X-ray

1
Chapter 13

• X-ray
• Protection

2
X-ray Protection

• X-rays (in a single large dose or repeated small
  doses) have been responsible for causing

• Inhibition of hematopoetic cells
• Neoplastic changes
• Inhibition of glandular activity
• Deformation of a growing fetus
• Death

• Dermatitis
• Endothelial Changes
• Skin Cancer
• Destruction of blood cells

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X-ray Protection

• We can therefore see that x-ray protection is a
  serious matter we must consider radiation
  protection for
• The Patient
• The Doctor
• Staff
• Those in the Vicinity

4
X-ray Protection

• This is extremely important when considering the
  cumulative effects of x-ray.
• This includes accumulated small dosages of
  radiation.

5
The Roentgen (R)

• The unit that is used to measure the amount of
  radiation is the Roentgen Unit (amount of x-ray
  in air).
• It is defined as the amount of radiation which
  produces in 0.1296 grams of air (1 cc) at 00
  Celsius 760 mm of mercury one electrostatic
  unit of either change.

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The Roentgen (R)

• The following chart appears in Handbook 76 -
  Medical X-ray Protection up to three Million
  Volts issued by the bureau of Standards, giving
  the exposure in roentgens for various exposures.

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The Roentgen (R)
Measured in air with total filtration equivalent
to 2.5mm Al.
8
The Roentgen (R)

• 1 R 1 RAD (radiation absorption dosage).
• This is the amount of radiation absorbed by any
  object
• 1 R 1 REM (radiation equivalent manual dosage)
• This measures the biological effects that
  radiation has on an organ.

9
The Roentgen (R)

• The exposure to the doctor in radiographing a
  patient can be measured directly by use of an
  r-meter mounted where he/she stands during the
  exposure, or by a dental film badge (used today),
  which is worn for a period than developed
  compared with a standard set of films.

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The Roentgen (R)

• Records of the amount of radiation received
  should be kept for the doctor as well as the
  patient.
• A room meter will be used in addition to the
  r-meter. This is placed outside the x-ray room to
  secure that no radiation is escaping the
  boundaries of the room.

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Maximum Safe Limits of Radiation

• In discussing the maximum safe limits of
  radiation it may well be stated that any amount
  of radiation causes some damage thus the
  maximum safe limits may be Zero.

12
Maximum Safe Limits of Radiation

• In considering safe limits it must be remembered
  that dosage may be divided into somatic
  gonadal.
• The Somatic deals with possible damage to the
  individual.
• The gonadal deals with possible damage to future
  generations.
• The somatic can be further subdivided into a
  limit for exposure at one time ( as the patient
  receives) a limit for continual daily dose ( as
  the doctor receives in his/her practice).

13
Todays greatest Concerns over the effects of
radiation are its life shortening effects and
cancer induction.
14
ALARA

• ALARA (as low as reasonably achievable) mandates,
  with economic and social factors being taken into
  account, that operational dose limits will be
  much more restrictive than the maximum
  permissible dose limit.

15
Exposure Incident to Some Common Diagnostic
Procedures(all exposures made with 0.5 mm Al as
a filter)
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Maximum Safe Limits of Radiation

• Tissues highly susceptible to radiation damage
  include
• Eye/Lens
• Thyroid
• Bone Marrow/Spleen
• Reproductive Organs
• Lymphocytes
• These cells undergo mitosis thus making them
  more susceptible to the damaging effects of
  radiation

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Maximum Safe Limits of Radiation

• 1994 Nuclear Regulatory Commission Standards
  state that the maximum permissible dose is as
  follows
• 5 REM/year for entire body
• 15 REM/year for the eye
• 50 REM/year for an extremity
• 1/2 REM/entire pregnancy (fetal dose)

18
Results of Exposure

• Dr. Harvey Helton DC, in an article in the March
  1962 issue of the Journal of the American
  Radiography Technologists, gives the following
  for varying amounts of exposure to the entire
  body
• 1.0 to 25 r - No obvious damage (includes a
  single dose)
• 25 to 50 r - Some slight drop in WBC

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Results of Exposure

• gt100 r lt 200 r - Nausea, vomiting, diarrhea.
• 200 to 1000 r - Nausea, vomiting, diarrhea,
  leukopenia, hemorrhage, anemia, infection risk
  of death increases.
• 1000 r - Survival rate is 21 to 56 days.
• 1000 to 5000 r - Electrolyte balance is
  disrupted, fluid loss shock, survival rate is 3
  to 10 days.
• gt5000 r - CNS effected, survival rate 1/2 to 3
  days.

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X-ray Protection in Practice

• As previously stated, we have an obligation to
  protect, ourselves all others from unnecessary
  exposure while making spinal x-ray examinations.
• Even though there is much overlapping we will try
  to treat these three areas separately in the
  order given.

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Protection of the Patient

• The x-ray is one of the most scientific methods
  of analyzing the patients health problem, but we
  must make every attempt to protect them from as
  much unnecessary radiation as possible.
• The following procedures are essential in keeping
  the patients dosage total exposure to a
  minimum
• Secure a history of previous exposure from any
  sources keep an accurate exposure record.
• Keep the patients exposure well WNL.

22
Protection of the Patient

• Use proper filtration (2 mm Al added, 3 mm added
  over 70 kV, an additional thin layer of cooper
  over 100 kV).
• Use proper collimation.
• Use fast films.
• Use gonadal shields when possible.
• Use a high kV technique (this will decrease the
  patient exposure. It will also decrease contrast
  which may produce a poor quality film).

23
ALARA

• ALARA (as low as reasonably achievable) mandates,
  with economic and social factors being taken into
  account, that operational dose limits will be
  much more restrictive than the maximum
  permissible dose limit.

24
Protection of the Patient

• Use 50 MA or less when possible (I.C.A.
  recommendation).
• Use 40 - 72 inch film-anode distance.
• Use good darkroom procedures to prevent improper
  developing necessitating re-takes.
• Avoid x-raying females during the 10 days before
  the menstrual period or during pregnancy
  (especially the first three months).

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Protection of the Doctor

• We should remember scattered (and secondary)
  radiation bouncing off the patient is a source of
  radiation for the doctor.
• Any factors that lowers the patients exposure
  therefore lowers the doctors.
• In addition
• Wear a radiation badge, have it properly checked
  record the results.

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Protection of the Doctor

• Have the radiography room properly set up - dont
  take shortcuts.
• Use a gonadal shield
• Have a lead lined booth (at least 1.5 for a
  maximum off 100 kV).
• Have periodic blood examinations (radiation badge
  is sufficient).
• Use a fixed position dead mans switch with a
  reliable timer.

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Protection for Others in the Vicinity

• In using x-ray equipment we are also responsible
  for protecting the people living or working in
  the area around the x-ray room.
• This is best accomplished by restricting
  radiation to the confines of the room or at least
  keeping the amount passing out within safe
  limits.

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Protection for Others in the Vicinity

• We can test for radiation leaks the room by
  placing loaded cassettes (a whole film is not
  necessary) on the other side of any wall
  suspected (especially the one that the primary
  beam strikes), on the floor of the office above
  against the ceiling of the office below.
• These films are developed at the examined for
  any sign of exposure.

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Protection for Others in the Vicinity

• If enough extra cassettes are not available one
  area must be checked each day.
• If this investigation proves that there is
  radiation escaping from the room, the following
  test should be done.

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Protection for Others in the Vicinity

• Check for primary radiation leaks in the tube
  head by cutting an 8 x 10 film into four parts,
  making four exposures, one with the cassette on
  the anode end of the tube, one with the cassette
  on the cathode end, one with the cassette on the
  right one on the left.
• Develop examine for signs of exposure.

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Protection for Others in the Vicinity

• In all these tests, signs of exposure are more
  easily seen if lead letters are used on the
  cassette.

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Tidbits

• Lightproofing a baffle/maze - like entrance is
  more light proof than a door provides better
  ventilation.
• The dark room does not have to be black or dull.
  If the safe light is safe than the reflected
  light will be too because we cant intensify
  light.
• We should use light green when using a green
  safelight beige for a red or yellow safelight.