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Medical exposure in radiology: Medical exposure in radiology: JustificationJustification

Module VIII.2: Justification of medical exposures

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IntroductionIntroduction

• Persons are medically exposed as part of their diagnostic or treatment.

• According to ICRP, BSS and national legislations, two basic principles of radiation protection are to be complied with : justification and optimization

• Justification requires a thorough co-operation between referral practionner and radiologist

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TopicsTopics

1. The framework of Radiation Protection

2. The principle of justification

3. Pregnancy, pediatrics

4. The role of the referral practitioner and the guidelines for imaging

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OverviewOverview

• We will briefly overview the framework of radiation protection in medical exposure and the principle of justification

• This justification can be more complex in case of pregnancy or children’s examinations

• Guidelines for imaging help correct implementation of the justification principle by communication between practitioner and radiological department

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Topic 1: Framework of Topic 1: Framework of radiation protectionradiation protection

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Concepts and aims of radiation Concepts and aims of radiation protectionprotection

• Radiation Protection (RP) is a tool for the management of measures to protect health against the risks (for people and environment) generated by the use of ionizing radiation

• Detriment: The total harm that would eventually be experienced by an exposed group and its descendents as a result of the group's exposure to radiation from a source

• Always consider BENEFITS Vs RISKS

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• According to the BSS, any human activity that introduces additional sources of exposure so as to increase the exposure or the likelihood of exposure of people or the number of people exposed is called practice .

• No practice should be authorized unless it produces sufficient benefit to the exposed individuals or to society to offset the radiation harm that it might cause; that is: unless the practice is justified, taking into account social, economic and other relevant factors

The framework of radiation protection The framework of radiation protection

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Medical exposure

versus

occupational

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Three types of exposureThree types of exposure

• Medical Exposure (principally the exposure of persons as part of their diagnostic or treatment)

• Occupational Exposure (exposure incurred at work, and practically as a result of work)

• Public Exposure (including all other exposures)

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Medical exposureMedical exposure

• Medical Exposure • Exposure of persons as part of their

diagnostic or treatment

• Exposures (other than occupational) incurred knowingly and willingly by individuals such as family and close friends helping either in hospital or at home in the support and comfort of patients

• Exposures incurred by volunteers as part of a program of biomedical research

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Framework of radiological protection Framework of radiological protection for for medicalmedical exposure exposure

• Justification

• Optimization

• The use of doses limits is NOT APPLICABLE !!!

• Dose constraints and guidance (or reference) levels ARE RECOMMENDED

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Guidance levels or constraints ?Guidance levels or constraints ?

Exposure of persons as part of their diagnostic or treatment

Comforters

Volunteers as part of a program of biomedical research

Guidance (or reference) levels

(a special type of constraint)

Constraints

Constraints

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• Dose constraints are not dose limits.

• Dose constraints do not apply to patients

• In general, dose constraints should be established on the basis of the results of optimization

Dose constraints Dose constraints

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Topic 2: JustificationTopic 2: Justification

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Justification of a practiceJustification of a practice

• Justification means that any exposure produces sufficient benefit to offset the radiation harm that it might cause.

• Thus, if the exposure has not any benefit it is not justified.

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The justification of a practiceThe justification of a practice

• The decision to adopt or continue any human activity involves a review of benefits and disadvantages of the possible options

• E.g.: choosing between the use of X Rays or ultrasound

• Often, the radiation detriment will be only a small

part of the total detriment • Most of the assessments needed for the

justification of a practice are made on the basis of experience, professional judgement, and common sense

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The justification: a dynamic processThe justification: a dynamic process

• Recommendations or judgments of a practice will change with time and location• Availability of equipment

• Availability of available manpower

• Technological progress• E.g. Stents by interventional radiology

instead of surgery

• New protocols

• New modalities

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Three levels of justificationThree levels of justification

• General level: The use of radiation in medicine is accepted as doing more good than harm

• Generic level (specific procedure with a specific objective: chest radiographs for patients showing relevant symptoms)

• Third level: the application of the procedure to an individual patient

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Generic justification (I)Generic justification (I)

• It is a matter for national professional bodies, sometimes in conjunction with national regulatory authorities

• The exposures to staff (occupational) and to members of the public should be taken into account

• The possibility of accidental or unintended exposures (potential exposure) should also be considered

• The decisions should be reviewed from time to time as new information or technologies become available

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Generic justification (II)Generic justification (II)

• The resources in a country or region should be considered (fluoroscopy for chest imaging could be the procedure chosen instead of radiography for economical reasons)

• The justification of diagnostic investigations for which the benefit to the patient is not the primary objective needs special consideration (e.g. radiography for insurance purposes)

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• 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.

• If an exposure can not be justified, it should be prohibited.

Generic justification (III)Generic justification (III)

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Justification for an individual patient Justification for an individual patient (third level) (third level) (1)(1)

• Not justified if the required information is already available

• The prescriber and the practitioner, shall seek, where practicable, to obtain previous diagnostic information or medical records relevant to the planned exposure and consider these data to avoid unnecessary exposure.

•If a type of practice involving a medical exposure is not justified in general, a specific individual exposure of this type could be justified in special circumstances, to be evaluated on a case-by-case basis.

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Justification for an individual Justification for an individual patient (third level) patient (third level) (2)(2)

• Once the procedure is generically justified, no additional justification is needed for simple diagnostic investigations

• For complex procedures (such as CT, IR, etc) delivering high doses an individual justification should be taken into account by medical practitioner (radiologist, referral doctor..)

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New and old practicesNew and old practices

• all new types of practices involving medical exposure shall be justified in advance before being generally adopted,

• existing types of practices involving medical exposure may be reviewed or abandoned whenever new, important evidence about their efficacy or consequences is acquired.

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Topic 3: Pregnancy, pediatricsTopic 3: Pregnancy, pediatrics

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PregnancyPregnancy

• Thousands of pregnant women are exposed to ionizing 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 is minimal

• Or outweights other risks

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If pregnancy is established or likely: Review justification Can examination be deferred until after

delivery Does delaying examination involve

greater risk If procedure is to undertaken, the fetal

dose should be kept to the minimum consistent with the diagnostic purpose(s)

Patient definitely or probably pregnantPatient definitely or probably pregnant

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Fetal skull

ribs

Blood outside uterus

Fetal dose 20 mGy

Example of justified use of CT in a pregnant Example of justified use of CT in a pregnant female who was in a motor vehicle accidentfemale who was in a motor vehicle accident

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Free blood

Kidney ripped

off aorta (no contrast in it) Splenic laceration

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

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• Risk factors

• As children are at greater risk of incurring stochastic effects, pediatric examinations should require special consideration in the justification process

• Thus the benefit of some high dose examinations (e.g. computed tomography, IVU, etc.) should be carefully weighed against the increased risk

General recommendations for pediatric General recommendations for pediatric radiologyradiology

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• Some radiological examinations are of questionable value in children (like some follow-up chest radiographs in simple pneumonia, abdominal radiographs in suspected constipation, etc.)

• The repetition of a radiological examination in pediatrics should always be decided by the radiologist.

General recommendations for pediatric General recommendations for pediatric radiologyradiology

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Topic 4: The referral Topic 4: The referral practitioner and the guidelines practitioner and the guidelines

for imagingfor imaging

Based on:European Commission, Radiation Protection 118: Referral guidelines for imaging; ISBN 92-828-9454-1

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The referral practitionerThe referral practitioner

•A useful investigation is one in which the result —positive or negative — will alter management or add confidence to the clinician’s diagnosis.

•A significant number of radiological investigations do not fulfil these aims and may add unnecessarily to patient irradiation

•The referral practitioner plays an important role in the justification of the planned examination

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• The referral practitioner has to provide appropriate clinical information and questions that the imaging investigation should answer.

•Problems for the justification• Over-investigating: Some clinicians tend to rely

on investigations more than others. (Some patients take comfort in being investigated)

•Failing to provide appropriate clinical information and questions that the imaging investigation should answer. May lead to the wrong technique being used

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Referral Guidelines for ImagingReferral Guidelines for Imaging

•Radiation Protection 118 - European Commission’s Experts and the UK Royal College of Radiologists

•A document prepared to help referring clinicians make the best use of a department of clinical radiology. Continued use of recommendations of this kind leads to• a reduction in the number of referrals for

investigation

•a reduction in medical radiation exposure

•AND improvement of medical practice

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Categories Categories

• Indicated.•Shows the investigation(s) most likely to

contribute to clinical diagnosis and management. This may differ from the investigation requested by the clinician: e.g. US rather than venography for deep vein thrombosis.

• Specialised investigation. •These are complex or expensive investigations

which will usually be performed only for doctors who have the relevant clinical expertise to evaluate the clinical findings and act on the imaging results. They usually justify individual discussion with a specialist in radiology or nuclear medicine.

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CategoriesCategories•Not indicated initially.

• Situations where experience shows that the clinical problem usually resolves with time; suggest deferring the study for three to six weeks and only performing it then if symptoms continue. Ex: Shoulder pain

•Not indicated routinely. • Request will only be carried out if a clinician gives cogent

arguments for it. Example: plain radiography in a patient with backache in whom there were clinical findings to suggest something more than a degenerative disease (e.g.? Osteoporotic vertebral fracture).

•Not indicated. • Examinations in this group are those where the supposed

rationale for the investigation is untenable (e.g. intravenous urogram (IVU) for hypertension).

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The referral guidelinesThe referral guidelines

•The referral guidelines of RP-118 may be adopted as models

• But it is recognised that local adaptation may be needed according to varying health care practice and provision.

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SummarySummary

• Exposure of patients as part of their diagnostic or treatment, has to be justified

• Generically or individually

• Special attention for the justification is required for pregnant patients and in pediatrics

• The referral practitioner plays a central role in justification procedure and in dose reduction

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Where to get more informationWhere to get more information

• Rational use of diagnostic imaging in pediatrics. WHO, 1987.

• International Basic Safety Standards for Protection Against Ionizing Radiation and for the Safety of Radiation Sources. 115, Safety Standards. IAEA, February 1996.

• European Commission, Radiation Protection 118: Referral guidelines for imaging; ISBN 92-828-9454-1