Biomed Imaging Interv J 2007; 3(2):e22
doi: 10.2349/biij.3.2.e22
© 2007 Biomedical Imaging and
Intervention Journal
Review Article
Radiation injury is a potentially serious complication to fluoroscopically-guided complex interventions
LK Wagner, PhD
Department of Diagnostic and Interventional Imaging, The
University of Texas Medical School at Houston, Houston, Texas, USA.
ABSTRACT
Radiation-induced injury to skin is an infrequent but
potentially serious complication to complex fluoroscopically-guided
interventional procedures. Due to a lack of experience with such injuries, the
medical community has found fluoroscopically-induced injuries difficult to
diagnose. Injuries have occurred globally in many countries. Serious injuries
most frequently occur on the back but have also occurred on the neck, buttocks
and anterior of the chest. Severities of injuries range from skin rashes and
epilation to necrosis of the skin and its underlying structures. This article
reviews the characteristics of these injuries and some actions that can be
taken to reduce their likelihood or seriousness. © 2007 Biomedical Imaging and
Intervention Journal. All rights reserved.
Keywords:
INTRODUCTION
A 154 kg patient presented at the Emergency Center
complaining of a prolonged rash located medially on the upper part of his back.
The rash was almost rectangular and well demarcated, measuring about 40 mm by
60 mm. The affected skin had a central blackened area about 10 mm in dimension.
The rash first appeared about six months previously; initially it was red and
very itchy. The patient sought medical help shortly afterwards. The dermatitis
of unknown aetiology was treated topically. With time, the rash worsened.
Further medical assistance was sought but was ineffective. The patient admitted
himself to an emergency centre. That visit also proved unsatisfactory in
diagnosing the cause of the injury. Now, the patient presented at a different
emergency centre. The patient had a history of heart disease and about one
month prior to the onset of the rash had undergone a complex coronary
angioplasty and stent procedure. By the recollection of the patient’s spouse,
the procedure lasted about six hours. The equipment used for the procedure was
a state-of-the-art flat-panel digital angiography system. The patient had never
been advised that radiation received from that prolonged study could cause such
an injury. Therefore, with the rash developing several weeks later he had no
reason to suspect that the treatment for his heart condition might have any
significance. It was a classic case of radiation injury from
fluoroscopically-guided coronary intervention. Many such cases with similar
scenarios have occurred in the past decade [1-5]. The cases frequently involved
delayed diagnosis of a well-demarcated rash, with a prolonged and intractable
progression to a necrotic wound. Even so, diagnosis of the lesion’s aetiology
has proven difficult. In some situations, after a prolonged period without
diagnosis, a member of the patient’s family performed the research necessary to
discover the cause.
Hundreds of injuries from complex fluoroscopically-guided
interventions have been reported, ranging in severities from mild erythema and
hair loss to deep skin necrosis, sometimes involving deeper tissues to the
level of bone and spine. Severe injuries have occurred worldwide from Europe to
the Americas, and Asia [1-12]. The equipment involved has ranged from poorly
designed systems to contemporary state-of-the-art machines. Severe injuries
have occurred, ranging from the neck to the buttocks (Figures 1-2). Injuries
have occurred anteriorly [12] and on the sides of the torso (Figure 3), but
most have occurred posteriorly due to the conventional orientation of the
fluoroscope. Conspicuously, the author knows of no severe injuries in the
scalp, although depilation has been observed on many occasions (Figure 4).
The pain and suffering associated with severe injuries and
their inevitably prolonged wound management is only one element in the scale of
effects. The medical treatment sometimes involves surgical grafting that
results in permanent disfigurement and compromised mobility (Figure 5). In some
cases the family’s lifestyle is radically altered. This includes daily changes
of wound dressings, limited ability to perform simple tasks, inability to work,
loss of income and indebtedness due to high medical costs and loss of
employment. In some cases, the patient must learn to sleep in awkward positions
because the wound prevents the patient from reclining in a normal way.
Psychological depression in both the patient and the patient’s closest family
members is a further complication that has sometimes required treatment. In
some cases, the pain associated with the injury is permanent and the patient
requires a lifetime of medication and treatment for pain.
The medical benefits of complex fluoroscopically-guided interventions
are well established. They include lower morbidity with reduced risk of
mortality with a much shortened recovery period when compared to that of
conventional surgical methods. It is estimated that about two million such
procedures are performed worldwide each year. Since only hundreds of injuries
are known, the occurrence of radiation injury as a complication to these
procedures is extremely rare. Consequently, the concern about radiation and the
motivation for improved techniques to avoid such complications is not in the
frequency of the occurrence; rather it is the severity of the complication that
warrants improved dose-limiting techniques. An added impetus for better
radiation management is to prevent an increase in the occurrence of these injuries
as procedures become more aggressive and complex with future advances. Concern
over radiation injury should not become a cause for a physician to prematurely
terminate a procedure that is deemed necessary to save the life of a patient.
On the other hand, using equipment that is appropriately
designed for complex interventions and assuring that medical personnel are
properly trained in the use of that equipment as well as in methods on how to
limit dose during such procedures is a reasonable medical goal. This will
ensure that the risks of radiation are appropriately minimised. The benefits
will be the avoidance of injury in many cases and the reduced potential for
long-term neoplastic effects of radiation. An added benefit is limited
radiation exposure to personnel resulting in a lower carcinogenic risk for
them.
The characteristics of radiation injury from fluoroscopy
Although a radiation injury is often referred to as a
“burn”, the development of the injury is considerably different from that of a
thermal or chemical burn [13-14]. Since the physical appearance of the injury
reminds one of a thermal “burn”, it is natural to think about the causes of the
wound in the same context. Thus, it is natural to try to identify some thermal
or chemical agent with which the patient has recently come into contact. As the
wound is often sharply demarcated, one naturally looks for agents that would
cause sharp borders. This often leads to frustration and misdiagnoses. The
situation is often exacerbated by attempts to treat the wound in the same
manner as a thermal or chemical burn. For thermal or chemical injuries, the
wound develops rapidly once the agent of cause is removed. Within a matter of
days, the full extent of development is usually known. Results of treatment
begin to appear in a short interval and progress relatively rapidly, over a
period of days, sometimes weeks. Radiation injuries, especially those involving
severe injuries, do not have these characteristics.
Most frequently, in the case of fluoroscopic radiation skin
injury, symptoms of the injury are not promptly apparent. This is because
damage to the cells by ionising radiation is very different from that caused by
heat and chemical agents.
Heat and chemical agents cause a global damage that affect
the entire cell and groups of cells by introducing energy. This causes
molecules to break apart. Chemical and biochemical reactions ensue. Heat and
chemicals must progress through all superficial layers of cells to penetrate to
deeper layers. Thus with heat and chemicals, every cell in the superficial
structures of the contact zone of the skin is wholly and adversely affected.
Nerves sense this and immediately signal the individual to reduce contact with
the offending agent. Fluoroscopic X-ray radiation does not do that.
An X-ray beam is comprised of billions of individual X-ray
photons. An X-ray photon can be considered to be an uncharged particle of pure
energy with no mass. It is about the size of an atom. These properties allow
the photon to bypass many layers of cells without interacting in the cells.
When a photon does happen to interact in a cell, it interacts with electrons in
individual atoms or molecules inside the cell. Thus, the cell can be injured
internally in a very localised area without damage to its outer structures. In
this way, the structure of the cell often remains intact but the replicating
capacity of the cell can be compromised. This, in fact, is a characteristic of
cell damage by ionising radiation. In general, immature cells that reproduce frequently
are more susceptible to the lethal effects of radiation than mature cells.
As a result of the internal cellular damage affecting
replication, patients who undergo very high-dose interventional procedures
often have no sense of a radiation skin injury before they leave the hospital.
However, the basal cell layer of the epidermis might have damages that will
compromise skin renewal. As the skin proceeds through its normal replication
and renewal process, it will find itself incapable of completing this function.
As the process takes many days to develop, there will be a characteristic delay
between the induction of the injury and the recognition of symptoms, which
begin as a rash. The delay is typically, but not always, about two to three
weeks before symptoms emerge and three to four weeks before it is sufficiently
irritating for the patient to see a doctor. Thus, physicians and patients do
not usually associate the rash with the angiographic procedure.
In a few cases, symptoms of fluoroscopically-induced
radiation injury have occurred promptly, within a matter of hours. Reported
symptoms are pain on the back or a rash. The prompt rash is thought to be
caused by a mechanism different than that described previously. In short, the
ionisation caused by the radiation is thought to lead to an activation of
histamine-like substances, resulting in a dilation of capillaries [14]. This
type of rash often fades after a day or so. However, depending on the amount of
radiation delivered, the rash may seem to blend with that of the delayed
erythema associated with damage to the basal cells of the epidermis. While
early symptoms have been reported, they either occur infrequently or they are
not usually recognised.
Skin erythema is one of the first symptoms to be noticed
because the affected cells are superficial and are in a state of continual
replication. However, even if a lethal amount of radiation is delivered to a
cell, the cell might still continue to function for a time. Eventually,
however, the cell dies and must be replaced. This process occurs on a different
time scale for different cells. For instance, the epithelial cells of the
vascular structures of the dermis might be damaged. As time evolves, these
cells need to be replaced. However, the repair mechanisms might be compromised
and this results in a shutdown, rather than a replenishment of the blood supply
to the skin. Edema that slowly develops might also contribute to vascular
collapse. The ultimate result is necrosis that begins to be evident within months
after the angiographic procedure, with the time course dependent on many
factors like radiation dose and skin type.
Table 1 provides a summary of some observed patterns of
radiation damage to the skin. With the exception of skin cancer, the important
lesson is that these effects do not occur unless the dose of radiation is
greater than the minimum necessary to cause sufficient damage. Also, because
the temporal course of radiation injury by fluoroscopy is delayed and is quite
unlike that for thermal injury, it is possible to reach a diagnosis by
analysing the relationship of the temporal progression from the time of the
previous fluoroscopic procedure. This coupled with the shape and location of
the injury leads to a reliable diagnosis. The injury must be located in the
area of the skin where the radiation enters the patient and the shape of the
injury will depend on how the radiation was delivered. If the beam was
stationary, never adjusted for collimation and located over the same area of
skin for most of the procedure, then the injury will take on the shape of the
X-ray port and will have sharply demarcated borders. The shape might be
rectangular or circular, depending on the type of collimator. Deviations from
this, e.g., re-oriented beam or adjusted collimators, may result in less
sharply demarcated borders or more oddly shaped injuries (e.g., Figure 1 versus
Figure 2). Such an analysis is likely to be sufficient for diagnosis. This will
both avoid the need for biopsy and the associated complications of an open
wound in skin already damaged by radiation.
How to minimize risk for radiation-induced injury in
patients
Radiation management for the patient has three phases:
before the procedure begins, during the procedure and after the procedure is
over.
Before the procedure
Important considerations before a procedure are:
1.
the skill sets of the physician
2.
the physicians’ and the technologists’ knowledge about their
angiographic machine
3.
the medical history of the patient
4.
the likely difficulty of the procedure
5.
the body habitus of the patient.
Some injuries have been associated with procedures for which
the physician was inexperienced and not sufficiently trained. Insufficient
experience leads to prolonged use of radiation. Conversely, well-trained and
experienced physicians are likely to be more efficient in completing the
procedure. Training and experience in the technical aspects of a medical
intervention are important components of radiation management. Physicians must
be properly trained and experienced in procedures before attempting them and
must exercise prudent judgment when attempting procedures that challenge their
skill sets. They should seek assistance early in a procedure if the difficulty
presents a new or unexpected challenge.
Training includes lessons in the prudent use of fluoroscopy
and fluorography. Learning to limit fluoroscopy to the minimum time necessary
for every engagement of the switch is essential. Prudently limiting serial runs
in number and in duration is also essential.
Setting up the machine for a procedure requires not only
knowledge about radiation management, but also training on how to set up a
particular machine to make use of that knowledge. Knowing the options and
capabilities of a particular machine is essential. Many features can be
adjusted during the procedure to reduce radiation use or to improve image
quality, depending on the demands of the situation.
Some patients are at greater risk for radiation injury than
others. Some drugs, such as actinomycin D and Adriamycin®, are known
to increase sensitivity to X rays [1, 16]. Some rare health conditions render
patients highly sensitive to radiation, e.g., patients with the homozygous form
of the ataxia telangiectasia gene [1, 16]. Diseases such as collagen vascular
diseases and diabetes mellitus are suspected in rendering patients more
susceptible to injury [1, 17, 18]. Diabetes compromises the vascular supply and
this leads to a greater risk for long-term complications. The reasons why some
patients with collagen vascular disease are more sensitive to radiation are
unknown. Medications that the patient is taking may be one reason for the
heightened sensitivity [9]; but the sensitivity might also be related to the
status of the disease at the time of the procedure. However, having the disease
does not absolutely predispose patients to heightened sensitivity. Only a few
patients with collagen vascular disease have been identified to have greater
radiation sensitivity [1, 9, 17].
If the patient has had previous fluoroscopically-guided procedures,
it is wise to examine his or her skin for erythema or residual radiation injury
from those procedures. A previous injury may never have been reported by the
patient as it might not have caused sufficiently severe symptoms. It may have
healed into a slightly scarred or discoloured area and might not be in an area
where the patient can see it. If a residual injury is identified, that skin
area will be at heightened risk for injury. This should be brought to the
attention of the patient. Furthermore, the physician might be able to plan the
current procedure to avoid irradiation of that skin area.
If the procedure is likely to be difficult, requiring a
prolonged course of fluoroscopy with more than the usual number of imaging
run-offs, then the patient will be at risk for an unusually high radiation dose
to the skin. This is especially true if the patient is large. To compensate for
the increased absorption of radiation by the increased body mass, the X-ray
machine will automatically adjust the radiation output to high levels. Thus, radiation dose will accumulate much faster when the X-ray beam must traverse increased body mass.
This occurs not only in large
patients, but also in smaller patients for whom the beam angle is tilted in oblique,
cranial-caudal or caudal-cranial orientations.
When the patient is at risk for a high dose procedure,
obtaining informed consent should be considered. Some suggestions and
considerations for the informed consent are provided in Table 2.
During the procedure
A friend once told me that for angiographic procedures,
radiation should be managed in the same context as iodinated contrast agents
[Stephen Balter, 2005]. All angiographers can relate to the risks associated
with iodine. The amount of iodine administered to a patient is monitored and
the physician makes a benefit/risk decision regarding the amount to be used.
The physician also knows how to use iodine wisely, so as to avoid situations
that might place the patient at unnecessary risk. Radiation is similar: the
amount delivered should be monitored and the physician must know how to use it
wisely so as not to place the patient at unnecessary risk.
Wagner and Archer have reviewed methods of radiation
management [19] and these methods have been reviewed in many other articles
[2-5, 20]. This paper will highlight important lessons of radiation management
as they relate to observed injuries. For a more thorough discussion, the reader
is referred to the referenced publications.
Thick tissue masses
Injuries are often associated with large patients and beam
projections through thick body masses, as is evident for many injuries shown in
this review. This occurs when patients are large, beam angles are steep, or
arms or other obstructing body parts are in the path of the beam. The entrance
dose rate increases for both fluoroscopy and fluorography (serial imaging such
as runoffs or cine). The cause of the increased radiation rate is two-fold.
First, the goal of all fluoroscopy and fluorography is to produce a residual
radiation beam on the exit-beam side of the patient sufficient to result in a
satisfactory image for the task. However, X rays do not readily penetrate
through patients. Typically for abdomens, less than 1% of the radiation that
enters a patient actually penetrates through to make the image. The rest of the
radiation interacts inside the patient. Fluoroscopic X-ray energy absorption is
greatest at the surface where the beam enters the patient, about 100 times
greater than at the exit surface when the projection is through a typical
abdomen or mediastinum. For thicker body masses, more radiation has to be
delivered in order to get the same amount through. Typically for every 3-5 cm
of tissue that has to be traversed, the radiation output must increase by
another factor of two. By governmental regulation, the output of fluoroscopy is
usually capped at a limited maximum output. However, typically there is no such
cap or limit placed on serial runs. So, for thick body masses the fluoroscopy
output might be operating at the maximum allowed level while the serial run
output is not limited and could be running at dangerously high levels, as has
occurred in some cases of injury.
The second reason why dose rates on the skin are higher is
due to the proximity of the entrance skin surface to the X-ray source. X rays
emanate from a tiny point inside the X-ray tube. The beam diverges from this
point and expands into an ever widening area as distance from the source
increases (Figure 8). As the skin gets closer to the source, the area of the
beam is smaller. This means that all the X rays are confined to a smaller area
as the source is approached, resulting in an increasing intensity of radiation.
Big patients, thick body masses and arms, all contribute to situations where
the skin surface of the patient is closer to the source than for thin body
sections.
To help abate large dose build-up under the situations
described above, the following principles can be applied:
1.
Assure that the patient’s skin surface is maintained at a reasonable
distance from the source.
2.
Rotate the beam to a different angle so as not to irradiate the same
skin site for a prolonged period of time.
3.
Position patients so that the arms can be moved out of the X-ray field.
4.
Try not to use beam angles where the female breast is directly exposed
to the entrance beam.
Execution of these principles requires prudent judgment. The
relationship of the source to the patient has boundary conditions that are
imposed by the situation. If an isocentric configuration is used in a cardiac
procedure, the heart of the patient will be at a fixed position relative to the
source, which in turn determines the position of skin surface in relation to
the source. But if an isocentric configuration is not required, the table of the
patient might be raised somewhat. The table height will depend on the height of
the physician who must maintain a comfortable working level. Rotating the beam
is often possible, but in some cases this will reduce the visibility of the
lesion and might compromise the quality of the procedure. Arms can usually be
moved away from the path of the beam and efforts to do so with arm boards or
other methods are highly recommended. Several cases of arm injuries (Figures 6,
9, 10) have been reported [1, 4, 8]. Staff should be trained to look for arms
in the field so that they can alert the physician of the circumstance and
correct it as necessary. Breast cancer from high doses delivered to the mammary
tissues of female patients is a known risk [21]. Young women or girls are at
greatest risk [22]. Figure 11 shows an injury to the flank of a 17-year-old
girl from an electrophysiological and ablation procedure. The skin dose was
obviously very high. Due to the close proximity of the right breast, dose to
that breast was also very high from both direct irradiation and indirect
scattered radiation. Avoiding exposure to the breast, especially direct
entrance beam exposure, is highly recommended. Collimating to the area of
interest is an effective way to reduce scattered radiation.
The position of the image receptor
With few exceptions, the image receptor should be placed as
close to the patient as is practicable for the procedure. As the image receptor
is moved closer to the patient, the output of the X-ray device decreases, thus
decreasing dose rate to the patient.
Output settings of the equipment
The following are a few of the options or features available
on many modern machines.
1.
Variable pulsed fluoroscopy
2.
Variable dose rate fluoroscopy
3.
Variable dose level fluorography
4.
Variable image rate fluorography
5.
Collimator devices
6.
Virtual collimation
7.
Virtual patient positioning
8.
Last image hold
9.
Capture of last image hold
10. Last
fluoroscopy replay
Physicians and technologists should be very familiar with
such options and employ them as necessary. For example, most cardiology
procedures can be performed at a fluoroscopic pulse rate of 15 pulses per
second as opposed to a rate of 30 per second. The dose savings from this
selection can be very considerable. A rate of 7.5 per second can be used for
many vascular procedures. The physician should select the minimum rate that is
consistent with the safe and efficient completion of the procedure. Similarly,
many machines have dose rate selections that use different beam filters or
different tube currents. The minimum dose rate consistent with the needs of the
task should be employed. The same principles apply with respect to
fluorographic frame rates and dose level settings. Settings should change with
the progression of the procedure. Physicians should work with technologists on
managing these settings. Technologists should assist the physician and be
familiar with the physician’s procedure so that the technologist knows when
different settings should be employed.
Physicists should be consulted on the settings. They can
determine which settings actually save dose and by how much. For example, lower
pulse rates for fluoroscopy do not always reduce the dose rate. Whether or not
various settings actually reduce dose should be verified for every machine. The
physicist can perform tests to assess the dose rates for each setting.
Last image hold is a very familiar feature on all modern
machines. The last fluoroscopic frame is stored in memory and remains displayed
on a video monitor once the X rays are turned off. A new feature on many units
is fluoroscopy replay wherein the last 10-20 seconds of fluoroscopy is stored
in memory. Replaying the fluoroscopy or using last image hold to study a
procedure is a proven method of good dose management. Sometimes this image can
be used to document the satisfactory placement of a device. Storing the image
for this documentary purpose can save an additional radiation run in many
cases.
The use of collimators to narrow the imaging field is also a
recommended practice. Virtual collimator controls allow the physician to narrow
the collimators without applying the X rays. The edges of the collimators are
displayed by computer simulation using the last image hold for anatomic
reference. Similarly, the table can be repositioned and the virtual positioning
option uses last image hold to show the physician where the anatomy is being
relocated in the image. No radiation is necessary.
Use of all the above tools and options in a wise and prudent
manner will result in considerable dose savings to the patient with the added
benefit of improved radiation limitation for personnel.
Dose monitoring
In all cases of radiation injury with which the author is
familiar, the capability to monitor dose for the patient was either not used or
not available.
At the author’s teaching hospital, a case of an unusually
high radiation dose was investigated. The patient weighed 131 kg and was 1.7 m
in height. The only dose monitor available was a kerma-area-product meter,
which is known to be difficult to employ as a skin dose monitor [23, 24]. The
patient had undergone a bi-plane electrophysiological and ablation procedure
that involved 110 minutes of fluoroscopy with a dose-area product of 194,000
cGy * cm2. On the face of it, this could have resulted in a serious
skin injury. The department had in place a policy that the radiation physicist
would be called anytime the fluoroscopy time exceeded 40 minutes. The physicist
could then make an assessment of the potential skin dose based on the
kerma-area product. The policy also required the technologist to inform the
physician of the prolonged procedure and that the physician should consider
reorienting the beam so as to avoid irradiation of the same skin area. All
these policies were followed for that particular procedure. The beam was
re-oriented twice and the physicist was appropriately called to make sure
policies were followed and to estimate the skin dose. This realistically saved
the patient from harmful radiation dose buildup in the skin. The patient was
visited by a nurse who examined the patient’s back six weeks after the
procedure. No skin rashes or other indications of radiation injury were
present.
This vignette demonstrates that sophisticated dosimetry
equipment need not be available for a facility to establish sound policies on
radiation management. All that needs to be in place is a procedure that permits
the physician to make prudent judgments about radiation delivery during
difficult procedures. While sophisticated dosimetry equipment is desired, lack
of it does not preclude effective dose monitoring practices.
The use of fluoroscopy time as a surrogate measure for
radiation dose is the least accurate method of determining risk to the patient
[23, 24]. There are many reasons for this, the biggest being that it fails to
record anything about serial imaging and provides no information relative to
radiation output rates for different sizes of patients. But, as we have seen,
it can be a valuable monitor for potential risk. While more informative than
time, kerma-area product is likewise a poor method of dose assessment. It can
be useful but usually requires assistance from a physicist or other experts in
dosimetry.
Another method of dose estimation is to monitor air kerma at
a reference point. All modern machines have this capability. Usually, the air
kerma at the reference point is cumulatively updated. For most angiographic
equipment the reference point is located 15 cm from the isocentre and towards
the X-ray source. This roughly approximates the position of the patient’s skin
surface during cardiac procedures when the heart is positioned at the
isocentre. It is more accurate than kerma-area-product, but has some
deficiencies. These include the following:
1.
the skin dose is roughly 40% greater than the indicated air kerma
2.
the air kerma will be underestimated in some cases and overestimated in
others (Figure12)
3.
no accounting is made for risk to different skin sites when the beam is
re-oriented
So, using air kerma at a reference point to estimate skin dose
must be done with discretion. Some facilities use a 3, 6, 9 rule to help manage
radiation delivery during difficult procedures. By this rule, the physician is
advised when the reference air kerma reaches 3 Gy. This first alert is just for
the physician’s information. The purpose is to help the physician gauge the
pace of the procedure and to project just how much radiation might be necessary
for its completion. The physician might wish to re-orient the beam. At 6 Gy,
the second alert is provided. At this point, the physician knows that there is
a risk of erythema or more severe effects if the beam has not been rotated to a
new orientation. This gives the physician a chance to consider options for dose
abatement. At 9 Gy, the third alert is issued. The degree of risk to the
patient will depend on whether previous dose abatement actions have been
implemented. This does represent a potentially serious dose level and a
benefit-risk decision is necessary, just as a physician would make a
benefit-risk decision about whether or not the iodine burden from the contrast
agent is too great. Further warnings at 3 Gy intervals would be provided, with
the physician making commensurate decisions about benefit versus risk.
Other methods for dose monitoring include computer
dose-mapping programs and dosimetry film [24]. Computer dose-mapping programs
are not easily acquired and the reader is referred to other articles on this
method. A radiochromic dosimetry “film” (technically called media)
[International Specialty Products, Incorporated, Wayne, New Jersey, USA] has
special properties that permit it to be used to accurately assess skin dose
(Figure 13). The film is not particularly sensitive to light. It is placed
under the patient at the site where the beam enters the skin. As X rays pass
through the film, the film turns black; no processing is required. The darkness
of the film indicates the dose to the skin. To assess the dose, a calibration
strip of film with different grey levels can be compared to the darkness on the
procedure’s film. The method is easy to use and provides valuable dosimetry
information [25]. During a prolonged procedure, if there is a concern over skin
dose, the film can be removed and immediately examined for darkness to assess
skin dose.
After the procedure
Professional societies [20, 24] and others [26] recommend
that patients should be advised about procedures that may have delivered high
doses to the skin of a patient. They should be advised to report any skin
changes. Specifically, the patient should be advised about the area on the skin
of the back where a rash might develop. The patient should be asked to examine
him- or herself about 2 to 3 weeks after the procedure for any skin changes in
those areas. Some facilities place a follow-up call to the patient during this
time to query about any skin irritation.
The benefits of these activities are as follows:
1.
The patient knows ahead of time that this is a potential but rare event.
2.
There is a mechanism for feedback on how often skin effects might be occurring.
Data on erythema that eventually fades should create an action item to review
the procedure. Information extracted from that review should be used to
reassess procedures and improve them if necessary.
3.
Should an erythema develop, the patient can be advised to see a
dermatologist and the dermatologist should be contacted, advising him or her on
the particular details of the patient’s complaint. For instance, you can advise
the dermatologist where the rash would be located if it is a radiation-induced
rash. Furthermore, the dermatologist knows to include radiation in the
differential diagnoses.
4.
If it is a radiation rash, the patient will have prompt knowledge about
the cause and not be frustrated with incorrect diagnoses and unsatisfactory
medical explanations about the progression of the lesion.
Without a follow-up, the patient leaves the facility with no
knowledge about the potential skin effects. If an effect develops, the patient
is not likely to associate it with the procedure, which was performed previously.
If the patient seeks medical help for the rash, the physician might not realize
that the angiographic procedure could cause the effect and will look for other
diagnoses, all of which are incorrect. Care will be uncertain. And, the
facility will have no feedback that this has occurred, leaving a false sense of
security about the safety of future procedures.
Final comments
This author recently received this e-mail:
"My husband was diagnosed with a biopsy in May 2006 with a radiation burn from several heart catherizations (sic). We have been seeing a wound specialist since June. Along with the wound, he has been suffering with severe burning and stabbing pain and trouble breathing. We have been to pulmonary specialists, thorasic (sic) surgeons, cardiologists and pain specialists all say they have no experience with a radiation burn. We are desperate for help in this matter..."
Only through education and adequate programs to monitor and
manage radiation delivery during fluoroscopically-guided interventional
procedures will we be able to stop this type of message from coming across our
desk.
REFERENCES
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Koenig TR, Wolff D, Mettler FA et al. Skin injuries from fluoroscopically guided procedures: part 1, characteristics of radiation injury. AJR Am J Roentgenol 2001; 177(1):3-11.
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Received 7 January 2007; accepted 3 April 2007
Correspondence: Department of Diagnostic and Interventional Imaging, The University of Texas Medical School at Houston, Houston, Texas, USA. E-mail: louis.k.wagner@uth.tmc.edu (Louis Wagner).
Please cite as: Wagner LK,
Radiation injury is a potentially serious complication to fluoroscopically-guided complex interventions, Biomed Imaging Interv J 2007; 3(2):e22
<URL: http://www.biij.org/2007/2/e22/>
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