Download Radiation Protection Of Medical Staff

European Journal of Radiology 76 (2010) 20–23
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European Journal of Radiology
journal homepage: www.elsevier.com/locate/ejrad
Radiation protection of medical staff
John Le Heron a,∗ , Renato Padovani b , Ian Smith c , Renate Czarwinski a
a
Radiation Safety & Monitoring Section, Division of Radiation, Transport and Waste Safety,
International Atomic Energy Agency, Wagramer Strasse 5, P.O. Box 100, 1400 Vienna, Austria
b
Medical Physics Department, University Hospital, Udine, Italy
c
St Andrew’s Medical Institute, St Andrew’s War Memorial Hospital, Brisbane, Australia
a r t i c l e
i n f o
Article history:
Received 14 June 2010
Accepted 15 June 2010
Keywords:
Radiation protection
Occupational exposure
Image-guided interventional procedures
Protective tools
Protective clothing
Monitoring
a b s t r a c t
The continuing increase in the worldwide use of X-ray imaging has implications for radiation protection of
medical staff. Much of the increased usage could be viewed as simply a workload issue with no particular
new challenges. However, advances in technology and developments in techniques have seen an increase
in the number of X-ray procedures in which medical personnel need to maintain close physical contact
with the patient during radiation exposures. The complexity of many procedures means the potential
for significant occupational exposure is high, and appropriate steps must be taken to ensure that actual
occupational exposures are as low as reasonably achievable. Further attention to eye protection may be
necessitated if a lowering of the dose limit for the lens of the eye is implemented in the near future.
Education and training in radiation protection as it applies to specific situations, established working
procedures, availability and use of appropriate protective tools, and an effective monitoring programme
are all essential elements in ensuring that medical personnel in X-ray imaging are adequately and acceptably protected.
© 2010 Elsevier Ireland Ltd. All rights reserved.
1. Introduction
The use of radiation in medical applications continues to
increase worldwide. Latest UNSCEAR estimates suggest that there
are about 4 billion X-ray examinations per year, worldwide [1]. All
these procedures need to be performed by medical personnel with
the accompanying potential for occupational radiation exposure.
Does the increasing demand for X-ray imaging have implications
for radiation protection of medical staff? The increasing usage could
be viewed as simply a workload issue with no particular new challenges. However, there is also a change in the types of X-ray imaging
procedures being performed and by whom – procedures requiring
personnel to be close to the patient, and these procedures present
a challenge to ensure appropriate radiation protection of medical
staff.
The term X-ray imaging is used in this paper to cover both
diagnostic radiology and image-guided interventional procedures.
Occupational radiation protection is achieved by application of the
three ICRP principles of justification, optimization and dose limitation [2]. In practice, to afford radiation protection for medical
staff in X-ray imaging, it is the application of optimization and
∗ Corresponding author. Tel.: +43 1 2600 21416.
E-mail addresses: [email protected] (J. Le Heron),
[email protected] (R. Padovani), [email protected]
(I. Smith), [email protected] (R. Czarwinski).
0720-048X/$ – see front matter © 2010 Elsevier Ireland Ltd. All rights reserved.
doi:10.1016/j.ejrad.2010.06.034
dose limitation that is arguably the most important. However, it
should be recognized that the lack of rigorous application of the
justification principle is resulting in the performance of significant
numbers of unnecessary X-ray imaging examinations, and these
add to occupational exposure.
This paper cannot cover all the aspects of radiation protection
of medical staff, but instead focuses more on the challenges in the
never ending story of occupational radiation protection, including
a brief discussion of factors that determine the level of occupational
exposure in X-ray imaging, the implications of recent trends in Xray imaging for occupational radiation protection, and the basis for
ensuring effective radiation protection of medical staff in the light
of these new developments.
2. What determines the level of occupational exposure in
X-ray imaging?
The level of occupational exposure associated with X-ray imaging procedures is highly variable and ranges from potentially
negligible in the case of simple chest X-rays, to significant for complex interventional procedures. What are the reasons for this? From
the occupational perspective, there are two “sources” of radiation
exposure. Clearly the X-ray tube is the true source of radiation,
but in practice there should be very few situations in which personnel have the potential to be directly exposed to the primary
beam. This leaves the other “source”, which is the patient. Interac-
J. Le Heron et al. / European Journal of Radiology 76 (2010) 20–23
tion of the primary X-ray beam with the part of the patient’s body
being imaged produces scattered radiation, which emanates from
the patient in all directions. So, in most cases, the main determinant
for occupational exposure is proximity of personnel to the patient
when exposures are being made. Furthermore, the level of scatter is determined largely by the dose to the patient, resulting in an
important corollary that reducing the patient dose to the minimum
necessary to achieve the required medical outcome also lowers
potential occupational exposures. A common and useful maxim is
that when personnel take care of the patient, they will also take
care of their occupational exposure.
2.1. Working at some distance from the patient
For many situations, such as radiography, mammography and
general CT, there is usually no need for personnel to be physically close to the patient. This provides two opportunities to afford
good occupational radiation protection. First, being distant from the
patient reduces the levels of scatter reaching personnel. Divergence
of the scattered X-rays from the patient results in radiation intensities falling off rapidly with distance. This is the so-called “inverse
square law” where, for example, a doubling of the distance results
in a four-fold reduction in radiation intensity.
The second factor is that structural shielding can be placed
between the patient and personnel. For example, shielding may
be incorporated into the wall and window of the control room
barrier, resulting in negligible levels of scatter reaching personnel.
Appropriate room design with shielding specification by a medical
physicist or radiation protection expert (RPE) also should ensure
that occupational exposure will be essentially zero for these X-ray
imaging situations.
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protective value. Gloves also may slow down the procedure and
engender a false sense of safety: it is much better to train personnel to keep their hands out of the primary beam. Ensuring the X-ray
tube is under the table provides the best protection when the hands
must be near the X-ray field, as the primary beam is then attenuated
by the patient’s body.
Ceiling-suspended protective screens can provide significant
protection, but their effectiveness depends on them being positioned correctly. Screens provide protection to only part of the body
(typically the upper body, head and eyes) and their use is additional
to wearing protective clothing. Sometimes a protective screen cannot be deployed for clinical reasons. Table-mounted protective
curtains also provide additional shielding, typically to the lower
body and legs. A further option for complex image-guided interventional procedures is the use of disposable protective patient
drapes. These are attenuating drapes placed on the patient after
the operative site has been prepared.
Because radiological workloads can be very different for the different specialties, the necessary protective tools should be specified
by a medical physicist or a RPE. For example, a person with a high
workload in a cardiac laboratory should use all the described protective tools, while a person in an orthopedic suite may need only
a simple front-only protective apron.
Many factors can influence how fluoroscopic examinations and
image-guided interventional procedures are performed, and hence
the patient dose and occupational exposure. It is therefore essential that personnel performing such procedures have had effective
training in radiation protection so they understand the implications
of these factors. Moreover, because of the wide variability in potential occupational exposures from these procedures, it is also crucial
that personal monitoring is performed continuously and correctly.
Both these aspects are discussed in this chapter.
2.2. Working close to the patient
There are some situations, typically in fluoroscopic examinations and in image-guided interventional procedures, where it is
necessary to maintain close physical contact with the patient when
radiation is being used. Distance and structural shielding are not
options, so what can be done for these personnel?
Scattered radiation can be attenuated by protective clothing worn by personnel, such as aprons, spectacles, and thyroid
shields, and by protective tools, such as ceiling-suspended protective screens or table-mounted protective curtains or wheeled
screens, which are able to be placed between the patient and personnel. Depending on its lead equivalence and the energy of the
X-rays, an apron will attenuate 90% or more of the incident scattered radiation. Protective aprons come in different thicknesses and
shapes, ranging from the simple front-only apron to a full coat: the
former being effective only if the wearer is always facing the source
of the scattered radiation.
The lens of the eye is highly radiation sensitive. For persons working close to the patient, doses to the eyes can become
unacceptably high. Wearing protective eyewear, particularly those
incorporating side protection, can reduce the dose to the eyes from
scatter by 90%, but to achieve maximum effectiveness, careful consideration needs to be given to issues such as the placement of the
viewing monitor to ensure the eyewear intercepts the scatter from
the patient. It is likely that measures to protect the eyes will receive
further attention if the dose limit for the lens of the eye is lowered
as a result of a review of current scientific evidence [2].
There are some situations, usually associated with imageguided interventional procedures, when the hands of the operator
may inadvertently be placed in the primary X-ray beam. Protective
gloves may appear to be indicated, but such gloves can prove to
be counter-productive as their presence in the primary beam leads
to an automatic increase in the radiation dose rate, offsetting any
3. Implications of recent trends in X-ray imaging for
medical staff
In the area of radiography, including mammography, there has
been a shift from film-based to digital systems. Patient doses
remain broadly similar, but patient throughput for a given imaging
room may have increased. Overall, the implications for occupational radiation protection have been minimal.
CT imaging has seen the advent of multi-detector CT scanners
(MDCT). Again, depending on how well imaging protocols have
been optimized, patient doses are broadly similar to their single
slice antecedents and future trend are likely to lower patient doses
as manufacturers continue to introduce more dose-saving features.
Image acquisition is considerably faster and usage of CT is increasing, resulting in higher workloads in the CT room. This has often
resulted in a need for increased structural shielding to maintain
acceptable standards of occupational radiation protection.
New technologies and techniques have also allowed the performance of complex diagnostic and interventional procedures
with the advantage of avoiding more risky surgical interventions
in several cases. These procedures present several challenges for
radiation protection of medical staff.
3.1. CT-fluoroscopy
CT-fluoroscopy facilitates the performance of biopsies by generating live tomographic images to better guide the intervention.
However, as the interventionalist is very near to the patient, there
is the potential for the hands to be exposed to the primary beam
and hand doses of up to 0.6 mSv for a procedure lasting only 20 s
have been reported [3]. Without protective measures, dose limits
(see Table 1) for the hands could easily be exceeded.
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J. Le Heron et al. / European Journal of Radiology 76 (2010) 20–23
Table 1
Recommended dose limits for occupational exposure in X-ray imaging (adapted
from ICRP[2]).
Dose quantity
Occupational dose limita
Effective dose
20 mSv per year averaged over 5 consecutive
years (100 mSv in 5 years), and 50 mSv in any
single year
Equivalent dose in:
Lens of the eyeb
Skinc
Hands and feet
a
b
c
150 mSv in a year
500 mSv in a year
500 mSv in a year
Dose limits can be different in national regulations.
This limit is currently being reviewed by an ICRP Task Group.
Averaged over 1 cm2 of the most highly irradiated area of the skin.
3.2. Interventional radiology and cardiology
In interventional radiology or cardiology the main operators
stay very close to the patient table where the intensity of scattered
radiation can be very high. For example, in a cardiology procedure
when the X-ray tube is under the table, the dose rate of incident
scattered radiation at the position of the operator can typically
range from around 0.5 to 10 mSv/h, from head height down towards
the legs. It is easy to see how cumulative doses can exceed dose
limits and reach hundreds of mSv per year if protective measures
were not taken, as described briefly in Section 2.2. This is described
more comprehensively, in the case of interventional radiology, in
the recent guidelines on occupational radiation protection published by the Cardiovascular and Interventional Radiology Society
of Europe and the Society of Interventional Radiology [4].
3.3. Image-guided procedures outside radiology departments
Many fluoroscopy-guided procedures today are performed outside radiology departments, using mobile C-arm or O-arm units
in, for example, orthopaedic, gastroenterology, urology, and vascular operating theatres. The use of radiation in these procedures
can range from very short fluoroscopy times (<0.5 min for a typical orthopaedic procedure) to very long fluoroscopy times, such as
60–90 min for an aortic aneurysm treatment. The main issue is that
the non-radiologist specialists and nurses involved in these procedures are often outside the umbrella of the radiology department,
and hence may not receive adequate training (including training in
radiation protection) in the use of modern equipment, which allows
not only simple fluoroscopy, but also pulsed fluoroscopy, digital
acquisition, angiography and digital subtraction angiography.
4. Ensuring effective radiation protection of medical staff
A radiation protection programme (RPP) is one means of
implementing occupational radiation protection by the adoption
of appropriate management structures, policies, procedures and
organizational arrangements. For medical staff in X-ray imaging,
topics would include the need for local rules and procedures for
personnel to follow, arrangements for the provision of personal
protective equipment, a programme for education and training in
radiation protection, arrangements for individual monitoring, and
methods for periodically reviewing and auditing the performance
of the RPP. The following sections describe aspects of two of these
topics. Further details on RPPs can be found in the BSS [5], and
IAEA SRS No 39 [6].
4.1. Radiation protection training
Education and training underpin the implementation of radiation protection in practice, and most countries have regulatory
requirements for such training. In X-ray imaging, personnel need
training not only in occupational radiation protection, but also in
patient radiation protection as the latter can influence occupational
exposure. Guidance has been published on what the training for
medical staff should cover, such as by the European Commission [7].
Several resources for training are freely available, including IAEA
material for diagnostic and interventional radiology and cardiology
[8], and the MARTIR project (multimedia tool for training in interventional radiology) [9], which is particularly useful for distance
learning purposes.
For the reasons noted previously, it is crucial that programmes
for radiation protection training in hospital settings include those
medical personnel who are outside the radiology department but
who are involved in X-ray imaging procedures.
4.2. Monitoring of occupational exposure in X-ray imaging
Occupational exposure is subject to dose limits as given in
Table 1, established to ensure that the risks arising from occupational exposure are not unacceptable [2]. The dose limit expressed
as effective dose addresses cancers and hereditary effects, while the
other dose limits (in terms of equivalent dose) are to prevent radiation effects in particular tissues or areas of the body. In addition,
the application of the principle of optimization of protection should
ensure that occupational doses to medical staff in X-ray imaging are
as low as reasonably achievable (ALARA principle), and typically
well below the dose limits.
The purpose of individual radiation monitoring is to ensure the
dose limits are not exceeded. Further, through regular review, the
results of individual monitoring are used to assess the effectiveness
of strategies for optimization. It is always hoped that the monitoring results confirm that good practice is taking place.
Estimates of effective dose and equivalent dose can be made
using appropriately designed and calibrated dosimeters, such as
those provided by an accredited individual monitoring service,
worn by medical personnel when performing X-ray imaging. It is
important that personal dosimeters are worn correctly. In X-ray
imaging this can become complicated, depending on the roles of
the person being monitored and whether they are sometimes or
even always wearing protective clothing. If a person is normally distant from the patient and is being protected by structural shielding,
then wearing a single dosimeter on the front of the torso, between
the shoulders and the waist, would normally suffice. However, if
a person is working close to the patient during imaging and is
wearing a protective apron, then a single dosimeter worn under
the apron will provide a good estimate of exposure to the shielded
parts of the body, but will underestimate exposure to the organs
and tissue outside the apron. In these cases, as dose to the eyes is
often of most concern, it is recommended that two dosimeters are
worn, one under the apron and the other outside the apron, often
at shoulder or collar level. The results of the two dosimeters can
be combined to give a better estimate of effective dose, as well as
providing an estimate for the dose to the eyes.
In some cases in X-ray imaging, monitoring of the fingers and
hands may be indicated. This requires special dosimeters, such as
ring or bracelet dosimeters. It is important to position the dosimeter in the position most likely to receive the highest exposure. This
may not be the dominant hand. In all cases of individual monitoring,
specific advice from a medical physicist or RPE should be obtained.
One of the practical difficulties in individual monitoring is ensuring
that monitored personnel actually always wear their dosimeters
when working with radiation. Incomplete compliance means that
a person’s occupational exposure is underestimated and, if this lack
of compliance with monitoring is widespread, then doses to that
occupational group as a whole would also be underestimated. The
reality is that many medical personnel do not always wear their
J. Le Heron et al. / European Journal of Radiology 76 (2010) 20–23
dosimeters, for a variety of reasons that range from simple negligence to deliberate avoidance to ensure that monitored results
remain below the threshold for administrative or regulatory investigation. It is important that monitoring is not viewed negatively,
but rather as a means for adding value to occupational radiation
protection by confirming good practice when this is the case, and
for improvement through corrective actions when problems are
identified.
Developments in individual dosimetry may help solve the
monitoring compliance issue. For example, technology is being
developed that utilises compact personal electronic monitoring
devices that wirelessly connect to a base station. Multiple devices
can be monitored simultaneously, so all staff involved in a complex imaging procedure can monitor their doses and dose rates in
real-time and use this information to modify their practice if indicated. Future technology may even negate the need for dosimeters
or devices to be worn by personnel. It is feasible that a person’s location in a room can be monitored in real-time, and their real-time
occupational exposure calculated from the real-time knowledge of
the X-ray equipment and how it is being used.
23
5. Conclusions
The continuing increase in the worldwide use of X-ray imaging
is creating new challenges for occupational radiation protection of
medical staff. Advances in technology and developments in techniques have seen an increase in the number of X-ray procedures
in which medical personnel must maintain close physical contact
with the patient during radiation exposures. The complexity of
many procedures means the potential for significant occupational
exposure is high, and appropriate steps must be taken to ensure
actual occupational exposures are as low as reasonably achievable.
Further attention to eye protection may be necessitated if a lowering of the dose limit for the lens of the eye is implemented in
the near future. Education and training in radiation protection as it
applies to specific situations, plus established working procedures,
availability and use of appropriate protective tools, and an effective monitoring programme are all essential elements in ensuring
that medical staff in X-ray imaging are adequately and acceptably
protected.
References
4.3. Current occupational doses to medical staff
There is a large number of publications giving occupational
doses per given procedure in X-ray imaging in a given facility,
and others that estimate likely annual doses. UNSCEAR provides a
comprehensive source of information on occupational doses worldwide, and in its 2010 report (covering the period 2002–2006) it
concludes that over 80% of general and CT radiographers did not
receive measurable doses [1], confirming that for personnel who
are protected by structural shielding, doses are very low. The report
notes that only a few countries were able to provide data that distinguished between conventional techniques in diagnostic radiology
and interventional procedures. From these limited data, for conventional diagnostic radiology the reported mean annual effective
dose was about 0.5 mSv for monitored personnel, while for interventional procedures it was about 1.6 mSv. A recent study with data
from 23 countries gave an average median effective dose for interventional cardiologists of 0.7 mSv, averaged per country (Padovani
et al., unpublished results). These figures would seem to be underestimates when compared with published facility-specific data,
again raising the issues of monitoring compliance.
[1] UNSCEAR 2008 Report: Sources of ionizing radiation, vols. I & II; in press.
[2] International Commission on Radiological Protection. The 2007 recommendations of the International Commission on Radiological Protection. ICRP
Publication 103. Ann ICRP 2007;37:1–332.
[3] Stoeckelhuber Beate M, Leibecke T, Schulz E, et al. Radiation dose to the radiologists hand during continuous CT fluoroscopy-guided interventions. Cardiovasc
Intervent Radiol 2005;28:589–94.
[4] Miller DL, Vano E, Bartal G, et al. Occupational radiation protection in interventional radiology: a joint guideline of the Cardiovascular and Interventional
Radiology Society of Europe and the Society of Interventional Radiology. Cardiovasc Intervent Radiol 2010;33:230–9.
[5] Food and Agricultural Organization of the United Nations, International Atomic
Energy Agency, International Labour Organization, OECD Nuclear Energy
Agency, Pan American Health Organization, World Health Organization. International basic safety standards for protection against ionizing radiation and for
the safety of radiation sources. In: Safety Series No. 115. Vienna: IAEA; 1996.
[6] International Atomic Energy Agency. Applying radiation safety standards in
diagnostic radiology and interventional procedures using X rays. In: Safety
Report Series No. 39. Vienna: IAEA; 2006.
[7] European Commission. Radiation protection 116. Guidelines on education
and training in radiation protection for medical exposures. Luxembourg:
Directorate-General for the Environment, European Commission; 2000.
[8] Accessible at: http://rpop.iaea.org/RPOP/RPoP/Content/AdditionalResources/
Training/1 TrainingMaterial/index.htm.
[9] MARTIR. Multimedia and audio-visual radiation protection training in interventional radiology, radiation protection 119. Luxembourg: Office for Official
Publications of the European Communities; 2002.