Chapter 40 Radiation Protection Procedures

1
Chapter 40 Radiation Protection Procedures

• ALARA and Occupational Exposure

2
ALARA

• ALARA stands for As Low As Reasonably Achievable.
  It is the basic principle of radiation protection
  procedures.
• There is much that we can do to keep exposure to
  the patient and the operator as low as possible.
• The chiropractor is unique in the fact that you
  can perform radiography and refer your patients
  for other types of examinations.

3
Occupational Exposures

• In radiologic technology, 95 of the occupational
  exposure comes from fluoroscopy and mobile
  radiography.
• Neither would be used in your office so the worst
  case scenario is that you would receive 5 of the
  exposure that a technologist would receive.

4
Occupational Exposures

• During radiography, the operator should be behind
  a protective barrier.
• These barriers are usually considered as
  secondary barriers so protection would be from
  tube leakage and scatter from the patient. The
  tube should never be pointed toward this type
  barrier.
• If the barrier can have the tube angled toward
  the barrier. It must be a primary barrier.
• Staying behind the barrier effectively eliminates
  the source of occupational exposure if the
  shielding is adequate.

5
Occupational Exposures

• Medical Imaging Exposures
• Fluoroscopy All personnel will wear protective
  apron. If extremities get into the beam lead
  gloves can be worn.
• The radiologist will usually be close to the
  machine during fluoroscopy so their exposure will
  be higher than that the technologist. Aprons
  between the Image intensifier and Bucky Slot
  covers reduce radiologist exposure.
• The technologist should stand as far away from
  the table as possible during the exam and move
  closed only when necessary.
• The radiologist will use short burst of exposure
  and keep the exposure time as short as possible.
  The 5 minute clock timer will alarm when 5
  minutes of fluoroscopy has been used.

6
Occupational Exposures

• Medical Imaging Exposures
• Mobile radiography
• The technologist must wear a lead apron during
  mobile plain film or fluoroscopy examinations.
• An apron must be assigned to each portable
  machine.
• The exposure cord for portable radiographic
  machines must be 2 meters long to maximize
  distance from the tube during exposures.

7
Occupational Exposures

• Radiology Ancillary Staff
• Assuming the rooms are adequately shielded, the
  receptionist, file room and darkroom staff
  should not receive any occupational exposure.
• Radiology ancillary staff should not be used to
  hold patients during radiography.

8
Occupational Radiation Monitoring

• Occupational Radiation Monitoring is required if
  there is any likelihood that an individual will
  receive more than 1/10 of the recommended dose.
• With just plain film radiography, monitoring may
  not be required as long as the operator stays in
  the control booth during all exposures.
• There are some exams such as stress views of the
  ankle where the operator would be in the room
  with the patient. If this is done, monitoring
  would be necessary.
• If the operator ever holds a patient monitoring
  would be necessary.

9
Occupational Radiation Monitoring

• Occupational radiation monitoring offers no
  protection against exposure. It merely records
  the exposure received.
• If needed, find a certified laboratory to process
  the dosimeters.
• Types of monitors
• Film badges
• TLD
• OSL

10
Film Badges

• Film badges have been used since the 1940s and
  are still used today.
• Exposures below 10 mR are not measured on the
  film.
• Filters along with the window in the badge allow
  estimation of the energy of the exposure.
• The must be worn with the proper side to the
  front.
• They are typically worn on the collar so they
  would remain outside the lead apron.

11
Film Badges

• Advantages
• Inexpensive
• Easy to handle and process
• Reasonably accurate
• Disadvantages
• Can not be reused
• Sensitive to heat and humidity
• Must be changes monthly

12
TLD

• TLD has several advantages over film badges.
• Not sensitive to heat or humidity
• Measure exposures to 5mR More sensitive and
  accurate.
• Can be changed quarterly instead of monthly
• Disadvantages
• Cost but changing badges less frequently than
  monthly eliminates cost problem.

13
Optically Stimulated Luminescence

• All of the advantages of the TLD over film badges
  plus
• Can be re-read to confirm exposure
• More accurate than TLD

14
Where to wear the monitor

• The whole body badge is typically worn at collar
  level so it can be outside the lead apron.
• Fetal monitoring badges used during pregnancy are
  worn at waist level under the apron.
• Hand or finger TLDs are worn on the extremity.

15
Occupational Radiation Monitoring Reports

• State and federal regulations require that the
  results of the occupational radiation monitoring
  program be recorded in a precise fashion and
  maintained for review.
• Specific information is required to be on the
  report including current and cumulative exposure.
• Each site of monitoring must be identified
  separately.
• There will also be a control monitor to measure
  the background exposure during transport,
  handling and storage.

16
Occupational Radiation Monitoring Reports

• The supplier of the badges must know the type of
  radiation for proper calibration of the
  equipment.
• The badges are control are shipped back to the
  supplier in a timely manner.
• For lost or damaged badges, a health physicist
  will estimate the exposure.
• The annual exposure is discussed with each worker
  and receipt of the information is documented.
  Monthly reports may be posted but care must be
  taken with sensitive information.

17
Protective Apparel

• Lead apron used for operator or patient
  protection must be the equivalent of 0.5mm of
  lead.
• They must be worn when in a room during the
  exposure or during fluoroscopy.
• Half aprons are effective means to provide gonad
  protection during radiography.
• 0.25 mm of lead aprons should be avoided as they
  only attenuate 66 of the beam at 76 kVp.

18
Protective Apparel

• Aprons used in interventional radiology should be
  a wrap around type. Thyroid shields may also be
  worn.
• Lead gloves can be worn when the hands are in the
  beam.
• Aprons must be stored on specially designed racks
  or laid flat on the floor. They are never folded.
• Aprons are tested annually for cracks or holes in
  the lead, usually by fluoroscopy.

19
Position

• During fluoroscopy radiologic technologist should
  stand as far as possible from the machine.
• Standing behind the radiologist offers added
  protection.
• If you must be in the room, position your body as
  far away from the primary beam as possible.

20
Patient holding

• Many patients will find the x-ray examination to
  be physically demanding. Some may not be capable
  of staying in position.
• This is a particular challenge for weight-bearing
  radiography. Mechanical supportive devices are
  limited for erect studies.
• If you have a radiographic table, the patient may
  be examined recumbent. Sponges may be used as
  supportive devices.

21
Patient holding

• Radiology or office staff should never hold a
  patient. Family or friends may be called upon to
  assist the patient.
• The person assisting the patient must wear a lead
  apron and if their hands will be in the beam lead
  gloves.
• Position the person as far away from the primary
  beam as possible.
• Since the person holding the patient may be a
  parent, make sure they are not pregnant.

22
Reducing Unnecessary Patient Dose

• As a doctor, you have the responsibility to
  determine if the radiography is necessary and
  justified.
• There are more practice guidelines available
  every year to assist in determining if the
  examination will yield necessary diagnostic
  information.
• There are many examinations that are performed
  knowing that they will yield little helpful
  information so they in no way justify the patient
  radiation dose.

23
Reducing Unnecessary Patient Dose

• Check to see if the patient has previous
  examinations that may make the new examination
  not necessary.
• You may be sued if you dont take films and the
  treatment plan fails because you missed something
  the films would show.
• The yield of information must be greater than the
  risk of radiation exposure.

24
Reducing Unnecessary Patient Dose

• Routine x-ray examinations should not be
  performed.
• Used the most accurate tests to confirm or rule
  out your working diagnosis.
• Consider using MR instead of CT

25
Repeat Examinations

• One area of unnecessary patient exposure is
  repeated x-ray examinations. Past estimates of
  frequency has been as high as 10 but they should
  normally not exceed 5.
• Most of the retakes are of the lumbar spine,
  abdomen and thoracic spine.
• Most retake are due to the exposure factors being
  incorrect resulting in an over exposed or under
  exposed film. Proper measurement are important.

26
Repeat Examinations

• Positioning errors account for about 25 of
  retakes. Proper training and practice is
  important to fine tune positioning skills.
• Motion causes about 11 of retakes so proper
  patient communication during the exam is
  important.
• But do not be afraid to retake a poor quality
  film. If you can not see a problem makes it
  likely you will miss it. Poor quality exams are
  never justified.

27
Radiographic Technique

• Use as high kVp as possible to get adequate
  contrast and reduce patient exposure.
• Collimate the beam to slightly smaller than film
  size or the area of interest, whichever is
  smaller.
• Use the fastest-speed screen-film combination
  consistent with the nature of the examination.

28
Positioning

• When taking films with the patient seated, do not
  allow the gonad to be in the primary beam.
  Position the patient lateral to the beam.
• For female patients turn the patient PA to reduce
  breast and gonad exposures when possible.

29
Patient shielding

• Some form of patient shielding should be used on
  all patients able to reproduce.
• All children should have shielding.
• Pre-menopausal women should be shielded except
  when the shield would interfere with the
  examination.
• Men should be shielded beyond 50 years.

30
Patient shielding

• Patient shielding includes contact shields and
  shadow shields.
• Contact shields are placed on the patient and
  include aprons, the heart shaped filter and the
  bell.
• Shadow shields are placed between the patient and
  the tube. Here we attach it to the tube.

31
Patient shielding

• Shielding must be used when the gonads lie in or
  near the useful beam and when it does not
  interfere with obtaining the required diagnostic
  information.
• Accurate placement is extremely important.
  Repeated examinations can result form improper
  placement of the shield.
• Proper patient positioning and collimation should
  not be relaxed when gonad shields are in use.

32
Ten Commandments of ALARA

1. Understand and apply the cardinal principles of
   radiation control time, distance and shielding.
2. Do not allow familiarity to result in a false
   security.
3. Never stand in the primary beam.
4. Always wear protective apparel when not behind a
   protective barrier.
5. Always wear a radiation monitor and position it
   outside the protective apron at collar level.

33
Ten Commandments of ALARA

1. Never hold a patient during radiographic
   examinations. Use mechanical restraining devices
   when possible. Otherwise, use patients or friends
   to hold the patient.
2. The person holding the patient must wear
   protective apron and if possible, gloves.
3. Use gonadal protective on all people of
   childbearing age when it will not interfere with
   the examination.

34
Ten Commandments of ALARA

1. Examinations of the pelvis or lower abdomen of a
   pregnant patient should be avoided whenever
   possible, especially during the first trimester.
2. Always collimate to the smallest field size
   appropriate to the examination.

35
Chapter 31 Quality Control

• Two areas of activity are designed to ensure the
  best possible image quality with the lowest
  possible exposure and minimum costs.
• Quality Assurance deals with people
• Quality Control deals with instrumentation and
  equipment.

36
Chapter 31 Quality Control

• Two areas of activity are designed to ensure the
  best possible image quality with the lowest
  possible exposure and minimum costs.
• Quality Assurance deals with people
• Quality Control deals with instrumentation and
  equipment.

37
Ten Step Approach to Quality Assurance

1. Assign responsibility
2. Delineate scope of care
3. Identify aspects of care
4. Identify outcomes that effect the aspects of
   care.
5. Establish limits of the scope of assessment.

38
Ten Step Approach to Quality Assurance

1. Collect and organize data.
2. Evaluate care when outcomes are reached.
3. Take action to improve care
4. Assess and document actions
5. Communicate information to organization-wide QA
   Program

39
QA Projects

• Things that QA can evaluate includes
• Scheduling of patients
• Instructions given to patients
• Wait times in the office
• Interpretation of films
• Retake analysis
• Record accuracy

40
QA Program

• Quality Assurance deals with people and processes
  used to complete tasks.
• QA involves training and record keeping.
• As the owner of the equipment, you will be
  responsible for your radiology services.
• The State of California Department of Radiologic
  Health established the Standards of Good Practice
  that is the foundation of QA and QC in
  radiography.

41
QA and QC Requirements

• Degree of requirements vary by state. California
  and New York have very tight standards for
  quality control of the radiographic and
  processing equipment.
• We are required by statue to teach QA and QC in
  the radiology program. It is covered in detail in
  9th Quarter. My textboook covers QC in detail.

42
Quality Control

• An acceptable QC program has three steps
• Acceptance Testing
• Routine performance monitoring
• Maintenance

43
Acceptance Testing

• The x-ray machine, cassettes and film processor
  or digital system are the largest capital expense
  you may experience.
• It makes economic sense to make sure that the
  equipment meets the performance standards.
• It is recommended that a third party such as a
  health physicist do the testing.

44
Acceptance Testing

• Areas that should be tested include on the x-ray
  machine
• Shielding of Room
• Focal spot size
• Calibration of mA, timer or mAs
• Calibration of kVp
• Linearity of exposure
• Beam alignment
• Grid centering
• Collimation
• Filtration (HVL)

45
Acceptance Testing

• Areas that should be tested on the x-ray
  cassettes
• Screen contact
• Screen speed
• Light leaks
• Light spectrum matching

46
Acceptance Testing

• Areas that should be tested on the x-ray film
  processor
• Developer temperature
• Replenishment rates
• Travel time
• Water flow
• Hypo retention

47
Quality Control

• The acceptance testing ensures that the machine
  was installed and calibrated properly.
• The performance may drift or deteriorate over
  time. Consequently, periodic testing is required
  to monitor the performance.
• With the exception of film processing most
  testing is annual or semiannual.

48
Quality Control

• After a major repair, the machine should be
  retested to ensure that it was repaired properly.
• When the testing shows that the machine is not
  performing properly, service or preventive
  maintenance is required.
• Manufactures establish recommended preventive
  service schedules. When these are followed many
  repairs become unnecessary.

49
Radiographic Quality Control

• Areas of concern in x-ray machine
• Focal Spot Size will impact spatial resolution
• Filtration will impact patient exposure
• Collimation will impact patient exposure
• kVp calibration will impact image quality and
  exposure.
• Exposure timer accuracy will impact image quality
  and exposure

50
Radiographic Quality Control

• Areas of concern in x-ray machine
• Exposure linearity will impact exposure and image
  quality
• Exposure reproducibility will impact exposure and
  image quality.
• Alignment of tube and image receptor will impact
  exposure and image quality.

51
Focal Spot Testing

• When the machine is installed or the tube is
  replaced, the focal spot size should be measured.
  Then annually thereafter.
• A pin hole camera, star test pattern or line pair
  test tool.
• As the tube ages, the focal spot tends to grow
  and spatial resolution is lost.

52
Filtration

• The filtration is measured but determining the
  half value layer of the beam at specific exposure
  levels. Minimum filtration is 2.5mm aluminum.
• As a tube ages, tungsten will plate the x-ray
  port and increase filtration. This can cause
  technique problems. Inadequate filtration will
  significantly increase patient exposure.

53
Collimation

• If the collimation is misaligned, intended
  anatomy can be missed.
• It can be tested in many ways from using pennies
  to using test patterns.
• Misalignment can not exceed 2 of the SID.
• It is tested semiannually and after the
  replacement of the collimator lamp.

54
kVp Calibration

• In diagnostic radiology, any change will impact
  patient exposure. A variation of about 3 will
  impact contrast and image density.
• Can be tested with filtered ion chambers,
  filtered photodiodes or even a cassette with
  calibrated filters.
• Tested annually.

55
Exposure Timer Accuracy

• The exposure time is the responsibility of the
  operator. It will impact the density of the image
  and spatial resolution.
• Tested with an ion chamber, multi-meter
  internally or even a spinning top.
• Exposure time must be within 5 for exposure
  times greater than 10 ms and 20 less than 10 ms.

56
Exposure Linearity

• Many combinations of mA and time will produce the
  same mAs value. The ability of the machine to
  produce a constant level of exposure with various
  combinations of mA and time is called exposure
  linearity.
• Can be tested with a step wedge and densitometer
  or rate meter.
• Should be within 10 for adjacent stations.

57
Exposure Reproducibility

• Any exposure using the same factors should
  produce the same level of density and contrast on
  the image.
• Sequential exposure should be reproducible to
  within 5
• Can be tested with a rate meter or step wedge and
  densitometer.

58
Performance standards for x-ray equipment
Measurement Frequency Tolerance US Tolerance Ca
Filtration Annually 2.5 mm Al 2.7mm Al
Collimation Semiannually 2 of SID 2 of SID
Focal Spot Annual 50 50
kVp Annual 10 2 kVp between 60 100 kVp
Timer Annual 5 gt 10 ms 20 20 ms 3 phase 5 1 phase 10
Linearity Annually 10 10
Reproducibility Annual 5 5
59
Darkroom and Processing

• The development of the image is dependent upon
  the temperature of the developer, its
  concentration and how long the film is in the
  developer.
• The film is sensitive to variations in the
  environment and processing from the time it is
  manufactured until it is processed.
• Darkroom and Processor QC is the key process of
  Quality Control.

60
Processing

• Processor densitometry is performed daily before
  the first patient is exposed.
• A sensitometer is used to produce a step wedge
  image on the film that is evaluated with a
  densitometer.
• The densitometer reads the optical density of the
  processed image.
• A digital thermometer is used to test the
  chemical temperatures in the processor.

61
Processing

• Key densities on the processed film are measured
  and then graphed.
• Base plus Fog is measured on an area of unexposed
  film to check the darkroom environment.
• Speed is tested at the level of exposure that
  produces a density of 1.25OD
• Contrast is tested at the level that produced a
  density of 0.40 OD and one that produced a
  density of 2.20.

62
Processing

• By monitoring these densities, problems with film
  processing can be detected before image quality
  deteriorates.
• In 9th Quarter we will cover how to perform
  processor QC and problem solve.

63
Waste Records

• Since used fixer is classified as a hazardous
  waste material, it is important to maintain
  accurate records of usage and disposal.
• The extent of records vary by city, county and
  state. You are responsible for the proper
  disposal of the waste. Some regions include
  developer as hazardous waste.

64
Silver Recovery

• If the silver ions are removed from the fixer, it
  may be disposed of in the normal waste when
  diluted with water.
• There are two primary types of silver recovery
  systems.
• Metallic replacement uses steel wool and can
  recover 95 of the silver in the effluent
• Electrolytic recovery passes direct current
  through the solution and nearly pure metallic
  silver is deposited on the cathode.

65
Silver Recovery

• Old radiographic films and repeated films are
  retained for silver recovery. X-ray images can
  not be disposed of in normal trash.
• They also can not be used to clean the processor
  rollers.
• Waste recovery companies will either burn or
  chemically remove the silver from the film.

66
Performance standards for film processor and
darkroom equipment
Measurement Frequency Tolerance CA Tolerance US
Sensitometry Daily BF 0.05 MD 0.10 OD Contrast 0.10OD BF0.08 OD MD 0.15 OD Contrast 0.15 OD
Safelight Semiannual lt 0.05 OD in 2 minutes n/a
Darkroom temp Monthly 70ºF 5º n/a
Darkroom humidity Monthly 50 10 n/a
Developer temp Daily 0.5ºF 2-3º
Replenishment Daily 5
Transport Annual 3 3
67
Accessory QC

• The cassettes and screens are the area of chief
  concern. Problems with either will result in
  artifacts on the images and increased retakes.
• The screens need to be properly cleaned
  frequently. Mammography screens are cleaned
  daily. California recommends monthly cleaning.

68
Accessory QC

• Dirty screens produce white artifacts on the
  image.
• Multiple white artifacts indicate the need to
  replace the screens.
• Screen contact is tested semiannually. A problem
  with screens contact will cause a loss of
  resolution.
• As screens age, they loose speed so this is also
  tested.

69
Accessory QC

• The other important accessory is the gonad
  protection devices and lead aprons.
• Improper care of the apron can result in cracks
  and holes in the lead that reduces their
  effectiveness.
• Aprons and shields are tested semiannually. The
  easiest was to test them is with
  video-fluoroscopy but film can be used.

70
Performance Standards for Accessories
Measurement Frequency Tolerance CA Tolerance US
Screen contact Semi annual No problems detected No problems detected
Aprons/shields Annually No holes No holes
Screen matching Annually 0.05 OD for all cassettes used
Screen cleaning Monthly Semimonthly
71
Record keeping

• All electromechanical devices need periodic
  service.
• There are three types of maintenance.
• Scheduled maintenance such as processor monthly
  or weekly service. It includes observing moving
  parts and lubrication.
• Preventive maintenance is planned service and
  replacement of parts at regular intervals before
  they fail at inopportune times.

72
Record keeping

• Non-scheduled maintenance is the worst type of
  service because it impacts patient service. It
  may also be very expensive.
• With proper scheduled and preventive maintenance,
  non-scheduled service can be minimized.
• All service schedules should meet manufacture
  recommendations.
• All service should be documented as part of the
  quality assurance program.

73
Retake Analysis

• Required part of a QA program in California.
• Evaluation includes
• View repeated
• Cause of the repeat
• Rate of retakes should be less than 5.
• Information can be gathered from the log that the
  state mandates for patients being exposed to
  radiation.

74
Retake Analysis

• Done every three months using a relatively large
  sample of data to see trends in
• Type of examination being repeated.
• Reasons for the repeated films.
• Determine if additional training or review is
  needed.
• Determine if equipment service might be required.

75
Repeat Analysis

• Your patient log can be designed to capture both
  films usage and repeated films.
• Data is gathered from log for analysis
• Repeated films can be put into two main
  categories
• X-ray Personnel Errors
• Equipment malfunctions

76
X-ray Personnel Errors

• Failure to measure patient.
• Use of improper technical factors (mAs, kVp or
  distance)
• Incorrect positioning
• Improper Collimation
• Improper use of accessories such as cassettes,
  grids or filters

77
X-ray Personnel Errors

• Improper handling of exposed or unexposed films.
• Failure to clearly communicate to the patient
  breathing instructions and to remain still.
• Failure to observe patient during exposure.

78
X-ray Equipment and Accessory Failure or
Malfunctions

• Inaccurate calibration of kVp and mA.
• Inaccurate timer calibration
• Dirty or damaged cassettes
• Improperly labeled or damaged grids
• Malfunctioning collimator
• Improper film storage or processor function.

79
Reasons for Retake Films

• Over or under exposure accounts for over 50 of
  retakes nationally.
• Errors in positioning (25)
• Patient motion 11
• Processing errors 6
• Wrong view, beam alignment,cassette screen or
  grid errors and artifacts.

80
Retake Films by Region

• Cervical Spine Exams 7
• Thoracic Spine Exams 17
• Lumbar and Abdominal X-rays 40
• Skull, Chest,Lower Extremities 15
• Majority or retake results in unnecessary
  exposure to gonads or blood forming organs of the
  body.

81
Daily Log Design

• Most regulatory agencies will require a log of
  patients having radiation exposure.
• Columns can be added to capture film usage,
  repeats, views repeated and reason.
• This data can be gathered and analyzed.

82
Retake Analysis

• In this example, most of the retakes were of the
  T-spine. Potential reasons include
• Improper use of filters
• Incorrect measurements
• Faulty technique chart

83
Retake Analysis

• The reason of each retake is recorded and
  percentages are computed to determine the
  overall rate and rate by reason.
• Less than 5 is ideal.

84
End of Lecture

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