- Email: [email protected]
The SCVIR Radiation Dose in Interventional Radiology (RAD-IR) Study
5:35 p.m. Panel Discussion Panelists: Dorothy B. Abel, BSBME Susan Alpert, PhD, MD Grant Bagley, JD, MD Gary J. Becker, MD, FACC, fACR Stuart C. Geller, MD Katharine L. Krol, MD Anne C. Roberts, MD Daniel Schultz, MD Brian Stainken, MD Sean Tunis, MD Bram Zuckerman, MD (FDA)
5:55 p.m. Radiation Safety and Protection Issues: The FDA Perspective Thomas B. Shope, PhD Center for Devices and Radiological Health Rockville, Maryland 6:10 p.m. The SCVIR Radiation Dose in Interventional Radiology (RAD-ffi) Study Donald 1. Miller, MD National Naval Medical Center Rockville, Maryland The opinions expressed herein are those of the author and do not necessarily reflect those of the United States Navy, the Department of Defense, or the Department of Health and Human Services. Learolng Objectives: Upon completion of thl:S presentation, the attendee should be able to: 1) Describe the FDA's recommendations for dose recording; 2) state the dose thresholdfor skin injury; 3) Describe the goals ofthe RAD-IR study.
some lnJunes are not reported and because the incidence of injury cannot be determined. The RAD-IR study's primary aim was to estimate the frequency with which certain interventional radiology procedures produced cumulative doses greater than tl1e 2 Gy injury threshold. The study was conducted by the SCYIR under a grant from CIRREF. There were seven participating institutions: Beth Israel Medical Center (New York, NY), the Cleveland Clinic (Cleveland, OH), the Mayo Clinic (Rochester, MN), the National Naval Medical Center (Bethesda, MD), Northwestern University Hospital (Chicago, IL), The State University of New York Upstate Medical Center (Syracuse, NY), and The University of Texas Southwestern (Dallas, TX). The fluoroscopic units in the study generated the dose data automatically, as part of their normal operation. The dose measuring equipment on each fluoroscopic unit was calibrated at the beginning of the study and checked at frequent intervals during the study. Data on fluoroscopy time, number of images obtained, dosearea-product (DAP) and cumulative dose at the interventiona I reference point were collected for apprOXimately 2000 cases. Peak skin dose data were also collected for many of these cases. Twenty-one procedures were stucUed, including embolization of specific organs, angiopJasty of or stent placement in specific arteries, inferior vena cava filter placement, TIPS, biliary drainage, nephrostomy and vertebroplasty. We have been able to distinguish between procedures with a high likelihood of exceeding a 2 Gy cumulative dose threshold and those with a low likelihood of exceeding the threshold. We have also been able to determine the relationship between cumulative dose and peak skin dose for certain procedures. Additional data analyses include the effects of patient age and weight on patient dose, the effect of operator training level on patient dose, and the effect of dose-saving pulsed fluoroscopy on patient dose.
It is known that absorbed skin doses greater than 2
The data have also permitted procedure-specific cor-
Gy have the potential to ca~se skin injUry (1). However, until the early 1990's, most radiologists and cardiologists did not consider these doses likely to occur during fluoroscopically guided interventions. The impetus for the Radiation Dose in Interventional Radiology study (the RAD-IR study) was the 1994 and 1995 recommendations by the Food and Drug Administration that 'information permitting estimation of the absorbed dose to the skin be recorded in the patient's medical record' for procedures with the potential to produce high skin doses (2,3). At that time there was relatively little published information available to classify procedures by their risk of skin injUry. FDA suggested that dose data be collected for certain carcUac interventions and for specific interventional radiology procedures-vascular embolization, TIPS, and percutaneous endovascular reconstruction (stents and stent-grafts) (3). FDA's recommendation was based on reports of injuries, rather than on published dose data. This method is inherently flawed because
relations between the various dose analogues. These correlations are useful for estimating skin dose when procedures are performed with fluoroscopic equipment that prOVides only fluoroscopy time or DAP data. Unfortunately, much of the fluoroscopic equipment in use in the United States tod~y falls into this category.
References 1. Koenig TR, Wolff D, Mettler FA, Wagner LK. Skin injuries from fluoroscopically guided procedures: Part 1. Characteristics of radiation injury. AJR Am J RoentgenoI2001;177:3-11. 2. Food and Drug Administration. Public Health Advisory: Avoidance of serious x-ray-induced skin injuries to patients during fluoroscopically-guided procedures. 1994. Rockville MD, Center for Devices and Radiological Health. 3. Food and Drug Administration. Recording informa-
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tion in the patient's medical record that identifies the potential for serious x-ray-induced skin injuries. 1995. Rockville MD, Center for Devices and Radiological Health.
6:15 p.rn. Panel Discussion Panelists: Stephen Balter, PhD John F. Cardella, MD M. Victoria Marx, MD
Monday, April 8, 2002 12:30 p.m.-2:30 p.m. Moderator: Anne C. Roberts, MD
Objectives: Upon completion of this course, the attendee should be able to: 1. Explain how grafts and fistulas are placed surgically, and the surgical options for revising them. 2. Describe various methods to declot dialysis grafts including mechanical and pharmacologic methods.
3. List the types of dialysis catheters that are available and the complications associated with these catheters. 4. Summarize the effect that access dysfunction has on dialysis quality, and the role of the screening in patients with a dialysis access. 12:30 p.m.
Mechanical Thombolysis for Dialysis Grafts Brian F. Stainken, MD University of Maryland Baltimore, Maryland
Successful preservation and salvage of thombosed prosthetic AV access grafts depends upon two factors: effective thrombectomy and restoration of venous outflow. It's not hard to achieve the first objective. In fact, there are so many ways of effectively d~clotting an AV graft that the pertinent question is not one of relative success but rather relative safety, speed, and cost. Conversely, durable treatment of the underlying venous outflow stenosis has proven much more difficult. Because the venous stenosis is the usual cause of thrombosis, this means that we can restore flow, but can not impact on patency until a more effective solution for outflow lesions is identified. Significant future developments in the area of AV access will rest in techniques for prevention or durable repair of the venous outflow stenosis, not in techniques for graft declotting. The benchmark procedure, operative thrombectomy with or without revision of the venous anastomosis was
P206
described over 30 years ago and remains a popular solution. Unfortunately, without image gu'idance, the only information available to the operator with which to gauge success is gross restoration of flow. Residual thrombus, arterial emboli, and the offending venous stenosis are not visualized. We know that the primary patency after operative graft thrombectomy with revision is only 25% at 1 year. Thrombolysis, using pharmacomechanical techniques, or the "lyse-and wait" approach is another reasonable solution. Drug related bleeding complications are rare and the operator can treat the inevitable venous stenosis with angioplasty at the same setting. While there is no conclusive evidence that the primary patency is any better, this approach improves on the surgical solution because it can be repeated, thereby conserving the limited number of sites available for access. But lyric therapy is slow. Even with aggreSSive pharmacomechanical techniques, suite times of 1-2 hours are the norm. The "lyse-and-wait" approach may use less suite time, but still takes several hours. Lytic therapy also fails to dissolve the arterial plateletrich plug. This must generally be drawn into the graft with a mechanical maneuver using a balloon device. Finally, there is a point wherein aggressive "rapid" pharmacomechanical therapy, with the use of clot macerating balloons and eternal massage, becomes a primarily mechanical rather than a chemical process. In this sense, operative embolectomy and pharmacomechanical thrombolysis are both mechanical thrombectomy procedures. The first is limited by imprecision and wasted conduit and the latter by duration of therapy, cost, and failure to impact Significantly on primary patency. So what's next? Can we continue to refine our approach to mechanical thrombectomy and address the shortcomings of our current techniques? What are the features of the ideal mechanical thrombectomy device? Speed: The device should clear thrombus from the prosthetic graft conduit in one or two applications. Precision: the device should be steerable to the area requiring ~reatme!1t. Its effect should be confined to the treated area. Power' The device should remove all thrombus, not just fresh clot. It should leave a smooth nonthrombogenic flow lumen. We do not know if it is preferable everything down to bare graft or to leave the fibrinous pseudointima. The device should also remove the arterial plug without risk of embolization. Cost: The value of the device rests in the needs it satisfies. Unless it cures the venous stenosis, improves primary patency or Significantly shortens the procedure length, its value will be no different that the cost of a Fogaty balloon and 5 mg of t-PA. Safety: The device must not injure endothelial surfaces, or wash debris into the arterial tree. Arguably,
5:55 p.m. Radiation Safety and Protection Issues: The FDA Perspective Thomas B. Shope, PhD Center for Devices and Radiological Health Rockville, Maryland 6:10 p.m. The SCVIR Radiation Dose in Interventional Radiology (RAD-ffi) Study Donald 1. Miller, MD National Naval Medical Center Rockville, Maryland The opinions expressed herein are those of the author and do not necessarily reflect those of the United States Navy, the Department of Defense, or the Department of Health and Human Services. Learolng Objectives: Upon completion of thl:S presentation, the attendee should be able to: 1) Describe the FDA's recommendations for dose recording; 2) state the dose thresholdfor skin injury; 3) Describe the goals ofthe RAD-IR study.
some lnJunes are not reported and because the incidence of injury cannot be determined. The RAD-IR study's primary aim was to estimate the frequency with which certain interventional radiology procedures produced cumulative doses greater than tl1e 2 Gy injury threshold. The study was conducted by the SCYIR under a grant from CIRREF. There were seven participating institutions: Beth Israel Medical Center (New York, NY), the Cleveland Clinic (Cleveland, OH), the Mayo Clinic (Rochester, MN), the National Naval Medical Center (Bethesda, MD), Northwestern University Hospital (Chicago, IL), The State University of New York Upstate Medical Center (Syracuse, NY), and The University of Texas Southwestern (Dallas, TX). The fluoroscopic units in the study generated the dose data automatically, as part of their normal operation. The dose measuring equipment on each fluoroscopic unit was calibrated at the beginning of the study and checked at frequent intervals during the study. Data on fluoroscopy time, number of images obtained, dosearea-product (DAP) and cumulative dose at the interventiona I reference point were collected for apprOXimately 2000 cases. Peak skin dose data were also collected for many of these cases. Twenty-one procedures were stucUed, including embolization of specific organs, angiopJasty of or stent placement in specific arteries, inferior vena cava filter placement, TIPS, biliary drainage, nephrostomy and vertebroplasty. We have been able to distinguish between procedures with a high likelihood of exceeding a 2 Gy cumulative dose threshold and those with a low likelihood of exceeding the threshold. We have also been able to determine the relationship between cumulative dose and peak skin dose for certain procedures. Additional data analyses include the effects of patient age and weight on patient dose, the effect of operator training level on patient dose, and the effect of dose-saving pulsed fluoroscopy on patient dose.
It is known that absorbed skin doses greater than 2
The data have also permitted procedure-specific cor-
Gy have the potential to ca~se skin injUry (1). However, until the early 1990's, most radiologists and cardiologists did not consider these doses likely to occur during fluoroscopically guided interventions. The impetus for the Radiation Dose in Interventional Radiology study (the RAD-IR study) was the 1994 and 1995 recommendations by the Food and Drug Administration that 'information permitting estimation of the absorbed dose to the skin be recorded in the patient's medical record' for procedures with the potential to produce high skin doses (2,3). At that time there was relatively little published information available to classify procedures by their risk of skin injUry. FDA suggested that dose data be collected for certain carcUac interventions and for specific interventional radiology procedures-vascular embolization, TIPS, and percutaneous endovascular reconstruction (stents and stent-grafts) (3). FDA's recommendation was based on reports of injuries, rather than on published dose data. This method is inherently flawed because
relations between the various dose analogues. These correlations are useful for estimating skin dose when procedures are performed with fluoroscopic equipment that prOVides only fluoroscopy time or DAP data. Unfortunately, much of the fluoroscopic equipment in use in the United States tod~y falls into this category.
References 1. Koenig TR, Wolff D, Mettler FA, Wagner LK. Skin injuries from fluoroscopically guided procedures: Part 1. Characteristics of radiation injury. AJR Am J RoentgenoI2001;177:3-11. 2. Food and Drug Administration. Public Health Advisory: Avoidance of serious x-ray-induced skin injuries to patients during fluoroscopically-guided procedures. 1994. Rockville MD, Center for Devices and Radiological Health. 3. Food and Drug Administration. Recording informa-
P205
tion in the patient's medical record that identifies the potential for serious x-ray-induced skin injuries. 1995. Rockville MD, Center for Devices and Radiological Health.
6:15 p.rn. Panel Discussion Panelists: Stephen Balter, PhD John F. Cardella, MD M. Victoria Marx, MD
Monday, April 8, 2002 12:30 p.m.-2:30 p.m. Moderator: Anne C. Roberts, MD
Objectives: Upon completion of this course, the attendee should be able to: 1. Explain how grafts and fistulas are placed surgically, and the surgical options for revising them. 2. Describe various methods to declot dialysis grafts including mechanical and pharmacologic methods.
3. List the types of dialysis catheters that are available and the complications associated with these catheters. 4. Summarize the effect that access dysfunction has on dialysis quality, and the role of the screening in patients with a dialysis access. 12:30 p.m.
Mechanical Thombolysis for Dialysis Grafts Brian F. Stainken, MD University of Maryland Baltimore, Maryland
Successful preservation and salvage of thombosed prosthetic AV access grafts depends upon two factors: effective thrombectomy and restoration of venous outflow. It's not hard to achieve the first objective. In fact, there are so many ways of effectively d~clotting an AV graft that the pertinent question is not one of relative success but rather relative safety, speed, and cost. Conversely, durable treatment of the underlying venous outflow stenosis has proven much more difficult. Because the venous stenosis is the usual cause of thrombosis, this means that we can restore flow, but can not impact on patency until a more effective solution for outflow lesions is identified. Significant future developments in the area of AV access will rest in techniques for prevention or durable repair of the venous outflow stenosis, not in techniques for graft declotting. The benchmark procedure, operative thrombectomy with or without revision of the venous anastomosis was
P206
described over 30 years ago and remains a popular solution. Unfortunately, without image gu'idance, the only information available to the operator with which to gauge success is gross restoration of flow. Residual thrombus, arterial emboli, and the offending venous stenosis are not visualized. We know that the primary patency after operative graft thrombectomy with revision is only 25% at 1 year. Thrombolysis, using pharmacomechanical techniques, or the "lyse-and wait" approach is another reasonable solution. Drug related bleeding complications are rare and the operator can treat the inevitable venous stenosis with angioplasty at the same setting. While there is no conclusive evidence that the primary patency is any better, this approach improves on the surgical solution because it can be repeated, thereby conserving the limited number of sites available for access. But lyric therapy is slow. Even with aggreSSive pharmacomechanical techniques, suite times of 1-2 hours are the norm. The "lyse-and-wait" approach may use less suite time, but still takes several hours. Lytic therapy also fails to dissolve the arterial plateletrich plug. This must generally be drawn into the graft with a mechanical maneuver using a balloon device. Finally, there is a point wherein aggressive "rapid" pharmacomechanical therapy, with the use of clot macerating balloons and eternal massage, becomes a primarily mechanical rather than a chemical process. In this sense, operative embolectomy and pharmacomechanical thrombolysis are both mechanical thrombectomy procedures. The first is limited by imprecision and wasted conduit and the latter by duration of therapy, cost, and failure to impact Significantly on primary patency. So what's next? Can we continue to refine our approach to mechanical thrombectomy and address the shortcomings of our current techniques? What are the features of the ideal mechanical thrombectomy device? Speed: The device should clear thrombus from the prosthetic graft conduit in one or two applications. Precision: the device should be steerable to the area requiring ~reatme!1t. Its effect should be confined to the treated area. Power' The device should remove all thrombus, not just fresh clot. It should leave a smooth nonthrombogenic flow lumen. We do not know if it is preferable everything down to bare graft or to leave the fibrinous pseudointima. The device should also remove the arterial plug without risk of embolization. Cost: The value of the device rests in the needs it satisfies. Unless it cures the venous stenosis, improves primary patency or Significantly shortens the procedure length, its value will be no different that the cost of a Fogaty balloon and 5 mg of t-PA. Safety: The device must not injure endothelial surfaces, or wash debris into the arterial tree. Arguably,