AMRI310 - WK9-10
What QC test is performed to prevent a reduction in SNR by detecting off-resonance operation?
Center frequency
What is the daily/weekly QA/QC indicator testing for the accuracy of the magnetic field in determining coil tuning and consistent magnetic field strength?
Center frequency
Accreditation Fees
Checks should be made payable to the American College of Radiology (include modality accreditation ID#, if available). American Express, MasterCard, and Visa are accepted. The charge for the phantom is paid directly to the manufacturer.
online resources on ACR accreditation/phantoms
https://www.acraccreditation.org/-/media/ACRAccreditation/Documents/MRI/LargePhantomGuidance.pdf https://aapm.org/meetings/99AM/pdf/2728-58500.pdf https://www.acraccreditation.org/-/media/ACRAccreditation/Documents/MRI/ACR-Large--Med-Phantom-GuidanceFinal.pdf
You must submit localizer or scout sequences with each clinical examination with cross-reference locations for each sequence. Sites cannot submit examinations performed on
models or volunteers. All clinical images must be from actual patients. Use of volunteers or models may result in withholding, denial or revocation of accreditation. The images submitted for each individual exam must be from the same patient (i.e., all brain images must be from the same brain study). The only exception to this is in the event that the facility is only submitting one examination for the cardiac module, in which case it is acceptable to have the black blood sequence from a different patient than the delayed enhanced cine examination.
low contrast detectability in phantoms
Assesses the extent to which objects/structures of low contrast are discernable. • Slices with 10 low contrast patterns (spokes). • Need to make sure you run slices exactly through low contrast disks. Must be able to see a total of 10 complete spokes.
Accreditation Testing - Clinical Images
Between four and six examinations per unit are required for accreditation. The exact number of examinations depends on the number of modules for which the unit is used. The facility may select which examinations it will submit for accreditation evaluation (see selection list below). .
Withdrawn, Added, or Replacement Units
- facilities must notify the ACR if they have permanently withdrawn, replaced, or added - over 13 months: needs to submit only unit info and additional testing materials. Once approved, the new unit's expiration date will be the same as previous expiration date. - less than 13 months: The facility must renew accreditation for all units at the facility including the new one. Once approved, all of the units at the facility will have an expiration date that is three years from the old expiration date.
For accredited facilities that receive reimbursement from Medicare for the technical component of imaging examinations under the Fee Schedule there are additional mandatory requirements:
1. Each facility must have a process in place for all patients to obtain copies of their records and images that is HIPAA compliant. Patients should be made aware of this process at the time of examination or if requested by the patient at a later date. 2. Each facility must have a procedure for documenting the qualifications of the facility's personnel from the primary source when appropriate for licenses and certifications. Facilities must also verify that personnel are not included on the Office of Inspector General's (OIG) exclusion list at http://oig.hhs.gov/fraud/exclusions.asp. 3. All facilities must make publically available a notification for patients, family members or consumers that they may file a written complaint with the ACR. While these procedures are mandatory only for facilities that receive reimbursement from Medicare for the technical component of imaging examinations under the Fee Schedule, the ACR encourages all facilities to implement such procedures.
When acquiring ACR QA data, the slice correlating to this image requires what visual discernment?
10 visible spokes of 3 discs each
ACR realizes that surveys cannot usually be scheduled exactly on the anniversary date of the previous survey. Therefore a period of up to
14 months between surveys is acceptable. If the facility has been conducting QC for less than one quarter, the facility will submit whatever they have on these forms. Additionally, if the Annual MRI System Performance Evaluation and/or QC files show performance deficits (e.g. problems with the system and/or data outside of the action limits), the facility must state what steps it has taken to correct the problems. All QC testing must be carried out in accordance with the written procedures and methods outlined in the ACR 2015 MRI Quality Control Manual by July 1, 2016.
When assessing geometric accuracy for the X and Y gradients, results should be ___________.
190mm ±2mm
Percent signal ghosting must be less than __________.
2.5%
A state licensed technologist must obtain _____ hours of continuing education every two years.
24
When performing slice thickness accuracy, perform the scan with __________ of slice thickness.
5.0mm
Personnel Qualifications
All interpreting physicians, medical physicists and technologists working in MRI (including part- time and locum tenens staff) must meet and document specific requirements in order for their facility to be accredited by the ACR.
All facilities applying for accreditation must maintain a documented quality control (QC) program and must comply with the minimum frequencies of testing outlined below.
A qualified medical physicist/MR scientist must have the responsibility for overseeing the equipment quality control program and for monitoring performance upon installation and routinely thereafter. All facilities applying for accreditation or renewal must demonstrate compliance with the ACR requirements for quality control (QC) by including a copy of the facility's most recent Annual MRI System Performance Evaluation Summary (must be performed and signed by a medical physicist/MR scientist and must include evaluation of the technologist QC and MR Safety Program Assessment).
Each set of clinical images will be evaluated for:
A. Pulse sequences and image contrast B. Anatomic coverage and imaging planes C. Spatial resolution D. Artifacts E. Exam ID (All patient information annotated on clinical exams will be kept confidential by the ACR.) Please refer to the MRI Accreditation Testing Instructions for specific recommendations and requirements for each examination.
phantoms must be passed through
ACR accreditation to be accredited
Quality Control - Acceptance Testing
Acceptance testing is intended to measure quantifiable system parameters, which may then be compared to the manufacturer's specifications. A complete evaluation of the system performance should be performed by a qualified medical physicist/MR scientist after completion of installation and prior to patient imaging.
loaner unit
Accredited facilities may use a "loaner" unit to temporarily replace an accredited unit that is out of service for repairs, etc. for up to six months without submitting clinical and phantom images for evaluation. The accredited facility must immediately notify the ACR of the installation date, manufacturer and model of the loaner. Any loaner unit that is in use for more than one month will be required to submit evidence of testing by a qualified medical physicist/MR scientist within 90 days of installation. If the loaner is in place for longer than six months, the facility must submit the unit for accreditation evaluation, including clinical and phantom image assessment and the corresponding fee.
Transmit gain is a quality measure evaluating for?
Accuracy of flip angles
Phantom Testing and Image Quality
Clinical image review and phantom review are intended to complement each other for a comprehensive evaluation of the quality of MRI services. The criteria for evaluation are independent of field strength and can be applied uniformly so that all magnets are measured against a single standard. Depending on the type of scanner, one of two phantoms will be required for the facility to scan and submit images on. The ACR will provide this information in the testing materials for each unit once the application is processed. Each facility is required to submit phantom images for each unit using the ACR protocols for T1 and T2 weighting and phantom images using its own routine T1 and T2 weighted scan protocol.
Facilities are strongly encouraged to submit images by electronic upload. Images submitted by electronic upload or CD must be in
DICOM format and CD submissions must have an embedded viewer that meets the minimum requirements (see MR Accreditation Testing Instructions). The reviewers assume that the images submitted are examples of your best work. All images must demonstrate adequate positioning, resolution, noise, patient and facility identification, and lack of artifacts.
what is a Physicist/MR Scientist's annual QC test?
Evaluation of technologist weekly QC
Physician Peer-Review Requirements
Examinations should be systematically reviewed and evaluated as part of the overall quality improvement program at the facility9 . Monitoring should include evaluation of the accuracy of interpretation as well as the appropriateness of the examination. Complications and adverse events or activities that may have the potential for sentinel events must be monitored, analyzed and reported as required, and periodically reviewed in order to identify opportunities to improve patient care. These data should be collected in a manner that complies with statutory and regulatory peer-review procedures in order to ensure the confidentiality of the peer-review process. All sites initially applying for ACR accreditation and all sites renewing their accreditation must actively participate in a physician peer review program. There are several options available to meet this requirement. Sites may develop their own peer review program, use a vendor product or RADPEER, a peer review process developed by the ACR.
Emergency Use of Units
Facilities may use units that are not accredited in specific modules for other types of MR imaging in emergency cases without jeopardizing a facility's accreditation status. An emergency situation would be one in which less than 10 examinations are performed outside a unit's accreditation status in any 30 day period, or less than 50 examinations in any 12 month period. If the volume of examinations exceeds these limits, the facility must notify the ACR and submit testing for this module.
The continuing education and continuing experience requirements are based on previous full calendar years.
For example, if a site renews their accreditation in July 2014, the physicians and medical physicists/MR scientists at that site must have met the full requirement for continuing education from January 1, 2011 to December 31, 2013. Likewise, they must have met the full continuing experience requirements from January 1, 2011 to December 31, 2013. If they did not meet these requirements in the given timeframes, the ACR will accept continuing education credits or continuing experience obtained in 2014.
What QC test is performed to ensure that an image is scaled in a manner directly related to the dimensions of the body part being imaged?
Geometric accuracy
In acquiring ACR QA data, this image is used to evaluate for what quality measure?
Geometric accuracy -- X/Y gradients
In acquiring ACR QA data, this image is used to evaluate for what quality measure?
Geometric accuracy -- Z gradient
What is being measured in the image below, represented by the green dotted lines?
Geometric accuracy of the XY gradient
In acquiring ACR QA data, this image is used to evaluate for what quality measure?
High contrast spatial resolution
spatial resolution in phantoms(2)
High contrast spatial resolution: Resolution patterns (1.1, 1.0 and 0.9mm) For the middle set of dots (1.0mm), must be able to see at least. • One column of 4 separated dots • One row of 4 separated dots
spatial resolution in phantoms
High contrast spatial resolution: Tests MR unit's ability to discern (resolve) small objects/structures. • Slice 1 of ACR Axial T1 - 3 sets of holes. • Adequate results = observable holes (4) in UL and LR arrays.
This measures the uniformity of the image intensity over a large water-only region near the center of the coil.
Image intensity uniformity
In acquiring ACR QA data, this image is used in evaluating what quality measure?
Low contrast spatial resolution
spatial resolution in phantoms(3)
Low contrast spatial resolution: • Using slice #8-11, of ACR axial T1, select slice containing the most "spokes" of low contrast holes. (contrast decreases furthest from slice #11). • Count complete spokes (all three discs) - adequate low contrast resolution = 10 detectable spokes.
Consistent room temperature of 65-75°F, humidity of 50-70%, and sufficient air flow in the MR scan room is recommended to:
Make patients less vulnerable to the RF heating effects
MIPPA
Medicare Improvements for Patients and Providers Act of 2008 all facilities that bill for advanced diagnostic imaging services, such as breast MRI, under technical component of part B of the Medicare Physician Fee Schedule must be accredited by a CMS designated accrediting organization by January 1, 2012 to qualify for Medicare reimbursement.
percent signal ghosting in phantoms
Percent signal ghosting must be less than <0.025 (2.5%).
Preventive Maintenance
Preventive maintenance shall be scheduled, performed and documented by a qualified service engineer on a regular basis. Service performed to correct system deficiencies shall also be documented and service records maintained by the MR site.
__________ utilizes the goal of maintaining a desired level of consistency and image quality requirements within Radiology.
Quality Assurance
difference between quality assurance and quality control
Quality Assurance: • Quality Assurance (QA) utilizes the goal of maintaining a desired level of consistency and image quality requirements within Radiology. • QA asks the question, "Are we operating the devices or equipment correctly?" Quality Control: • Quality Control (QC) asks the question, "Is the equipment operating correctly?", and QC reflects the set of activities and/or techniques used to fulfill the requirements for quality.
____________ reflects the set of activities and/or techniques used to fulfill the requirements for quality.
Quality Control
_______________ is a series of technical procedures that help to ensure satisfactory products and/or production.
Quality control
Which of the following is a Physicist/ MR Scientist's annual QC test?
Radiofrequency coil checks
MRI Safety
Safety guidelines, practices, and policies must be written, enforced, reviewed, and documented at least annually by the MR supervising physician. See ACR Guidance Document on MR Safe Practices: 2013 and the ACR Manual on Contrast Media. The annual medical physicist/MR scientist performance evaluation must also include an assessment of the MRI safety program (signage, access control, screening procedures and cryogen safety) as well as an inspection of the physical and mechanical integrity of the system.
This tests the MR unit's ability to generate slices accurately.
Slice thickness accuracy
What QC test is performed to ensure an MRI scanner's ability to resolve small objects based on FOV and matrix selected?
Spatial resolution
Mandatory Accreditation Time Requirements
Submission of all accreditation materials is subject to mandatory timelines. Detailed information about specific time requirements is located in the Overview for the Diagnostic Modality Accreditation Program. Please read and be familiar with these requirements.
slice thickness accuracy in phantoms
Tests MR unit's ability to generate slices accurately • Use two sets of intersecting wedges • Perform scan with 5.0mm of slice thickness Slice thickness must be 5.0 ± 0.7mm
Continuous Quality Control
The following is a list of QC tests and frequencies that must be performed by technologists and medical physicists/MR scientists:
why do we ask if console and patient mic is ok?
The purpose of this question is to ensure sufficient ability to communicate with patients, via verification of microphone / console functionality.
The MR equipment specifications and performance shall meet all state and federal requirements.
The requirements include, but are not limited to, specifications of maximum static magnetic field strength, maximum rate of change of magnetic field strength (dB/dt), maximum radiofrequency power deposition (specific absorption rate), and maximum auditory noise levels.
What QC test acquires several signals while varying the transmitter attenuation in order to determine problems when transmitting a chain of RF pulses?
Transmit gain or attenuation
continuing education(2)
Upon renewal must meet one of the following: 1. Currently meets the Maintenance of Certification (MOC) requirements for ABR (See ABR MOC) or the Osteopathic Continuous Certification (OCC) for AOBR (See AOBR OCC) OR 2. Completes 150 hours (that includes 75 hours of Category 1 CME) in the prior 36 months pertinent to the physician's practice patterns (See ACR Parameter) OR 3. Completes 15 hours CME in the prior 36 months specific to the imaging modality or organ system
Continuing Experience
Upon renewal, physicians reading MRI examinations must meet the following: Currently meets the Maintenance of Certification (MOC) requirements for ABR (See ABR MOC) or the Osteopathic Continuous Certification (OCC) for AOBR (See AOBR OCC) OR Physicians reading MRI examinations across multiple organ systems must have read 200 exams over the prior 36 months. OR For physicians reading organ system specific exams (i.e., body, abdominal, musculoskeletal, head) across multiple modalities they must read a minimum of 60 organ system specific MRI exams in 36 months. However, they must read a total of 200 cross-sectional imaging (MRI, CT, PET/CT and ultrasound) studies over the prior 36 months.3
Using slice #5, of ACR axial T1, measuring the phantom horizontally and vertically ensures accuracy of the __________________.
X and Y gradients
If the unit replaces an existing MRI unit after accreditation is granted, it will
be treated as a new unit and follow the procedures above. If the unit begins performing examinations from a module that was not included on the original application, at least one examination from that module must be submitted. If less than thirteen months are left on the facility's accreditation, it must renew the accreditation of all of its equipment at the same time.
For ACR accreditation testing, how many examinations per unit are required?
between 4-6
For the High Contrast Spatial Resolution test, you have to consider the _____ set of dots
center
The purpose ________________ is to ensure integrity of MR system operating frequency, at which all system coils will be tuned to.
center frequency
MRI accreditation program evaluates the
qualifications of personnel, the quality control program, MR safety policies and image quality specifics to MRI. it involves the acquisition of clinicals and phantom images and corresponding data for each unit.
The physician shall have the responsibility for all aspects of the study including, but not limited to,
reviewing all indications for the examination, specifying the pulse sequences to be performed, specifying the use and dosage of contrast agents, interpreting images, generating written reports, and assuring the quality of both the images and interpretations.
___________ is the ability to define adjacent points in an image (detail).
spatial resolution
In addition to being in compliance with the interpreting physician qualifications stated above, the supervising physician also has the following responsibilities:(2)
• Be responsible for notifying the ACR within 15 days of any changes in imaging equipment (units) or changes in the use of equipment that could affect clinical or phantom images (i.e., in MR starting to use the magnet for a module that is not accredited). • Ensure that all accreditation criteria are met and that the same standard of performance is maintained during the 3-year accreditation period. • Provide immediate written notice to the ACR upon the termination of any accredited services provided by the Practice Site or a change in ownership of the operating location. • Ensure that all physicians providing services at this facility are actively participating in a formal peer review program that meets the stated accreditation requirements.
Various components encompass a QA program in the MRI suite, including but not limited to:
• Center frequency, transmit gain, SNR and visual inspections. • Record keeping of the data collected is an industry standard, producible upon request and accessible to technologists, physicists and radiology managers.
In addition to being in compliance with the interpreting physician qualifications stated above, the supervising physician also has the following responsibilities:
• Develop, implement and enforce policies and procedures in compliance with the ACR White Paper on Magnetic Resonance (MR) Safety. • Develop, implement and enforce policies and procedures to address safety issues, including contrast use and sedation, for pediatric patients. • Ensure that a physician is present and immediately available when contrast is administered to patients. • Develop, implement and enforce policies and procedures to identify pregnant or potentially pregnant patients. • Develop, implement and enforce policies and procedures consistent with ACR's Position Statement on Quality Control and Improvement, Safety, Infection Control, and Patient Education. • Be responsible for assuring compliance with the recommendations of the medical physicist. • Be responsible for the oversight and submission of all materials, including clinical and phantom images, as appropriate, quality control data and such other information as required by the MRI Accreditation Program.
Transmitter Gain or Attenuation:(2)
• Fluctuations in the transmitter attenuation levels suggest problems with the radiofrequency chain. • The ACR MRI phantom is used, and the transmitter attenuation is displayed on the scanner console. • The MRI technologist records the value displayed in column 5 on the Data Form. • If action limits are exceeded, the technologist reports the problem to the qualified physicist or MRI scientist.
ACR has modified the MRI Accreditation Program to offer modules based on these anatomic applications. The ACR offers the following modules:
• Head • Body • Spine • Magnetic Resonance Angiography (MRA) • Musculoskeletal (MSK) • Cardiac
Sites not using RADPEER must use a program that performs the follows functions:
• Includes a double reading (2 MDs interpreting the same study) assessment. • Allows for random selection of studies to be reviewed on a regularly scheduled basis. • Exams and procedures representative of the actual clinical practice of each physician. • Reviewer assessment of the agreement of the original report with subsequent review (or with surgical or pathological findings). • A classification of peer review findings with regard to level of quality concerns (One example is a 4-point scoring scale). • Policies and procedures for action to be taken on significant discrepant peer review findings for the purpose of achieving quality outcomes improvement. • Summary statistics and comparisons generated for each physician by imaging modality. • Summary data for each facility/practice by modality.
Phantom Testing and Image Quality - The images and testing data will be used to assess:
• Limiting high-contrast spatial resolution • Slice thickness accuracy • Distance measurement and accuracy • Signal uniformity • Image ghosting ratio • Low-contrast detectability • Slice positioning accuracy • Image artifacts Phantom data must be submitted in the form of uncompressed DICOM images, either uploaded or on a CD-ROM without a viewer.
image intensity uniformity in phantoms
• Measures the uniformity of the image intensity over a large water-only region near the center of the coil. • Image uniformity must be greater than >87.5%.
The medical physicist/MR scientist:
• Must be familiar with the principles of MRI safety for patients, personnel, and the public; the Food and Drug Administration's guidance for MR diagnostic devices; and other regulations pertaining to the performance of the equipment being monitored. • Must be knowledgeable in the field of nuclear MR physics and familiar with MRI technology, including function, clinical uses, and performance specifications of MRI equipment, as well as calibration processes and limitations of the performance testing hardware, procedures, and algorithms. • Must have a working understanding of clinical imaging protocols and methods of their optimization. This proficiency should be maintained by participation in continuing education programs of sufficient frequency to ensure familiarity with current concepts, equipment, and procedures.
a comprehensive imaging QA program consists of:
• Personnel Qualification standards • Re-accreditation (typically a 3 year cycle) - Submission of clinical cases by category - Submission of phantom scans ensuring accuracy / quality • Scanner performance monitoring - Acceptance testing after installation, upgrade and major service - Scheduled daily / weekly QA - Quarterly / Annual physicist testing of coils - Preventive maintenance - Testing for advanced applications • Protocol optimization and standardization • Technologist education and training • Continuous Improvement Process • Including image quality assessments • Artifact reporting / troubleshooting
what is quality assurance?
• Quality Assurance (QA) utilizes the goal of maintaining a desired level of consistency and image quality requirements within Radiology. • QA asks the question, "Are we operating the devices or equipment correctly?"
what is quality control?
• Quality Control (QC) asks the question, "Is the equipment operating correctly?", and QC reflects the set of activities and/or techniques used to fulfill the requirements for quality.
SNR value
• Repetitive recording of the SNR value taken from identical pulse sequence acquisitions within the same coil ensures adequate SNR for image quality. • Action limits should be set to indicate requirement for service call when recorded values exceed normal threshold.
ACR Signal to Noise Ratio (SNR) Quality Assurance:
• SNR is by far the most important parameter to monitor. • For this reason, we should make SNR measurements daily and continually monitor a plot of the daily measurements for any unexpected decreases. • Measurements should be made on an image of a homogeneous portion of the phantom. • ROIs (Region of Interest) are placed to occupy about 70% of the phantom area, and multiple ROIs are placed in the corners of the image. • The standard deviation from each background ROIs (in the outer dark area) is averaged together and used with the mean signal from the phantom ROI (big circle inside the brighter phantom area) to compute SNR.
slice position accuracy in phantoms
• Test's MR unit's ability to accurately prescribe slices at a given point. • Slice position must be within ± 5.0mm.
The primary function of the MRI technologist:(2)
• Testing can be performed on a manufacturer-supplied phantom for SPT/PIQT testing, whereas ACR regulations require imaging acquired on a specific phantom providing multiple regions of targeted testing. • Tracking of system performance can be accomplished by quantitative data entries into an accrediting body-approved (ACR, IAC, etc.) log sheet. • By gathering extensive data, variations from the expected norm can be addressed.
The primary function of the MRI technologist:
• The MRI technologist is to evaluate the overall image quality, by running a series of repetitive (daily vs. weekly) images, recording specific values, and flagging deviations from the normal range. • The myriad of categories tracked regularly include system center frequency, transmit gain, geometric accuracy, and low/high contrast spatial resolution.
what is center frequency?
• The purpose of this is to ensure integrity of MR system operating frequency, at which all system coils will be tuned to. • Variations from acceptable range warrant notification to manufacturer service engineers.
Room temperature & Room humidity
• The purpose of this question is to ensure maintenance of room temperature/ humidity levels, standardized to minimize RF heating effects. • Imaging outside acceptable ranges increases risks of SAR thermal absorption / patient burns. • Goal? Consistent room temperature of 65- 75°F, humidity of 50-70%.
why do we ask is the table ok?
• The purpose of this question is to verify accuracy of laser light to table position. • Periodically, the MRI technologist / MR physicist should verify the accuracy of the isocenter position in the magnet. • Simply ensure the center of the phantom image is positioned ±0-2mm in the H-F or S-I dimension by placing the crosshair / isocenter mark at the top edge of the dark vertical bars (orange arrow in image to left).
System Performance Testing (SPT), or PIQT (Periodic Image Quality Test):
• This is an inherent manufacturer quality mechanism by which a technologist, physicist or field service engineer might evaluate the performance of an MRI system. • Normal ranges are established following installation, and testing is performed daily or weekly to ensure adherence to normal ranges of QA monitoring.
Transmitter Gain or Attenuation:
• This test is done after establishing the resonant frequency of the system. • The transmitter attenuation or gain values are usually recorded in units of decibels (dB). • Establishing the transmitter gain levels is important in MR imaging because this provides information relating to the proper flip angles. • Accurate flip angle measurements ensure appropriate SAR calculations in addition to consistent expected image contrast.
geometric accuracy(2)
• Using slice #5, of ACR axial T1, measuring the phantom horizontally and vertically ensures accuracy of X and Y gradients. • Results should be = 190mm ±2mm.
geometric accuracy
• Using the sagittal localizer, top to bottom measurement ensures accuracy of the Z gradient. • Results should = 148mm ±2mm.
ACR Phantom Scans:
• When performing ACR quality assurance, using the ACR-approved phantom, specific measures can be attained via evaluation of specific slices. • Adhere to rigorous parameter settings and planning regimens to ensure accurate measurements taken. • Each of the 11 transverse slices obtained following the sagittal scout has a specific function or purpose that can be evaluated for various aspects within the MRI department QA program.
Set up quality control program to be run at least weekly to assess:
• center frequency • table positioning • setup and scanning • geometric accuracy • high contrast resolution • low contrast resolution • artifact analysis • film quality control • visual checklist • scan of ACR MRI head phantom