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CORONADO, CALIF. – Skin injury following fenestrated endovascular aortic stent grafting is less prevalent than expected, results from a single-center retrospective study showed.
“Radiation-induced skin injury is a serious potential complication of fluoroscopically guided interventions,” Dr. Melissa L. Kirkwood said at the annual meeting of the Western Vascular Society. “These injuries are associated with a threshold radiation dose, above which the severity of injury increases with increasing dose. Instances of these injuries are mostly limited to case reports of coronary interventions, TIPS procedures, and neuroembolizations.”
These radiation-induced skin lesions can be classified as prompt, early, mid-term, or late depending on when they present following the fluoroscopically guided intervention. “The National Cancer Institute has defined four grades of skin injury, with the most frequent being transient erythema, a prompt reaction within the first 24 hours occurring at skin doses as low as 2 Gy,” said Dr. Kirkwood of the division of vascular and endovascular surgery at the University of Texas Southwestern Medical Center, Dallas. “With increasing skin doses, more severe effects present themselves. Atrophy, ulceration, and necrosis are possibilities.”
She went on to note that fenestrated endovascular aneurysm repairs often require high doses of radiation, yet the prevalence of deterministic skin injury following these cases is unknown. In a recent study, Dr. Kirkwood and her associates retrospectively reviewed 61 complex fluoroscopically guided interventions that met substantial radiation dose level criteria (SRDL), which is defined by the National Council on Radiation and Protection Measurements as a reference air kerma (RAK) greater than or equal to 5 Gy (J. Vasc. Surg. 2014; 60[3]:742-8). “Despite mean peak skin doses as high as 6.5 Gy, ranging up to 18.5 Gy, we did not detect any skin injuries in this cohort,” Dr. Kirkwood said. “That study, however, was limited by its retrospective design. There was no postoperative protocol in place to ensure that a thorough skin exam was performed on each patient at every follow-up visit. Therefore, we hypothesized that a more thorough postoperative follow-up of patients would detect some skin injury following these cases.”
For the current study, she and her associates sought to examine the prevalence of deterministic effects after FEVAR as well as well as any patient characteristics that may predispose patients to skin injury.
In June 2013, the researchers implemented a new policy regarding the follow-up of FEVAR patients, which involved a full skin exam at postoperative week 2 and 4, and at 3 and 6 months, as well as questioning patients about any skin-related complaints. For the current study, they retrospectively reviewed all FEVARs over a 7-month period after the change in policy and highlighted all the cases that reached a RAK of 5 Gy or greater. The RAK was the dose metric used in this study. It is a measure of the radiation dose to air at the interventional reference point, which, on standard fluoroscopes, is 15 cm along the beam axis toward the focal spot from isocenter. Dr. Kirkwood characterized RAK as “the best real-time indicator of patient dose, because it roughly estimates the dose at the entry point on the patient’s skin.” Peak skin dose, a dose index, and simulated skin dose maps were calculated using customized software employing input data from fluoroscopic machine logs.
Of 317 cases performed, 22 met or exceeded a RAK of 5 Gy. Of these, 21 were FEVARs and one was an embolization. Most patients (91%) were male and their mean body mass index was 30 kg/m2. Comorbidities and risk factors for skin injury included smoking, diabetes, and the concomitant applications of chemotherapeutic agents.
Dr. Kirkwood reported that the average RAK for all FEVARs was 8 Gy, with a range of 5-11 Gy. Slightly more than half of patients (52%) had multiple fluoroscopically guided interventions within 6 months of their SRDL event. The average RAK for this subset of patients was 10 Gy (range of 5 to 15).
The mean peak skin dose for all FEVARs was 5 Gy (a range of 2 to 10 Gy), and the dose index was 0.69. The average peak skin dose for the subset of patients with multiple procedures was 7 Gy (a range of 3 to 9 Gy).
In terms of the follow-up, all 21 FEVAR patients were examined at the 1- or 2-week mark, 81% were examined at 1 month, 52% were examined at 3 months, and 62% were examined at 6 months. No radiation skin injuries were reported. “Based on the published data, we would expect to see all grades of skin injury, especially in the cohort of the 5-10 Gy,” Dr. Kirkwood said.
In the previous study, conducted prior to the new follow-up policy, the dose index for FEVARs was 0.78, “meaning that the peak skin dose that the patient received could be roughly estimated as 78% of the RAK dose displayed on the monitor,” Dr. Kirkwood explained. “In the current work, the dose index decreased to 60%. This suggests that surgeons in our group have now more appropriately and effectively employed strategies to decrease radiation dose to the patient. However, even when the best operating practice is employed, FEVARs still continue to require high radiation doses in order to complete. “
The present study demonstrated that deterministic skin injuries “are uncommon after FEVAR, even at high RAK levels and regardless of cumulative dose,” she concluded. “Even with more comprehensive patient follow-up, the fact that no skin injuries were reported suggests that skin injuries in this patient cohort are less prevalent than the published guidelines would predict.”
Dr. Kirkwood reported having no financial disclosures.
On Twitter @dougbrunk
The dramatic paradigm shift in vascular surgery in the last decade and a half, resulting in the increased and widespread application of catheter-based fluoroscopic interventions makes the topic of radiation injury timely for all of us. This report is a follow up of a study by the same group published in the Journal of Vascular Surgery in 2013 (58:715-21) in which they demonstrated that the use of a variety of radiation safety measures including increasing table height, utilizing collimation and angulation, decreasing magnification modes, and maintaining minimal patient-to-detector distance resulted in a 60% reduction in skin dose to their patients when measured as an index of peak skin dose to reference air kerma (PSD/RAK). Unfortunately, skin exposure remained high for FEVAR despite these measures, underscoring the fact that for very complex interventions, even with excellent radiation safety practices, the risk of skin injury remains a reality.
The fact that skin doses as high as 11 Gy did not result in any deterministic injuries is both reassuring and a little surprising. According to the Centers for Disease Control and Prevention, radiation doses of greater than 2 Gy but less than 15 Gy will usually result in erythema within 1-2 days, with a second period of erythema and edema at 2-5 weeks, occasionally resulting in desquamation at 6-7 weeks. Late changes can include mild skin atrophy and some hyperpigmentation. Although complete healing can usually be expected at these doses, squamous skin cancer can still occur, often more than a decade after exposure.
So why were no injuries seen? It may be that some were missed since follow-up examinations were not performed in 100% of their patients at any time interval, and it’s not stated whether exams were routinely performed in the first 1-2 days, when I would presume most patients were still hospitalized and the first stage of skin erythema is usually seen. Alternatively, it may be that the surrogate measure of either RAK or the index of PSD/RAK overestimated the true radiation skin dose, which seems highly likely, especially if the time of exposure in any one location was based less on the frequent changes in gantry angle and table position so commonly used in these procedures.
In our hospital, the Massachusetts Department of Public Health regulations require the patient and their physician be notified by letter when the estimated total absorbed radiation dose equals or exceeds 2 Gy. This is based on calculations by our physicist who reviews the details of any case in which the RAK measured equals or exceeds 2 Gy. Like the experiences of the authors, this most commonly occurs with lengthy and complex interventions. In our experience, we have never observed a significant skin injury presumably for the same reason – the exposure in any one location tends to be far less than the total calculated skin dose. Nevertheless, this study should not lull surgeons into a sense of complacency regarding the risk to the patient (and themselves and their staff). As our comfort and expertise with complex interventions increases, it is likely that radiation exposure will continue to increase, placing our patients at increased risk. Understanding the risk of radiation skin injury and how to minimize it is critical for any surgeon performing FEVAR and any other complex intervention utilizing fluoroscopic imaging.
Dr. Frank Pomposelli is an associate professor of surgery at Harvard Medical School; clinical chief, division of vascular surgery at the Beth Israel Deaconess Medical Center; and section chief, division of vascular surgery, New England Baptist Hospital, Boston. He is also an associate medical editor for Vascular Specialist.
The dramatic paradigm shift in vascular surgery in the last decade and a half, resulting in the increased and widespread application of catheter-based fluoroscopic interventions makes the topic of radiation injury timely for all of us. This report is a follow up of a study by the same group published in the Journal of Vascular Surgery in 2013 (58:715-21) in which they demonstrated that the use of a variety of radiation safety measures including increasing table height, utilizing collimation and angulation, decreasing magnification modes, and maintaining minimal patient-to-detector distance resulted in a 60% reduction in skin dose to their patients when measured as an index of peak skin dose to reference air kerma (PSD/RAK). Unfortunately, skin exposure remained high for FEVAR despite these measures, underscoring the fact that for very complex interventions, even with excellent radiation safety practices, the risk of skin injury remains a reality.
The fact that skin doses as high as 11 Gy did not result in any deterministic injuries is both reassuring and a little surprising. According to the Centers for Disease Control and Prevention, radiation doses of greater than 2 Gy but less than 15 Gy will usually result in erythema within 1-2 days, with a second period of erythema and edema at 2-5 weeks, occasionally resulting in desquamation at 6-7 weeks. Late changes can include mild skin atrophy and some hyperpigmentation. Although complete healing can usually be expected at these doses, squamous skin cancer can still occur, often more than a decade after exposure.
So why were no injuries seen? It may be that some were missed since follow-up examinations were not performed in 100% of their patients at any time interval, and it’s not stated whether exams were routinely performed in the first 1-2 days, when I would presume most patients were still hospitalized and the first stage of skin erythema is usually seen. Alternatively, it may be that the surrogate measure of either RAK or the index of PSD/RAK overestimated the true radiation skin dose, which seems highly likely, especially if the time of exposure in any one location was based less on the frequent changes in gantry angle and table position so commonly used in these procedures.
In our hospital, the Massachusetts Department of Public Health regulations require the patient and their physician be notified by letter when the estimated total absorbed radiation dose equals or exceeds 2 Gy. This is based on calculations by our physicist who reviews the details of any case in which the RAK measured equals or exceeds 2 Gy. Like the experiences of the authors, this most commonly occurs with lengthy and complex interventions. In our experience, we have never observed a significant skin injury presumably for the same reason – the exposure in any one location tends to be far less than the total calculated skin dose. Nevertheless, this study should not lull surgeons into a sense of complacency regarding the risk to the patient (and themselves and their staff). As our comfort and expertise with complex interventions increases, it is likely that radiation exposure will continue to increase, placing our patients at increased risk. Understanding the risk of radiation skin injury and how to minimize it is critical for any surgeon performing FEVAR and any other complex intervention utilizing fluoroscopic imaging.
Dr. Frank Pomposelli is an associate professor of surgery at Harvard Medical School; clinical chief, division of vascular surgery at the Beth Israel Deaconess Medical Center; and section chief, division of vascular surgery, New England Baptist Hospital, Boston. He is also an associate medical editor for Vascular Specialist.
The dramatic paradigm shift in vascular surgery in the last decade and a half, resulting in the increased and widespread application of catheter-based fluoroscopic interventions makes the topic of radiation injury timely for all of us. This report is a follow up of a study by the same group published in the Journal of Vascular Surgery in 2013 (58:715-21) in which they demonstrated that the use of a variety of radiation safety measures including increasing table height, utilizing collimation and angulation, decreasing magnification modes, and maintaining minimal patient-to-detector distance resulted in a 60% reduction in skin dose to their patients when measured as an index of peak skin dose to reference air kerma (PSD/RAK). Unfortunately, skin exposure remained high for FEVAR despite these measures, underscoring the fact that for very complex interventions, even with excellent radiation safety practices, the risk of skin injury remains a reality.
The fact that skin doses as high as 11 Gy did not result in any deterministic injuries is both reassuring and a little surprising. According to the Centers for Disease Control and Prevention, radiation doses of greater than 2 Gy but less than 15 Gy will usually result in erythema within 1-2 days, with a second period of erythema and edema at 2-5 weeks, occasionally resulting in desquamation at 6-7 weeks. Late changes can include mild skin atrophy and some hyperpigmentation. Although complete healing can usually be expected at these doses, squamous skin cancer can still occur, often more than a decade after exposure.
So why were no injuries seen? It may be that some were missed since follow-up examinations were not performed in 100% of their patients at any time interval, and it’s not stated whether exams were routinely performed in the first 1-2 days, when I would presume most patients were still hospitalized and the first stage of skin erythema is usually seen. Alternatively, it may be that the surrogate measure of either RAK or the index of PSD/RAK overestimated the true radiation skin dose, which seems highly likely, especially if the time of exposure in any one location was based less on the frequent changes in gantry angle and table position so commonly used in these procedures.
In our hospital, the Massachusetts Department of Public Health regulations require the patient and their physician be notified by letter when the estimated total absorbed radiation dose equals or exceeds 2 Gy. This is based on calculations by our physicist who reviews the details of any case in which the RAK measured equals or exceeds 2 Gy. Like the experiences of the authors, this most commonly occurs with lengthy and complex interventions. In our experience, we have never observed a significant skin injury presumably for the same reason – the exposure in any one location tends to be far less than the total calculated skin dose. Nevertheless, this study should not lull surgeons into a sense of complacency regarding the risk to the patient (and themselves and their staff). As our comfort and expertise with complex interventions increases, it is likely that radiation exposure will continue to increase, placing our patients at increased risk. Understanding the risk of radiation skin injury and how to minimize it is critical for any surgeon performing FEVAR and any other complex intervention utilizing fluoroscopic imaging.
Dr. Frank Pomposelli is an associate professor of surgery at Harvard Medical School; clinical chief, division of vascular surgery at the Beth Israel Deaconess Medical Center; and section chief, division of vascular surgery, New England Baptist Hospital, Boston. He is also an associate medical editor for Vascular Specialist.
CORONADO, CALIF. – Skin injury following fenestrated endovascular aortic stent grafting is less prevalent than expected, results from a single-center retrospective study showed.
“Radiation-induced skin injury is a serious potential complication of fluoroscopically guided interventions,” Dr. Melissa L. Kirkwood said at the annual meeting of the Western Vascular Society. “These injuries are associated with a threshold radiation dose, above which the severity of injury increases with increasing dose. Instances of these injuries are mostly limited to case reports of coronary interventions, TIPS procedures, and neuroembolizations.”
These radiation-induced skin lesions can be classified as prompt, early, mid-term, or late depending on when they present following the fluoroscopically guided intervention. “The National Cancer Institute has defined four grades of skin injury, with the most frequent being transient erythema, a prompt reaction within the first 24 hours occurring at skin doses as low as 2 Gy,” said Dr. Kirkwood of the division of vascular and endovascular surgery at the University of Texas Southwestern Medical Center, Dallas. “With increasing skin doses, more severe effects present themselves. Atrophy, ulceration, and necrosis are possibilities.”
She went on to note that fenestrated endovascular aneurysm repairs often require high doses of radiation, yet the prevalence of deterministic skin injury following these cases is unknown. In a recent study, Dr. Kirkwood and her associates retrospectively reviewed 61 complex fluoroscopically guided interventions that met substantial radiation dose level criteria (SRDL), which is defined by the National Council on Radiation and Protection Measurements as a reference air kerma (RAK) greater than or equal to 5 Gy (J. Vasc. Surg. 2014; 60[3]:742-8). “Despite mean peak skin doses as high as 6.5 Gy, ranging up to 18.5 Gy, we did not detect any skin injuries in this cohort,” Dr. Kirkwood said. “That study, however, was limited by its retrospective design. There was no postoperative protocol in place to ensure that a thorough skin exam was performed on each patient at every follow-up visit. Therefore, we hypothesized that a more thorough postoperative follow-up of patients would detect some skin injury following these cases.”
For the current study, she and her associates sought to examine the prevalence of deterministic effects after FEVAR as well as well as any patient characteristics that may predispose patients to skin injury.
In June 2013, the researchers implemented a new policy regarding the follow-up of FEVAR patients, which involved a full skin exam at postoperative week 2 and 4, and at 3 and 6 months, as well as questioning patients about any skin-related complaints. For the current study, they retrospectively reviewed all FEVARs over a 7-month period after the change in policy and highlighted all the cases that reached a RAK of 5 Gy or greater. The RAK was the dose metric used in this study. It is a measure of the radiation dose to air at the interventional reference point, which, on standard fluoroscopes, is 15 cm along the beam axis toward the focal spot from isocenter. Dr. Kirkwood characterized RAK as “the best real-time indicator of patient dose, because it roughly estimates the dose at the entry point on the patient’s skin.” Peak skin dose, a dose index, and simulated skin dose maps were calculated using customized software employing input data from fluoroscopic machine logs.
Of 317 cases performed, 22 met or exceeded a RAK of 5 Gy. Of these, 21 were FEVARs and one was an embolization. Most patients (91%) were male and their mean body mass index was 30 kg/m2. Comorbidities and risk factors for skin injury included smoking, diabetes, and the concomitant applications of chemotherapeutic agents.
Dr. Kirkwood reported that the average RAK for all FEVARs was 8 Gy, with a range of 5-11 Gy. Slightly more than half of patients (52%) had multiple fluoroscopically guided interventions within 6 months of their SRDL event. The average RAK for this subset of patients was 10 Gy (range of 5 to 15).
The mean peak skin dose for all FEVARs was 5 Gy (a range of 2 to 10 Gy), and the dose index was 0.69. The average peak skin dose for the subset of patients with multiple procedures was 7 Gy (a range of 3 to 9 Gy).
In terms of the follow-up, all 21 FEVAR patients were examined at the 1- or 2-week mark, 81% were examined at 1 month, 52% were examined at 3 months, and 62% were examined at 6 months. No radiation skin injuries were reported. “Based on the published data, we would expect to see all grades of skin injury, especially in the cohort of the 5-10 Gy,” Dr. Kirkwood said.
In the previous study, conducted prior to the new follow-up policy, the dose index for FEVARs was 0.78, “meaning that the peak skin dose that the patient received could be roughly estimated as 78% of the RAK dose displayed on the monitor,” Dr. Kirkwood explained. “In the current work, the dose index decreased to 60%. This suggests that surgeons in our group have now more appropriately and effectively employed strategies to decrease radiation dose to the patient. However, even when the best operating practice is employed, FEVARs still continue to require high radiation doses in order to complete. “
The present study demonstrated that deterministic skin injuries “are uncommon after FEVAR, even at high RAK levels and regardless of cumulative dose,” she concluded. “Even with more comprehensive patient follow-up, the fact that no skin injuries were reported suggests that skin injuries in this patient cohort are less prevalent than the published guidelines would predict.”
Dr. Kirkwood reported having no financial disclosures.
On Twitter @dougbrunk
CORONADO, CALIF. – Skin injury following fenestrated endovascular aortic stent grafting is less prevalent than expected, results from a single-center retrospective study showed.
“Radiation-induced skin injury is a serious potential complication of fluoroscopically guided interventions,” Dr. Melissa L. Kirkwood said at the annual meeting of the Western Vascular Society. “These injuries are associated with a threshold radiation dose, above which the severity of injury increases with increasing dose. Instances of these injuries are mostly limited to case reports of coronary interventions, TIPS procedures, and neuroembolizations.”
These radiation-induced skin lesions can be classified as prompt, early, mid-term, or late depending on when they present following the fluoroscopically guided intervention. “The National Cancer Institute has defined four grades of skin injury, with the most frequent being transient erythema, a prompt reaction within the first 24 hours occurring at skin doses as low as 2 Gy,” said Dr. Kirkwood of the division of vascular and endovascular surgery at the University of Texas Southwestern Medical Center, Dallas. “With increasing skin doses, more severe effects present themselves. Atrophy, ulceration, and necrosis are possibilities.”
She went on to note that fenestrated endovascular aneurysm repairs often require high doses of radiation, yet the prevalence of deterministic skin injury following these cases is unknown. In a recent study, Dr. Kirkwood and her associates retrospectively reviewed 61 complex fluoroscopically guided interventions that met substantial radiation dose level criteria (SRDL), which is defined by the National Council on Radiation and Protection Measurements as a reference air kerma (RAK) greater than or equal to 5 Gy (J. Vasc. Surg. 2014; 60[3]:742-8). “Despite mean peak skin doses as high as 6.5 Gy, ranging up to 18.5 Gy, we did not detect any skin injuries in this cohort,” Dr. Kirkwood said. “That study, however, was limited by its retrospective design. There was no postoperative protocol in place to ensure that a thorough skin exam was performed on each patient at every follow-up visit. Therefore, we hypothesized that a more thorough postoperative follow-up of patients would detect some skin injury following these cases.”
For the current study, she and her associates sought to examine the prevalence of deterministic effects after FEVAR as well as well as any patient characteristics that may predispose patients to skin injury.
In June 2013, the researchers implemented a new policy regarding the follow-up of FEVAR patients, which involved a full skin exam at postoperative week 2 and 4, and at 3 and 6 months, as well as questioning patients about any skin-related complaints. For the current study, they retrospectively reviewed all FEVARs over a 7-month period after the change in policy and highlighted all the cases that reached a RAK of 5 Gy or greater. The RAK was the dose metric used in this study. It is a measure of the radiation dose to air at the interventional reference point, which, on standard fluoroscopes, is 15 cm along the beam axis toward the focal spot from isocenter. Dr. Kirkwood characterized RAK as “the best real-time indicator of patient dose, because it roughly estimates the dose at the entry point on the patient’s skin.” Peak skin dose, a dose index, and simulated skin dose maps were calculated using customized software employing input data from fluoroscopic machine logs.
Of 317 cases performed, 22 met or exceeded a RAK of 5 Gy. Of these, 21 were FEVARs and one was an embolization. Most patients (91%) were male and their mean body mass index was 30 kg/m2. Comorbidities and risk factors for skin injury included smoking, diabetes, and the concomitant applications of chemotherapeutic agents.
Dr. Kirkwood reported that the average RAK for all FEVARs was 8 Gy, with a range of 5-11 Gy. Slightly more than half of patients (52%) had multiple fluoroscopically guided interventions within 6 months of their SRDL event. The average RAK for this subset of patients was 10 Gy (range of 5 to 15).
The mean peak skin dose for all FEVARs was 5 Gy (a range of 2 to 10 Gy), and the dose index was 0.69. The average peak skin dose for the subset of patients with multiple procedures was 7 Gy (a range of 3 to 9 Gy).
In terms of the follow-up, all 21 FEVAR patients were examined at the 1- or 2-week mark, 81% were examined at 1 month, 52% were examined at 3 months, and 62% were examined at 6 months. No radiation skin injuries were reported. “Based on the published data, we would expect to see all grades of skin injury, especially in the cohort of the 5-10 Gy,” Dr. Kirkwood said.
In the previous study, conducted prior to the new follow-up policy, the dose index for FEVARs was 0.78, “meaning that the peak skin dose that the patient received could be roughly estimated as 78% of the RAK dose displayed on the monitor,” Dr. Kirkwood explained. “In the current work, the dose index decreased to 60%. This suggests that surgeons in our group have now more appropriately and effectively employed strategies to decrease radiation dose to the patient. However, even when the best operating practice is employed, FEVARs still continue to require high radiation doses in order to complete. “
The present study demonstrated that deterministic skin injuries “are uncommon after FEVAR, even at high RAK levels and regardless of cumulative dose,” she concluded. “Even with more comprehensive patient follow-up, the fact that no skin injuries were reported suggests that skin injuries in this patient cohort are less prevalent than the published guidelines would predict.”
Dr. Kirkwood reported having no financial disclosures.
On Twitter @dougbrunk
AT THE WESTERN VASCULAR SOCIETY ANNUAL MEETING
Key clinical point: No skin injuries were found after fenestrated endovascular aortic stent grafts (FEVAR) cases that involved high radiation doses.
Major finding: Even though the average reference air kerma (RAK) for all FEVARs was 8 Gy, with a range of 5-11 Gy, no radiation skin injuries were reported.
Data source: An single-center analysis of 21 FEVARs over a 7-month period that reached a RAK of 5 Gy or greater.
Disclosures: Dr. Kirkwood reported having no financial disclosures.
