Medical and Dental Patient Issues

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
  •  Miscellaneous
Diagnostic X Ray and CT
Q2874   –   Risk of many tests
Q4327   –   Risk of x rays
Q7263   –   Risk to my infant who had multiple chest x rays
Q7265   –   Computed Tomography Dose Index (CTDI)
Q7303   –   Dose limit to thyroid
Q7406   –   Risk from chest-abdomen CT
Q7532   –   Concern about CT heart scans
Q7597   –   Have I had too much radiation from medical scans?
Q7748   –   Worried about head CT on daughter
Q9761   –   Nurses performing fluoroscopy
Q10494   –   Compare effective doses from medical procedures to natural background
Q10525   –   Occupational exposure due from C-Arm
Q10527   –   Doses from a six-view cervical spine series and a right rib series
Q10528   –   Is a CT scan more dangerous than a bone scan?
Q10540   –   How does CT scan dose in mGy relate to dose in mSv?
Q10543   –   Many x rays
Q10549   –   Radiation exposure while waiting for procedure
Q10552   –   Radiation exposure to infant from barium swallow study
Q10574   –   Risk from CT scan and x rays of lower back (lumbar section) and abdomen
Q10576   –   Dose from lumbar spine series
Q10577   –   Film speed vs. radiation dose to patient
Q10578   –   Radiation dose from HSG tests
Q10592   –   Doses from a barium swallow study
Q10599   –   DLP CT conversion factor
Q10610   –   Radiation exposure from multiple procedures including MRI, CT, and ultrasound
Q10613   –   Effects from many CT scans and alternatives
Q10655   –   Effects from a pediatric upper GI exam
Q10683   –   CT dose and risk
Q10695   –   Pediatric CT scans
Q10723   –   Can a CT scan cause male infertility or genetic problems?
Q10731   –   What is the effective dose from CT and MRI scans?
Q10753   –   Given DLP, what is my radiation dose?
Q10787   –   Radiation output differences for 1.02 m vs. 1.83 m SID
Q10788   –   Effects of a single exposure compared to prolonged exposure
Q10831   –   Is radiation retained in clothes and other common material?
Q10866   –   Could a series of x rays cause a burning sensation of the skin?
Q10908   –   What is the purpose and validity of patient dose tracking?
Q10922   –   CT head angiogram
Q10970   –   What are the risks from multiple head CT scans?
Q11089   –   How does patient size affect radiation dose?
Q11109   –   Radiation risk from holding a patient without a protective apron during an x-ray procedure
Q11112   –   Was radiation dermatitis caused by a portable chest x ray?
Q11116   –   Can a CT scan cause hypoimmunity, or alter immune functions?
Q11118   –   How can I convert CTDI(vol) in mGy and/or DLP in mGy-cm to effective dose in mSv?
Q11145   –   X rays and childhood leukemia
Q11147   –   Can the radiation doses from CT scans and cigarette smoke be added?
Q11153   –   CT scan of the eye socket
Q11173   –   Does head CT cause brain cancer?
Q11177   –   Calculating CT dose from control parameters
Q11211   –   Cancer risk from CT of upper rib cage
Q11294   –   Risk from medical exams and flying
Q11307   –   Risk from diagnostic imaging procedure
Q11310   –   Effects of head CT scan on infant
Q11369   –   Cumulative effects of CT scans and x rays
Q11404   –   Scattered x rays during podiatry exam
Q11414   –   Long-term health effects of head CT scan
Q11447   –   Dose units for head CT scan
Q11455   –   Exposure from machines that are not in use
Q11472   –   Shielding for patient during forearm x rays
Q11493   –   Obtaining dose from CT scans
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?
Q11711   –   Cancer risk from multiple x-ray exams
Q11712   –   Radiation dose from multiple dental exams
Q11742   –   Worried about childhood exposure to CT head exam
Q11749   –   Risk from CT chest angiography
Q11781   –   Scatter radiation dose from elbow x ray
Q11793   –   Difference between milligray and millisievert with barium swallow (fluoroscopy)
Q11816   –   Cancer risk for 18FDG PET/CT studies
Q11819   –   Worries about dental radiation side effects
Q11836   –   Dose from CT colonoscopy
Q11846   –   Radiation to five-month-old child to determine leg growth
Q11855   –   Worried about a head CT and dental x rays after an ER visit
Q11859   –   CT scan comparison between a newborn and five-year-old patient
Q11883   –   Help with understanding a CT dose calculation
Q11944   –   Pediatric head CT exams and future cancer risks
Q11982   –   Accumulated radiation from x-ray tests and future cancer risks
Q12016   –   Radiation risk from a head CT and scoliosis screening exam
Q12032   –   Calculating patient CT dose with phantoms and software
Q12033   –   Radiation dose from discogram
Q12043   –   Radiation dose after automobile trauma
Q12047   –   Why don't we use MRI instead of CT for abdominal studies?
Q12077   –   Are Omnipaque and barium used in fluoroscopy studies radioactive?
Q12083   –   Acceptable lifetime exposure
Q12125   –   Adding CTDIw and DLP to patient records
Q12152   –   Wearing a protective lead apron on my back for a panoramic x-ray exam
Q12216   –   Head CT dose from older exams
Q12236   –   X-ray collimator leakage radiation
Q12274   –   Radiation dose from chiropractor's back x rays
Q12342   –   Which procedures produce enough radiation to harm cells?
Q12437   –   Short-term vs long-term radiation exposure
Q12472   –   Dose to areas near the x-ray tube, but not in primary beam
Q12477   –   How x-ray dose factors are set for panoramic dental x ray
Q12486   –   Can radiation of the head cause Alzheimer’s disease?
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
Q12746   –   When is patient lead shielding necessary?
Q12748   –   No gonad shielding for swallowed battery
Q12763   –   Applying study results and risk to worries about pediatric CT scan
Q12774   –   Possible genetic damage from many CT scans
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
Q12862   –   Risk from multiple tests over short period of time
Q12892   –   The majority of an x-ray dose is to a limited area and gonadal shielding is not necessary
Q12924   –   DNA repair helps minimize risk from x ray
Q12948   –   Body size can affect radiation dose
Q12962   –   Fluoroscopy dose factors and terms
Q12992   –   DLP and how it is determined
Q13013   –   The DLP value is used to estimate your dose
Q13118   –   Explanation of CT terms—multiplanar, VRT, scout, and phantom CM of body
Q13150   –   Dose from multiple x rays is negligible risk to premature baby
Q13164   –   CT of child—risk in perspective
Q13194   –   100 mrem from diagnostic x rays—the risk in perspective
Q13211   –   Protective covering may not be best practice
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?
Q10779   –   How can I describe dental exposures to patients?
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 x rays taken for TMJ issue
Q11012   –   Radiation safety certification for dental personnel
Q11055   –   Dental x-ray dose
Q11072   –   X-ray settings for a six year old
Q11088   –   Risk from dental procedures on child using adult settings
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 dental x rays?
Q11299   –   Cephalometric and panoramic x-ray doses
Q11372   –   Porcelain and zirconia crowns
Q11426   –   Titanium dental implants
Q11492   –   Exposed to too much radiation during dental x rays
Q12162   –   Radiation risk from dental implants
Q12200   –   Safety features of dental x-ray exposure switch
Q12203   –   Remote-control exposure switch for dental x rays
Q12483   –   Risks of pediatric dental x rays
Q12492   –   Did I receive too much radiation dose from a 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
Q13098   –   Being in area of x ray does not result in significant dose
Q9517   –   Dosimetry for ultrasound and MRI technologists
Q10931   –   Risk of dislodging blood clots from magnetic resonance imaging (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
Q10518   –   Time, distance, and shielding precautions after iodine-125 seed permanent implant
Q10975   –   Are there regulations limiting radiation doses from medical procedures?
Q11479   –   Ultrasound damage to reproductive organs
Q11588   –   Radiation worker exposure without protective equipment
Q12730   –   Risk from being in an adjacent area during an x-ray procedure
Q12755   –   Using linear no threshold (LNT) to determine risk
Q12793   –   Applying time, distance and shielding if in fluoroscopy room to assure no risk
Q12835   –   Explanation of effective dose (mSv), absorbed dose (mGy), and dose-length product (DLP)
Q12836   –   How an x ray interacts and can a metal button increase patient dose?
Q12965   –   Effective dose and my individual risk
Q13190   –   Old x-ray machines can change from film to digital image

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 – U.S. Food and Drug Administration
  External website   Radiation-Emitting Products, Computed Tomography (CT) – U.S. Food and Drug Administration
  External website   Reducing Radiation from Medical X Rays, U.S. Food and Drug Administration
  External website   The Radiology Information Resource for Patients – Radiological Society of North America and American College of Radiology