jalal jalal shokouhi – md president of iranian society of radiology president of cooperation of...

Management in radiology seminar February 2-32013Tehran-Iran

o Safety and protection

Jalal Jalal Shokouhi – MDPresident of Iranian society of radiology

President of cooperation of Iranian radiologistsTechnical manager of Jaam e Jam and koorosh medical imaging centers

j a l a l j a l a l s h o k o u h i @ h o t m a i l . c o m w w w. m e d i m a g e . i r

mailto:[email protected]

http://www.medimage.ir/

Safety and Protection in medical imaging

Using Ionising Radiation in Medicine

There are 3 main uses of ionising radiation in medicine:

Treatment

Diagnosis

Sterilisation

Radiotherapy Treatment Planning

Planning Simulation Treatment

Every treatment using radiotherapy has to be rigorously planned. The planning process consists of three phases:

Radiotherapy Treatment Planning

The cancerous tumour has to be located so that its size and position can be analysed. This information can be obtained from:

•X-rays•CT scans•MRI scans•Ultrasound images

Radiotherapy Treatment PlanningSimulation

Once the amount of radiation to be given has been accurately calculated, the patient then goes to the simulator to determine what settings are to be selected for the actual treatment using a linear accelerator.

The settings are determined by taking a series of x-rays to make sure that the tumour is in the correct position ready to receive the ionising radiation.

TracersThere are many uses of ionising radiation based on the fact that it is easy to detect. In such applications, the radioactive material is used in the form of a tracer.

In nuclear medicine, a tracer is a radioactive substance which is taken into the body either, as an injection, or as a drink. Such a substance is normally a gamma emitter which is detected and monitored.

This gives an indication of any problems that may be present in body organs or tissues by how much, or how little, of the substance has been absorbed.

DiagnosisStatic Imaging

There is a time delay between injecting the tracer and the build-up of radiation in the organ.

Static studies are performed on the brain, bone or lungs scans.

Summary

There are 3 main uses of ionising radiation in medicine: treatment, diagnosis and sterilisation.

Radiotherapy is used to treat cancers by irradiating them with ionising radiation.

Radioactive tracers are used to diagnose and investigate several medical conditions.

Ionising radiation is used to sterilise medical equipment as it kills germs and/or bacteria.

RADIATION PROTECTION INDIAGNOSTIC AND

INTERVENTIONAL RADIOLOGY

L 9: Medical Exposure - BSS (Potential exposure and investigation of accidental

medical exposures)

IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology

9: Medical Exposure - BSS 20

Main International Institutions involved in Regulatory aspects

IAEA (The International Atomic Energy Agency) IEC (International Electro-technical Commission) ICRP ( The International Commission on

Radiological Protection) OECD/NEA (The Nuclear Energy Agency) CEC (The Commission of European Communities) WHO (The World Health Organization) ILO (The International Labor Organization) ISO (International Organization for

Standardization)


Several revised versions of “The Basic Safety Standards” (BSS) published: 1962, 1967, 1982, 1994, 1996, 2011

The last version “Safety series N° 115” (2011) reflects knowledge and developments in radiation protection and safety and related fields at that time

Regulatory aspects (II)


Responsibilities

Main responsibilities: registrants and licensees

employers

Subsidiary include:suppliersworkersradiation protection officersmedical practitioners & health professionalsqualified experts, ethical review committees


Medical exposure responsibilities (I)

REGISTRANTS AND LICENSEES SHALL ENSURE THAT: No patient be administrated a diagnostic or

therapeutic medical exposure unless the exposure is prescribed by a medical practitioner

Medical practitioners be assigned the primary task and obligation of ensuring overall patient protection and safety in the prescription of, and during the delivery of, medical exposure


Medical exposure responsibilities (II)

REGISTRANTS AND LICENSEES SHALL ENSURE THAT: Medical and paramedical personnel be available

as needed, and either be health professionals or have appropriate training adequately to discharge assigned tasks

For therapeutic uses of radiation, the calibration, dosimetry and quality assurance requirements of the Standards be conducted by or under the supervision of a qualified expert in radiotherapy physics


REGISTRANTS AND LICENSEES SHALL ENSURE THAT:

The exposure of individuals incurred knowingly while voluntarily helping in the care, visit, support or comfort of patients undergoing medical diagnosis or treatment be constrained so that it is unlikely that her or his dose will exceed 5 mSv during the period of a patient’s diagnostic examination or treatment.

Training criteria be specified or be subject to approval, as appropriate, by the Regulatory Authority in consultation with relevant professional bodies

Medical exposure responsibilities (III)


Radiation Protection Requirements - JUSTIFICATION (I)

GENERIC MATTER› No practice or source within a practice should be

authorized unless the practice produces sufficient benefit to the exposed individuals or to society to offset the radiation harm that it might cause i.e.: unless the practice is justified, taking into account social, economic and other relevant factors

MEDICAL EXPOSURE› Medical exposure should be justified by weighing the

diagnostic or therapeutic benefits they produce against the radiation detriment they might cause, taking into account the benefits and risk of available alternative techniques that not involve medical exposure


Radiation Protection Requirements - JUSTIFICATION (II)

MEDICAL EXPOSURE› In justifying each type of diagnostic examination by

radiography, fluoroscopy or nuclear medicine, relevant guidelines will be taken into account, such as those established by the WHO

› Any radiological examination for occupational, legal, or health insurance purposes undertaken without reference to clinical indications is deemed to be not justified unless it is expected to provide useful information on the health of the individual examined or unless the specific type of examination is justified by those requesting it in consultation with relevant professional bodies


Radiation Protection Requirements - JUSTIFICATION (III)

MEDICAL EXPOSURE› Mass screening of population groups involving

medical exposure is deemed to be not justified unless the expected advantages for the individual examined or for the population as a whole are sufficient to compensate for the economic and social costs, including radiation detriment


Radiation Protection Requirements - JUSTIFICATION (IV)

MEDICAL EXPOSURE› The exposure of humans for medical research is

deemed to be not justified unless it is: in accordance with the provisions of the Helsinki

Declaration and follows the guidelines for its application prepared by Council for International Organization of Medical Sciences (CIOMS) and WHO

subject to the advice of an Ethical Review Committee and to applicable national and local regulations


OPTIMIZATION - DESIGN CONSIDERATIONS (IV)

With regard to equipment consisting of radiation

generators, registrants and licensees should ensure that: Whether imported into or manufactured in the

country where it is used, the equipment conform to applicable standards (IEC, ISO)

Performance specifications and operating and maintenance instructions be provided in a major world language understandable to the users and in compliance with the relevant IEC and ISO standards

Radiation beam control mechanisms be provided (devices indicating clearly and in a fail-safe manner whether the beam is “on” or “off”)


OPTIMIZATION - DESIGN CONSIDERATIONS (V)

With regard to equipment consisting of radiation generators, registrants and licensees should ensure that:

As nearly as practicable, the exposure be limited to the area being examined by using collimating devices aligned with the radiation beam

The radiation field within the examination area without any radiation beam modifiers (wedges) be as uniform as practicable and the non uniformity be stated by the supplier

Exposure rate outside the examination area due to radiation leakage or scattering be kept as low as reasonably achievable


OPTIMIZATION OF PROTECTION FOR MEDICAL EXPOSURES - DESIGN CONSIDERATIONS (VI)

With regard to equipment consisting

of radiation generators...: Radiation generators and their

accessories be designed and manufactured so as to facilitate the keeping of medical exposures to the minimum necessary to obtain adequate diagnostic information

Operational parameters (kVp, filtration, focal spot position, source-image receptor distance, field size, either tube current and time or their product) be clearly indicated


OPTIMIZATION - DESIGN CONSIDERATIONS (VII)

With regard to equipment consisting of radiation

generators...:

Radiographic equipment be provided with devices that automatically terminate the irradiation after a preset time, current-time product or dose

Fluoroscopic equipment be provided with a device that energizes the X Ray tube only when continuously depressed (such as a “dead-man’s switch” and equipped with indicators of the elapsed time and/or entrance dose monitors


OPTIMIZATION - OPERATIONAL CONSIDERATIONS (I)

Registrants and licensees should ensure for

diagnostic radiology that: The medical practitioners who prescribe or conduct

radiological examinations: ensure that the appropriate equipment be used ensure that the exposure of patients be the

minimum necessary to achieve the required diagnostic objective, taking into account norms of acceptable image quality

take into account relevant information from previous examinations in order to avoid unnecessary additional examinations


OPTIMIZATION - OPERATIONAL CONSIDERATIONS (II)

Registrants and licensees shall ensure ... that:

The medical practitioner, the technologist or other imaging staff select the following parameters such that their combination produce the minimum patient exposure consistent with acceptable image quality and the clinical purpose of the examination

the area to be examined, the number and size of views per examination and the fluoroscopy time

the type of image receptor (e.g. high v.s. low speed screens)

the use of anti-scatter grids


OPTIMIZATION - OPERATIONAL CONSIDERATIONS (III)

proper collimation of the primary X Ray

beam to minimize the volume of patient tissue being irradiated and to improve image quality

appropriate values of operational parameters (kVp, mA…)

appropriate image storage techniques in dynamic imaging (number of images per second)

adequate image processing factors (chemicals, developer temperature, …)


OPTIMIZATION - OPERATIONAL CONSIDERATIONS (IV)

Registrants and licensees should ensure …….

that: Portable and mobile radiological equipment be

used only for examinations where it is impractical or not medically acceptable to transfer patients to a stationary radiological installation

Radiological examinations causing exposure of the abdomen or pelvis of women who are pregnant or likely to be pregnant be avoided unless there are strong clinical reasons for such examination

Whenever feasible, shielding of radiosensitive organs such as gonads, lens of the eye and thyroid be provided as appropriate


OPTIMIZATION - CLINICAL DOSIMETRY

Registrants and licensees should ensure that in radiological examinations, representative values for typical sized adult patients of entrance surface dose, dose-area products, dose rates and exposure time, or organ doses be determined and documented


OPTIMIZATION -QUALITY ASSURANCE (I)

Registrants and licensees should establish a

comprehensive QA program with the participation of appropriate qualified experts in radiation physics taking into account the principles established by the WHO and the PAHO


OPTIMIZATION - QUALITY ASSURANCE (II)

Quality Assurance programs should include:› measurements of the physical parameters of

the radiation generators, imaging devices at the time of commissioning and periodically thereafter

› verification of the appropriate physical and clinical factors used in patient diagnosis or treatment

› written records of relevant procedures and results

› verification of the appropriate calibration and conditions of operation of dosimetry and monitoring equipment


GUIDANCE LEVELS

Registrants and licensees should ensure that guidance levels be determined as specified in the Standards, revised as technology improves and used as guidance by medical practitioners, in order that:› corrective action be taken as necessary if doses fall

substantially below the guidance levels and the exposures do not provide useful diagnostic information and do not yield the expected medical benefit to patient

› reviews be considered if doses exceed the guidance levels as an input to ensuring optimized protection of patients and maintaining appropriate levels of good practices

› for diagnostic radiology, including CT and pediatric examinations, the guidance levels be derived from the data from wide scale quality surveys for the most frequent examinations

INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION

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Controlling dose to staff

Wear protective apron & glasses, use shielding, monitor doses – hand dose is often important

Correct positioning to machine to minimise dose

If beam horizontal (or near to) operator should stand on image intensifier side, if possible

If beam vertical (or near to) keep the tube under the patient

Plan view of an interventional operating x-ray unit with isodose curves

In high dose mode – dose rates will be mSv/hr (same numerical values)


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UNSCEAR 2000


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Why increased frequency? 20 years ago, a standard CT of the

thorax took several minutes while today similar information can be accumulated in a single breath hold making it attractive, patient & user friendly

Advances in CT technology have made possible CT fluoroscopy and interventional procedures, in some cases replacing ultrasound guided interventions

Recently CT screening is picking up


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Why increased dose… Unlike radiography where over-exposure

results in blackening of film, better image quality is obtained with higher exposures in CT

There is a tendency to increase the volume covered in a particular examination

Modern helical CT involves volume scanning with no inter-slice gap and with possibility of overlapping scans

Repeat CT examinations


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Why increased dose (cont’d)

Same exposure factors used for children as for adult

Same exposure factors for pelvic (high contrast region) as for abdomen (low contrast region)

INTERNATIONAL COMMISSION ON RADIOLOGICAL

PROTECTION ——————————————————————————————————————

What is the dose from CT? How high?

The effective dose in chest CT is in the order of 8 mSv (around 400 times more than chest radiograph dose) and in some CT examinations like that of pelvic region, it may be around 20 mSv

The absorbed dose to tissues from CT can often approach or exceed the levels known to increase the probability of cancer as shown in epidemiological studies

Effective doses in CT and radiographic examinations

CT examination

Effective dose (mSv)

Radiographic examination

Effective dose (mSv)

Head 2 Skull 0.07

Chest 8 Chest PA 0.02

Abdomen 10-20 Abdomen 1.0

Pelvis 10-20 Pelvis 0.7

Ba swallow 1.5

Ba enema 7


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Organ doses in CT

Breast dose in thorax CT may be as much as 30-50 mGy, even though breasts are not the target of imaging procedure

Eye lens dose in brain CT, thyroid in brain or in thorax CT and gonads in pelvic CT receive high doses


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Tissues in the field although they are not the area of interest for the procedure

Lens of the eye Breast tissue

Typical doses in mGy during CT in adults (Shrimpton et al. 1991)

Examination Eyes Thyroid Breast Uterus Ovaries Testes

Head 50 1.9 0.03 * * *

Cervical spine 0.62 44 0.09 * * *

Thoracic spine 0.04 0.46 28 0.02 0.02 *

Chest 0.14 2.3 21 0.06 0.08 *

Abdomen * 0.05 0.72 8.0 8.0 0.7

L. spine * 0.01 0.13 2.4 2.7 0.06

Pelvis * * 0.03 26 23 1.7

The symbol * indicates that dose is < 0.005 mGy


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Does spiral CT give more or less radiation dose?

It depends upon the choice of factors

Even though it is possible to perform a spiral CT with lower radiation dose than slice-by-slice CT, in practice the patient gets higher dose due to the factors chosen (scan volume, mAs, pitch, slice width


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Does multi-slice CT impart more or less radiation dose?

An increase by 10-30% may occur with multi-slice detector array


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Some observations

Most doctors including many radiologists have a feeling that modern CT scanners which are very fast give lesser radiation dose

Unfortunately ‘time’ and ‘radiation dose’ are not proportional in such a situation

Over the years the x-ray tubes are becoming more and more powerful such that they can give high bursts of x-rays which can give satisfactory image in shorter exposure time

INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION ——————————————————————————————————————

What can be done to manage patient dose in CT?


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What can operators do…?

Limit the scanned volume Reduce mAs values Use automatic exposure control by

adapting the scanning parameters to the patient cross section. 10-50% reduction in dose documented, without any loss of image quality


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What can operators do (cont’d)

Use of spiral CT with pitch factor>1 and calculation of overlapping images instead of acquiring overlapping single scans

Shielding of superficial organs such as thyroid, breast, eye lens and gonads particularly in children and young adults. This results in 30-60% dose reduction to the organ


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What can operators do (cont’d)

Separate factors for children. Can reduce dose by a factor of 5 or more

Use of partial rotation e.g. 270 degree in Head CT (refer figure on next slide)

Adequate selection of image reconstruction parameters

Use of z-filtering with multi-slice CT systems

Record of dose, exposure factors


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Actions for manufacturers

Introduce automatic exposure control Be conscious of high doses in CT Include safety features to avoid

unnecessary dose Display of dose Convenience in using low dose protocols Draw attention of users to selecting

separate protocols for paediatric patients


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Actions for physician & radiologist…

Justification: Ensure that patients are not irradiated unjustifiably

Request for CT examination should be generated only by properly qualified medical or dental practitioners depending upon national educational and qualification system. The physician is responsible for weighing the benefits against risks

Clinical guidelines advising which examinations are appropriate and acceptable should be available to clinicians and radiologists


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Actions for physician & radiologist (cont’d)

Consider whether the required information be obtained by MRI, ultrasonography

Consider value of contrast medium enhancement prior to commencing examination

CT scanning in pregnancy may not be contraindicated, particularly in emergency situations, although examinations of the abdomen or pelvis should be carefully justified


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CT examination should not be repeated without clinical justification and should be limited to the area of interest

Clinician has the responsibility to communicate to the radiologist about previous CT examination of the patient

CT examination for research purpose that do not have clinical justification (immediate benefit to the person undergoing the examination) should be subject to critical evaluation by an ethics committee


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CT examination of chest in young girls and young females needs to be justified in view of high breast dose

Once the examination has been justified, radiologist has the primary responsibility for ensuring that the examination is carried out with good technique

LD 50

LD 50/60

THE AMOUNT OF RADIATIONTHAT WILL CAUSE 50% OF EXPOSED INDIVIDUALS TO DIE WITHIN 60 DAYS

BIOLOGIC ASPECTS OF RADIATIONDose response curves (Sherer)

Line 1

No level of radiation can be considered safe.

Response to exposure is directly proportional

Line 2

Threshold is assumed, response expected at lower doses

Response to exposure is directly proportional

Cataractogenesis

BIOLOGIC ASPECTS OF RADIATION

Dose response curves (Sherer)

Line 3

Non linear (sigmoid or hypothetical sigmoid) dose response

DIAGRAM B

Non linear, threshold dose response used in radiation therapy

Radiosensitivitybased on Wt factors

What is more radiosensitive? CNS or GI? Rectum or Small bowel? Erythoblasts or Myelocytes? red bone marrow or gonads? Adult or elderly? Lung or thyroid?

Spontaneous abortions during first 2 weeks of pregnancy-- 25 RAD or higher

2nd week to 10th week – major organogenesis –IF radiation is high enough can cause congenital abnormalities

Principle response after that may be malignant disease in childhood

PREVENTING ACCIDENTAL IRRADITATION TO PATIENT

FIRST TWO MONTHS, CRITICAL 10 DAY RULE ELECTIVE BOOKING QUESTIONAIRE POSTING

IF A PREGNANT PATIENT MUST BE X-RAYED

TIGHT COLLIMATION HIGH KVP SHIELDING REDUCED # OF IMAGES MAKE SURE TO CHECK WITH YOUR

SUPERVISOR AND BE AWARE OF THE SITE’S PROTOCOL

MINIMIZING PATIENT EXPOSUER

SHIELDING› Gonadal shielding females reduces gonad dose by

50%› Gonadal shielding males reduces gonad dose by

95%› Flat, shadow shields

COLLIMATION› DID YOU KNOW THAT THERE ARE A HIGHER SET

OF LEAD SHUTTERS PLACED NEAR THE X-RAY TUBE WINDOW TO ABSORB OFF-FOCUS RADIATION?

FILTRATION› INCREASED FILTRATION (HVL)

INCREASES THE AVERAGE BEAM ENERGY

› No filtration on a 70 kVp tube (0-70) would produce an average energy of 35 kVp

› However, if you filter out the lower energies (30-70 kVp) is 50 kVp

› Inherent› Added› _________is required for machines

operating at 70 kVp

PERSONNEL PROTECTIONLet’s keep safe!

THE ENVIRONMENT

CONTROLLED AREA

OCCUPANCY FACTOR

UNCONTROLLED AREA

USE FACTOR

WORKLOAD

Badged personnel

Who,what is where

Everyone else!

% of time primary beam is directed at a particular wall # of x-ray exams per week

Primary barrier 7 feet, 1/16 inch of lead

Secondary barrier Extend to ceiling 1/32 inch of lead

Which of these regulations are accurate?

DL for eye is 50 mSv? Cumulative whole body is 10mSv x age? Leakage radiation – 100 mR/hr at 2 meters? Lead aprons at 0 .25 mm pB equivalent? ESE in 10R/min in fluoro? Exposure cord on portable must be 1 meter long? Pregnant radiographer DL for fetus is 500 mrem

for period of pregnancy? The public exposure DL is 100 mrem per year? Bucky slot cover and protective curtain,

minimum of 0.5 pB equivalent?

INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION ——————————————————————————————————————

Pregnancy and Medical Radiation


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Contents

Introduction Fetal radiation risks Informed consent, notices, pregnancy

determination Fetal doses from procedures Pregnant workers Research involving radiation during

pregnancy Issues regarding termination of pregnancy


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Introduction

Thousands of pregnant women are exposed to ionising radiation each year

Lack of knowledge is responsible for great anxiety and probably unnecessary termination of pregnancies

For most patients, radiation exposure is medically appropriate and the radiation risk to the fetus is minimal

Example: justified use of CT Pregnant female, was in motor vehicle accident

Fetal skull

ribsBlood outside uterus

Fetal dose 20 mGy


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3 minute CT exam and taken to the operating room. She and the child survived

Free blood

Kidney tornoff aorta (no contrast in it) Splenic laceration

Fetal radiation risk There are radiation-related risks

throughout pregnancy that are related to the stage of pregnancy and absorbed dose

Radiation risks are most significant during organogenesis and in the early fetal period, somewhat less in the 2nd trimester, and least in the 3rd trimester

Less Least

Most risk


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Radiation-induced malformations

Malformations have a threshold of 100-200 mGy or higher and are typically associated with central nervous system problems

Fetal doses of 100 mGy are not reached even with 3 pelvic CT scans or 20 conventional diagnostic x-ray examinations

These levels can be reached with fluoroscopically guided interventional procedures of the pelvis and with radiotherapy


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Central nervous system effects

During 8-25 weeks post-conception the CNS is particularly sensitive to radiation

Fetal doses in excess of 100 mGy can result in some reduction of IQ (intelligence quotient)

Fetal doses in the range of 1000 mGy can result in severe mental retardation and microcephaly, particularly during 8-15 weeks and to a lesser extent at 16-25 weeks

Heterotopic gray matter (arrows) near the ventricles in a mentally retarded individual occurring as a result of high dose in-utero radiation exposure

Frequency of microcephaly as a function of dose and gestational age occurring as a result of in-utero exposure in atomic bomb survivors (Miller 1976)

Dose (cGy)


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Leukaemia and cancer…

Radiation has been shown to increase the risk for leukaemia and many types of cancer in adults and children

Throughout most of pregnancy, the embryo/fetus is assumed to be at about the same risk for carcinogenic effects as children


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Leukaemia and cancer (cont’d)

The relative risk may be as high as 1.4 (40% increase over normal incidence) due to a fetal dose of 10 mGy

For an individual exposed in utero to 10 mGy, the absolute risk of cancer at ages 0-15 is about 1 excess cancer death per 1,700

Probability of bearing healthy children as a function of radiation dose

Dose to conceptus (mGy) above

natural background

Probability of no malformation

Probability of no cancer (0-19 years)

0 97 99.7

1 97 99.7

5 97 99.7

10 97 99.6

50 97 99.4

100 97 99.1

>100 Possible, see text Higher


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Pre-conception irradiation Pre-conception irradiation of either

parent’s gonads has not been shown to result in increased risk of cancer or malformations in children

This statement is from comprehensive studies of atomic bomb survivors as well as studies of patients who had been treated with radiotherapy when they were children


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Higher dose procedures

Radiation therapy and interventional fluoroscopically-guided procedures may give fetal doses in the range of 10-100 mGy or more depending on the specifics of the procedure

After such higher dose medical procedures have been performed on pregnant patients, fetal dose and potential fetal risk should be estimated by a knowledgeable person


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Nuclear medicine and pregnant patients…

Most diagnostic procedures are done with short-lived radionuclides (such as technetium-99m) that do not cause large fetal doses

Often, fetal dose can be reduced through maternal hydration and encouraging voiding of urine

Some radionuclides do cross the placenta and can pose fetal risks (such as iodine-131)


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Nuclear medicine and pregnant patient (cont’d)

The fetal thyroid accumulates iodine after about 10 weeks gestational age

High fetal thyroid doses from radioiodine can result in permanent hypothyroidism

If pregnancy is discovered within 12 h of radio-iodine administration, prompt oral administration of stable potassium iodine (60-130 mg) to the mother can reduce fetal thyroid dose. This may need to be repeated several times


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Research on pregnant patients

Research involving radiation exposure of pregnant patients should be discouraged


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Termination of pregnancy…

High fetal doses (100-1000 mGy) during late pregnancy are not likely to result in malformations or birth defects since all the organs have been formed

A fetal dose of 100 mGy has a small individual risk of radiation-induced cancer. There is over a 99% chance that the exposed fetus will NOT develop childhood cancer or leukaemia


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Termination of pregnancy (cont’d)

Termination of pregnancy at fetal doses of less than 100 mGy is NOT justified based upon radiation risk

At fetal doses in excess of 500 mGy, there can be significant fetal damage, the magnitude and type of which is a function of dose and stage of pregnancy

At fetal doses between 100 and 500 mGy, decisions should be based upon individual circumstances


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Risks in a pregnant population not exposed to radiation

Risks: Spontaneous abortion > 15% Incidence of genetic abnormalities 4-

10% Intrauterine growth retardation

4% Incidence of major malformation 2-4%

THANK YOU FOR YOUR ATTENTION

jalal jalal shokouhi – md president of iranian society of radiology president of cooperation of...

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