Medical and Dental Patient Issues

This category covers  dose and risk from diagnostic x-rays, fluoroscopy and CT scans, dental x-rays, radiation therapy procedures, etc.

Worried about x rays? Watch this video.


Pregnant and worried about x rays? Watch this video.

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   Dental-Patient Issues
  HPS FAQ   Medical CT
  HPS FAQ   Reference Books and Articles on Diagnostic X Ray and CT
  HPS FAQ   Therapy—Radiation Oncology

Relevant HPS Web Pages

The following HPS Web pages also address this category:

  PDF   ATE SI Conversion Chart
  HTML page   Benefits of Medical Radiation Exposures
  PDF   CT Imaging Information Sheet
  HTML page   Dental Patient Doses Information
  HTML page   Doses from Medical Radiation Sources
  PDF   Radiation Dose Information Sheet
  PowerPoint   Radiation Doses in Perspective
  PDF   Radiation Exposure from Medical Exams and Procedures
  HTML page   Risk/Benefit of Medical Radiation Exposures

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:
  •  Diagnostic X Ray and CT
  •  Dental
  •  MRI
  •  Therapy - Radiation Oncology
  •  Therapy - Nuclear Medicine
  •  Worker Issues
  •  Pediatric Issues
  •  Miscellaneous
Diagnostic X Ray and CT
Q7532   –   Concern about CT heart scans
Q10494   –   Compare effective doses from medical procedures to natural background
Q10540   –   How does CT scan dose in mGy relate to dose in mSv?
Q10543   –   Many x rays
Q10549   –   Radiation exposure while waiting for procedure
Q10578   –   Radiation dose from HSG tests
Q10610   –   Radiation exposure from multiple procedures including MRI, CT, and ultrasound
Q10613   –   Effects from many CT scans and alternatives
Q10723   –   Can a CT scan cause male infertility or genetic problems?
Q10788   –   Effects of a single exposure compared to prolonged exposure
Q10866   –   Could a series of x rays cause a burning sensation of the skin?
Q11089   –   How does patient size affect radiation dose?
Q11112   –   Was radiation dermatitis caused by a portable chest x ray?
Q11118   –   How can I convert CTDI(vol) in mGy and/or DLP in mGy-cm to effective dose in mSv?
Q11153   –   CT scan of the eye socket
Q11294   –   Risk from medical exams and flying
Q11307   –   Risk from diagnostic imaging procedure
Q11404   –   Scattered x rays during podiatry exam
Q11455   –   Exposure from machines that are not in use
Q11550   –   Comparison of x ray vs CT for TMJ study
Q11591   –   Gonadal dose from bone density measurements
Q11603   –   Dose to the patient due to various knee procedures
Q11607   –   Worried about holding a patient during an x-ray procedure
Q11614   –   CT radiation dose misinformation
Q11710   –   How do you calculate an effective dose for CT given the CTDIvol and DLP?
Q11749   –   Risk from CT chest angiography
Q11781   –   Scatter radiation dose from elbow x ray
Q11836   –   Dose from CT colonoscopy
Q12033   –   Radiation dose from discogram
Q12047   –   Why don't we use MRI instead of CT for abdominal studies?
Q12077   –   Are Omnipaque and barium used in fluoroscopy studies radioactive?
Q12216   –   Head CT dose from older exams
Q12342   –   Radiation dose and cellular repair
Q12437   –   Short-term vs long-term radiation exposure
Q12472   –   Dose to areas near the x-ray tube, but not in primary beam
Q12486   –   Can radiation of the head cause Alzheimer’s disease?
Q12746   –   When is patient lead shielding necessary?
Q12778   –   X-ray risk and is the CT/x ray really necessary?
Q12820   –   Dose from multiple x rays are generally not additive
Q12830   –   Hypothetical risks do not mean you are doomed to cancer
Q12948   –   Body size can affect radiation dose
Q12962   –   Fluoroscopy dose factors and terms
Q13013   –   The DLP value is used to estimate your dose
Q13118   –   Explanation of CT terms—multiplanar, VRT, scout, and phantom CM of body
Q13194   –   100 mrem from diagnostic x rays—the risk in perspective
Q13211   –   Protective covering may not be best practice
Q13510   –   Could a CT scan result in fertility or genetic effects? Can I reverse the effects?
Q13538   –   Dose and Risk from High Resolution Chest CT (HRCT)
Q13565   –   A simple explanation of CTDI-vol and DLP
Q13600   –   Do I emit radiation after having an x ray?
Q13626   –   CT: Low risk with significant benefit
Q13689   –   Skin dose, total dose, and effective dose are not equal
Q13694   –   Single CT/CT series used to gain lots of information
Q13908   –   Same CTDIvol or DLP results in different effective dose for different procedures
Q14100   –   Explanation of the risk from medical x rays and putting the risk into perspective
Q14123   –   No increased risk of medical issues or cancer from childhood medical x-rays
Q14228   –   Underwire bra will not affect CT image
Q14287   –   What is the risk from mammography?
Q14389   –   Multiple diagnostic x rays days, weeks, or years apart do not result in an increase in risk
Q14391   –   I am so scared after having two CT scans
Q14413   –   Effects on brain from head CT
Q14662   –   Many types of oversight to assure medical x rays are safe
Q14907   –   There is no limit for patient dose and worker dose limit is considered minimal risk
Q15024   –   Dose to visitors in a CT room is very low
Q15027   –   Medical x rays are beneficial, and risk is not cumulative
Q15054   –   Why there may be differences in assessment of risk
Q15061   –   Why different online calculators give different results; all results low risk
Q15076   –   Should I get a 2D or 3D mammogram or digital breast tomosynthesis?
Q15101   –   Having CT scans or diagnostic x rays should not interfere with life decisions
Q15163   –   Shielding patient with lead apron is not recommended
Q15333   –   A high reported fluoroscopy dose is likely a skin dose, which has a different concern
Q1713   –   Dental doses
Q3992   –   Frequent dental x rays
Q4322   –   Dental x ray concerns
Q4411   –   Dental x rays and sore throat
Q8152   –   Uranium in glaze on porcelain denture teeth
Q8568   –   Radioactivity in porcelain dentures and crowns
Q10565   –   Safe time between repeat x-ray procedures
Q10700   –   Risk from dental x rays
Q10721   –   Why repeatedly operate a dental x-ray machine with no patient receiving an x ray?
Q10785   –   Radiation exposure from handheld dental x-ray units
Q10794   –   Radiation exposure from older dental x-ray units and risk of brain cancer
Q10936   –   Doses from digital imaging in dental radiology
Q10940   –   Panoramic (panoral) x rays taken for TMJ issue
Q11055   –   Dental x-ray dose
Q11072   –   X-ray settings for a six year old
Q11136   –   Am I being overexposed to x rays in an open bay dental layout?
Q11138   –   Radiation doses from cone-beam CT
Q11139   –   Is there a radiation-free alternative for panoramic (panoral) dental x rays?
Q11372   –   Porcelain and zirconia crowns
Q11426   –   Titanium dental implants
Q11492   –   Exposed to too much radiation during dental x rays
Q11712   –   Radiation dose from multiple dental exams
Q11819   –   Worries about dental radiation side effects
Q12152   –   Wearing a protective lead apron on my back for a panoramic (panoral) x-ray exam
Q12162   –   Radiation risk from dental implants
Q12200   –   Safety features of dental x-ray exposure switch
Q12203   –   Remote-control exposure switch for dental x rays
Q12477   –   How x-ray dose factors are set for panoramic (panoral) dental x ray
Q12492   –   Did I receive too much radiation dose from a panoramic (panoral) x ray?
Q12809   –   Associated risk from many x rays on a single tooth
Q12900   –   Immediate burning sensation after x ray due to cause other than the x ray
Q13077   –   Radiation exposure from Cad/Cam digital dentistry
Q13098   –   Being in area of x ray does not result in significant dose
Q13391   –   No dose to baby from mother's dental x rays
Q13641   –   Panoramic (panoral) (dental OPG) x ray and some common safety concerns explained
Q13785   –   Detailed explanation of root canal and benefits of cone beam computed tomography (CBCT) to image area
Q13809   –   Panoramic (panoral) vs. 3D cone beam and associated low dose
Q13960   –   How often should a dentist perform x rays?
Q14048   –   Lead apron no longer required due to enhanced collimation
Q14272   –   Panoramic (panoral) "test" mode does not generate x rays and helps ensure correct patient positioning
Q14523   –   Low dose from cone beam CT (CBCT)
Q14547   –   CBCT explained
Q14581   –   Operation of dental panoramic (panoral) explained
Q14752   –   Reasons for using a positioning indicator device
Q14962   –   Pushing button does not mean radiation is being emitted
Q15149   –   Comparing CBCT vs. standard panoramic
Q15377   –   Handheld dental x-ray units are safe
Q9517   –   Dosimetry for ultrasound and MRI technologists
Q10931   –   Risk of dislodging blood clots from magnetic resonance imaging (MRI)
Q13577   –   Risk from MRI vs. cellphone
Q14004   –   Risks from MRI
Therapy - Radiation Oncology
Q8592   –   Probability of secondary cancer after radiation therapy
Q10964   –   Can radiation affect hearing aids?
Q11069   –   Caregiver safety when patient is administered radium-223
Q11311   –   Risk from implanted radon seeds
Q11501   –   Breast-feeding during radiation therapy for a brain tumor
Q11740   –   Radiation dose from Gamma Knife treatments
Q12494   –   Radiation effects from ingestion of thorium dioxide
Q12708   –   Each radiation therapy treatment is patient specific
Q12761   –   Radiation therapy prescription and application of dose painting and dose fractionation
Therapy - Nuclear Medicine
Q12945   –   Decay results in radioactive contamination going away
Q13563   –   Risks from caring for an I-131 therapy patient
Worker Issues
Q7265   –   Computed Tomography Dose Index (CTDI)
Q7303   –   Dose limit to thyroid
Q10251   –   Veterinary nurse
Q10577   –   Film speed vs. radiation dose to patient
Q10779   –   How can I describe dental exposures to patients?
Q11012   –   Radiation safety certification for dental personnel
Q11177   –   Calculating CT dose from control parameters
Q11588   –   Radiation worker exposure without protective equipment
Q12793   –   Applying time, distance and shielding if in fluoroscopy room to assure no risk
Q13454   –   What is the risk to the dentist/hygienist from a handheld x-ray device?
Q13700   –   Dose from personal medical procedures is not included in worker dose limits
Q13856   –   Concerned about dose after forgetting lead apron
Q14412   –   Radiation dose from dental cone-beam computed tomography systems (CBCT)
Q14893   –   No risk from being in area during an x ray
Pediatric Issues
Q7748   –   Worried about head CT on daughter
Q10528   –   Is a CT scan more dangerous than a bone scan?
Q10552   –   Radiation exposure to infant from barium swallow study
Q10592   –   Doses from a barium swallow study
Q11088   –   Risk from dental procedures on child using adult settings
Q11145   –   X rays and childhood leukemia
Q11299   –   Cephalometric and panoramic x-ray doses
Q11310   –   Effects of head CT scan on infant
Q11472   –   Shielding for patient during forearm x rays
Q11859   –   CT scan comparison between a newborn and five-year-old patient
Q12016   –   Radiation risk from a head CT and scoliosis screening exam
Q12236   –   X-ray collimator leakage radiation
Q12483   –   Risks of pediatric dental x rays
Q12489   –   Recent articles relating head CTs to increased cancer risk in children
Q12685   –   Explanation of millisievert and effective dose
Q12706   –   Fluoroscopy dose variables and risk
Q12730   –   Risk from being in an adjacent area during an x-ray procedure
Q12748   –   No gonad shielding for swallowed battery
Q12836   –   How an x ray interacts and can a metal button increase patient dose?
Q12892   –   The majority of an x-ray dose is to a limited area and gonadal shielding is not necessary
Q13150   –   Dose from multiple x rays is negligible risk to premature baby
Q13164   –   CT of child—risk in perspective
Q13717   –   Panoramic x ray
Q13997   –   No fertility or testicular cancer concerns needed from childhood x ray
Q14888   –   Standard x rays are very low dose and do not increase risk
Q15112   –   Lead apron no longer consider appropriate for patient safety
Q15128   –   Radiation dose, age when dose occurred, and spacing of dose can all effect risk
Q10518   –   Time, distance, and shielding precautions after iodine-125 seed permanent implant
Q10831   –   Is radiation retained in clothes and other common material?
Q10975   –   Are there regulations limiting radiation doses from medical procedures?
Q11109   –   Radiation risk from holding a patient without a protective apron during an x-ray procedure
Q11479   –   Ultrasound damage to reproductive organs
Q12755   –   Using linear no threshold (LNT) to determine risk
Q12835   –   Explanation of effective dose (mSv), absorbed dose (mGy), and dose-length product (DLP)
Q12965   –   Effective dose and my individual risk
Q13190   –   Old x-ray machines can change from film to digital image
Q13191   –   AAPM position statement revision due to caution, not new evidence
Q13292   –   Will my clothing, cell phone, keys, or a wallet increase my radiation dose?
Q13516   –   Possible deterministic effects change with skin dose
Q13532   –   Medical x rays did not cause genetic condition
Q13535   –   Putting medical dose and 100 mSv in perspective
Q13693   –   Bone Density/DEXA dose and risk
Q13720   –   Whole-body vs. organ dose
Q13829   –   Cumulative CT scan exposure in children
Q13844   –   Safety features on x-ray machines
Q13862   –   Risk of pelvic x ray during pregnancy
Q13883   –   What does "too much radiation" mean?
Q14203   –   Radiation risk from dental panoramic x rays is minimal
Q14655   –   Radiation dose from diagnostic medical procedures is not cumulative
Q14688   –   Important difference between procedure tissue dose, patient radiation dose, worker dose limits, and background dose
Q14694   –   Explaining some dose metrics—millisieverts (mSv), milligray (mGy), and DAP
Q14719   –   Diagnostic CT does not significantly increase cancer risk associated with secondhand smoke
Q14797   –   Why don’t clinicians provide effective dose to patients?
Q14961   –   Being in same building with x-ray equipment does not result in significant dose
Q14969   –   Many x rays over a few months does not result in significant increase in risk
Q15165   –   Similar to exposure to the sun, exposure from medical radiation procedures is not cumulative
Q15171   –   Minimal risk, significant benefits from medical procedures involving radiation exposure

Other Useful Websites

The following websites may also be useful:

  External website   Answers to Your Radiation Therapy Questions – American Society for Radiation Oncology
  External website   Cancer Mechanisms - Radiation Effects Research Foundation
  External website   Dose and Risk Calculator for Standard Medical Radiation Procedures – American Society of RadiologicTechnologists
  External website   Image Gently During Dental Procedures – The Alliance for Radiation Safety in Pediatric Imaging
  External website   Image Gently: Enhancing Radiation Protection During Pediatric Fluoroscopy – The Alliance for Radiation Safety in Pediatric Imaging
  External website   Medical Uses of Radiation – Health Physics Society "Radiation Answers"
  External website   Patient Information on Radiation-Emitting Products – US Food and Drug Administration
  External website   Radiation-Emitting Products, Computed Tomography (CT) – US Food and Drug Administration
  External website   Reducing Radiation from Medical X Rays, US Food and Drug Administration
  External website   The Radiology Information Resource for Patients – Radiological Society of North America and American College of Radiology