Procedures for staff working with patients who have undergone radioactive
diagnostic tests
The
purpose of this section is to enable nursing and other staff at the Liverpool Hospital to
understand and follow safe procedures while working with patients who have nuclear
diagnostic tests.
Important
issues
Research finding
To determine nursing
precautions, a study was carried out by the Nuclear Medicine department on 15 patients who
received a gallium radioisotope injection. This involved measuring the radiation exposure
at distances of 3m, 1m and 0m (skin surface) from the patient and at different time
intervals, following the injection of the gallium radioisotope. We estimate, at 1m
distance away from the patient, the measured dose rate varied between 1.38
µSv/hr and 20 µSv/hr. The measured dose rate was reduced by a factor of 4 at 2m from the patient.
Radiation risks
In
general, risks attributable to radiation are a complex issue. But it should be noted that
a return trans-pacific flight contributes about 8 µSv/hr and natural back ground radiation
per day is reported as 7 µSv. According to ICRP60, the maximum permissible dose to a
member of public is 1mSv per year and to medical personnel is 20 mSv per year averaged over
five years. In general, dealing with patients who have had Nuclear Medicine scans are
generally considered safe, as long as simple precautions are effectively taken. Radiation
exposure to the nursing and other staff can be considerably reduced by:
- Minimise the time
spend with the patient,
- Maximise the distance
from the patient.
This
is consistent with the delivery of good clinical care.
Patients
administered radioactive tests
A
patient, who has been administered a radioactive substance, is temporarily an emitter of
radiation and should be treated as such. The amounts of radioactive material given to the
patient will vary widely. However, it is good practice to apply the same precautions to
all patients irrespective of other factors to avoid confusion. Since the hazard is
confined to the radiation field around the patient, radiation safety can be reduced to two
words: "TIME" and "DISTANCE". When staff are required to
enter the vicinity of the patient for nursing care, it is obvious that the less time spent
in the area, the less the exposure to radiation. However patient care should always be the
first priority. As the radiation intensity falls off rapidly with increasing distance from
the source, the time spent by nursing staff in close proximity to the patient should be
kept to a minimum. If nursing care is required, it is safe to provide this care.
Other risk
factors and precautions
Urine,
perspiration and saliva:
The
urine excretes most of the administered radioisotope as well as perspiration and saliva.
Nursing staff coming into contact with the patient, bed linen, etc. while preparing the
patient, should wear a pathology gown and disposable gloves. If accidents like urination
and vomiting happen, it must be assumed until proven otherwise, that the contamination is
radioactive. During the day the Radiation Safety Officer, or if not available, the Chief
Nuclear Medicine Technologist should be called to assess the situation and
supervise the cleaning up procedures. If nursing staffs are required to help, they should
be gowned and gloved appropriately. All soiled material should be placed in separate
contaminated waste bags and kept in a room until checked by the Radiation Safety Officer.
Organising
combination tests:
In
the case of a patient requiring a combination of gallium scans, bone marrow biopsy and CT
scans, a little forward planning can ensure the correct order of investigations.
The
suggested order of investigation is
(Bone marrow biopsy – CT scans – Gallium scans)
Where ever possible,
invasive procedures such as biopsy should be done prior to the nuclear medicine scans. In
situations where gallium scans have been done prior to CT scan, there has been no known
report that the diagnostic value of the CT scan has been affected by nuclear scan. This is
due to the fact that radioactivity inside the patient has negligible effect on the CT
scanner.
RECOMMENDATION
- Minimise duration of
patient contact at a distance consistent with the delivery of good clinical care
- Undertake invasive
procedures(e.g. bone marrow biopsy) prior to Nuclear medicine scans
- CT should be
performed prior to nuclear scans
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