Medical and Dental Equipment and Shielding

This category covers medical and dental equipment and shielding, including questions about lead aprons and other protective gear.

What's My Risk?

The risks of health effects from radiation doses received during diagnostic imaging procedures are either too small to be observed or are nonexistent. The benefits from properly performed clinically indicated diagnostic imaging procedures, including CT scans, far outweigh any hypothetical cancer risk. Diagnostic medical imaging procedures provide a medical benefit to you even if they do not appear to reveal anything and are of less risk than their alternatives, such as exploratory surgery.

Even if the result of the imaging exam was negative, the physicians were provided information they could use to determine the next course of action. Refusing medical imaging procedures may result in real and substantial risk by not receiving the clinical benefits of the procedures.

Because the Health Physics Society recommends against quantitative estimates of health risks for radiation doses below 100 mSv, we will not calculate hypothetical risks for diagnostic imaging procedures. The Society's position statement "Radiation Risk in Perspective" explains in more detail why it is inappropriate to estimate health risks at these doses. Some risk information is available from

What's My Dose?

If you want to know the specific dose you or a family member may have received for a particular exam you underwent, you need to contact your health care provider and ask for the effective dose due to the procedures. Typical doses from many diagnostic imaging procedures are posted on our website.

FAQs Developed by the HPS

The following FAQs have been developed by our topic editors for this category:

  HPS FAQ   Lead Garments (Aprons, Gloves, etc.)
  HPS FAQ   Living and Working Near an X-Ray Room

Relevant HPS Web Pages

The following HPS Web pages also address this category:

  PDF   Shielding of Gamma Radiation
  HTML page   X-Ray Equipment Disposal

Questions Answered by HPS Experts

The following health physics questions have been answered by an expert and approved by our editors for inclusion in our "Ask the Experts" feature. Click on the question to see the answer.

Questions in this Category Are in the Following Subcategories:
  •  Equipment
  •  Shielding
  •  Lead Aprons
  •  Miscellaneous
Q7270   –   Safe number of x rays I can perform
Q7279   –   Diagnostic x-ray quality control references
Q7569   –   Dose rate standing next to CT machines
Q7820   –   Position of patient in fluoroscopy
Q7856   –   Radiation dose to office personnel from veterinary x ray
Q8232   –   Safety of older x-ray units
Q8695   –   Transition to digital x ray
Q8867   –   Scatter radiation dose to neonates
Q9085   –   Meter to evaluate shielding in diagnostic radiology department
Q9121   –   Dose limit for public
Q9513   –   Convert DAP to EAP
Q9524   –   Workload units for diagnostic and therapy
Q10458   –   Radiation detector selection for cabinet x ray
Q10461   –   Testing lead aprons
Q10817   –   Bone density noninvasive testing
Q10818   –   Image on CR plates from scattered radiation
Q10824   –   Measuring cobalt teletherapy leakage radiation in "ON" position
Q10971   –   Lead in walls after removal of x-ray equipment
Q11074   –   Radiation dose from CT scout scan
Q11198   –   Differences in medical and industrial x-ray tubes
Q11396   –   Scattered radiation after x-ray machine is turned off
Q11477   –   Electromagnetic waves and x-ray equipment
Q11520   –   Material used to produce x rays
Q11688   –   Cobalt-60 teletherapy reference field size
Q11780   –   Radiation dose from x-ray scatter
Q12046   –   Assay of iodine-131 source with a survey meter
Q12398   –   Standards for radiation escaping from medical diagnostic equipment
Q12711   –   Use of a fume hood for iodine-131 (I-131)
Q12911   –   Does x-ray room require interlock or warning light?
Q12934   –   Is there excessive scatter radiation if image receptor is not properly positioned?
Q12936   –   Will a power surge to an x-ray unit create x rays?
Q13035   –   Difference between CR and DR
Q13045   –   Radiation dose to person standing in CT room
Q13084   –   Calculating effective dose for fluoroscopy procedures
Q13560   –   DRL and CTDI settings on CT scanners
Q13994   –   Risks from x-ray tube oil
Q14394   –   Risk of being near x-ray equipment not in operation
Q14443   –   Testing x ray "on" lights
Q14461   –   Thorium in x-ray tubes
Q14517   –   Use of an electronic personnel dosimeter
Q14600   –   Dark current in x-ray units
Q14879   –   Transmission x-ray scanner for research
Q15332   –   Risk from cracked x-ray tube head
Q7162   –   Iodine-131 shielding with concrete
Q7237   –   Shielding of thyroid and breast for CT head scans
Q7257   –   Shielding
Q7659   –   Shielding in CT scanner control wall
Q8095   –   Labeling x-ray room shielding
Q8119   –   X-ray shielding to protect the general public
Q8159   –   Inspection of mobile x-ray shields
Q8187   –   Shielding doors in a radiotherapy treatment room
Q8273   –   Syringe shield glass cracks
Q8455   –   CT leakage limits and dose
Q8573   –   Radiation dose behind a mobile shield
Q8624   –   Use of screws in lead-lined drywall
Q8696   –   Use of lead apron while holding patients
Q8785   –   Shielding floors in diagnostic x-ray installations
Q8825   –   Hands in the fluoroscopy beam
Q9049   –   Diagnostic x-ray room control area opening
Q9237   –   Two lead aprons in interventional cardiology
Q9288   –   Radiation exposure from an adjacent x-ray room
Q9385   –   Shielding patients in the operating room
Q9456   –   Radiation dose to workers in the emergency department
Q9483   –   Tenth-value layer for photons in paraffin
Q9544   –   Patient shielding with lead aprons and shadow shields
Q9586   –   Shielding height in wall for diagnostic x ray
Q9699   –   Use of lead drapes for under-table fluoroscopy units
Q9793   –   Lead apron for family member in CT room
Q9954   –   Concerns about shielding in dental facility
Q9978   –   Concerns about metal objects in x-ray room
Q10024   –   Scatter contributions to measured entrace skin exposure rate
Q10114   –   Is there radiation after the x ray?
Q10188   –   Radiation safety and C-arms
Q10189   –   Shielding pediatric patients in the operating room
Q10235   –   Shielding a lingual thyroid
Q10265   –   Veterinary personnel in room during CT scans
Q10276   –   Use of lead cap on head during fluoroscopy
Q10304   –   Gonad shielding location for males
Q10394   –   TVL of neutron capture gamma rays in lead
Q10411   –   Storage of cesium-137 µCi survey meter check source
Q10462   –   Use of a C-arm spacer cones in Radiation Therapy Department
Q10489   –   Lead thyroid collar protection in dental applications
Q10638   –   Use of leaded glasses after cataract surgery
Q10730   –   NCRP minimal shielding recommendations
Q10784   –   Health risks from handheld dental x-ray units
Q10905   –   Cobalt teletherapy beam output calibration
Q11009   –   Shielding material thickness as part of shielding calculation
Q11015   –   Shielding for LINAC
Q11092   –   Is wearing only a lead vest adequate protection?
Q11137   –   Does lead shielding get radioactive?
Q11148   –   Best place to stand during an x-ray exposure
Q11186   –   Hand exposure during fluoroscopy
Q11245   –   Use of head protective shielding during an x ray
Q11434   –   Lead apron not given to patient during x ray
Q11505   –   High dose rate in linear accelerator modulator room
Q11553   –   Dose Limits in Accelerator Shielding Design
Q11739   –   Lack of shielding in ceiling of CT room
Q11764   –   CT shielding to protect family member outside room
Q12042   –   Thyroid shields for people holding patients
Q12112   –   Lead shielding in operating rooms
Q12148   –   Checking lead goggles for cracks
Q12406   –   Shielding for persons in the x-ray room with the patient
Q12614   –   Do handheld x-ray machines give a greater dose to the face than a stationary machine?
Q12989   –   How to penetrate x-ray room lead shielding with data cable
Q13155   –   Risk from x-ray exposure while working in office under an x-ray room
Q13272   –   Radiation dose when walking past an x-ray room
Q13310   –   X rays performed without patient shielding
Q13331   –   Radiation risk from not wearing a lead apron while holding a patient
Q13348   –   Radiation dose outside a dental room with no door
Q13943   –   Cone-Beam Computed Tomography (CBCT) scanners and worker safety
Q13972   –   Removal and disposal of sheet lead
Q14425   –   Shielding gap in door to CT room
Q14699   –   How far to be from mobile x ray without a lead apron
Q14742   –   X-ray patient not shielded
Q14746   –   Shielding aspects of cone-beam CT room
Q14761   –   CT patient not shielded and radiation dose concern
Q14902   –   Can turning head and closing eyes reduce x-ray exposure to lens of eyes?
Q14913   –   Does lead shielding in x-ray room walls need to be removed?
Q15103   –   Closing the door to the x-ray room during exposures
Lead Aprons
Q7565   –   Lead-apron testing with CT
Q8389   –   Refusal to provide lead apron to a worker during fluoroscopy
Q9545   –   Where to stand when working with a C-arm
Q9730   –   Cardiologist and wrap-around lead aprons
Q9899   –   Useful life of lead aprons
Q10071   –   Length of time to wear lead aprons
Q10449   –   Thyroid collars
Q10628   –   Lead apron use in a fluoroscopy room
Q10863   –   Radiation dose to persons inside the CT room
Q11059   –   Lead aprons in the operating room
Q11184   –   Lead apron body coverage
Q11188   –   Lead aprons on patients aren't necessary
Q11539   –   Rolling up lead aprons for storage
Q11608   –   Do lead aprons become radioactive after exposure to x rays?
Q11792   –   Wrinkles in lead aprons
Q11996   –   Fluoroscopy techniques for testing lead aprons
Q12169   –   Characteristics of x-ray beam scattered from a lead apron
Q12359   –   Am I safe standing behind someone who is wearing a lead apron?
Q12468   –   Requirements to provide lead aprons to x-ray workers
Q12469   –   Working in veterinary x ray without lead apron
Q12701   –   Who can test lead aprons?
Q12870   –   Life expectancy of lead aprons
Q12977   –   Lead apron wasn't used for all spine x rays
Q13157   –   Patient radiation exposure risk if physician or staff are wearing bismuth gloves
Q13176   –   Must lead aprons be x rayed to be inspected?
Q13461   –   Why can I see my hand through a lead apron in an x-ray image?
Q13777   –   Lead aprons and portable x-ray machines
Q13787   –   Use of lead aprons with Technetium-99m
Q13958   –   How to document a missing lead apron
Q14090   –   Lead apron thickness requirements
Q14499   –   Radiation dose to person in x-ray room without a lead apron
Q15341   –   Where to mount lead apron rack
Q9504   –   Metal eyeglass frames on during dental scan
Q11419   –   Nonlead aprons
Q11804   –   Personnel dosimeters in the operating room
Q12002   –   Risk of painting walls in an x-ray room
Q12318   –   Radiation scatter to thyroid and breast after head CT
Q12710   –   Posting for C-arm room
Q12823   –   Oil leaking from x-ray tube head
Q12824   –   Powering down x-ray units between patients
Q12983   –   Effect of x-rays on insulin pump
Q13593   –   Potential for scattered or leaked radiation exposure from a nearby radiology facility
Q14371   –   What is air kerma rate (AKR), dose area product (DAP), and dose length product (DLP)?
Q14952   –   Am I exposed to radiation if I’m next to a "caution radioactive materials" sign?

Other Useful Websites

The following website may also be useful:

  External website   X-Ray Equipment Disposal – Health Physics Society Publication