1 Introduction 1
2 Survey details 2
3 Data analysis 3
4 Historical trends 4
5 Variation in the types of procedures performed at each nuclear 7
6 Administered activities 9
7 Dose to the population 16
8 Comparison with other developed countries 18
9 Discussion and conclusions 21
A: Covering letter and survey forms sent to the nuclear medicine 26
B: Tabulated dosimetry data for nuclear medicine use in 31
C: Quantification of radiation risk arising from medical exposure
to ionising radiation 38
The National Radiation Laboratory (NRL)a
has surveyed the use of radioactive
materials in medicine in New Zealand each decade since 19661,2,3,4
. The most recent
survey was carried out in 2006 and used data on the diagnostic use of nuclear medicine
collected nationally for the period January-December 2005. This report documents the
findings of the most recent survey.
Any diagnostic procedure involving the use of ionising radiation must be justified and
performed in such a way as to obtain the necessary diagnostic information for the
minimum practicable radiation dose (and hence minimum risk) to the patient, staff and
public. In determining the minimum practicable radiation dose there will always be an
element of uncertainty and judgement. Consequently, the principal aims of the survey
• assess trends in the frequency of different diagnostic nuclear medicine procedures
in comparison with previous national surveys;
• assess the distribution by age group (age 0-4, age 5-9, age 10-14, age 15-19 and
adult) of different nuclear medicine procedures and compare with similar studies
carried out elsewhere;
• determine the annual collective effective dose to the New Zealand population
from nuclear medicine and the relative contributions of the different procedures;
• compare the mean activities of the administered radionuclides for some common
procedures with published reference levels and to allow for peer review;
• compare practices and patient doses in New Zealand with those in other countries.
NRL’s project team for this work comprised Karen Beach, Tony Cotterill, Glenn Stirling
and John Laban.
The NRL under a system of delegated authorities administers the New Zealand radiation protection
legislation. Under the Radiation Protection Act 1965 persons using ionising radiation are required to be
licensed and through a condition of their licence, users of radioactive materials in medical diagnosis must
comply with NRL’s code of safe practice NRL C3 'unsealed radioactive material in medical diagnosis,
therapy and research'. As part of its regulatory function NRL is charged with collecting data on practices
and patient doses.
2 Survey details
The survey was designed to obtain and analyse information provided on:
1 the frequencies and types of procedures being performed;
2 the radiopharmaceuticals being used for each type of procedure;
3 the frequency of administrations and mean activity administered for each of the
age groups - child aged 0-4, child aged 5-9, child aged 10-14, child aged 15-19
4 the methods used by nuclear medicine staff to determine the amount of activity to
5 significant periods of 'down time' at the nuclear medicine centres.
To obtain this information, each of the fourteen nuclear medicine centres in New
Zealand were asked to answer two sets of questions on NRL-supplied forms. The first
set related to such matters as the method used to determine the amount of activity to be
administered. The second set asked for data on the frequency and mean activity
administered for each of the age groups and for specified procedures. The forms were
supplied to each facility both in hard copy and electronic formats.
The list of procedures was taken from the Australian and New Zealand Society of
Nuclear Medicine (ANZSNM)/Australasian Radiation Protection Society (ARPS) Table
of Reference Activities for Nuclear Medicine5
The covering letter and forms sent to each facility are shown in Appendix A.
Respondees were asked, if possible, to complete the forms electronically. This was to
facilitate transfer of the data into an Excel spreadsheet, thereby minimising the
possibility of transcription errors.
3 Data analysis
Each of the responses from the nuclear medicine centres were imported as separate
worksheets in to a single spreadsheet. The supplied information was manipulated and
dosimetric data applied to calculate effective doses (refer to section 7 for a discussion of
this dose quantity). Calculations utilised the most recent data published by the
International Commission on Radiological Protection (ICRP)6,7,8
Data that was entered manually at NRL was re-checked prior to importing it into the
master spreadsheet. All data on the master spreadsheet and the formulae used within it
were independently verified.
A few of the centres were unable to provide detailed paediatric data as it was not easily
accessible retrospectively. In some instances the centres were able to give a detailed
breakdown for a procedure commonly carried out on paediatric patients, namely renal
scans. In cases where detailed paediatric data was not provided it was assumed that all
of the procedures were carried out on adults. This had minimum effect on the overall
collective effective dose as the relative number of procedures treated in this way was
Several of the centres provided data on procedures that were not included on the NRL-
supplied list. This was not surprising as the nuclear medicine field is continually
developing and the ANZSNM/ARPS Table of Reference Activities5
about five years prior to the survey. The additional procedures were reconciled and
added to the master list.
A wide range of administered activities was reported for lung ventilation procedures
using either Tc-99m DTPA or Tc-99m Technegas (eg, for Technegas this was
10-1500 MBq). The reason for these differences is that some centres reported an
estimate of the activity absorbed by the patient whereas others provided the activity
loaded into the nebuliser. For establishments providing data in terms of activity
dispensed, the activity taken up by the patient was estimated to be 10% of the dispensed
. In some cases this may be an overestimate.
Some centres reported administering I-131 activities in excess of 1 GBq for some
procedures. It was identified that these scans were performed following a therapeutic
administration and therefore the data was discounted from this study.
The analysed data is presented either in tabular and/or graphic format in the following
4 Historical trends
In this section the frequency of use of nuclear medicine investigations are summarised
and compared against equivalent data from earlier surveys. The historical data used for
comparisons in this section was obtained from NRL survey report4
for 1993 apart from
the 2001 data which was obtained from the New Zealand branch of the ANZSNM10
Table 1 shows the number of total administrations and administrations per 1000 members
of the New Zealand population (1000 population) for the years that have been surveyed.
Table 1: Total annual administrations and administrations per 1000 population
1966 1973 1983 1993 2000* 2005
Population (millions) 2.68 2.97 3.23 3.48 3.86 4.10
Number of diagnostic
6164 17720 24113 29056 29600 26895
Number per 1000 2.3 6.0 7.5 8.4 7.7 6.6
* data obtained as part of this study is incomplete. Missing data has been estimated based on the
2005 survey data
It can be seen that the number of administrations per 1000 population in 2005 was
lower than in previous surveys (excluding 1966) and has remained relatively static over
the last 30 years. Table 2 shows the total annual numbers of the main types of
procedures performed for the years that have been surveyed.
Table 2: Total annual numbers of the main types of procedures performed
Number of procedures performed
1973 1983 1993 2000* 2005
Bone scans 1032 7126 14260 13973 13945
Cardiac (cardiovascular) 206 847 1653 593
Cardiac (myocardium) - 178 459
Renal 512 1787 2959 2860 2558
Lung 1373 2284 2617 2793 2063
Liver/spleen 2932 4407 298 71 82
GB + biliary - 51 277 259 341
Brain 4491 3762 878 564 57
Thyroid 5352 3031 2428 1857 1675
Gastro-intestinal - - - 497 229
Sentinel lymph node biopsy 53** 626
* data obtained as part of this study is incomplete; the number of procedures may be 10% higher.
** this value may include a small number of lymphangiograms.
Bone scans continue to be the most common nuclear medicine procedure, representing
over 50% of the total. In fact, New Zealand has the highest contribution of bone scans
to the total number of procedures of all developed countries listed in the 2000 United
Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR)
. However, the number of bone scans in New Zealand amounts to about 3 per
1000 population which is consistent with data for other developed countries.
The frequency of brain scans and liver tests have continued to fall as other techniques,
namely computerised tomography (CT), magnetic resonance imaging (MRI) and
ultrasound scanning, have taken over. The numbers of cardiovascular scans have also
reduced significantly over the past twelve years for similar reasons. In contrast, the
numbers of myocardial perfusion studies have increased almost ten-fold since 1993, and
now amounts to about 15% of the total number of procedures performed.
The use of nanocolloid labelled Tc-99m for sentinel lymph node biopsy has not been
reported in previous NRL studies. This is a relatively new procedure which is already
being performed at a number of clinical sites. It is expected that the number of these
procedures will increase significantly over the next few years.
The use of positron emitting radionuclides for diagnostic procedures commenced in
early 2006 at two of the nuclear medicine centres. It is envisaged that several other
centres will be able to provide this service within the next five to ten years. Data on this
type of procedure will therefore be collected as part of the next NRL survey.
Paediatric data was collected as part of the 1993 study and it has therefore been possible
to compare the numbers of the main types of procedures performed with data from the
2005 study. This is given in Table 3 below.
From this data it can be seen that the number of paediatric bone scans has reduced
significantly since 1993, particularly in the 10-14 and 15-19 age groups, whereas the
number of renal studies has remained constant. There has also been a reduction in the
number of other procedures carried out such as cardiac studies, lung studies and thyroid
Table 3: Total annual numbers of paediatric procedures performed
Number of procedures performed
0-4 years 5-9 years 10-14 years 15-19 years
1993 2005 1993 2005 1993 2005 1993 2005
Bone 146 190 256 202 554 285 694 425
Cardiac 0 1 0 3 12 2 18 4
Lung 0 11 6 15 12 15 73 6
Renal 560 600 274 355 91 155 97 98
Thyroid 12 31 6 0 24 7 61 26
For comparative purposes the paediatric data has been normalised with the population
data for the relevant age group and is shown graphically for the two main types of
procedure, bone scans and renal studies in Figure 1.
About 50% of all renal studies are carried out on patients aged 0-15 years which is
significantly higher than in other countries11
. This is believed to be because renal
studies on adults have recently tended towards the use of CT and ultrasound techniques
rather than the use of nuclear medicine. In contrast, when the relatively high prevalence
of urinary infections is considered alongside the usefulness of nuclear medicine in the
diagnosis of urological problems in paediatric patients, it is not surprising that there are
relatively high numbers of renal scans in the paediatric age groups.
Figure 1: Number of paediatric procedures shown by age group
0-4 5-9 10-14 15-19
5 Variation in the types of
procedures performed at each
nuclear medicine centre
In this section the relative numbers of the main types of procedures carried out at the
fourteen nuclear medicine centres have been compared. The data has been normalised
using the total number of procedures performed at each centre and is shown in Figure 2.
Figure 2: Percentage of total procedures for each centre
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Nuclear Medicine Centre
Bone Scan Cardiac (cardiovascular) Cardiac (Myocardium) Renal
Lung Liver/spleen GB + biliary Brain
Thyroid GI Tract Other
It can be seen from Figure 2 that the most frequent procedure carried out at each of the
centres is a bone scan. However, the percentage contribution to the total number of
procedures ranges from 40% to more than 80%.
The number of cardiac studies carried out by each of the centres varies significantly,
with one centre not carrying out any cardiac studies and another centre having cardiac
studies contributing more than 40% to its total workload. This variation in different
types of studies is consistent with that previously reported10
The variation between centres is due to a number of factors. These include the
functional capability (some types of procedure require more specialist knowledge and
equipment) and the preferences of referring specialists, some of whom use other
diagnostic images procedures, eg, ultrasound or CT scans.
6 Administered activities
Reference levels for administered activities of radiopharmaceuticals have been
published in the International Atomic Energy Agency’s (IAEA) Basic Safety Standards
. The reference activity is defined as the activity that should normally be
administered to a 70 kg adult. Also, NRL’s Code of Safe Practice NRL C313
table of reference activities. In 1998 a Working Party was jointly established by the
ANZSNM and the ARPS to develop diagnostic Reference Levels for Nuclear Medicine
in Australia and New Zealand5
. In addition to adult reference activities,
ANZSNM/ARPS has also produced reference levels for paediatric procedures14
Each of the nuclear medicine centres indicated that they use reference levels based on a
70 kg patient. For large or small patients the activity administered may be increased or
decreased. However, the basis of these reference levels varies from centre to centre. In
general they are based on the previously mentioned guidelines, used in addition to
literature supplied by the pharmaceutical companies and information published
elsewhere, eg, the UK Administration of Radioactive Substances Advisory Committee
Table 4 provides a comparison of the mean and the range of activities administered to
patients aged 20 and over (ie, adults) during 2005, with the BSS, NRL C3 and
ANZSNM/ARPS reference levels. Overall the mean activity administered is consistent
with the reference levels. However, the range of activities administered for some
procedures is significant. For illustrative purposes some of this data is shown as a series
of histograms in Figure 3 for several common procedures.
Generally, the maximum and minimum administrations are appreciably different from
the mean. This range of administrations is attributable to a number of factors. Different
centres base their reference levels on different sets of published data and there is likely
to be variation in the techniques used and in the technical specification of the detectors,
eg, counting efficiency. The administered activity also varies by at least 10-20% for
obese or petite patients.
The mean activity administered has been compared with the results from the 1993
survey. These are summarised in Table 5. Generally the activities are similar,
indicating that procedures have generally become standardised in line with the reference
From Table 4 it can be seen that there is a wide range of administered activities for GFR
procedures using Tc-99m. This is because two different types of procedure have
actually been reported – the use of DTPA for a renogram which typically requires an
activity of up to about 200 MBq and the use of DTPA for an in vivo GFR measurement
which typically requires an activity of about 10 MBq.
Table 5: Trends in mean administered activity adults
Mean Administered Activity (MBq)Procedure
Bone scan (MDP/HDP) 699 751
Brain (DTPA) 744 740
Brain (HMPAO) 705 661
Cardiac GHPS/first pass 586 670 / 550
GIT blood loss (RBCs) 603 656
GIT gastric emptying (colloids) 34 29
Infection (citrate) 110 155
Liver/spleen (colloid) 198 125
Lung perfusion (MAA) 144 134
Meckel’s diverticulum 307 300
Renal scan (DTPA) 354 320
Renal scan (DMSA) 98 127
Renal scan (MAG3) 228 221
Thyroid (pertechnetate) 190 123
GFR (DTPA) 222 136
GFR (EDTA) 3 4
Red cell volume (RBCs) 2 1
There is a relatively wide range of mean administered activities for the main paediatric
procedures. These are shown in Table 6a. This is to be expected due to the small
number of procedures performed and the relatively wide age and weight range within
each group. The activity to be administered to paediatric patients is generally calculated
individually based on a fraction of the adult activity for each centre, which is
determined by the weight and/or age of the patient. The European Association Nuclear
Medicine (EANM) paediatric task force reference minimum16
and the ANZSNM/ARPS
reference minimum (Amin) and maximum (Amax) activities for administration to
are also shown in Table 6a. In some instances the activity administered to
infants was found to be below the ANZSNM/ARPS reference minimum activity.
The mean effective doses received by paediatric patients have been calculated based on
the mean activities administered given in Table 6a (see Section 7 for the radiation dose
calculation methodology used). These are given in Table 6b. It should be noted that
although the effective dose to paediatric patients is similar to that to adults the overall
risk will be higher due to the application of the age correction re-normalisation factors
for radiation risk17
. These vary from 3.0 at age 1 to 1.5 at age 15 (see Appendix C).
Table 6a: Comparison of mean activities administered for paediatric patients
Mean activity administered (MBq)
(Range shown in brackets)
Radionuclide Pharmaceutical EANM
Age 0-4 years Age 5-9 years Age 10-14 years Age 15-19 years
MDP or HDP
255 (201 -432)
Table 6b: Comparison of mean effective doses received by paediatric patients
Mean radiation dose per procedure (mSv)Procedure
Radionuclide Pharmaceutical Mean adult
(mSv) Age 0-4 years Age 5-9 years Age 10-14 years Age 15-19 years
MDP or HDP
Several different methods have been reported as being used to determine the fraction of
the adult activity to be administered to a paediatric patient. The main ones used are the
EANM paediatric task force protocol16
, the use of a nomogram18
and also direct scaling
as a fraction of the standard adult 70 kg weight. These are compared in Figure 4. From
the graph it can be seen that paediatric administrations could vary by up to 10-100% at
different centres depending on the method used to assess the fraction of the adult
activity. The variation in the fraction administered is highest for infants and reduces as
the patient weight increases. These variations are of significance, particularly when
considered alongside the increased radiation risk factors for paediatric patients.
Figure 4: Fractional activity administered to children
0 10 20 30 40 50 60 7
EANM proportion of standard adult `70 kg' weight
nomogram - bone nomogram - renal DMSA
7 Dose to the population
Any administration of a radiopharmaceutical to a patient delivers a certain radiation
dose to that patient. The magnitude of the radiation dose depends on the radionuclide
used, the pharmaceutical used and the activity administered. For a given
radiopharmaceutical, various organs in a patient’s body will be irradiated in differing
proportions as a result of the biological distribution and kinetics of the particular
pharmaceutical. In order to be able to make meaningful comparisons of radiation dose
between different procedures in which different organs are irradiated, a quantity known
as effective dose has been defined. Effective dose converts a distribution of known
radiation doses to individual organs into an equivalent uniform whole body radiation
dose presenting the same overall risk. In this way, for example, the risk to a patient
undergoing a lung ventilation study can be compared to the risk due to exposure to
x-rays in the course of a CT examination. It should be noted that the risk-based
weighting factors strictly only apply to normal healthy adults, so the extension to
medical patients of all ages has limitations. However, it is generally considered that
effective dose is useful as an index for comparison of risks between different modalities
using ionising radiation, but should be treated with care. The unit of effective dose is
the Sievert (Sv).
Collective effective dose takes account of the group of persons exposed to radiation. It
is obtained by multiplying the number of exposed persons by the mean radiation dose
they received. The unit of collective effective dose is the man Sievert (man Sv). Care
should be taken when using this measure of dose. Collective dose is a quantity designed
for optimisation and is not suitable for use in epidemiologic risk assessment and is
therefore inappropriate to use in risk projections based on epidemiological studies (ie,
the calculation of cancer deaths based on small exposures to large populations is not a
Effective dose data for the range of nuclear medicine procedures currently carried out in
New Zealand have been obtained from ICRP publications6,7,8
. These effective dose data
have been applied to the results of this survey to calculate the effective dose per
administration and the collective effective dose for each of the procedures. The results
are provided in Appendix B for each of the patient age groups.
For non-thyroid studies using pertechnetate, it has been assumed that a thyroid-blocking
agent has not been used.
A summary of the collective effective doses and the mean effective doses per
examination for the main examination types are given in Table 7 below. The total
collective effective dose for all diagnostic procedures carried out during 2005 amounted
to 100 man Sv (see Table 7).
A collective effective dose of 100 man Sv for the population equates to a mean effective
dose of 25 µSv per capita per annum. As a comparison, the effective dose from all
sources of naturally occurring radiation is approximately 1.8 mSv per capita per annum
in New Zealand19
Table 7: Summary of collective effective doses from the main nuclear medicine
procedures and summary of mean effective dose per administration for some
Collective effective doses Effective doses per mean administration (adult)
Main procedure type Collective
Examination Effective dose (mSv)
Bone scan – HDP
Gated cardiac – RBC
Myocardium – MIBI
Renal – DTPA
Renal – DMSA
Lung perfusion – MAA
Lung Ventilation - DTPA
Liver – tin colloid
Brain scan DTPA
Thyroid scan – TcO4
Biliary – IDA
GI bleeding - RBC
In terms of effective dose to the population from all man-made sources, the effective dose
from nuclear medicine represents a relatively small contribution, of the order of about 5%.
The mean effective dose per procedure for adults and paediatric patients is 3.8 mSv and
2.8 mSv respectively.
The calculation of effective dose and the associated risk factors are all based on an
average population. For a given radiation dose, the risk to an individual is higher than
the average if the radiation dose is received in childhood and it is lower than the
average if received in later life17
. Appropriate risk factors to use in the quantification of
radiation risk are given in Appendix C.
For nuclear medicine the major contribution to collective dose is from bone scans, of
which a proportion are carried out on elderly patients, a significant proportion of whom
will have on average reduced life expectancies. Consequently, the overall risk arising
from collective dose will be proportionately lower than would be calculated using the
ICRP nominal risk coefficients20
8 Comparison with other developed
In this section the frequency of nuclear medicine use, and the mean activities for some
common procedures are compared with practices in other developed countries.
Table 8 shows a comparison of New Zealand’s diagnostic nuclear medicine
administrations per 1000 population with some other developed countries. The majority
of the information currently available is taken from the latest UNSCEAR report11
provides data for the period 1991-1996. Several countries have also independently
reported relevant data in the previous five years and this is also provided in Table 8.
Although the data for 2005 is limited, it can be reasonably concluded that the frequency
of diagnostic nuclear medicine administrations in New Zealand is relatively low when
compared with other countries. As Positron Emission Tomography (PET) scans only
generally amount to less than 1% of the total number of procedures in countries that use
PET, this does not account for the relatively low frequency of nuclear medicine
procedures in New Zealand.
Table 8: Comparison of examination (administration) rates with other developed
Examinations per 1000Country
Argentina 11.1 -
Australia 12.0 -
Canada 64.6 -
Czech Republic 28.3 -
Denmark 15.2 -
Germany 34.1 4721
Italy 11.0 -
Japan 11.7 -
Netherlands 11.6 -
New Zealand 8.4 6.6
Romania 3.0 -
Sweden 13.6 11.622
United Kingdom 8.2 10.823
USA 31.5 -
Table 9 shows a comparison of the annual per capita effective dose received by the
population of New Zealand with a number of other developed countries. The majority
of the information currently available is in the latest UNSCEAR report11
Although the data for 2005 is limited, it can be reasonably concluded that the annual per
capita effective dose from diagnostic nuclear medicine administrations in New Zealand
is also relatively low when compared with other countries.
Table 9: Comparison of annual per capita effective dose (µSv) with other
Annual per capita effective dose (µSv)Country
Australia 64 -
Canada 160 -
Germany 100 12021
Netherlands 67 -
New Zealand 26 25
Romania 49 -
United Kingdom 36 3023
USA 140 -
Table 10 provides a comparison of the mean activities administered in New Zealand for
some common examinations with those from other developed countries. It can be seen
that the mean activity administered for these procedures is consistent with those
reported by other countries.
There is limited data available from other developed countries with respect to the use of
nuclear medicine specifically on paediatric patients. The available data is given in
Table 11. For comparative purposes the New Zealand paediatric data covers the age
range 0-14 years, rather than age 0-20 years as reported earlier in this report. The
number of paediatric administrations expressed as a percentage of the total number of
administrations is comparable with those reported by other countries. Similarly, the
mean effective dose per administration is of a comparable magnitude. Although the
main types of procedures performed by each country are the same, there is a noticeable
variation in the percentage numbers of these procedures performed. Renal studies,
however, are the most common type of paediatric procedure for all of the countries
Table 10: Comparison of mean radionuclide activities (in MBq) administered to adult patients during 2005 for some common
examinations with mean activities administered in other developed countries (data taken from UNSCEAR report11
Bone Brain Cardiovascular Liver/spleen Lung RenalCountry
phosphates HMPAO MIBI colloid MAA DMSA DTPA MAG3
Canada 925 740 600 111 185 - 400 -
Czech Republic 730 740 680 148 188 188 250 -
Denmark 637 667 615 83 112 - 165 92
616 584 949 114 142 57 53 81
Italy 630 720 600 150 150 148 148 -
Japan - 787 - - - 197 377 -
Netherlands - 500 650 80 100 - - 80
New Zealand 751 661 810 125 134 127 320 221
Romania - - - 140 125 - 300 -
528 940 629 163 121 45 107 96
598 - 414 98 89 77 203 89
Table 11: Comparison of paediatric nuclear medicine with other countries
Percentage of procedures on paediatric
patients compared to total population
Breakdown of main types of procedure
(expressed as a percentage of the total)
by number of
by collective effective
(mSv) Bone Renal Thyroid
Czech Republic (age <18 years)24
7.5% 5.1% 2.9 17% 64% 3%
Germany (age <15 years) 21
3.3% 2.1% 1.9 20% 60% 4%
Iran (age <15 years)25
5.3% 4.0% 3.8 27% 38% 27%
New Zealand (age <15 years) 7.3% 4.7% 2.4 35% 57% 2%
Sweden (<15 years) 22
5.4% - - 11% 60% 0.2%
9 Discussion and conclusions
The use of nuclear medicine as a diagnostic tool has reduced in the decade since 1993
with the number of administrations decreasing by 21% from 8.4 per 1000 population
per annum in 1993 to 6.6 per 1000 population per annum in 2005. This reduction is
believed to be mainly due to competition from other imaging modalities such as CT,
MRI and ultrasound. However, there has also been a significant increase in the
numbers of myocardial perfusion scans and sentinel lymph node biopsies performed
since 1993. Bone scans remain the most commonly performed procedure representing
52% of the total number of procedures carried out in 2005.
Although the total number of bone scans carried out has remained approximately
constant, the number of bone scans performed on paediatric patients has reduced
significantly (by approximately 33%) from 1650 in 1993 to 1102 in 2005. The numbers
of other types of procedures carried out on paediatric patients have, however, remained
There is a significant variation in the numbers of different types of procedure carried
out at each of the nuclear medicine centres. For example, one centre does not carry out
any cardiac studies whereas the significant workload of another centre is due to cardiac
studies (more than 40%). This is due to a number of factors including differences in the
functional capability and the types of specialists associated with the different centres
and the preferred diagnostic techniques of referring specialists.
The mean activities of radionuclides administered for some common examinations have
been compared with practices in other developed countries. Overall, New Zealand
practice is in line with the rest of the developed world. The mean activities of
radionuclides administered for adults for some common examinations have been
compared with those published in NRL C313
reference activities and
guidance levels of activity in the 1996 IAEA BSS publication12
. There is reasonable
consistency with the activity levels given in these publications. The mean activity
administered to adults for the common examinations has largely remained unchanged in
the last decade although there are significant variations between different centres.
Compared to the adult data there is a much wider range of mean administered activities
for the common paediatric procedures. This is largely due to variations between centres
in the methods employed to calculate the paediatric activity as a fraction of the adult
activity. This can account for a variation in the administered activity of up to 100%.
The minimum administered activity in some instances was found to be below the
ANZSNM/ARPS minimum reference activity.
The mean effective dose received by paediatric patients was found in some cases to be
higher than the comparable effective dose received by adults. For bone scans, the mean
effective dose received by the age group 10-14 years was found to be nearly 40%
greater than the mean effective dose received by adults. This is compounded by the
higher risk factors for the paediatric age group.
The average effective dose per capita to the population from the administration of
radiopharmaceuticals for diagnostic purposes was found to be approximately 25 µSv
per annum, which is comparable to the 1993 survey (26 µSv per annum). The mean
effective dose per capita is relatively low when compared with other countries with
comparable effective doses ranging from 30 µSv to 160 µSv. It also tends to be higher
in countries which perform significant numbers of myocardial perfusion studies,
especially if Tl-201 is used instead of Tc-99m (the mean effective dose per study is
approximately 7 mSv using Tc-99m and about 20 mSv using Tl-201).
Although there is limited data available from other countries with respect to the use of
nuclear medicine procedures on paediatric patients the data obtained from this survey is
comparable to that reported.
This survey would not have been possible without the co-operation of the staff from the
following nuclear medicine centres who completed the nuclear medicine questionnaires:
Auckland Radiology Group
Fulford Radiology Services
Hawkes Bay District Health Board
New Zealand Medical Imaging, Auckland
New Zealand Medical Imaging, Hamilton
Palmerston North Hospital
Kevin Smidt and Peter Gene, Palmerston North Hospital, for reviewing and providing
comments on the nuclear medicine questionnaires.
Kevin Smidt for clarifying medical related queries arising during the drafting of the
report and for commenting on the draft report.
John Turner and Darin O’Keeffe, Christchurch Hospital for reviewing the draft report.
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from radiopharmaceuticals. Oxford: ICRP, 1998. ICRP publication 80.
9 Early P.J. and Sodee D.B. Principles and practice of nuclear medicine. St Louis:
C V Mosby Co., 1985.
10 Private communication with K. Smidt. New Zealand Nuclear Medicine
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Meeting in 2002.
11 UNSCEAR 2000 Report to the General Assembly: Sources and effects of
Ionizing Radiation Volume 1: Sources.
12 International Atomic Energy Agency. International basic safety standards for
protection against ionizing radiation and for the safety of radiation sources.
Vienna: IAEA, 1996. Safety series No. 115.
13 National Radiation Laboratory. Code of safe practice for the use of unsealed
radioactive materials in medical diagnosis, therapy and research. Christchurch:
National Radiation Laboratory, 1994. NRL C3.
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administered for paediatric nuclear medicine procedures in Australia. ANZ
Nuclear Medicine 32(1) 15-23.
15 Administration of Radioactive Substances Advisory Committee. Notes for
guidance on the clinical administration of radiopharmaceuticals and use of
sealed radioactive sources, 1998 (updated in March 2006).
16 Piepsz A., Hahn K., Roca I., Ciofetta G., Toth G., Gordon I., Kolinska J. and
Gwidlet J. A radiopharmaceutical schedule for imaging in paediatrics.
European Journal of Nuclear Medicine 1990 17:127-129.
17 International Commission on Radiological Protection ICRP Committee 3,
Minutes of the Wützberg Meeting, September 1995.
18 Private communication with M. Ellwood (Wairau Hospital) and L. Murray
19 Robertson M.K., Randle M.W. and Tucker L.J. Natural radiation in New
Zealand houses. Christchurch: National Radiation Laboratory, 1988. NRL
20 International Commission on Radiological Protection. 1990 Recommendations
of the International Commission on Radiological Protection. Oxford: ICRP,
1991. ICRP publication 60.
21 Stamm-Meyer A., Noβke D., Schnell-Inderst P., Hacker M., Hahn K. and Brix
G. Radiation exposure of patients undergoing nuclear medicine procedures in
Germany between 1996 and 2000. Nuklearmedizin 2005 44 (119-130).
22 Jönsson H. and Richter S. Isotopstatistik 2003 – för nukleärmedicinsk
verksamhet. Swedish Radiation Protection Authority, 2004. SSI report 2004:16.
23 Hart D. and Wall B.F. A Survey of nuclear medicine in the UK in 2003/04.
Health Protection Agency, 2005. HPA-RPD-003.
24 Hušák V., Petrová K., Prouza Z. and Mysliveček. Medical radiation exposure of
the Czech Republic paediatric population due to diagnostic nuclear medicine.
Nuclear Medicine Review 2000 3(2) (143-147).
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Medicine Examinations in Tehran. Iran. J. Radiol. 3(1)( 35-39).
A: Covering letter and survey forms sent to the nuclear
21 March 2006
Study of the Use of Nuclear Medicine in New Zealand 2005
During the course of 2006 NRL will be carrying out a study of the use of Nuclear
Medicine in New Zealand based on data obtained from 2005. This will update the
previous survey data collected in 1993. The information collected will be for the use of
Nuclear Medicine for diagnostic purposes only.
The aims of the study are:
• to assess trends in the frequency of different nuclear medicine procedures in
comparison with previous national surveys
• to assess the distribution by age group (child aged 0-4, child aged 5-9, child
aged 10-14, child aged 15-19 and adult) of different nuclear medicine
• to determine the annual effective dose to the NZ population from nuclear
medicine and the relative contributions of the different procedures
• compare the frequency of nuclear medicine use and the average activities of
the radionuclide administered for some common procedures compared with
other developed countries.
It would therefore be appreciated if you could complete the attached questionnaires
(Part A and Part B) and return them to NRL at the earliest opportunity and no later
than 31st May 2006.
Part A of the questionnaire comprises as a small number of questions relating to
procedures used within your nuclear medicine department. It can be forwarded to NRL
as a Word attachment to an e-mail to Karen_Beach@nrl.moh.govt.nz. or as a printed
out hard copy.
Part B requests data relating to the total number of administrations from 1 January 2005
to 31 December 2005 for each procedure and age group and the mean activity
administered. In the event of a procedure not being listed, please feel free to add
additional rows of data. The data should relate to the number of administrations
relating to diagnostic procedures only. It would be appreciated, though, if you could
give as much information as possible to enable the procedure to be compared with those
used at other centres.
It would be appreciated, if possible if Part B was forwarded to NRL as an Excel
attachment to an e-mail to Karen_Beach@nrl.moh.govt.nz. This will help to reduce
transcription errors when entering the data into our database. However, if it is not
possible to provide the data in this format a print out filled in is acceptable.
NRL Nuclear Medicine Study 2005 Questionnaire Parts A and B
NRL NUCLEAR MEDICINE STUDY 2005
Name and position of
Q1. Please describe the method used to assess the amount of activity to be
administered for a particular procedure to an adult.
Q2. Please describe the method used to assess the amount of activity to be
administered for a particular procedure to a child.
Q3. Are there any reasons why the data provided in Part B of the questionnaire
is atypical for a typical year’s activity, e.g. equipment inoperable for a number of
months etc? Please provide details.
Q4. If there is any other information which you would like to provide with
respect to the data entered in Part B of the questionnaire please enter it below.
B: Tabulated dosimetry data for nuclear medicine use in New Zealand
Table B.1: Data for child aged 0-4 years
Procedure description Radionuclide Pharmaceutical Number of
per unit activity
GIT oesoph reflux “milk scan”
Myocardial hot spot
Mucociliary Flow Studies
MDP or HDP
Table B.2: Data for child aged 5-9 years
Procedure description Radionuclide Pharmaceutical Number of
per unit activity
GIT blood loss
Myocardial hot spot
Myocardial perfusion – 2 day stress/rest (rest)
Myocardial perfusion – 2 day stress/rest (stress)
MDP or HDP
Procedure description Radionuclide Pharmaceutical Number of
per unit activity
Red cell volume
C: Quantification of radiation risk arising from medical
exposure to ionising radiation
Risk coefficients have been derived based on stochastic effects. These are discussed in
detail in ICRP60a
and summarised further in ICRP73b
The risk coefficients can either be expressed in terms of the probability of fatal cancer,
non-fatal cancer, severe hereditary effects or of total detriment. These are given in
Table C.1 below, which is taken from ICRP73.
Table C.1: Nominal probability coefficients for stochastic effects (probability per
unit effective dose)
Detriment (% per Sv)Exposed
Fatal cancer Non-fatal cancer Severe hereditary
Adult workers 4.0 0.8 0.8 5.6
Whole population 5.0 1.0 1.3 7.3
Generally the risk is either quoted as a total risk or a risk of death (fatal cancer). When
considering the risks arising as a consequence of working with ionising radiation the
risk factors for adult workers should be used, whereas for radiation risk to members of
the public the risk factors for the whole population should be used. However, there are
limitations with this generalised approach to calculating risk, particularly for doses
arising from medical exposure to radiation and additional normalisation factors should
be applied to take account of gender and age effects. Furthermore, the risk coefficients
given in Table 1 do not take into account deterministic effects.
Exposure of paediatric patients would lead to a greater risk than would be assessed
using only the coefficients in Table C.1, whereas conversely the risk to the geriatric
population would be lower. Therefore, Committee 3 of the ICRP introduced age-
dependent renormalisation factors to correct risk factors for the age effectc
. These are
given in Table C.2.
International Commission on Radiological Protection. 1990 Recommendations of the International Commission on Radiological
Protection. Oxford: ICRP, 1991. ICRP publication 60.
International Commission on Radiological Protection. Radiological protection and safety in medicine. Oxford: ICRP, 1996. ICRP
ICRP Committee 3, Minutes of the Wützberg Meeting, September 1995
Table C.2: Age correction renormalisation factors for radiation risk
Age (years) 1 5 10 15 50 70
Renormalisation factor 3.0 2.5 2.0 1.5 0.5 0.3
The correction factor for adults between the ages of 15 and 50 is taken to be unity.