Unit 9- Digital

Continuous Quality Improvement (CQI)

• ongoing process focused on evaluating and improving performance overtime

• proactive problem solving

CQI attempts to _____ the problems

anticipate

standards of quality are set by the___ and measured by _____

FDA, JC and PA DOH

The standards of quality does what

• specifies requirements for a quality management system

• demonstrates the ability to consistently provide products and services

ASRT involvement in Quality Control

• participates in ongoing quality assurance programs

• QC tests and monitoring, Preventive Maintenance and Corrective Maintenance

Quality control test of equipment is

• the calibration and monitoring of equipment and repeat analysis

what are the 4 components of a QC program

• acceptance

• baseline

• correctable deviations

• documentation

Preventative Maintenance Procedure

• testing is done on a semi-annual basis

  • goal of preventing breakdowns due to equipment failing without warning signs detectable by monitoring

Record Keeping

• data must be recorded after each performance test and kept on file

  • “if it wasn’t documented it didn’t happen”

What are the 2 levels of evaluation?

• 1st= results from the monitoring procedures- used to evaluate performance of equipment

• 2nd= evaluating the effectiveness of their program

What is a quality assurance program?

• organized effort to ensure that images are produced are of high quality, consistently provide adequate diagnostic info at the lowest possible cost and with the least possible exposure (WHO)

What does quality assurance do?

• prevent problems; plans and policies

  • fixes the system

what does quality control do?

• detect problems; checks and tests

  • finds the issues

what are the 2 aspects of image quality control

1. exposure indicator accuracy (EI or DI)

2. image integrity (verification that images are saved)

Who is the first line of defense in preventing, recognizing and reporting QC issues?

Techs

Image receptor maintenance

• inspection would be done: weekly

• cleaning should be done: monthly

• RH erasure should be done: weekly

CR acceptable erasure is an EI value of _____ in the re-exposed image

• 0-80

DR fails erasure test when:

• faint remnants of previous anatomy or objects

• non-uniform areas related to prior exposure

• repeatable artifacts indicating incomplete erasure

CR facilities shall erase all CR cassettes, at a minimum, on a _____ basis

• weekly

What is the only way to fix DRIFT

• calibration (tube age, temp, natural stresses)

what does equipment calibration do?

• checks the equipment’s accuracy and ensures consistent image quality

DR calibration:

• pixel sensitivity variations, detector non-uniformity

• machine typically automatically performs calibration

• BIOMED will calibrate after suervice

• ensures accurate signal response across the detector

CR Plate Reader Calibration:

• plate wear, change in system sensitivity

• ensures accurate plate reading and signal conversion

Uniformity test

• all digital detectors are INHERENTLY NONUNIFORM

• Uniformity corrections must be repeated on a regular basis

• should be tested ANNUALLY according to the AAPM

Spatial resolution test should be done:

semi-annually

spatial resolution tests what?

• the resolution test tool indicated line pairs per millimeter

  • due to changes in image quality

• test phantom is used

Repeat rates for radiographic procedures should not exceed:

4-6%

Reject analysis

• critical that repeat exposures are identified

  • repeat reason

  • # of repeats

  • tech responsible

• allows solutions to be found to minimize repeats

Reject analysis is performed:

• quarterly

  • min of 240-250 to be able to get an accurate quarterly analysis

The department monitors what with reject analysis:

• Causal: % of repeats from a specific cause

• Total: all repeats no matter what the cause

Patient exposure monitoring part of QA program:

• recording of modality specific dose indices, associated equipment settings and patient habitus, obtained

• identification and analysis of dose-index values and conditions that consistently deviate from corresponding norms

vendor-supplies software…

• radiation does index monitoring (RDIM) systems

• Dose Watch- automatically collect and analyze patient radiation and iodine exposure

Filtration and HVL

• minimum HVL levels must be achieved for pt safety reasons

• minimum of 2.5 mm of Al

• if it does not reach the minimum then pt dose will increase

• uses graded thicknesses of filters (usually aluminum)

protective filtration:

• used to remove low-energy x-rays from the beam that cannot penetrate the body and expose the IR efficiently

the only true measure of actual x-ray beam penetration is____

HVL

How often does HVL need to be tested?

annually

If HVL falls below the minimum requirements it indicates:

• calibration of kVp for the unit is off

• insufficient filtration in the beam

what is kVp accuracy

• it is what technique we are setting VS what is actually coming out of the tube

• testing tools

  • computerized radiation dosimeter or kVp meter

• can be within + or - 5 kVp of the control/set kVp

when is kVp accuracy tested?

• annually

Exposure linearity is

• the alignment of a particular mA station relative to other stations in its output of radiation

• testing tool:

  • computerized radiation dosimeter

• readout in mR/mAs

• when mA is doubled it can be withing + or - 10%

exposure linearity is performed

• annually

exposure reproducibility is

• ability to repeat the same technique setting and obtain the same results in exposure

• testing tool:

  • computerized dosimeter

• should be withing + or - 5%

exposure reproducibility is performed

• annually

timer accuracy

• computerized radiation dosimeter

• acceptance range + or - 5%

  • unless exposure times less than 10ms

time accuracy tests are performed

• annually

• OR IF

  • major repair performed

  • part replacement to generator or console

beam alignment is

• a tests that checks the perpendicularity of the beam

• testing tool:

  • x-ray beam alignment tool

• within 1 degree or 5 mm of vertical alignemnt

beam alignment test occurs

• semiannually

  • with age and use the x-ray tube can shift in its housing causing a lack of perpendicularity

collimator accuracy is checked by

• beam alignment test tool

• 9 penny test

collimator accuracy test is

• measures field size accuracy, field alignment, and vertical beam alignment

• must be within 2% of the SID

  • 40 SID - + or - .8

collimator accuracy is tested

• semi-annually

  • slippage of the collimator shutters

  • crooked collimator mirrors

SID indicator test is performed

• annually

  • after tube, collimator or suspensions system service

SID indicator is used to

• verify the SID accurately reflects the true distance between the x-ray tube focal spot and the IR

• ensures accurate exposure technique, image quality, and patient dose consistency

• + or - 2% of the actual SID or + or - 1 inch ( + or - 2 cm), depending on departmental or regulatory guidelines

Automatic exposure control (AEC)

• testing is done annually

• uses a dosimeter for testing

• accuracy range of + or - 10%

Back up timer test

• testing is done annually?

• place 3 sheets of leaded rubber over the activated cell(s)

• should automatically terminate exposure at the set back up time or at 600 mAs

QC of protective apparel

• testing is done annually

• look for : cracks, tears, and holes

• must replace any defected apparel (apron, gloves, gonadal shields)

fluoro exposure rate

• testing is done semi-annually

• testing tool is a calibrated radiation dosimeter

• standard: 88mGy/min

• high level control: 176mGy/min

Source to Skin distance (fluoro)

• doses established by the FDA

• fixed or stationary: 38 cm or 15 in

• mobile: 30 cm or 12 in

ABC or AERC (fluoro)

• assures that the automatic brightness control is functioning properly

• testing tool used is an ACR accredited test object

• acceptable range: 10-40 mR/s

exposure reproducibility (fluoro)

• testing is done semi-annually

• test tool used:

  • homogenous phantom

  • dosimeter

• should be within + or - 5%

exposure linearity (fluoro)

• testing tools used:

  • homogenous phantom

  • dosimeter

  • stop watch

• should be withing + or - 10%

focal spot size (fluoro)

• done to evaluate the degree of spot BLOOMING

• testing tools used:

  • pinhole cameras

  • focal spot test tool

  • resolution chart

  • homogenous phantom

• calculate according to test tool instructions

filtration and HVL (fluoro)

• test tools used:

  • aluminum plates

  • dosimeter

• value found on the x-axis should be greater than the min required HVL (2.5 mm Al)

collimator accuracy (fluoro)

• test tool used:

  • fluoroscopic bean alignment test tool

• withing 2% of the SID

beam alignment (fluoro)

• field size x spot film

• test tool used

  • fluoroscopic beam alignment device

• should be less than 2cm or (2%)

visual/audible monitors (fluoro)

• ensures exposure time is accurate

• audible alarm should go off after 5 min, exposure is terminated