Radiation Protection in Radiotherapy

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Radiation Protection inRadiotherapy
IAEA Training Material on Radiation Protection in
Radiotherapy

• Part 16
• Discharge of Patients

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Discharge of patients

• From a radiation safety perspective an issue...
• If patients are discharged with radioactive
  sources remaining in the patient after a
  temporary implant - this is a severe accident
• If a permanent radioactive implants are in place
  - others need to know about it
• If the patient has been treated with unsealed
  radioactive isotopes (e.g. 131-I, 89-Sr) - NOT
  subject of this course but covered in the
  companion course on nuclear medicine

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Advice from BSS appendix II.28.

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

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Objectives

• To appreciate the need for checks of patients
  before discharge after radioactive implants
• To understand the need to impose limit values for
  the discharge of patient
• To be familiar with the conditions for discharge
  of patients with radioactive implants
• To be able to provide patients, clinicians and
  others with advice regarding the radiation safety
  of the implant.

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Content

• 1. Monitoring of patients after temporary
  implants
• 2. Discharge rules for patients with permanent
  implants
• 3. Information for persons in contact with
  patients who are discharged with permanent
  implants

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1. Monitoring of patients after temporary implants

• If the implant is temporary, one MUST ensure that
  all sources are removed from the patient prior to
  discharge
• This applies to all isotopes and all types of
  implants including HDR and LDR remote
  afterloading
• All brachytherapy patients should be monitored
  before discharge

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Measurement objective

• Dose rate at 1m distance from the patient

1m
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Potential for severe accidents

• An example due to equipment design
• Sources were dislodged from the drive mechanism
  of an HDR remote afterloading machine and
  remained in the patient she died from radiation
• There were many contributing factors, such as
• Equipment seemed not sufficiently tested
• Conflicting signals of indicator for source
  position
• History of malfunction of a detector
• However, in any case the accident could have been
  prevented if appropriate patient monitoring would
  have been in place

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What needs to be established

• Appropriate procedures in writing
• An appropriately trained medical physicist and/or
  RSO must be involved in the treatment
• A monitor at the door of brachytherapy treatment
  rooms in the ward should be available
• A portable radiation monitor available for check
  of the patient prior to discharge

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Appropriate monitoring

• Requires trained personal
• Knowledge of the sources used
• Knowledge of the implant type

Radioactive source
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Brachytherapy with sealed sources

• Area monitor helps to monitor presence of
  radioactive sources
• Typically there is no hazard from contamination
  of linen (however, for seed implants watch for
  lost seeds)

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2. Permanent radioactive implants

• Short half life 198-Au seeds
• Most common 125-I seed for prostate implants
• Increasingly popular 103-Pd (palladium) seeds
  for prostate implants
• (Not considered here radioactive stents for
  prevention of restenosis in blood vessels
  (typically 32-P))

Mentor
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Characteristics of the isotopes
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Risks

• Dislocation of sources
• Irradiation of other persons in contact with the
  patient
• Irradiation of persons in case of a medical
  emergency involving the patient
• Irradiation of persons after the patients death

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IAEA BSS (1996) App. II.28

• In order to restrict the exposure of any member
  of the household of a patient who has undergone a
  therapeutic procedure with sealed or unsealed
  radionuclides and members of the general public,
  such a patient shall not be discharged from
  hospital before the activity of the radioactive
  substances in the body falls below the level
  specified in Schedule III.

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IAEA BSS (1996) App. II.28

• BSS Schedule III, Table III-VI Guidance level
  only given for 131-I Maximum activity for
  discharge 1100MBq
• Other isotopes not mentioned
• Legal limit values are stillapplicable

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Legal limit values

• May vary from state to state
• May not be available for the isotope of interest
• However, limit values should be established by
  each facility using professional judgement if no
  regulatory guidance is available

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Example for limit values in Australia
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Discharge rules

• In addition to the limit values for activity
  within the patient other discharge rules may be
  established. Examples are
• Maximum dose rate at different distances of the
  patient
• Likelihood of dislocation of sources
• Consideration of the performance and mental
  status of the patient

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A set of typical discharge rules
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3. Advice to patients

• IAEA BSS (1996) App. II.28
• Written instructions to the patient concerning
  contact with other persons and relevant
  precautions for radiation protection shall be
  provided as necessary.

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Advice to patients

• Must be in writing
• Easy to understand
• May require translation in other languages
• Should be discussed with the patient
• Should contain contact details for clinical and
  radiation protection staff

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Advice on the implant

• May be also provided to relatives and carers
• May be also provided to referring clinician
• Information should be carried by the patient at
  all times

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Advice to patients

• Describe the implant purpose
• Advice on precautions
• e.g. after 125-I seed implant in the prostate
  urinate through a strainer for a couple of days
  to catch all dislocated sources
• Any restrictions for contact
• e.g. go not stay in the vicinity of pregnant
  women for an extended period of time (best
  specify the time)

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Advice to others who may be in contact with the
patient

• Relatives
• Friends
• Carers
• Referring clinicians

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Also consider

• What happens if the patient requires emergency
  treatment?
• Surgery?
• What happens if the patient dies?
• Autopsies?
• Cremation?

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Also consider

• What happens if the patient requires emergency
  treatment?
• Surgery?
• What happens if the patient dies?
• Autopsies?
• Cremation?

In practice this depends on many factors - it is
best to involve the responsible medical physicist
or RSO in the procedure for advice
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Emergency surgery, autopsies, cremation

• Must involve a radiation expert
• Therefore it is essential that
• the patient can be identified as having a
  radioactive implant
• it is possible for others to contact someone who
  knows the radiation details of the implant

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Identification of patient who have a permanent
implant

• Patient and relatives must know about it
• Patient should carry relevant information
  (implant type, isotope, activity, date of
  implant, contact details) with him/her at all
  times
• wristband
• card in wallet

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Summary

• It is essential to monitor patients prior to
  discharge after they had received a temporary
  brachytherapy implant
• There are recommended limit values for the
  implanted activity above which patients should
  not be discharged from hospital.
• Written discharge rules should be established for
  patients with permanent implants which include
  limit values for activities in the patient
• Written advice must be provided to patients with
  permanent implants

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Where to Get More Information

• Parts 6 and 11
• References NRCP 37

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Any questions?
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Question

• What information would you look for in an
  information sheet handed out to a patient after a
  radioactive implant using 198-Au seeds of a half
  life of 2.7 days?

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Information required

• Description of the implant including isotope,
  half life and estimated activity
• Treating clinician and/or other persons who could
  provide more details on the implant
• Contact in case of emergency
• Advice on appropriate precautions e.g. Do avoid
  contact with pregnant women and children for
  days
• Advice on appropriate actions if a source becomes
  dislodged
• A note to make sure other clinicians or health
  professionals are informed about the nature of
  the implant if they are in contact with the
  patient within the next days