CT & Mammo QA/QC Exam Questions and Answers Latest Update 2025
How often is CT number accuracy checked? - Answers Weekly
What is allowed variance of CT number accuracy? - Answers 0 +/-4HU
How often is CT uniformity tested? - Answers Weekly
What is allowed variance of CT uniformity? - Answers Difference between mean CT number of ROI at
center of phantom and periphery must not exceed 2HU and baseline uniformity of CT number for water
must not be greater than +/=5HU
How often is CTDI checked? - Answers Semi-annually
What is allowed variance of CTDIw? - Answers 20% but highly recommended to strive for 10% of
manufactures specification
How often is CT noise checked? - Answers Weekly
What is allowed variance of CT noise? - Answers +/-10% or 0.2HU
How often is Calibration of CT number done and what is allowed variance? - Answers Monthly and 0+/-4
for water and -1000+/-10 for air
How often is patient support movement checked and what is allowed variance? - Answers Quarterly and
1mm or less
How often is low contrast resolution tested - Answers Quarterly
How often is slice thickness tested - Answers Semi-annually
How often is laser alignment tested and what is allowed variance - Answers Semi-annually and +/-2mm
with isocenter +/-5mm
How often is CT linearity tested - Answers Monthly
Often often is primary door interlock tested - Answers Quarterly
How often is spatial resolution tested - Answers Monthly
What does a mammography phantom need to be? - Answers Compatible with breast that is 50% fatty,
50% dense and with a 4.5cm compression
How many fibres and masses must be visible in a mammography phantom for QC? - Answers 4 of the
largest fibres and 3 of the largest masses
Mammo allowed variance for phantom EI test? - Answers +/-0.2 or 20%
Mammo allowed variance for phantom MAs test? - Answers +/-0.1 or 10%
How often is CT number accuracy checked? - Answers Weekly
What is allowed variance of CT number accuracy? - Answers 0 +/-4HU
How often is CT uniformity tested? - Answers Weekly
What is allowed variance of CT uniformity? - Answers Difference between mean CT number of ROI at
center of phantom and periphery must not exceed 2HU and baseline uniformity of CT number for water
must not be greater than +/=5HU
How often is CTDI checked? - Answers Semi-annually
What is allowed variance of CTDIw? - Answers 20% but highly recommended to strive for 10% of
manufactures specification
How often is CT noise checked? - Answers Weekly
What is allowed variance of CT noise? - Answers +/-10% or 0.2HU
How often is Calibration of CT number done and what is allowed variance? - Answers Monthly and 0+/-4
for water and -1000+/-10 for air
How often is patient support movement checked and what is allowed variance? - Answers Quarterly and
1mm or less
How often is low contrast resolution tested - Answers Quarterly
How often is slice thickness tested - Answers Semi-annually
How often is laser alignment tested and what is allowed variance - Answers Semi-annually and +/-2mm
with isocenter +/-5mm
How often is CT linearity tested - Answers Monthly
Often often is primary door interlock tested - Answers Quarterly
How often is spatial resolution tested - Answers Monthly
What does a mammography phantom need to be? - Answers Compatible with breast that is 50% fatty,
50% dense and with a 4.5cm compression
How many fibres and masses must be visible in a mammography phantom for QC? - Answers 4 of the
largest fibres and 3 of the largest masses
Mammo allowed variance for phantom EI test? - Answers +/-0.2 or 20%
Mammo allowed variance for phantom MAs test? - Answers +/-0.1 or 10%
