VIII.2. Medical Exposures in Nuclear Medicine. 1. Justification Postgraduate Educational Course in...

VIII.2. VIII.2. Medical Exposures in Medical Exposures in Nuclear Medicine.Nuclear Medicine.

1. Justification1. Justification

Postgraduate Educational Course in Radiation Protection and the Safety of Radiation Sources

VIII.2.1. Justification 2

SystemSystem of radiological protection of radiological protection for medical exposurefor medical exposure


SystemSystem of radiological protection of radiological protection for medical exposurefor medical exposure The system of radiological protection for The system of radiological protection for

medical exposure has basically to do with the medical exposure has basically to do with the general ethical principles of the health care general ethical principles of the health care systemsystem

Ethics is the science of morality; the principles of proper professional conduct concerning the rights and duties of the health care professional, his patients, and his colleagues.*

*Webster’s New World, Medical Dictionary


Principles Commonly Addressed Principles Commonly Addressed in any Ethical Theoryin any Ethical Theory

AUTONOMYAUTONOMYBENEFICIENCEBENEFICIENCECONFIDENTIALITYCONFIDENTIALITYJUSTICEJUSTICETRUTH TELLINGTRUTH TELLINGINFORMED CONSENTINFORMED CONSENT



AUTONOMY:AUTONOMY: The right of the individual patient to make The right of the individual patient to make

decisions regarding personal medical caredecisions regarding personal medical care The patient is to be given adequate The patient is to be given adequate

information about the alternatives so an information about the alternatives so an intelligent decision can be madeintelligent decision can be made

The health care worker is to respect the The health care worker is to respect the decision of the patient.decision of the patient.



BENEFICIENCEBENEFICIENCE

The duty of the health care worker to The duty of the health care worker to perform those acts or administer care perform those acts or administer care that will be of benefit to the patientthat will be of benefit to the patient

ALARAALARA Responsibility of the staff to monitor the Responsibility of the staff to monitor the

patient.patient.



CONFIDENTIALITYCONFIDENTIALITY

The legal right of privacyThe legal right of privacy

All patient records are confidential All patient records are confidential materialmaterial

The “need to know”The “need to know”



JUSTICEJUSTICE

All people are created equal and, All people are created equal and, therefore, should be treated as equalstherefore, should be treated as equals

The right to receive medical careThe right to receive medical care

Treat patients with the same level of Treat patients with the same level of courtesy and respectcourtesy and respect



TRUTH TELLINGTRUTH TELLING The patient’s right to a truthful diagnosis The patient’s right to a truthful diagnosis

and prognosisand prognosis It is the responsibility of the physician, not It is the responsibility of the physician, not

the health care worker, to discuss the the health care worker, to discuss the patient's diagnosis and prognosis with the patient's diagnosis and prognosis with the patientpatient



INFORMED CONSENTINFORMED CONSENT The patient The patient mustmust have adequate have adequate

information about the procedure in order to information about the procedure in order to be able to make an informed decisionbe able to make an informed decision

Truth telling must be practiced in the Truth telling must be practiced in the discussion of procedures with the patientdiscussion of procedures with the patient

The patient must be allowed autonomyThe patient must be allowed autonomy


Justification of Medical ExposuresJustification of Medical Exposures

BSS, appendix II: “Medical exposures BSS, appendix II: “Medical exposures should be justified by weighing the should be justified by weighing the diagnostic or therapeutic benefits they diagnostic or therapeutic benefits they produce against the radiation detriment produce against the radiation detriment they might cause, taking into account the they might cause, taking into account the benefits and risks of available alternative benefits and risks of available alternative techniques that do not involve medical techniques that do not involve medical exposure.” exposure.”


JUSTIFICATION OFJUSTIFICATION OFMEDICAL EXPOSUREMEDICAL EXPOSURE

Objective of Medical exposuretreatment/examination Radiation risks


Examination Radiopharmaceutical Effective dose Risk (mSv) (%)

Myocardium Tl-201 chloride 23 0.12Bone Tc-99m MDP 3.6 0.018Thyroid Tc-99m pertechnetate 1.1 0.006Lungs Tc-99m MAA 0.9 0.005Kidney clearance Cr-51 EDTA 0.01 0.00005

RADIATION RISKS IN RADIATION RISKS IN NUCLEAR MEDICINENUCLEAR MEDICINEEXAMINATIONSEXAMINATIONS


0 10 20 30 40 50 60 70 80

(age at exposure)

20

15

10

5

0

Male

Female

Risk of stochastic effects(%/ Sv)

Embryo and fetus


Absorbed dose to the Absorbed dose to the fetusfetus

ExaminationExamination Activity Dose to fetus Activity Dose to fetus

(MBq) (mSv)(MBq) (mSv)Bone (Tc99m)Bone (Tc99m) 600 4 600 4

Brain (CBF)Brain (CBF) 500 4 500 4

Lung (Tc99m-MAA)Lung (Tc99m-MAA) 160 0.4 160 0.4

Kidneys (MAG3)Kidneys (MAG3) 100 2 100 2

Tumour or abscess (Ga-67 citrate)Tumour or abscess (Ga-67 citrate) 300 28 300 28

Heart (Tc99m-MIBI)Heart (Tc99m-MIBI) 300 5 300 5

Heart (Tl-201)Heart (Tl-201) 100 10 100 10

Thyroid (Tc99m)Thyroid (Tc99m) 100 1 100 1

Thyroid (I-131)Thyroid (I-131) 100 7 100 7

Kidney clearance (Cr-51-EDTA)Kidney clearance (Cr-51-EDTA) 4 0.02 4 0.02

(Data from Russell, Stabin et al Radiation dose to the embryo/fetus from radiopharmaceuticals Draft, 1997


Absorbed dose to the Absorbed dose to the fetusfetus

(Data from Russell, Stabin et al Radiation dose to the embryo/fetus from radiopharmaceuticals Draft, 1997

0,0

0,1

0,2

0,3

Early 3 months 6 months 9 months

Pregnancy month

mG

y/M

Bq

I-131 iodide

Tc-99m-MAG3


0 10 20 30 40 50 60 70 80

(age at exposure)

20

15

10

5

0

Male

Female

Risk of stochastic effects(%/ Sv)

The higher risk for young people as well as for the fetus must be considered in the justification ofan examination. Special concernshould be given to:•Children•Pregnant women


The justification of a practiceThe justification of a practice The decision to adopt or continue any human activity The decision to adopt or continue any human activity

involves a review of the benefits and disadvantages of involves a review of the benefits and disadvantages of the possible optionsthe possible options

E.g.: choosing between the use of nuclear medicine or E.g.: choosing between the use of nuclear medicine or ultrasound or MRultrasound or MR

Often, the radiation detriment will be only a small part Often, the radiation detriment will be only a small part

of the total detrimentof the total detriment Most of the assessments needed for the justification of Most of the assessments needed for the justification of

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


Three levels of justificationThree levels of justification General level:General level: The use of radiation in The use of radiation in

medicine is accepted as doing more good medicine is accepted as doing more good than harmthan harm

Generic justificationGeneric justification (specific procedure with (specific procedure with a specific objective: bone scan for patients a specific objective: bone scan for patients with ca prostate showing relevant symptoms)with ca prostate showing relevant symptoms)

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


Generic justification (I)Generic justification (I)

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

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

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

The decisions should be reviewed from time to time The decisions should be reviewed from time to time as new information becomes availableas new information becomes available


The The resourcesresources in a country or region in a country or region should should be consideredbe considered (single detectors in renography (single detectors in renography instead of gammacamera for economical instead of gammacamera for economical reasons)reasons)

The The justificationjustification of diagnostic examinations of diagnostic examinations for which the for which the benefitbenefit to the patient is not the to the patient is not the primary objective primary objective needs special considerationneeds special consideration (e.g. examinations for insurance purposes or (e.g. examinations for insurance purposes or medical research)medical research)

Generic justification (II)Generic justification (II)


Justification for an individual Justification for an individual patientpatient To check that the required information is not To check that the required information is not

yet availableyet available Once the procedure is generically justified, no Once the procedure is generically justified, no

additional justification is needed for simple additional justification is needed for simple diagnostic examinations e.g. determination of diagnostic examinations e.g. determination of kidney clearance or other laboratory kidney clearance or other laboratory methods.methods.

For complex procedures and therapy For complex procedures and therapy individual justification by the nuclear medicine individual justification by the nuclear medicine specialist and the referring physician should specialist and the referring physician should be done be done


When radiation is the When radiation is the therapeutic agenttherapeutic agent

If the medical practitioner in If the medical practitioner in consultation with the patient has consultation with the patient has decided that radionuclide therapy is decided that radionuclide therapy is indicated, patient protection is usually a indicated, patient protection is usually a secondary concernsecondary concern


”II.6. 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.”

JUSTIFICATION (BSS)JUSTIFICATION (BSS)


Children Children (BSS II.17)(BSS II.17)

(e) administration of radionuclides to (e) administration of radionuclides to childrenchildren for diagnostic procedures be for diagnostic procedures be carried out only if there is a strong carried out only if there is a strong clinical indication, clinical indication, and the amount of and the amount of activity administered be reduced activity administered be reduced according to body weight, body surface according to body weight, body surface area or other appropriate criteria. area or other appropriate criteria.


BREASTFEEDINGBREASTFEEDING

Breastfeeding a baby should beconsidered in the justification ofa nuclear medicine procedure ofthe mother.Normally, breastfeeding should notexclude the mother from a justifiedexamination. The problem shouldbe solved by restrictions on thecontinuing feeding (optimization)


Nuclear Medicine (BSS II.17)Nuclear Medicine (BSS II.17)

(c) (c) administration of radionuclides for diagnostic administration of radionuclides for diagnostic or radiotherapeutic procedures to women pregnant or or radiotherapeutic procedures to women pregnant or likely to be pregnant be avoided unless there are likely to be pregnant be avoided unless there are strong clinical indications; strong clinical indications;


Therapeutic Procedures (BSS II.18)Therapeutic Procedures (BSS II.18)

(c) (c) administration of radionuclides for administration of radionuclides for therapeutic procedures to women who are therapeutic procedures to women who are pregnant or likely to be pregnant or who are pregnant or likely to be pregnant or who are nursing be avoided unless there are strong nursing be avoided unless there are strong clinical indications; clinical indications;

(d) (d) any therapeutic procedure for pregnant any therapeutic procedure for pregnant women be planned to deliver the minimum women be planned to deliver the minimum dose to any embryo or foetus; and ….dose to any embryo or foetus; and ….


In some circumstances, the unborn child In some circumstances, the unborn child may be at increased risk, which should be may be at increased risk, which should be considered in justification.considered in justification.

Prenatal doses from most properly done Prenatal doses from most properly done diagnosticdiagnostic procedures present procedures present no no measurably measurably increased risk of prenatal death, increased risk of prenatal death, malformation, mental impairment.malformation, mental impairment.

Higher dosesHigher doses such as those from therapeutic such as those from therapeutic procedures procedures can result in significant fetal can result in significant fetal harmharm..

JUSTIFICATION & PREGNANCYJUSTIFICATION & PREGNANCY


Radio-iodine therapyRadio-iodine therapy

As a rule, a pregnant woman should not be treated with a radioactive substance unless the therapy is required to save her life: in that extremely rare event, the potential absorbed dose and risk to the fetus should be estimated and conveyed to the patient and the referring physician. Considerations may include terminating the pregnancy.


Becoming pregnant after irradiationBecoming pregnant after irradiation

• ICRP has recommended that a woman not become pregnant until the potential fetal dose from remaining radionuclides is less than 1 mGy.

• This is not usually a consideration except for

radiopharmaceuticals labelled with 59Fe (for metabolism studies) or 75Se (for adrenal imaging).

• As a result of the long physical half-lives of these radionuclides and their long residence times in the body, it is recommended that pregnancy be avoided for 6 and 12 months respectively.


PREGNANCY AFTER PREGNANCY AFTER THERAPYTHERAPY

Radiopharmaceutical All activities Avoid pregnancy up to (MBq) (months)

Au-198 colloid 10000 2I-131 iodide (thyroid ca) 5000 4I-131 iodide (thyrotoxicosis) 800 4I-131 MIBG 5000 4P-32 phosphate 200 3Sr-89 chloride 150 24Y-90 colloid (arthritic joints) 400 0Y-90 colloid (malignancy) 4000 1


Research on Pregnant Research on Pregnant PatientsPatients Radiation Radiation

research research involving involving pregnant pregnant patients should patients should be discouragedbe discouraged


Other factors to considerOther factors to consider

Will the patient pose a risk to other persons Will the patient pose a risk to other persons such as members of the family or general such as members of the family or general public?public?

Is the patient scheduled for surgery or similar Is the patient scheduled for surgery or similar intervention?intervention?

Is there a risk that the patient will die within a Is there a risk that the patient will die within a short period of time?short period of time?

Is there an increased risk that the patient Is there an increased risk that the patient requires emergency treatment? requires emergency treatment?


Advise from BSS appendix II.28. Advise from BSS appendix II.28.

““In order to restrict the exposure of any members of In order to restrict the exposure of any members of the household of a patient who has undergone a the household of a patient who has undergone a therapeutic procedure with sealed or unsealed therapeutic procedure with sealed or unsealed radionuclides and members of the public, such a radionuclides and members of the public, such a patient patient shall not be discharged from hospitalshall not be discharged from hospital before before the activity of radioactive substances in the body falls the activity of radioactive substances in the body falls below the level specified in Schedule III, Table III-VI. below the level specified in Schedule III, Table III-VI. Written instructions to the patient concerning contact Written instructions to the patient concerning contact with other persons and relevant precautions for with other persons and relevant precautions for radiation protection shall be provided as necessary”.radiation protection shall be provided as necessary”.


IAEA BSS (1996) App. II.28IAEA BSS (1996) App. II.28 BSS Schedule III, Table III-VI: Guidance level only BSS Schedule III, Table III-VI: Guidance level only

given for 131-I: Maximum activity for discharge given for 131-I: Maximum activity for discharge 1100MBq1100MBq

Other isotopes not mentionedOther isotopes not mentioned Legal limit values are still Legal limit values are still

applicableapplicable


Also consider:Also consider:

What happens if the patient requires What happens if the patient requires emergency treatment?emergency treatment? Surgery?Surgery?

What happens if the patient dies? What happens if the patient dies? Autopsies?Autopsies? Cremation?Cremation?


Other factors to considerOther factors to consider

The other factors discussed should The other factors discussed should generally not impose on the justification generally not impose on the justification of an examination or treatment of the of an examination or treatment of the patient. The radiation protection patient. The radiation protection problems should be solved by problems should be solved by optimization of safety and a well trained optimization of safety and a well trained staff in case of emergencies.staff in case of emergencies.

VIII.2. Medical Exposures in Nuclear Medicine. 1. Justification Postgraduate Educational Course in...

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