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Minimizing Risks from Fluoroscopic X-rays Diagnostic Radiology Imaging Physics Course December 2004 Introduction Minimizing Risks from Fluoroscopic XX-rays ¬ Brent K Stewart, PhD, DABMP Professor, Radiology and Medical Education Director, Diagnostic Physics a copy of this lecture may be found at: http://courses.washington.edu/radxphys/PhysicsCourse04http://courses.washington.edu/radxphys/PhysicsCourse04-05.html On September 9th, 1994, the FDA issued an advisory for facilities facilities that use fluoroscopy for invasive procedures Recommendations… ¬ Appropriate credentials and training for physicians performing fluoroscopy ¬ Operators be trained and understand system operation, and implications of radiation exposure for each mode of operation ¬ Physicians be educated in assessing risks and benefits on a casecase-byby-case basis for patients ¬ Patients be counseled regarding the symptoms and risks of large radiation exposures ¬ Physicians justify and limit use of high dose rate modes of operation Brent K Stewart, PhD, DABMP Who can perform Fluoroscopy and Associated Radiography? ¬ Most states have regulations regarding the operation of radiation radiation producing equipment and these regulations vary from state to state state ¬ In some states, it may be illegal for an untrained person to operate operate an xx-ray machine even under the direct orders of a physician ¬ However, the fact is that many physicians who use fluoroscopy have have essentially no training in this area Washington State Law ¬ Brent K Stewart, PhD, DABMP Brent K Stewart, PhD, DABMP Brent K Stewart, PhD, DABMP WAC 246246-225225-020 ¬ Operators shall be adequately instructed in safe operating procedures and shall be able to demonstrate competence ¬ A medical xx-ray machine operator shall be licensed, certified or registered by the department as either: ¬ a licensed health care practitioner ¬ a certified diagnostic or therapeutic RT ¬ a registered xx-ray technician Minimizing Risks from Fluoroscopic X-rays Diagnostic Radiology Imaging Physics Course December 2004 What should an operator know? ¬ ¬ ¬ ¬ ¬ ¬ ¬ What an operator should know How to operate the machine How to properly position the patient How to minimize the use of radiation How to properly use shielding devices and personnel monitoring devices How the radiation is distributed in the room How to control the factors that optimize image quality (kVp, mA etc.) How to control factors that reduce radiation levels (collimation) (collimation) ¬ Two professionals trained in specific aspects of fluoroscopy are the radiological technologist and medical physicist ¬ Nurses or physician assistants should be trained in its safe and proper operation if asked to operate xx-ray equipment ¬ Physician is ultimately responsible for assuring that the xx-rays are safely and properly applied and that appropriate radiation protection protection measures are followed Brent K Stewart, PhD, DABMP Brent K Stewart, PhD, DABMP Potential effects in skin from fluoroscopy Skin Injuries ¬ During the application of xx-rays, the patient has no sensation of temperature rise in the skin, even if the patient is fully conscious conscious and even for all but the most massive doses of radiation ¬ Small doses from modern equipment might induce cancer, but the frequency of induction would be too low to detect a direct relationship with xx-rays ¬ Chronic exposure to low doses can also result in gradual erosion of tissue Brent K Stewart, PhD, DABMP Brent K Stewart, PhD, DABMP c.f Wagner and Archer Minimizing Risks from Fluoroscopic X-rays 1996 Brent K Stewart, PhD, DABMP Minimizing Risks from Fluoroscopic X-rays Diagnostic Radiology Imaging Physics Course December 2004 Skin Injuries – Case Reports Skin Injuries – Case Reports Three weeks post rf cardiac catheter ablation Ischemic dermal necrosis months post procedure Exposed to 20 minutes fluoro with elbow 2025 cm from focal spot Note circular pattern coinciding with x-ray beamport Suggesting that the 18 Gy threshold was passed during the procedure Deep ulceration with exposure of the humerus at 6.5 months post-procedure Some radiation ulcers never heal completely, but break down intermittently Progression of the ulcer may ensue and can be extensive, exposing deep tissues such as tendons, muscles or bones c.f Koenig TR, et al Skin Injuries from Fluoroscopically Guided Procedures: Part 1, Characteristics of Radiation Injury AJR 2001, 177, pp 3-11 c.f Koenig TR, et al Skin Injuries from Fluoroscopically Guided Procedures: Part 1, Characteristics of Radiation Injury AJR 2001, 177, pp 3-11 Brent K Stewart, PhD, DABMP Brent K Stewart, PhD, DABMP 10 Skin Injuries – Case Reports Three transjugular intrahepatic portosystemic shunt placements within a week Radiation Injuries of the Skin Injuries that are advanced to this stage require surgical excision and grafting ¬ ¬ Non-healing deep tissue necrotic ulcer with exposure of deep tissues, including spinous processes of vertebra at 22 mos At 23 months, musculocutaneous skin grafting was performed Disfigurement is permanent Many articles in literature about skin injuries (see Koenig manuscript) manuscript) Some case reports teach us two important lessons: ¬ Radiation dermatitis is delayed, from weeks to years after the exposure exposure ¬ Several procedures can result in very high cumulative doses to the the same area if the skin ¬ A conscientious effort should be made to avoid prolonged exposure exposure to the same area of the skin ¬ Documentation of certain conditions will help physicians if future future procedures are needed ¬ A careful record identifying the location of the exposed skin will will alert other physicians about the need to avoid irradiation of the same area ¬ A record of the estimated skin dose is also helpful c.f Koenig TR, et al Skin Injuries from Fluoroscopically Guided Procedures: Part 1, Characteristics of Radiation Injury AJR 2001, 177, pp 3-11 Brent K Stewart, PhD, DABMP Brent K Stewart, PhD, DABMP 11 Brent K Stewart, PhD, DABMP 12 Minimizing Risks from Fluoroscopic X-rays Diagnostic Radiology Imaging Physics Course December 2004 Commandment #1: Patient Size Controlling Image Quality, Dose and Dose Rate ¬ The following ten factors are the principal determinants of image image quality, radiation dose rate and total radiation dose to the patient patient and to personnel during fluoroscopy “the Ten Commandments” Commandments” ¬ patient size ¬ tube current (mA) and kVp ¬ proximity of the xx-ray tube to the patient ¬ proximity of the II to the patient ¬ image magnification ¬ x-ray field collimation and use of a grid ¬ shielding and position of personnel relative to patient and equipment ¬ beambeam-on time ¬ Brent K Stewart, PhD, DABMP Keep in mind that dose rates are greater and dose accumulates quicker for larger patients Brent K Stewart, PhD, DABMP 13 14 Commandment #2: Tube Current (mA) ¬ Commandment #3: Tube Kilovoltage (kVp) Keep the tube current as low as possible ¬ Brent K Stewart, PhD, DABMP Brent K Stewart, PhD, DABMP 15 Brent K Stewart, PhD, DABMP Keep the kVp as high as possible to achieve the appropriate compromise between image quality and low patient dose 16 Minimizing Risks from Fluoroscopic X-rays Diagnostic Radiology Imaging Physics Course December 2004 Commandment #4: Proximity of XX-ray tube to Patient ¬ Commandment #5: Proximity of the Image Intensifier to the Patient Keep the xx-ray tube at the maximal “reasonable” distance from the patient ¬ Brent K Stewart, PhD, DABMP Keep the image intensifier as close to the patient as possible ¬ To optimize image quality and reduce radiation dose ¬ Optimize image quality ⇒ distortion of anatomy and image blur decreases ¬ Radiation Dose decrease ⇒ x-ray intensity required to produce a bright image (automatic brightness control) decreases Brent K Stewart, PhD, DABMP 17 18 Commandment #6: Image Magnification (#6) Magnification ¬ ¬ Don’t overuse the magnification mode of operation ¬ Magnification can be achieved in ways: ¬ magnification option on the image intensifier ¬ geometric magnification Brent K Stewart, PhD, DABMP Brent K Stewart, PhD, DABMP 19 Brent K Stewart, PhD, DABMP Magnification options of the image intensifier ¬ This is achieved by making the xx-ray field smaller and displaying the smaller field over the full viewing area of the monitor ¬ The mode of least magnification (largest field) usually delivers the lowest dose rate ¬ Sometimes the dose rate does not change with magnification but frequently, the dose rate increases with magnification ¬ To optimize overall radiation management, use the lowest level of magnification consistent with the goals of the procedure and reduce the irradiated volume of the patient by employing narrow collimation 20 Minimizing Risks from Fluoroscopic X-rays Diagnostic Radiology Imaging Physics Course December 2004 (#6) Magnification ¬ ¬ Commandment #7: The Grid Geometric Magnification ¬ Achieved by increasing the distance between the patient and the image intensifier (contrary to dose reduction method) ¬ Geometric magnification can be used with isocentric systems ¬ Dose typically increases with the square of the magnification ¬ i.e., if magnification increases by 2x, dose rate goes up by 4x ¬ Maximum dose rates in this configuration may exceed 10 R/min (legal entrance exposure limit) ¬ this is because compliance dose rates are tested under conditions of least geometric magnification (patient closest to image intensifier) Again, the minimum magnification consistent with the goals of the the procedure should be used to manage radiation properly ¬ Brent K Stewart, PhD, DABMP Remove the grid during procedures on small patients, thin body parts or when the image intensifier cannot be placed close to the the patient Brent K Stewart, PhD, DABMP 21 22 Commandment #8: X-Ray field Collimation ¬ Commandment #9: Distance and Shielding Always use tight collimation ¬ Brent K Stewart, PhD, DABMP Brent K Stewart, PhD, DABMP 23 Brent K Stewart, PhD, DABMP Personnel must wear protective aprons, use shielding, monitor their their doses, and know how to position themselves and the imaging equipment for minimum dose 24 Minimizing Risks from Fluoroscopic X-rays Diagnostic Radiology Imaging Physics Course December 2004 (#9) Shielding and Distance (#9) Shielding and Distance ¬ The principal source of radiation for the patient is the xx-ray tube ¬ Brent K Stewart, PhD, DABMP The principal source of radiation for the operator and other personnel is scatter from the patient Brent K Stewart, PhD, DABMP 25 (#9) Shielding and Distance (#9) Shielding and Distance ¬ 26 ¬ One of the most important means by which personnel can reduce dose to themselves is by using shielding and properly positioning themselves relative to the patient and the fluoroscopic equipment ¬ ¬ Lead aprons ¬ lead equivalency: 0.25 mm to 0.50 mm ¬ 0.25 mm: absorbs > 90% of scatter ¬ 0.35 - 0.50 mm: absorbs 95 - 99% of scatter (but heavier) Lead aprons should be properly stored on a hanger when not in use use Aprons should be checked annually for holes, cracks or other forms forms of deterioration x-ray ¬ All personnel who are not positioned behind a radiation barrier must wear a lead apron during a procedure Brent K Stewart, PhD, DABMP Brent K Stewart, PhD, DABMP 27 Brent K Stewart, PhD, DABMP 28 Minimizing Risks from Fluoroscopic X-rays Diagnostic Radiology Imaging Physics Course December 2004 Protection of Physician’s Hands (#9) Shielding and Distance ¬ Aprons not protect the thyroid gland or the eyes ¬ Thyroid shields and leaded glass can be used ¬ Leaded glass attenuates 30%30%-70% depending on the content of lead in glass ¬ Protective gloves of 0.5 mm lead of greater should be worn if hands are going to be near the primary beam (false sense of protection) ¬ ¬ ¬ ¬ ¬ Dermal atrophy of the forearm and hands were observed in physician who performed fluoroscopy for years Convinced some physicians to wear special radiationradiation-attenuating surgical gloves or hand shields Such devices are not likely to protect hands if placed fully into into the beam The automatic brightness control (ABC) detect the reduction in brightness due to the attenuation by the gloves and boost the radiation output to penetrate the “protective” gear Protective hand gear can be relied on only to protect against radiation outside the field of view of the ABC Brent K Stewart, PhD, DABMP Brent K Stewart, PhD, DABMP 29 30 Protection of Physician’s Hands ¬ Protection of Physician’s Hands To protect hands during fluoroscopy, it is recommended: ¬ Keep hands out of and away from the xx-ray field when the beam is on unless physician control of invasive devices is requires for for patient care during fluoroscopy ¬ Work on the exitexit-beam side of the patient whenever possible ¬ x-ray tube should be below table for vertical orientations ¬ for oblique and lateral projections, stand on the side of the patient where the image intensifier is located ¬ for adult abdomen, exit radiation is only about 1% the intensity of the entrance radiation ¬ extra care must be exercised in situations where physician must work on the xx-ray tube side of the patient ¬ Brent K Stewart, PhD, DABMP 31 Brent K Stewart, PhD, DABMP To protect hands during fluoroscopy, it is recommended to: ¬ wear a ring badge to measure your hand exposure monthly ¬ ring monitors dose only at the base of the finger ¬ dose at the finger tips may be significantly higher c.f Wagner and Archer Minimizing Risks from Fluoroscopic X-rays – Supplement 1997 Brent K Stewart, PhD, DABMP 32 Minimizing Risks from Fluoroscopic X-rays Diagnostic Radiology Imaging Physics Course December 2004 (#9) Shielding and Distance ¬ ¬ ¬ (#9) Distance All personnel who perform fluoroscopic procedures are required to wear a radiation monitoring device, usually a film badge ¬ Personnel potentially exposed to 10% of the occupational annual limit (50 mGy or 5000 mrem) need a radiation badge It is recommended that personnel wear their badges anteriorly on their collar outside of lead apron Badge readings are monitored by the radiation safety office (RSO) ¬ Radiation Dose to personnel can be significantly reduced by increasing their distance from the radiation source ¬ InverseInverse-square law: the dose rate drops significantly as the distance from the source increases Brent K Stewart, PhD, DABMP Brent K Stewart, PhD, DABMP 33 Given: Exposure Rate at ft = 90 mR/hr (#9) Distance 34 (#9) Radiation at Meter From Patient About 0.1% of patient entrance radiation exposure reaches meter from patient 1m ft ft ft ft2 ft2 ft ft ft2 x-ray ft ft ft 100% 0.1% ft ⎛D ⎞ E2 = E1 ⎜⎜ ⎟⎟ ⎝ D2 ⎠ The NCRP recommends that personnel stand at least meters from the x-ray tube, whenever possible (6 feet = 1.82 m) Exposure Rate at ft = (90 mR/hr)(2ft/4ft)2 = 22.5 mR/hr Exposure Rate at ft = (90 mR/hr)(2ft/6ft)2 = 10 mR/hr Brent K Stewart, PhD, DABMP Brent K Stewart, PhD, DABMP 35 Brent K Stewart, PhD, DABMP 36 Minimizing Risks from Fluoroscopic X-rays Diagnostic Radiology Imaging Physics Course December 2004 (#9) CC-Arm FluoroscopyFluoroscopy-Shielding ¬ ¬ ¬ (#9) The Separator Device (or Spacer Cone) With the CC-arm oriented vertically, the xx-ray tube should be located beneath the patient with the II above In a lateral or oblique orientation, the xx-ray tube should be positioned opposite the area where the operator and other personnel are working In other words, the operator and II should be located on the same same side of the patient ¬ This orientation takes advantage of the patient as a protective shield ¬ ¬ ¬ ¬ ¬ ¬ ¬ Brent K Stewart, PhD, DABMP The FDA requires that fluoroscopic xx-ray machines be designed so that the patient’s skin is at least a specified fixed distance from the XX-ray source The purpose of this regulation is to prevent the dangerous situation situation in which the intense beam emerging from the xx-ray source is too close to the patient’s skin To provide flexibility for some procedures, the FDA permits machines machines to be designed with removable spacers For Dx procedures, the device is to remain attached to the xx-ray source For modern machines fixed in room, this distance is 38 cm For mobile machines, this distance is 30 cm For “special surgical procedures” the device may be removed and the minimum distance can be as short as 20 cm (potentially dangerous) dangerous) Brent K Stewart, PhD, DABMP 37 38 (#9) The Separator Device (or Spacer Cone) Commandment #10: Beam OnOn-Time ¬ ¬ ¬ ¬ c.f Wagner and Archer Minimizing Risks from Fluoroscopic X-rays – Supplement 1997 Brent K Stewart, PhD, DABMP Brent K Stewart, PhD, DABMP Keep beambeam-on time to an absolute minimum! - The Golden Rule Control over beam onon-time is almost always the most important aspect of radiation management It is essential practice to disengage fluoroscopic exposure when the image on the monitor is not being used Absentmindedly leaving the xx-rays on while viewing other factors associated with the procedure, such as direct observation of the patient or communication with other personnel in the room, must be strictly avoided Brent K Stewart, PhD, DABMP 39 40 10 Minimizing Risks from Fluoroscopic X-rays Diagnostic Radiology Imaging Physics Course December 2004 Good vs Bad Geometry: Patient Dose and the Position of the Fluoroscope Fluoroscopic Timer ¬ A 5-minute cumulative timer is required on all fluoroscopic units to remind the operator audibly of each 5-minute time interval and to allow the technologist to keep track of the total amount of fluoro time for the exam the Good Brent K Stewart, PhD, DABMP 41 c.f Wagner and Archer Minimizing Risks from Fluoroscopic X-rays – Supplement 1997 Good vs Bad Geometry: Patient Dose and the Position of the Fluoroscope c.f Wagner and Archer Minimizing Risks from Fluoroscopic X-rays – Supplement 1997 Brent K Stewart, PhD, DABMP Brent K Stewart, PhD, DABMP 42 Good vs Bad Geometry: Summary ¬ the Ugly the Bad Differences in geometry of as little as a few centimeters can have have a major impact on dose to a patient’s skin even Uglier Brent K Stewart, PhD, DABMP 43 c.f Wagner and Archer Minimizing Risks from Fluoroscopic X-rays – Supplement 1997 Brent K Stewart, PhD, DABMP 44 11 Minimizing Risks from Fluoroscopic X-rays Diagnostic Radiology Imaging Physics Course December 2004 Good vs Bad Geometry: Patient Dose and Physician Height No invasive devices present c.f Wagner and Archer Minimizing Risks from Fluoroscopic X-rays – Supplement 1997 Good vs Bad Geometry: Patient Dose and Physician Height 30% dose reduction Invasive devices present Brent K Stewart, PhD, DABMP 45 Good vs Bad Geometry: Patient Dose and Invasive Devices ¬ ¬ ¬ ¬ ¬ ¬ c.f Wagner and Archer Minimizing Risks from Fluoroscopic X-rays – Supplement 1997 Brent K Stewart, PhD, DABMP 46 Good vs Bad Geometry: Invasive Devices and Personnel Versus Patient Dose In many invasive procedures, syringes, catheters, or other devices devices may be protruding from the patient With the patient prone on the procedure table, some distance must must be maintained between the patient and the image intensifier to provide provide adequate working space In oblique orientations it is necessary to move the image intensifier intensifier to a position that avoids collisions with the patient and the invasive invasive devices This may place severe constraint on how far the xx-ray tube can be positioned from the patient For larger patients, the port of the xx-ray tube may actually come into contact with the patient’s skin Extreme caution is advised in these situations to reduce the potential potential of inducing skin burns Brent K Stewart, PhD, DABMP 47 Brent K Stewart, PhD, DABMP c.f Wagner and Archer Minimizing Risks from Fluoroscopic X-rays – Supplement 1997 Brent K Stewart, PhD, DABMP 48 12 Minimizing Risks from Fluoroscopic X-rays Diagnostic Radiology Imaging Physics Course December 2004 Good vs Bad Geometry: Recommendations on Managing Risks from Geometry ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ Good vs Bad Geometry: Where Do I Stand When Using a CC-Arm? Attach the separator cone to the port if at all possible Move the xx-ray tube away from the skin as far as practicable Move the image intensifier as close to the patient as possible Keep the beambeam-on time of the study as short as possible If the image contrast is not affected, remove the grid Routinely keep hands away from the imaged area and outside the housing housing of the image intensifier Use collimation to control image quality and reduce scatter Monitor hand dose Step back from the patient before engaging fluoroscopy Use a transparent shield for the head and neck if the xx-ray tube is above the patient Have assistants use extra shielding or stand well back from the patient if tube is above patient ¬ ¬ Brent K Stewart, PhD, DABMP When using lateral and oblique projections, the scatter radiation radiation and the primary beam are least intense on the exit beam side (image intensifier intensifier side) of the patient ¬ For example, in the lateral orientation scatter is about to 10x 10x greater on the xx-ray tube side than on the image intensifier side, depending on patient size and section of body irradiated In many situations, it is required that the physician work on the the xx-ray tube side ¬ For example, cardiologists work in a bibi-plane configuration and stand next to the laterally projecting xx-ray tube located on the right side of the patient, left side of cardiologist exposed ¬ lead aprons and ceiling suspended radiation shields should be used used to reduce exposure to the head and neck ¬ radiation badge should be worn on the left side Brent K Stewart, PhD, DABMP 49 50 Thoracic Fluoroscopy in Women Cataracts ¬ ¬ ¬ ¬ ¬ Cataracts are a potential risk for patients undergoing highhigh-dose interventional procedures in the head The threshold for radiationradiation-induced cataract is about Gy To reduce the potential for cataracts: ¬ for lateral orientation of the tube, the eyes can be shielded on the lateral side by using tight collimation to shield a large portion portion of the orbit that is closest to the xx-ray tube ¬ the frontal view should be performed with the xx-ray tube posterior to the head and the image intensifier anterior This ensures that that the eyes receive only the much reduced exit beam dose and not the much higher entrance dose ¬ ¬ ¬ Breast cancer has been induced in women who underwent thoracic fluoroscopic evaluation for the treatment of tuberculosis These women, for the most part, were positioned with their breasts facing the xx-ray tube This might occur with today’s procedures if the xx-ray c-arm is oriented for an oblique view through the thorax, perhaps to view the spine ¬ breast could get exposed to high xx-ray intensities It may be reasonable to turn the cc-arm over so that the xx-ray tube is above the back of the prone patient ¬ breast would receive only the reduced exit dose Position the beam so that the breast is not in direct line with the xx-rays or consider using tape or bandages to move some of the breast out of the direct xx-ray beam http://www.xray.hmc.psu.edu/rci/ss1/ss1_4.html http://www.optometry.co.uk/articles/20010406/brown.pdf Brent K Stewart, PhD, DABMP Brent K Stewart, PhD, DABMP 51 Brent K Stewart, PhD, DABMP 52 13 Minimizing Risks from Fluoroscopic X-rays Diagnostic Radiology Imaging Physics Course December 2004 Dose Reduction by Heavy Filtration ¬ ¬ ¬ Other Factors? Some modern fluoroscopy units now provide options for heavy xx-ray beam filtration under some conditions (e.g., Philips ‘Spectrabeam’) ‘Spectrabeam’) ¬ this filtration more effectively removes nonnon-penetrating, dosedoseenhancing, lowlow-energy xx-rays than does conventional filtration ¬ this results in reduced patient xx-ray exposure ¬ this heavy filtration typically consists of thin plates of copper copper inserted at the window of the xx-ray source To be effective, the tube current must be set very high The physician should be aware that the equipment has this special special feature and know when it is engaged so that unnecessary concerns over high tube currents can be avoided ¬ ¬ ¬ ¬ ¬ Brent K Stewart, PhD, DABMP Use modes of operation such as pulsed fluoro (30, 15, 7.5 and 3.75 3.75 pulses per second) which reduce dose dramatically over continuous continuous fluoro techniques Try to avoid long exposure time to same skin area Try to avoid high skin dose modes of operation such as cine, high highlevel control if possible Don’t allow any extraneous body parts in the beam RealReal-time dose monitoring is now standard on most newer fluoroscopic/angio/interventional systems Brent K Stewart, PhD, DABMP 53 54 Conclusions ¬ ¬ ¬ ¬ Be smart about radiation and use common sense Apply the riskrisk-reducing factors (“the Ten Commandments”) discussed herein for the patient’s safety as well as your own Keep the beambeam-on time to a minimum Consciously and conscientiously practice ALARA Brent K Stewart, PhD, DABMP 55 Brent K Stewart, PhD, DABMP 14 [...]... PhD, DABMP 43 c.f Wagner and Archer Minimizing Risks from Fluoroscopic X-rays – Supplement 1 1997 Brent K Stewart, PhD, DABMP 44 11 Minimizing Risks from Fluoroscopic X-rays Diagnostic Radiology Imaging Physics Course 9 December 2004 Good vs Bad Geometry: Patient Dose and Physician Height No invasive devices present c.f Wagner and Archer Minimizing Risks from Fluoroscopic X-rays – Supplement 1 1997... Stewart, PhD, DABMP 47 Brent K Stewart, PhD, DABMP c.f Wagner and Archer Minimizing Risks from Fluoroscopic X-rays – Supplement 1 1997 Brent K Stewart, PhD, DABMP 48 12 Minimizing Risks from Fluoroscopic X-rays Diagnostic Radiology Imaging Physics Course 9 December 2004 Good vs Bad Geometry: Recommendations on Managing Risks from Geometry ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ Good vs Bad Geometry: Where Do I Stand... Invasive Devices ¬ ¬ ¬ ¬ ¬ ¬ c.f Wagner and Archer Minimizing Risks from Fluoroscopic X-rays – Supplement 1 1997 Brent K Stewart, PhD, DABMP 46 Good vs Bad Geometry: Invasive Devices and Personnel Versus Patient Dose In many invasive procedures, syringes, catheters, or other devices devices may be protruding from the patient With the patient prone on the procedure table, some distance must must be maintained... of the total amount of fluoro time for the exam the Good Brent K Stewart, PhD, DABMP 41 c.f Wagner and Archer Minimizing Risks from Fluoroscopic X-rays – Supplement 1 1997 Good vs Bad Geometry: Patient Dose and the Position of the Fluoroscope c.f Wagner and Archer Minimizing Risks from Fluoroscopic X-rays – Supplement 1 1997 Brent K Stewart, PhD, DABMP Brent K Stewart, PhD, DABMP 42 Good vs Bad Geometry:.. .Minimizing Risks from Fluoroscopic X-rays Diagnostic Radiology Imaging Physics Course 9 December 2004 Good vs Bad Geometry: Patient Dose and the Position of the Fluoroscope Fluoroscopic Timer ¬ A 5-minute cumulative timer is required on all fluoroscopic units to remind the operator audibly of each 5-minute time interval and to allow the technologist to keep track of the total amount of fluoro time... http://www.optometry.co.uk/articles/20010406/brown.pdf Brent K Stewart, PhD, DABMP Brent K Stewart, PhD, DABMP 51 Brent K Stewart, PhD, DABMP 52 13 Minimizing Risks from Fluoroscopic X-rays Diagnostic Radiology Imaging Physics Course 9 December 2004 Dose Reduction by Heavy Filtration ¬ ¬ ¬ Other Factors? Some modern fluoroscopy units now provide options for heavy xx-ray beam filtration under some conditions (e.g., Philips ‘Spectrabeam’) ‘Spectrabeam’)... quality and reduce scatter Monitor hand dose Step back from the patient before engaging fluoroscopy Use a transparent shield for the head and neck if the xx-ray tube is above the patient Have assistants use extra shielding or stand well back from the patient if tube is above patient ¬ ¬ Brent K Stewart, PhD, DABMP When using lateral and oblique projections, the scatter radiation radiation and the primary... possible Move the xx-ray tube away from the skin as far as practicable Move the image intensifier as close to the patient as possible Keep the beambeam-on time of the study as short as possible If the image contrast is not affected, remove the grid Routinely keep hands away from the imaged area and outside the housing housing of the image intensifier Use collimation to control image quality and reduce scatter... pulsed fluoro (30, 15, 7.5 and 3.75 3.75 pulses per second) which reduce dose dramatically over continuous continuous fluoro techniques Try to avoid long exposure time to same skin area Try to avoid high skin dose modes of operation such as cine, high highlevel control if possible Don’t allow any extraneous body parts in the beam RealReal-time dose monitoring is now standard on most newer fluoroscopic/angio/interventional... entrance dose ¬ ¬ ¬ Breast cancer has been induced in women who underwent thoracic fluoroscopic evaluation for the treatment of tuberculosis These women, for the most part, were positioned with their breasts facing the xx-ray tube This might occur with today’s procedures if the xx-ray c-arm is oriented for an oblique view through the thorax, perhaps to view the spine ¬ breast could get exposed to high xx-ray