Radiation Safety Manual - Chapter 15: Human Use X-Ray Machines

Bone densitometers will be surveyed by the Radiation Safety staff at each source loading to ensure that anticipated exposure rates are not exceeded. All individuals using the devices will be registered with EHS as Radiation Workers. A trial period of personnel radiation monitoring may be put into effect.

Title

Radiation Safety Manual - Chapter 15: Human Use X-Ray Machines

Table of Contents

1. Radiation Emergency Procedures/Incident Reporting
2. Description
3. Rationale
4. Policy
   1. ALARA Policy
   2. Indications for the Use of Diagnostic X-Rays
   3. Requirements for Use
   4. Operator Qualifications
   5. Exposure Control and Beam Limitation
   6. Holding Subjects During Diagnostic X-Ray Procedures
   7. Protection of Professional Staff and Ancillary Personnel
   8. DXA and pQCT X-Ray Procedures
   9. Additional Procedures for Mobile X-Ray Equipment
   10. Special Considerations for the Use of Fluoroscopic Equipment
   11. Use of Hand-Held Dental Units
   12. Pregnant or Potentially-Pregnant Subjects
   13. Personnel Monitoring
   14. Quality Control
5. Additional resources

If you are accidentally exposed to the direct x-ray beam, or suspect an exposure, immediately follow these steps:

• Shut off the x-ray beam. Remain calm.
  • Call the contacts below until the incident is reported and medical advice is obtained (if necessary):

    Time of Day	Who to Call
    DAYTIME	EHS: 919-962-5507
    AFTER HOURS	UNC Police: 911 (Ask for Radiation Safety Assistance)

To describe the policy for the safe use of Human use x-ray equipment at the academic campus of UNC Chapel Hill. This policy does not include the Adams school of Dentistry, the campus departments that are run by UNC Health Care, or x-ray procedures that are intended for diagnostic or therapeutic use of X-ray machines.

NC Regulations for the Protection Against Radiation issued by the NC Radiation Protection Section (RPS) require UNC Chapel Hill to implement a radiation protection program for the safe use of x-ray equipment on humans. This policy applies to all non-healing arts use of x-ray equipment on humans, including fluoroscopy units, CT scanners, and DXA machines.

a. ALARA

In addition to meeting the occupational and public dose limits as specified in section 0.1601 of the North Carolina Regulations for Protection Against Radiation, efforts shall be made to maintain personnel, public, and subject radiation exposure due the use of x-ray equipment at UNC Chapel Hill at ALARA (“As Low As Reasonably Achievable”) levels.  

In general, these efforts are documented in the form of a radiation protection program and quality control program.  Basic components of these programs include:

1. Appropriate Indications and requirements for use
2. Continuing education and in-service training program  
3. Procedures for keeping radiation doses as low as reasonably achievable
4. An x-ray equipment survey/preventive maintenance program

b. Indications for the Use of X-Rays on Humans

1. Examinations for x-ray procedures shall be ordered by a Licensed Independent Practitioner (Physician, Dentist, Physician Assistant and Nurse Practitioner) or approved by the University’s Institutional Research Board.
2. Because suboptimal image quality (due perhaps to positioning or motion) may occur, limited retakes may be performed upon the discretion of the qualified x-ray equipment operator or if requested by a Licensed Independent Practitioner.
3. It should be kept in mind that not exposing an individual gives the largest dose reduction. 

c. Requirements for Use

1. All x-ray equipment that is used to image humans shall be used under the direction or supervision of a qualified licensed physician or an investigator listed on the IRB approval.
2. If an x-ray imaging procedure has been approved by an IRB committee or a licensed physician, those procedures must be followed, and other x-rays cannot be taken without approval from the IRB committee or a licensed physician. 
3. The only ones who can operate the x-ray unit, which means depressing the control switch and activating the production of x-rays, to image a human are those individuals that are specifically authorized by the IRB approval or have a physician’s approval to perform x-rays.
4. Written informed consent shall be obtained for all procedures involving direct exposure of x-rays to a subject.  
5. Exceptions to the requirements in this section or any other section must be approved by the Radiation Safety Subcommittee (RSS). 

d. Operator Qualifications

The qualifications for operating an x-ray machine for use on humans in a non-clinical environment are as follows:

1. IRB approved x-ray study
   1. Be registered as a Radiation worker at UNC.
   2. Take the human use X-ray course for UNC
   3. Manufacturer training for your specific instrument or equivalent training provided by the Primary Investigator.
   4. Listed and approved as an operator on the IRB approval
2. Physician led x-ray study
   1. Be registered as a Radiation worker at UNC
   2. Take the human use X-ray course for UNC
   3. Manufacturer training for your specific instrument or equivalent training provided by the physician.
   4. Any other training that the physician decides is necessary. 

e. Exposure Control and Beam Limitation

1. Exposure to an individual shall be kept to the practical minimum consistent with the objectives. 
2. Target exposure indicator values are to be established for all digital imaging systems. 
3. X-ray operators are to monitor the exposure indicator values to ensure they are within the target range. 
4. The smallest practical field sizes and shortest exposure times shall be employed so that everything complies with ALARA.
5. The possibility of reducing dose by techniques utilizing high tube potential and low current shall be considered, if image quality and IRB protocols are not compromised.
6. Care shall be taken to limit the useful beam to the smallest area consistent with requirements and to align accurately the x-ray beam with the individual and image receptor.
7. If available, the AEC (Automatic Exposure Control) feature should be utilized (with the photocell in the appropriate location) for all exposures.
8. If AEC is not available, or if one is not functioning properly, manual techniques must be utilized.
9. Technique charts indicating the exposure factors which normally yield an optimal image for a body part of specific size and position shall be available for each x-ray tube capable of making radiographic exposures and shall be used whenever applicable. 
10. Anatomical programming, when used in conjunction with a routine filming protocol, may meet technique chart requirements.

f. Holding Subjects During X-Ray Procedures

1. Mechanical supporting or restraining devices shall be used when a subject or image receptor must be held in position for the procedure. 
2. If a subject must be held by an individual, that individual shall be protected with appropriate shielding devices of at least 0.25 mm lead equivalence for whole body protection and at least 0.5 mm lead equivalence for any part of the holder’s body that is exposed to the primary x-ray beam.
3. Preferably, the individual holding the subject should be a member of the subject's family or non-radiation worker.
4. Minors or pregnant females may not be used for holding.
5. The operator shall provide radiation safety instructions to the holder to maintain doses ALARA.
6. No individual shall be used routinely to hold subjects or image receptors.
7. In general, imaging professionals should not hold subjects during x-ray exams.  However, it may be necessary under exceptional circumstances when there is no alternative.

g. Protection of Professional Staff and Ancillary Personnel

1. Only people whose presence is necessary shall be in the room/area during x-ray exposures.
2. All individuals shall be positioned such that no part of the body not protected by at least 0.5 mm lead equivalence lead apron or whole-body protective barrier will be exposed to the useful beam.
3. All people who are subject to direct scatter radiation shall be protected by lead aprons or whole-body protective barriers of not less than 0.25 mm lead equivalent.
4. The operator shall remain behind the protective barrier provided for their protection during exposures at permanent installations.
5. Operators must be able to observe the visible exposure indicator and hear the audible signal at or from the protective barrier provided. 
6. Exposures are only to be made in rooms or areas, where no individual member of the public or a person who is occupationally exposed will receive an annual radiation dose in excess of the annual dose limits, as specified in the North Carolina Regulations for Protection Against Radiation. 

h. DXA and pQCT X-Ray Equipment Procedures

1. A restricted area of 6 feet is to be maintained around bone densitometry equipment, e.g., DXA and pQCT, and kept clear of unnecessary people during exposures.
2. People who are subject to direct scatter radiation shall be protected by lead aprons when directly adjacent to the subject.
3. Operator positions should be at least 6 feet from the subject during exposures, or as far away as practical due to room space limitations. 
4. Unless positioned further from the subject, operators should remain in the approved operator position during exposures.
5. For Dexa scans that are used for body composition and performance assessment of athletes, no more than 5 can be performed per year outside of a medical/clinical setting in a healthcare facility.

i. Additional Procedures for Mobile X-Ray Equipment

1. Each operator of mobile equipment, prior to making an exposure, shall ask individuals whose presence is not required to leave the room or area until the exposure is complete. 
2. It may not be possible for all individuals to leave the room in certain areas; however the operator is responsible for making sure individuals are located as far away as practical and protected in accordance with the ALARA policy.
3. Individuals within 6 feet of the x-ray tube head and are subject to direct scatter radiation, including operators of mobile equipment, shall be protected by lead aprons or whole-body protective barriers of not less than 0.25 mm lead equivalent.
4. The operator shall:
   1. Stand as far as possible (at least 6 feet) from the x-ray tube head and the nearest edge of the image receptor.
   2. Give an audible warning before exposure is made.

j. Special Considerations for the Use of Fluoroscopic Equipment

1. Fluoroscopy shall be performed only by or under the immediate supervision of a physician, physician extender, or an IRB approved Primary Investigator properly trained in fluoroscopic procedures.
2. Contact Radiation Safety to determine the required training that is involved in performing Fluoroscopic procedures.
3. Fluoroscopy shall not be used as a substitute for radiography but shall be reserved for the study of dynamics or spatial relationships or for guidance in spot-film recording of critical details.
4. The exposure rate used in fluoroscopy shall be as low as is consistent with the fluoroscopic requirements and shall not normally exceed 10 R/min (measured in air) at the reference location.  Exceptions to this policy include fluoroscopic units equipped with a high-level option (provided that all requirements regarding high-level units are met).      
5. Protective drapes designed to intercept scattered radiation may only be removed from the equipment for those procedures specifically granted a waiver for removal.  The drapes must be reattached immediately upon completion of the procedure for which they were removed. 
6. The hand of the fluoroscopist shall not be placed in the useful beam unless the beam is attenuated by the subject and a protective glove of at least 0.5 mm lead equivalent is worn.
7. During fluoroscopy-based digital acquisition, special care shall be taken to limit subject exposure when, as is often the case, tube currents and potentials employed are significantly higher than those normally used in fluoroscopy. 
8. Total fluoroscopy time and reference air kerma (and other dose metrics, when available) are to be recorded.

k. Use of Hand-Held Units

Approved devices may be used for human use under the following conditions:

1. Operators must be qualified according to the Operator Qualifications section of this chapter. The unit must be secured when not in use to prevent use by a non-authorized operator.
2. If use requires angling the unit to a position that reduces operator protection, lead aprons or whole-body protective barriers must be utilized.
3. The back-scatter shield must be in place for use of the device.
4. Each device must be used at a single registered facility unless registered as a mobile facility.

l. Pregnant or Potentially Pregnant Subjects

Special precautions, consistent with needs, shall be taken to minimize exposure of the embryo or fetus to individuals known to be or suspected of being pregnant.  

1. It is the responsibility of the authorizing physician, or the IRB approved Primary Investigator to determine the pregnancy status of subjects of childbearing age each time they are imaged, and to make a note describing the indication for the study and confirming that this was discussed with the subject. 
2. A pregnant individual is not allowed to receive an x-ray unless specific approval is obtained.
3. Although it is the responsibility of the referring physician or IRB approved investigator to determine pregnancy status, those operating x-ray equipment should inquire about the pregnancy status of potentially pregnant individuals.
4. When pregnancy status is uncertain, a urine pregnancy test should be performed to exclude pregnancy.
5. Radiation exposure must be used judiciously and kept to a minimum, and imaging techniques not involving radiation should be considered.
6. Radiation Safety is available for consultation at 919-962-5507, Monday – Friday 8 am to 5 pm, and after-hours and on weekends and holidays by calling 919-962-6565 and asking to have Radiation Safety paged.  

m. Personnel Monitoring

The Radiation Safety Manual - Chapter 08: Personnel Monitoring shall be followed. 

1. According to this policy, all personnel who are likely to receive in excess of 10% of the occupational dose limits shall be provided with personnel monitoring devices.
2. Any radiation worker that is pregnant or planning a pregnancy should review “Laboratory Safety Manual - Chapter 8: section 15 Reproductive Hazards and the Pregnant Employee
3. Those workers who choose to formally, in writing, declare their pregnancy or pregnancy plans shall be protected in accordance with the policy. Control of employee exposures will occur without economic penalty or loss of job opportunity, including, if necessary, consideration for work assignment changes, consistent with University personnel policy. If you wish to take advantage of this policy, or are curious to find out more information then contact EHS.

n. Quality Control

1. Image processing materials and techniques shall be recommended by the system manufacturer or those otherwise tested to ensure the maximization of the imaging system.
2. Quality control methods shall be employed to ensure optimum results.
3. Radiation surveys of X-ray systems shall be performed before initial use and once per year. Each individual investigator or physician is required to maintain and ensure the machines comply with performance and use criteria as specified by state and federal regulations.
4. The exposure rates to which subjects are normally subjected to during fluoroscopy shall be determined annually by the radiation safety section of EHS.

• NC Radiation Regulations: Regulations that govern x-ray use in NC.
• Image wisely: Website that gives lots of information about human imaging
• Sport performance Dexa information: Information concerning x-ray use for athlete sport performance.
• International Atomic Energy Agency X-rays: what patients need to know

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Proceed to Chapter Sixteen