ÈÕº«ÎÞÂë

1. Any individual operating or using an x-ray analytical device shall register with the Radiation Safety Office (RSO) and attend a user safety lecture. Only authorized persons shall use x-ray analytical devices.
2. Operators and users of x-ray analytical devices shall be provided with a whole-body dosimeter. Each month the RSO will send a new dosimeter for exchange with the previous months.
3. A logbook shall be maintained which shall be kept available for inspection by the RSO. The logbook shall contain the following information:
   • name of operator or user
   • date and time of use
   • length of time used
   • film badge worn (yes/no)
4. A list of authorized persons shall be posted on the analytical device or in the logbook.
5. Operators or users shall notify the RSO of any incidents which are suspected to have caused radiation over-exposure.
6. In the event that the primary x-ray beam is not intercepted by the experimental apparatus under all conditions of operation, protective measures shall be provided to shield that primary x-ray beam.
7. If for any reason it is necessary to temporarily alter safety devices, such as by-passing interlocks or removing shielding, such action shall be:
   • dated and posted near the machine so other persons will know of the existing status.
   • terminated as soon as possible.
8. Unused tube ports shall be closed in such a fashion that accidental radiation exposure will not occur.

• X-rays are produced by bombarding a focus of high-speed electrons on a metal target. As the rapidly moving electrons are suddenly stopped by the metal target, x-rays are produced. (this takes place in an x-ray tube, see attached diagram)
• X-rays are a penetrating form of electromagnetic energy of short-wavelength photons that originate from the electron orbitals.
• Interaction of electrons with the metal target produce 2 main types of x-rays:
  • Characteristic
  • Bremsstrahlung

MilliRoentgen (mR) is a unit of exposure in air

• 1 R = 87.7 ergs/gm of air
  • 1 R = 2.08 x 109 ion pairs/cc of air
• millirem (mrem) is a unit of radiation dose
  • 1 R (of low energy x-rays) = 1 rem of radiation dose to tissue

Symptoms of large amounts of acute whole body radiation exposure:

• 0 - 25 rem ---- no observable effect
• 25 - 50 rem ---- possible blood changes - no serious injury
• 50 - 100 rem -- blood changes - some injury

Dose vs. Effect curve:

• threshold vs. non-threshold
• linear vs. non-linear

• 1 to 3 weeks after over-exposure - erythema, ulceration and blisters
• this may heal during the first month
• then skin may atrophy over the next few months
• after a year - ulceration and blistering may occur because of sun or heat burn
• Amputation may be necessary at dose greater then 10,000 rem

• Time - decrease time, decrease radiation dose (proportional)
• Distance - increase distance, decrease radiation dose (inverse square)
• Shielding - increase shielding, decrease radiation exposure (proportional)
• Signs and labels - decrease accidental radiation exposure

Exposure Limits:

NRC annual limit:

• 5 rems - effective dose equivalent (whole body)
• 50 rems - shallow dose equivalent (skin or to each extremity)
• 15 rems - eye dose equivalent (lens of the eye)
• 0.5 rem - dose to embryo/fetus during entire pregnancy

ALARA: As Low as Reasonably Achievable
ÈÕº«ÎÞÂë Dose limits: 10% of the NRC annual limits

Background and other dose levels:

• 295 mrem (millirem) - average background dose in U.S.
• 300 mrem - average dose from 1 abdomen radiograph
• 200 mrem - average dose from 1 dental radiograph
• 20 mrem - average dose from 1 chest radiograph
• 3 mrem - average dose to ÈÕº«ÎÞÂë personnel in 1 year

Radiation monitoring devices:

• film badge (exchanged every month)
• room monitor (exchanged every month)
• pelvic badge (pregnant radiation workers, exchanged every 2 weeks)

Working hours call the After working hours or on weekends call ÈÕº«ÎÞÂë Police Services at ext. 114