| Algos Fluoroscopy Tutorial |
Of the available forms of radiographic guidance for
precision needle placement (CT,MR,
Fluoroscopy,Ultrasound), only fluoroscopy offers the
combination of convenience, excellent image acquisition,
and real time imaging. Modern fluoroscopy units consist of
a generator, collimator, image intensifier, digital image
processing, monitor, and a data storage or transfer system.
Most states have strict output maximum requirements and
safety requirements concerning fluoroscopy units. The
Dept. of Health is the usual regulating authority for most
states and the regulations may be obtained from this entity.
Licensure for fluoroscopy use in any facility is mandatory.
Most modern fluoroscopy units do not require radiation
shielded rooms.
precision needle placement (CT,MR,
Fluoroscopy,Ultrasound), only fluoroscopy offers the
combination of convenience, excellent image acquisition,
and real time imaging. Modern fluoroscopy units consist of
a generator, collimator, image intensifier, digital image
processing, monitor, and a data storage or transfer system.
Most states have strict output maximum requirements and
safety requirements concerning fluoroscopy units. The
Dept. of Health is the usual regulating authority for most
states and the regulations may be obtained from this entity.
Licensure for fluoroscopy use in any facility is mandatory.
Most modern fluoroscopy units do not require radiation
shielded rooms.
| X-Ray Production, Generators, and Physics X-rays are high energy radiation produced by striking a tungsten anode with a beam of electrons from a cathode filament. X-rays are produced when the negatively charged electrons at high speed pass close to the positively charged tungsten nucleus. As the electrons slow down as they near the nucleus, they produce energy in the form of heat 99% and xrays 1% (Bremsstrahlung radiation). Modern xray tubes are vacuum tubes. Because of the enormous amount of heat produced, the tube must be cooled to prevent the tungsten from melting. Oil cooled and circulating oil cooled systems are the major methods of heat transfer from the very hot anode. In order to prevent focal pitting and meltdown of the anode, modern fluoroscopy units use a rotating anode in a glass xray tube as below. Anode Types |
| the electrons determines the density of the electron beam, and is directly related to the amount of x-ray radiation produced. The currentis measured in milliamperes (mA) and determines the overall sharpness of the image obtained. Therefore a higher mA value will produce sharper images but at the cost of significantly increased radiation exposure to the patient and potentially scatter radiation to the operator. Most modern fluoroscopy units have two or more filaments to provide different square surface area of x-ray output to cover different size image intensifier elements. The larger 9inch outputs produce a larger picture but a higher radiation exposure compared to the 6 inch. Larger C-Arms may have up to a 15 inch image intensifier requiring significant amounts of radiation. Modern fluoroscopy machines usually operate between 50-120kV and from 0.5-75mA depending on the settings. Normal fluoroscopy settings typically will produce a maximum mA current of 6, high dose fluoroscopy 20mA, digital spot mode (single shot high dose) up to 75mA. Low dose operates at only a fraction of the current of normal dose, typically about 30-40%. Therefore there is about a 75 fold difference (7500%) for the max output of the machine compared to low dose settings. Obviously, low dose is preferred and will typically result in operating currents of around 1.2mA for spinal imaging on a 80kg patient. A direct comparison of the image quality is seen below. Because of the minor differences in quality, I typically use a low dose setting on all fluoroscopy initially, then will revert to higher radiation doses if needed. |
| Note in the photos above, the patient received 1.18mA in low dose mode, 3.33mA in normal fluoro, 6.6mA in high dose mode, and 25.6mA in digital spot mode. Effectively this patient receives 25 times the radiation using digital spot vs low dose with only a marginal improvement in the quality of the picture. Selection of magnification also increases the dosage by 50% and 100% for Mag1 and Mag2 respectively. |
| Other methods of obtaining magnification without using the increased radiation associated with the magnify mode include placement of the image intensifier far above the patient as in the pic below. The source beam is moved toward the patient and the image intensifier is moved far away from the patient. If one elects to do this, low dose setting is preferred since placement of the beam close to the patient may result in increased focal radiation, especially to the skin. Another mode that may accomplish the same is post-fluoroscopy digital zoom. Many fluoroscopes are now offering this feature in which a smaller area of the image already displayed on the monitor is selected, and a digital zoom applied without requiring re-exposure to radiation. |
| There are times when the presence of dense anatomy degrades the image to the point low dose cannot be used or offers such poor resolution that it is undesireable. An example of this is shown below. This is especially true when fluoroscopic visualization in the cross table lateral position is used. Note the improvement in resolution in normal dose mode at a cost of 250% higher radiation |
Other Patient Protections Against Excess Radiation:
1. Use the lowest possible distance between the image intensifier and the patient. This maximizes the distance
between the beam generator and the patient, thereby lowering the intensity of radiation at the skin.
2. Avoid prolonged radiation exposure of the patient (keep the time <30 min if possible).
3. Avoid lateral and oblique views as much as is feasible due to the inherent increases in radiation in these
positions.
4. Avoid prolonged radiation exposure with the beam in one position. Patients can develop skin burns as
shown below 4 weeks after protracted procedures. The patient below had an exposure of >120 minutes.
1. Use the lowest possible distance between the image intensifier and the patient. This maximizes the distance
between the beam generator and the patient, thereby lowering the intensity of radiation at the skin.
2. Avoid prolonged radiation exposure of the patient (keep the time <30 min if possible).
3. Avoid lateral and oblique views as much as is feasible due to the inherent increases in radiation in these
positions.
4. Avoid prolonged radiation exposure with the beam in one position. Patients can develop skin burns as
shown below 4 weeks after protracted procedures. The patient below had an exposure of >120 minutes.
5. Use beam collimation to focus in on the target. This markedly reduces radiation.
6. Use a laser aiming device to pre-aim the beam before firing the beam
7. Avoid "panning" with a live beam...use spot shots instead
8. Lower the room lights to help with the visualization
9. Utilize a 2 needle technique when lateral position visualization is difficult (eg.
place one needle on the pedicle AP then turn to lateral and use the tip as a depth and
trajectory marker)
10. Look immediately preceeding fluoroscope activation
11. Avoid redundant views...re-exposing the same position over and over to improve
the image on the monitor is futile- you must change something, then re-expose
12. Do not permit the tech to activate the machine if you can control your use of the
pedal. Do not stand on the pedal. Know the pedal functions and which pedal does
what (for OEC, typically the left pedal is normal fluoro mode). Avoid needle
advancement under live fluoroscopy.
13. When the automatic image process controls make visualization difficult due to
excessive attenuation, instead of re-exposing, use manual bright/contrast adjustment
(see the example below: placement of a hemostat in the field causes excessive
brightness that can be corrected through manual controls.
6. Use a laser aiming device to pre-aim the beam before firing the beam
7. Avoid "panning" with a live beam...use spot shots instead
8. Lower the room lights to help with the visualization
9. Utilize a 2 needle technique when lateral position visualization is difficult (eg.
place one needle on the pedicle AP then turn to lateral and use the tip as a depth and
trajectory marker)
10. Look immediately preceeding fluoroscope activation
11. Avoid redundant views...re-exposing the same position over and over to improve
the image on the monitor is futile- you must change something, then re-expose
12. Do not permit the tech to activate the machine if you can control your use of the
pedal. Do not stand on the pedal. Know the pedal functions and which pedal does
what (for OEC, typically the left pedal is normal fluoro mode). Avoid needle
advancement under live fluoroscopy.
13. When the automatic image process controls make visualization difficult due to
excessive attenuation, instead of re-exposing, use manual bright/contrast adjustment
(see the example below: placement of a hemostat in the field causes excessive
brightness that can be corrected through manual controls.
Yet another method to use low dose settings and improve the image involves the use of "averaging". As long as there is not
significant patient movement, the fluoroscope will "average" several images together electronically to develop a sharper
picture. If there is significant patient or physician needle movement, averaging can be turned down or off. Without patient
movement, the averaging can be turned up to permit a crisper pictures, still at low dose in the example below.
significant patient movement, the fluoroscope will "average" several images together electronically to develop a sharper
picture. If there is significant patient or physician needle movement, averaging can be turned down or off. Without patient
movement, the averaging can be turned up to permit a crisper pictures, still at low dose in the example below.
| PHYSICIAN EXPOSURE TO RADIATION Physician radiation exposure effects are cumulative over a lifetime, therefore there are no "safe limits" per year. There are regulatory defined limits that when exceeded will require modification of practice in order to reduce the exposure, but these are artificially defined and do not take into account the long term effects of radiation. The two types of radiation physicians receive from fluoroscopy are primary and scatter radiation. Primary Beam Exposure It cannot be overemphasized the power of the primary beam. This beam goes through leaded aprons, leaded glasses, thyroid shields, and especially leaded gloves as though they are not even there. Therefore shielding protects only against scatter radiation, and does nothing to protect against primary beam radiation. Placement of leaded gloves in the primary beam may actually result in substantially increased radiation output from the fluoroscope as the device boosts the output beam to compensate for the increased density in the field. NEVER PLACE YOUR HAND IN THE PRIMARY BEAM!!!! Physicians risk tumor development, esp. sarcoma from such maneuvers. If one must advance a needle under live fluoroscopy, use collimation to exclude the hands from the field or use a hemostat to advance the needle. Scatter Radiation Exposure Scatter radiation represents the reflected radiation as the primary beam strikes bone and soft tissues, and is reflected at different angles laterally and on the side of the beam. This scatter radiation is of a much lower intensity than the primary beam radiation and has attenuated x-ray energies due to the absorption of the more powerful xrays by the patient's body. Distance from the primary beam is the primary determinate of the degree of scatter radiation, and falls off rapidly as one moves away from the beam. |
By comparison, patients receive 1200-4000mRem/hr from the primary beam. A chest xray exposure is
25mRem and a hip xray is 500mRem.
Scatter radiation is not homogeneous and varies with the position of the beam relative to the patient,
the angle of the C-arm rotation, and patient scatter characteristics. With the beam located directly
below the patient without any rotation, the maximum scatter comes as a reflection off the bones of the
patient and is primarily below the level of the table. Therefore in a normal beam configuration (below
the table), the maximum scatter radiation is to the physician's knees and feet. It is therefore important
to assure the radiation gowns cover at least the knees and preferably below. Shielded lead strips hung
from the side of the fluoroscopy table will further reduce scatter radiation. With the beam inverted and
above the patient, the scatter radiation occurs primarily above the level of the table, striking the eyes,
thyroid, and arms (which are usually unprotected). Therefore, one should endeavor to have the beam
source coming from beneath the table. The sole exception to this is in the case where an arm or
extremity are having a surgical procedure when using the I/I as an operating table. In this case, the
scatter radiation is less with the fluoroscopy configuration inverted than in a normal standard
configuration used for pain management.
25mRem and a hip xray is 500mRem.
Scatter radiation is not homogeneous and varies with the position of the beam relative to the patient,
the angle of the C-arm rotation, and patient scatter characteristics. With the beam located directly
below the patient without any rotation, the maximum scatter comes as a reflection off the bones of the
patient and is primarily below the level of the table. Therefore in a normal beam configuration (below
the table), the maximum scatter radiation is to the physician's knees and feet. It is therefore important
to assure the radiation gowns cover at least the knees and preferably below. Shielded lead strips hung
from the side of the fluoroscopy table will further reduce scatter radiation. With the beam inverted and
above the patient, the scatter radiation occurs primarily above the level of the table, striking the eyes,
thyroid, and arms (which are usually unprotected). Therefore, one should endeavor to have the beam
source coming from beneath the table. The sole exception to this is in the case where an arm or
extremity are having a surgical procedure when using the I/I as an operating table. In this case, the
scatter radiation is less with the fluoroscopy configuration inverted than in a normal standard
configuration used for pain management.
The image intensifier should
be above the patient as shown
to the left. Also, scatter
radiation is lessened by
increasing the distance
between the beam and the
patient, ie. by operating in a
smaller air gap between the
image intensifier and the
patient. The image intensifier
is recognizable because it is
always has a larger flat surface
than the beam.
be above the patient as shown
to the left. Also, scatter
radiation is lessened by
increasing the distance
between the beam and the
patient, ie. by operating in a
smaller air gap between the
image intensifier and the
patient. The image intensifier
is recognizable because it is
always has a larger flat surface
than the beam.
Scatter radiation in the AP view, primarily comes off the
patient at angles that have the highest scatter radiation
intensity under the table and just lateral to the table. The
illustration to the right demonstrates the highest, moderate,
and lower bands of intensity in red, yellow, and green
respectively. Therefore, the knees and feet are most
exposed in this fluoroscopic angle. However, note that if
one lowers their hands to the level of the table, there is
significant exposure to the hands. It is prudent to raise the
hands to the level of the physician's shoulders and bring the
hands towards the physician's body in order to reduce
scatter radiation to the hands. The more intense radiation
from the primary beam (eg. thick patients, high dose fluoro),
the more scatter radiation intensity.
patient at angles that have the highest scatter radiation
intensity under the table and just lateral to the table. The
illustration to the right demonstrates the highest, moderate,
and lower bands of intensity in red, yellow, and green
respectively. Therefore, the knees and feet are most
exposed in this fluoroscopic angle. However, note that if
one lowers their hands to the level of the table, there is
significant exposure to the hands. It is prudent to raise the
hands to the level of the physician's shoulders and bring the
hands towards the physician's body in order to reduce
scatter radiation to the hands. The more intense radiation
from the primary beam (eg. thick patients, high dose fluoro),
the more scatter radiation intensity.
Note the change in angle of scatter radiation when
the fluoro beam is rotated. When the beam is
pointed towards the physician, the scatter
radiation is primarily increased at the feet and
knees. When the beam is pointed away from the
physician, the primary scatter occurs at the level of
the physician's thyroid and eyes- undesireable.
Because of the increase in primary beam radiation
in the oblique and lateral views, the more oblique
the view, the more scatter radiation is produced.
Lateral views can produce 5 times the amount of
radiation vs PA views.
the fluoro beam is rotated. When the beam is
pointed towards the physician, the scatter
radiation is primarily increased at the feet and
knees. When the beam is pointed away from the
physician, the primary scatter occurs at the level of
the physician's thyroid and eyes- undesireable.
Because of the increase in primary beam radiation
in the oblique and lateral views, the more oblique
the view, the more scatter radiation is produced.
Lateral views can produce 5 times the amount of
radiation vs PA views.
Other ways to reduce scatter radiation exposure:
1. Reduce patient exposure time
2. Low dose radiation settings
3. Scatter shields: these may be purchased on line and are composed
of a transparent leaded material. The shield is placed in front of the
operator's face. There are versions that are stand alone and others
that are on swivel arms suspended from the wall or ceiling
4. Collimators, leaf or iris, reduce scatter radiation significantly
through reduction of exposed patient tissues. Use tight collimation
when possible.
5. Avoid lateral or extensive oblique views as these increase radiation
output
6. Avoid the use of magnification when possible
7. Use long radiation gowns and thyroid shields. Leaded glasses are
optimal when physicians use significant fluoroscopy time. Leaded
gloves may be useful, but only if the hands are kept from the primary
beam.
8. When moving the hands from the operating field during
fluoroscopy, do not drop the hands below the level of the patient's
body. The least scatter occurs with the hands held at the physician's
shoulder level and retracted away from the patient.
9. Take one step back during fluoroscopy, especially during oblique
or lateral rotation of the beam.
1. Reduce patient exposure time
2. Low dose radiation settings
3. Scatter shields: these may be purchased on line and are composed
of a transparent leaded material. The shield is placed in front of the
operator's face. There are versions that are stand alone and others
that are on swivel arms suspended from the wall or ceiling
4. Collimators, leaf or iris, reduce scatter radiation significantly
through reduction of exposed patient tissues. Use tight collimation
when possible.
5. Avoid lateral or extensive oblique views as these increase radiation
output
6. Avoid the use of magnification when possible
7. Use long radiation gowns and thyroid shields. Leaded glasses are
optimal when physicians use significant fluoroscopy time. Leaded
gloves may be useful, but only if the hands are kept from the primary
beam.
8. When moving the hands from the operating field during
fluoroscopy, do not drop the hands below the level of the patient's
body. The least scatter occurs with the hands held at the physician's
shoulder level and retracted away from the patient.
9. Take one step back during fluoroscopy, especially during oblique
or lateral rotation of the beam.
The best way to reduce scatter by far is use of
x-ray shielding around the fluoroscopy table.
These are attachable to many types of tables
and reduce scatter to extremely low doses. The
manufacturer's website is located here.
x-ray shielding around the fluoroscopy table.
These are attachable to many types of tables
and reduce scatter to extremely low doses. The
manufacturer's website is located here.
Fluoroscopy Bells and Whistles: Optimizing the Use of Fluoroscopy
1. Avoid parallax error- the x-rays leaving the beam do not travel parallel. The rays to the outside of the beam travel
at an angle to those in the center of the beam due to the image intensifier being larger than the beam source.
Therefore fine fluoroscopic image control is better achieved by visualization of the target in the dead center of the
fluoroscope monitor. Do not permit your technician operating the scope to force you to place needles at the edge of
the fluoroscopy monitor. The error in parallax may be up to 1-2 mm at the edge of the field compared to that of
placing the target image in the center of the monitor.
2. Set up the fluoroscopy views the same way every time. For instance, many physicians prefer the right side of the
fluoroscopy image to be the right side of the patient. This may entail reversing the image. Also, orientation of the
image is important...ie. rotate the image straight up and down or if it is your preference, laterally on the fluoroscopic
monitor, but do not use oblique monitor images as these are confusing. The consistency of set up of the
fluoroscopy image will save time during needle placement. I have found it useful to personally place the fluoroscope
in the starting position before the prep, and set up my monitor orientation and collimation (leaf or iris).
3. Know your fluoroscope better than the tech who is running it. If you know the proper terminology and location of
controls on the fluoroscope, you can save enormous amounts of time by avoiding the tech looking all over the
machine for a simple control. Spend some time playing with the machine...you cannot hurt it.
4. Digital subtraction is extremely useful in determining foraminal blood vessel injection and is strongly
recommended, especially in the cervical region. However, be aware the radiation exposure during digital
subtraction is significant. The views obtained during DS can be replayed over and over again as a cine at 8 frames
per second (more than this is not necessary for pain management) and there are cases where DS demonstrates
vessles that real time fluoro injections missed.
5. Electronic image integration. Most modern C-arms permit "smoothing" of images through integrating several
fluoro images together called "averaging". This produces very sharp images, but when there is patient movement, it
is useful to deactivate these features.
6. Electronic data storage. Modern c-arms permit storing the images selected in various formats: floppy disc,
DICOM, on board printer, datacards (company specific), on board DVD or CD burners, and now it appears the latest
machines will provide USB/card memory support. Salient image storage is mandatory in the litigious environment
today when such is available.
7. Post image processing- the latest machines provide excellent on board software activated through touch
screens to provide zoom, sharpening, negative images (may provide excellent detail with contrast injections),
advanced annotation and labeling of images, and other digital features. These can reduce radiation exposure
through post processing image optimization.
1. Avoid parallax error- the x-rays leaving the beam do not travel parallel. The rays to the outside of the beam travel
at an angle to those in the center of the beam due to the image intensifier being larger than the beam source.
Therefore fine fluoroscopic image control is better achieved by visualization of the target in the dead center of the
fluoroscope monitor. Do not permit your technician operating the scope to force you to place needles at the edge of
the fluoroscopy monitor. The error in parallax may be up to 1-2 mm at the edge of the field compared to that of
placing the target image in the center of the monitor.
2. Set up the fluoroscopy views the same way every time. For instance, many physicians prefer the right side of the
fluoroscopy image to be the right side of the patient. This may entail reversing the image. Also, orientation of the
image is important...ie. rotate the image straight up and down or if it is your preference, laterally on the fluoroscopic
monitor, but do not use oblique monitor images as these are confusing. The consistency of set up of the
fluoroscopy image will save time during needle placement. I have found it useful to personally place the fluoroscope
in the starting position before the prep, and set up my monitor orientation and collimation (leaf or iris).
3. Know your fluoroscope better than the tech who is running it. If you know the proper terminology and location of
controls on the fluoroscope, you can save enormous amounts of time by avoiding the tech looking all over the
machine for a simple control. Spend some time playing with the machine...you cannot hurt it.
4. Digital subtraction is extremely useful in determining foraminal blood vessel injection and is strongly
recommended, especially in the cervical region. However, be aware the radiation exposure during digital
subtraction is significant. The views obtained during DS can be replayed over and over again as a cine at 8 frames
per second (more than this is not necessary for pain management) and there are cases where DS demonstrates
vessles that real time fluoro injections missed.
5. Electronic image integration. Most modern C-arms permit "smoothing" of images through integrating several
fluoro images together called "averaging". This produces very sharp images, but when there is patient movement, it
is useful to deactivate these features.
6. Electronic data storage. Modern c-arms permit storing the images selected in various formats: floppy disc,
DICOM, on board printer, datacards (company specific), on board DVD or CD burners, and now it appears the latest
machines will provide USB/card memory support. Salient image storage is mandatory in the litigious environment
today when such is available.
7. Post image processing- the latest machines provide excellent on board software activated through touch
screens to provide zoom, sharpening, negative images (may provide excellent detail with contrast injections),
advanced annotation and labeling of images, and other digital features. These can reduce radiation exposure
through post processing image optimization.
Note the sharpened border of the head of the
humerus above in the post x-ray sharpened
edge processing. Also not the digital zoom to
the left. Both are features that must be
activated on the monitor console of the
OEC9800 and can be a useful way to save
radiation exposure. Note since the processing
was performed after the xray exposure has
been made, there is no additional radiation
produced during the processing. Sharpening
the image renders it more grainy, but can also
produce sharp edges. This can be very useful
in injected facet joints with fine sharp edges.
humerus above in the post x-ray sharpened
edge processing. Also not the digital zoom to
the left. Both are features that must be
activated on the monitor console of the
OEC9800 and can be a useful way to save
radiation exposure. Note since the processing
was performed after the xray exposure has
been made, there is no additional radiation
produced during the processing. Sharpening
the image renders it more grainy, but can also
produce sharp edges. This can be very useful
in injected facet joints with fine sharp edges.
Know the Fluoro Controls functions!!! Below are some of the controls for the
OEC9800 located on the C-arm control panel.
OEC9800 located on the C-arm control panel.
To the right are some
of the more useful
controls located on
the monitor column to
the left of the keypad
on the OEC9800. The
averaging control is a
real time fluoro
control whereas the
zoom, sharpen, and
negate are post-image
digital processing
controls.
The swap button is a
very useful way to
compare one fluoro
view on the right
monitor with another
fluoro view on the left.
of the more useful
controls located on
the monitor column to
the left of the keypad
on the OEC9800. The
averaging control is a
real time fluoro
control whereas the
zoom, sharpen, and
negate are post-image
digital processing
controls.
The swap button is a
very useful way to
compare one fluoro
view on the right
monitor with another
fluoro view on the left.
| Buying a Fluoroscope Rule of thumb: If someone else is buying the fluoroscope, try to get the best possible system. If you are buying the fluoroscope for your office, then you may want to consider a used system or leased system. Most fluoroscopy units for pain management are mobile C-arms, although there are other units such as biplaner fluoroscopy or fixed fluoroscopy units or ceiling mounted units. The decision to buy a fluoroscope should be based on several variables: INCREASED INCOME FACTORS 1. Medicare and other insurer patient class mix percentage for those that pay a premium for keeping the procedures in the office (Anthem, Medicare, and some workman's comp are now paying extra to the physician to avoid surgery centers and hospitals for pain procedures). Medicare pays the physician approximately $150 more for a transforaminal ESI performed in the office compared to a surgery center or hospital 2. Relative increase in operating efficiency compared to hospitals...time is money and often hospitals don't care about your time waiting 45 min between cases for turnover time....also the paperwork requirements for performing procedures in hospitals are usually excessive, redundant, and do not increase patient safety but do cost time. INCREASED EXPENSE FACTORS: 1. Disposable item cost 2. Monitor costs (for any cervical procedures one needs at least a pulse oximeter and automated BP if not an ECG) 3. Resuscitation equipment costs (Defibrillator or ACD), Intubation equipment, suction, oxygen, drugs for resuscitation, LMAs 4. C-arm table (usually $10-30K), 6. C-arm (used $20K-100K, new $100K-$160K), 7. Increased space rental requirements 8. Increased staffing requirements, 8. C-arm technician costs in states requiring techs. C-arms may be leased for $1200-3000 per month depending on the lease terms and cost. The minimum quality for a C-arm should be at least an OEC 9400, Ziehm 7000, Sirecast, etc. The minimum features of such a system should include datastorage system (printout is not absolutely necessary as long as images can be accessed), adequate visualization of image, at least 10mA usable beam current (20 is better), and pedal control. The C should be easy to move in all directions, and replacement equipment and repair capabilities should be available. While the OEC is the most commonly sold equipment in the US, the Ziehm makes an excellent machine (2nd generation), and the Phillips and Siemans machines are nearly all equivalent in capabilities. If one plans to perform vertebroplasty in the office setting, a fluoroscope of at least the quality of an OEC 9600 should be used. FEATURES THAT MAY BE IMPORTANT **Machines with active cooling and rotating anodes: OEC 9800, 9600, Phillips Pulsera (these are for high dose, extended use with excellent imaging....the anode will not pit out as much as stationary anodes, therefore the image quality will be maintained for a longer period of time. **Machines with a very wide arc of range Siemans Iso-C (190degree rotational arc- effectively one never has to invert the fluoroscope tube), Elmstech Imperium (190 degree arc), Phillips Endura and Pulsera (135 degree arc), Ziehm 7000 **Isocentric Rotation Ziehm Vario, Siemans Iso-C series, Elmstech Imperium **Extra patient scatter protection- Phillips Filters **Digital Subtraction- OEC9800 Neurovasc (the pain model of OEC9800 does not), Imperium, Higher end models of other manufacturers Manufacturers Web Sites OEC (GE) Phillips Siemans Ziehm Elmstech Simad |
Leaded aprons for fluoroscopy: At least 1mm lead equivalent is required for adequate shielding (80%) for normal
C-arm operation. Do not confuse this with the ultralight 1/2 mm lead equivalent aprons that are available for mini-C use...this
provides inadequate shielding. Also, the two piece vest/apron is more comfortable than one piece but is cumbersome to put
on and take off when performing several short procedures. The aprons with the built in thyroid shields may be very
uncomfortable if the thyroid shield is attached along its border to the gown. If one decides to buy a x-ray apron with a
thyroid shield, then buy one with the thyroid shield tethered to the gown via attached plastic string. Hang the aprons up on
a rack after using them and do not fold the aprons as this creates cracks in the shielding.
C-arm operation. Do not confuse this with the ultralight 1/2 mm lead equivalent aprons that are available for mini-C use...this
provides inadequate shielding. Also, the two piece vest/apron is more comfortable than one piece but is cumbersome to put
on and take off when performing several short procedures. The aprons with the built in thyroid shields may be very
uncomfortable if the thyroid shield is attached along its border to the gown. If one decides to buy a x-ray apron with a
thyroid shield, then buy one with the thyroid shield tethered to the gown via attached plastic string. Hang the aprons up on
a rack after using them and do not fold the aprons as this creates cracks in the shielding.
Other Shielding Methods and Equipment
The use of leaded glass eyeware, external shield panels, and radiation gloves are all available. Thyroid shields should be
worn by the pain management physician due to the oblique fluoroscopy views that increase thyroid exposure. If one is
performing vertebroplasty or any high radiation exposure procedure, then consider wearing leaded glasses. The use of
external shields and panels may help protect the eyes and thyroid without additional glasses or thyroid shields, but these
make the placement of needles somewhat cumbersome. Certainly a full body radiation screen is effective, but causes the
procedures to be extremely protracted. Radiation gloves protect against scatter radiation only. The penetration of
primary beam into radiation gloves is 95% of that when wearing non-leaded gloves, therefore keep the hand out of the
beam. Scatter radiation is reduced by 10-35% with radiation gloves, but if the hands are brought up to the levels of the
shoulders, the scatter to the hands is minimal anyway.
The use of leaded glass eyeware, external shield panels, and radiation gloves are all available. Thyroid shields should be
worn by the pain management physician due to the oblique fluoroscopy views that increase thyroid exposure. If one is
performing vertebroplasty or any high radiation exposure procedure, then consider wearing leaded glasses. The use of
external shields and panels may help protect the eyes and thyroid without additional glasses or thyroid shields, but these
make the placement of needles somewhat cumbersome. Certainly a full body radiation screen is effective, but causes the
procedures to be extremely protracted. Radiation gloves protect against scatter radiation only. The penetration of
primary beam into radiation gloves is 95% of that when wearing non-leaded gloves, therefore keep the hand out of the
beam. Scatter radiation is reduced by 10-35% with radiation gloves, but if the hands are brought up to the levels of the
shoulders, the scatter to the hands is minimal anyway.
| Electrons are accelerated to increasing velocities dependent on the voltage difference between the cathode and the anode. X-rays are produced above 40,000 volts (40kV) and the higher the voltage, the higher energy x-rays are produced. Humans absorb some of these x-rays and scatter the remainder. Because lower energy x-rays do not penetrate the entire body, but can cause skin and soft tissue burns, the lower energy x-rays are filtered out of the primary beam through use of absorbing filters. The higher the energy (kV), the more is the penetration of the human body, and the less is absorbed by the body. However, at high kV, the differences between tissue absorption is not significant, and therefore the pictures obtained lack contrast to discern fine details. The x-ray machine usually automatically determines the proper kV based on patient size (obese patients receive a higher kV) and the image contrast. The current flowing to produce |
