

What are the principles of QC?

A

Establish: critical parameters, methods, action levels, frequency, sys of work

Carry out: action response, carry out protocols, reactive action, investigations

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4
Q

Critical Imaging parameter planar:

A

Resolution: Spatial/Energy

Uniformity, linearity, sens, leakage

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5
Q

Critical Imaging parameter SPECT:

A

Coll hole angulation, uniformity, CoR, SPECT res, overall quality

SPECT CT: CT QC + Registration

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6
Q

Acceptance and routine tests

A

NEMA, elec, safety establish QC program

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7
Q

Daily SPECT

A

Photo peak position

Intrinsic uniformity flood - vis and quant

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8
Q

Monthly SPECT

A 
Uniformity (higher count)
Sensitivity
Resolution
Centre of rotation
Tomographic performance with phantom
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9
Q

Uniformity measures (6)

A 
System - Flood
Intrinsic - Point source 
Integral - CoV / min/max - UFOV / CFOV 
Differential 
SPECT 
Whole body - different isotopes
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10
Q

How is daily uniformity tested?

A

1 Remove collimator

2 Use point source with about 0.6 MBq positioned between detector heads
64x64 matrix

3 Acquire 10 million count acquisition

4 Calculate integral and differential non uniformity

Create via corr matrix

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11
Q

Resolution tests

A 
•System 
	Line source
	Phantom
•Intrinsic
	Line source
	Phantom 
•Quantitative 
•Qualitative 
•Planar 
•SPECT
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12
Q

PET Acceptance tests (EANM)

A
  • Physical inspection
  • Computer clock
  • Sensitivity
  • Uniformity
  • Spatial resolution
  • Count rate performance
  • Image quality
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13
Q

Example PET routine tests

A

Daily: Physical inspection, Background count rate, Detector check

Weekly: Energy resolution

Monthly: Calibration

Quarterly: Spatial resolution, Sensitivity, Image quality

Annual: Uniformity

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14
Q

Types of PET events

A

All coincidences have to be within energy acceptance window and time co-incidence window

True events: due to a single event on a line between the two point of detection

Scattered events: incorrectly placed as one or both photon are scattered prior to detection

Random coincidences: arise from 2 separate events

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15
Q

What is the noise equivalent count rate?

A

Count rate to obtain the same SNR in the absence of scatter and randoms

Scatter fraction: The fraction of total co-incidences in the photo-peak window that have been scattered.

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16
Q

Scatter / Count testing process PET

A

Cylindrical phantom with a small tube containing F18 which is allowed to decay and make repeated measurements

17
Q

Sensitivity measurement process PET

A

Nema method

  • Use a line source with a series of concentric aluminium sleeves.
  • Measure counts which each sleeve successively added and then extrapolate back to theoretical position of no attenuating material
  • This method is required as material is required for annihilation
18
Q

Image quality testing PET

A

Phantom with series of hot and cold spheres

19
Q

Requirements of routine QC

A
  • Simple and sensitive
  • Impact - able to be promptly reviewed
  • Documented - procedure and results recorded and tracked
20
Q

What is two bed testing?

A

Using the Ge68 phantom this is a quick full-system test (8 mins)

Position the phantom on the bed and align it so that two bed positions will be required to image its full extent

Images may be reviewed visually or an offline software analysis:

  • PET CT alignment
  • PET uniformity, inc atten and scatter corr
  • Consistency of quantification
  • Bed position stitching artefacts
21
Q

What is SUV?

A

Standardized uptake value, used for pharmo modelling

The SUV is the ratio of the image derived radioactivity concentration cimg and the whole body concentration of the injected radioactivity

SUV errors: incorr act records, air bubbles in phantom, ct/pet sys errors, calib perf

issues: no sens to patient weight, physio uptake, tissue inj error

22
Q

What is CCCF ?

A

Cross Calibration Correction factor. It relates the sensitivity to Ge68 phantom measured on the scanner to the sensitivity of F18 measured in the calibrator

Req when new QC phantom intro’d by resetting CCCF

23
Q

Potential PET measurement sources of error

A 
Patient scales
Calibrator
Blood glucose monitor
CT scanner
Processing software
Data transfer
Display station
Safety equipment

Medical physics 2: Nuclear Medicine (11 decks)

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