Quality Assurance

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Quality

• Three levels
• Expected Quality the level of quality that is
  expected by the customer. This may be influenced
  by outside factors, i.e. word of mouth from
  friends, relatives, etc.
• Perceived Quality Customers perception of the
  product or service. Highly subjective.
• Actual Quality Uses statistical data considers
  all factors that can influence the final outcome.
  

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Quality Management

• In a modern diagnostic imaging department quality
  management involves medical director, medical
  staff, administrators, supervisors, technologists
  support staff working together to ensure that
  adequate processes are in place to
• properly care for the patient
• achieve the highest quality image possible
• obtain the correct diagnosis from that image
• Processes need to be continuously reviewed by all
  parties and modified as the need arises.

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Quality Assurance

• An all encompassing program, used to ensure
  excellence in healthcare through the systematic
  collection and evaluation of data
• Main emphasis of a quality assurance program is
  on the human factors that can lead to variations
  in the quality of care

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Primary Objective

• The enhancement of patient care, which includes
• Scheduling of patients staff
• Management techniques
• Departmental policies procedures
• Technical effectiveness efficiency
• Inservice education
• Timeliness of interpretation reports

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The Program

• Establishes standards
• Determines defect levels the point of variance
  from the normal baseline which represent the
  minimum and maximum tolerance levels.
• Determines action levels the point of variance
  from the normal baseline which will trigger
  corrective measures.
• Action level is less than the defect level

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Main Advantages

• Improved department efficiency
• Lower department costs
• Greater customer satisfaction, i.e.,
• Physicians
• Patients

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Test Validation Statistics Terminology

• Gold Standard
• True Positive
• True Negative
• False Positive
• False Negative
• Sensitivity
• Specificity
• Positive Predictive Value
• Negative Predictive Value
• Overall Accuracy

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Gold Standard

• A test which is assumed to always be correct for
  diagnosing a particular pathology.
• For ultrasound and other noninvasive exams the
  gold standard exams are radiological imaging
  exams, i.e., venography, arteriography, MRI, MRA,
  CT, CTA
• Ideally the noninvasive exam would agree with the
  gold standard exam 100 of the time.
• Realistically, an exam which agrees with the gold
  standard at least 90 of the time is considered a
  good exam for a given pathology.

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True False Positive Exams

• True Positive (TP) The noninvasive exam and the
  gold standard exam said abnormal.
• Both exams results are positive for pathology.
• False Positive (FP) The noninvasive exam said
  abnormal but the gold standard exam said normal.
  The noninvasive exam is falsely positive.

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True False Negative Exams

• True Negative (TN) The noninvasive exam and the
  gold standard exam said normal. Both exams
  are negative for pathology.
• False Negative (FN) The noninvasive exam said
  normal and the gold standard exam said abnormal.
  The noninvasive exam is falsely negative.

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Sensitivity Specificity

• Sensitivity The ability of a test to detect
  disease. The abnormal ultrasound examination is
  confirmed by an abnormal gold standard result.
• Calculation TP / TP FN
• TP FN all gold standard positive exams
• Specificity The ability of a test to identify
  normality. The normal ultrasound examination is
  confirmed by a normal gold standard result.
• Calculation TN / TN FP
• TN FP all gold standard negative exams

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Positive Negative Predictive Values

• Positive Predictive Value (PPV) The percentage
  of ultrasound examination results that accurately
  predict abnormality.
• Calculation TP / TP FP
• TP FP all positive noninvasive exams
• Negative Predictive Value (NPV) The percentage
  of ultrasound examination results that accurately
  predict normality.
• Calculation TN / TN FN
• TN FN all negative noninvasive exams

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Overall Accuracy

• Overall accuracy The percentage of correct
  ultrasound diagnoses, positive and negative.
• Calculation TP TN / TP FP TN FN
• TP TN Number of all noninvasive exams which
  are correct
• TP FP TN FN Total number of all
  noninvasive exams, correct and incorrect
• Overall accuracy will always fall between the
  values determined for sensitivity specificity
  and the values determined for positive negative
  predictive values.

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2 x 2 Factorial Table

• Utilized to compare noninvasive and gold standard
  test results
• Always set up the same

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2 x 2 Factorial Table End Result
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Sensitivity, Specificity, PPV NPV
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Overall Accuracy
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ATS

• Dead Zone (Ringdown)
• 2 10 mm
• Resolution Array
• 5, 4, 3, 2, 1 mm Axial Lateral
• Vertical Group
• 1 cm
• Horizontal Group
• 2 cm

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Nuclear Associates

• Group A
• Axial
• 5, 4, 3, 2, 1 mm
• Lateral
• 15, 10, 5, 3 mm
• Group B
• Dead zone
• 1 8 mm
• Group C
• Vertical distance
• 1 cm
• Group D
• Horizontal distance
• 2 cm

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Fluke Biomedical

• Near Field
• 1 9 mm
• Vertical Resolution
• .5 5 mm
• Lateral Resolution
• 1 5 mm
• Vertical Plane
• 2 cm
• Horizontal Plane
• 2 cm

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CIRS

• Axial Resolution
• .5, 1, 2, 3, 4, 5 mm
• Near field
• 1 6 mm
• Vertical plane
• 2 cm
• Horizontal plane
• 2 cm