Catheterization and Cardiovascular Interventions 86:841–848 (2015)
Achievable Radiation Reduction during Pediatric Cardiac Catheterization: How Low Can We Go? Sharon Borik, MD, Sunder Devadas, MRT, Dariusz Mroczek, CVT, BIOMED-ENG, Kyong Jin Lee, MD, FRCPC, Rajiv Chaturvedi, MD, PhD, and Lee N. Benson,* MD, FRCPC, FACC, FSCAI Objectives: To assess the effectiveness of radiation-reduction measures implemented during pediatric catheterization, and provide data on the radiation doses for common interventional and diagnostic procedures, indexed to body weight. Background: Ionizing radiation exposure must be minimized to “as low as reasonably achievable,” by instituting radiation-limiting techniques and knowledge of expected radiation exposure. Methods: Radiation-reduction measures included pulsed-fluoroscopy at 7.5 pulses/ second (0.032–0.045 mGy/pulse), an air-gap magnification technique for children 30 kg, P < 0.001). Dose exposure using radiation-reduction techniques were the lowest reported in the literature for all procedure types compared (e.g. median DAP for pulmonary valvuloplasty 163 mGy*m2 vs. 405 to 1,230 mGy*m2 reported by 3 large centers). Reduction of fluoroscopy acquisition to 7.5 pulses/second nearly halved radiation exposure (P < 0.001). Conclusions: Implementing a radiation dose reduction and awareness program can lead to documented reduction in exposure, across a variety of procedures performed by multiple operators. VC 2015 Wiley Periodicals, Inc. Key words: pediatric catheterization; radiation exposure; interventional cardiology
INTRODUCTION
Over the last three decades the cardiac catheterization laboratory has evolved from an instrument of diagnosis to a modality for therapy. As such, the strategies for management of heart disease have changed and with it the reliance on X-ray based imaging. Parallel with this evolution in therapy is awareness to minimize exposure (both to the patient and laboratory personnel) to ionizing radiation to “as low as reasonably achievable” (the so-called ALARA principle). Detrimental effects of ionizing radiation are well known [1,2], and the exposure burden greatest in children with complex congenital heart disease requiring long and frequently repetitive procedures [3,4]. For these reasons, many pediatric catheterization labs have instituted measures for radiation safety, dose reduction and monitoring [5–9], and recently methods for standardization of radiation dose according to patient weight [7]. In C 2015 Wiley Periodicals, Inc. V
this work, we sought to evaluate our catheterization laboratories’ radiation profile and the techniques used to reduce and monitor exposure, update the existing radiation reference library for various pediatric
Department of Pediatrics, Division of Cardiology, the Labatt Family Heart Centre, the Hospital for Sick Children, the University of Toronto School of Medicine, Toronto, Canada Conflict of interest: Nothing to report. *Correspondence to: L. Benson, MD, The Hospital for Sick Children, 555 University Avenue, Toronto, ON, Canada M5G 1X8. E-mail: [email protected] Received 15 January 2015; Revision accepted 18 April 2015 DOI: 10.1002/ccd.26024 Published online 22 May 2015 in Wiley Online Library (wileyonlinelibrary.com)
842
Borik et al.
diagnostic and interventional procedures, and document the degree of exposure reduction that can be achieved. METHODS Data Collection and Definitions
Radiation data of all diagnostic and interventional cases between July 2007 and May 2014 at the Hospital for Sick Children (HSC), were extracted retrospectively R clinical database (Siemens from the AXIOM SensisV Medical Solutions, Erlangen, Germany), excluding electrophysiology studies, procedural categories with 30 kg. Measurements of total air kerma, DAP, and DAP/kg were compared amongst the weight categories for each of these five interventions.
Median DAP and DAP/kg for specific intervention types previously published were collected from the literature, according to the type of radiation data available [6–9]. This was used to compile a comparison of the radiation doses extracted from our database with other centers’ accessible information. To facilitate comparisons of radiation dose, published DAP values were converted to mGy*m2 as published by Stecker et al [10]. The impact of various changes in radiation protection strategies were assessed during the following time periods: July 2007 through November 2009 representing baseline safety measures; December 2009 through June 2011 the period after implementation of the air-gap technique for children 30 kg (49)
Total air kerma (mGy)
DAP (mGy*m2)
DAP/weight (mGy*m2/kg)
61 (30–128) 41 (5–562) 62 (21–409) 140 (21–2,769) 32 (9–408) 46 (7–273) 59 (19–378) 257 (38–2,019) 40 (4–176) 46 (5–562) 174 (76–425) 377 (101–1,168) 32 (7–420) 54 (12–569) 81 (69–153) 551 (4–2,025) 113 (13–755) 191 (12–2,100) 476 (107–1,932) 1,289 (145–4,328)
291 (178–882) 283 (34–4,268) 471 (193–2,987) 1,270 (193–24,456) 137 (38–1,893) 245 (48–1,238) 411 (91–1,948) 2,087 (294–18,131) 145 (14–709) 48 (5–1,955) 1,472 (738–3,222) 4,454 (805–11,091) 114 (22–1,222) 356 (91–4,039) 748 (549–1,156) 5,090 (87–18,847) 500 (42–3,860) 1,217 (88–16,559) 3,747(642–18,893) 13,343 (1,425–35,936)
31 (22–89) 16 (2–213) 22 (8–136) 23 (6–369) 19 (5–208) 17 (4–86) 17 (4–91) 37 (7–251) 31 (8–125) 42 (9–128) 57 (26–141) 77 (24–211) 27 (6–344) 24 (8–311) 34 (22–42) 99 (1–345) 78 (14–483) 93 (8–910) 167 (30–871) 216 (41–689)
Radiation dose expressed as median (range); P < 0.0001 for variation amongst medians by the Kruskal-Wallis test. Abbrev: As in Table II and Ao valv: aortic valvuloplasty, P valv: pulmonary valvuloplasty, PA dil: pulmonary artery angioplasty.
Fig. 2. Graph of DAP/kg stratified by weight, for 5 common interventions. Bars marked with a black dot above represent a statistically significant difference between this weight group and others.
maintaining diagnostic quality imaging [7]. As both dose-dependent deterministic and thresholdindependent stochastic effects increase in frequency and severity with the total amount of radiation exposure [12,13], it is important to have a reference library of radiation doses from various pediatric cardiac interventions and diagnostic categories [5–9] to ensure that a laboratory’s performance is within acceptable limits. We report here as well, median radiation doses for relatively new procedure types not previously published, such as the hybrid stage I procedure (arterial ductal stenting and bilateral pulmonary artery banding), and post-surgical exit angiography (e.g., following aortic arch reconstruction, cavopulmonary connection, and atrial septectomy, or unifocalization of aortopulmonary
collaterals). Our observations underscore there is substantial radiation exposure during many of these procedures, often performed within the first year of life. Children with complex congenital heart disease will have an increased ionizing radiation burden throughout their lives and as such, attempts to reduce this overall burden, mostly from cardiac catheterization [3,4,14], must be a component of all management strategies. A radiation-safety protocol is an essential component of any quality assurance program [5,13,15–17]. We report in this study the various measures, which have been used in our laboratory over the last several years. Using the exposure database reference values (graphs depicting DAP/kg) it is possible to evaluate performance and patient safety on an individual basis as an ongoing process, to determine if case exposure is greater than expected. In this regard, we review case exposure in a weekly multi-disciplinary meeting to identify outliers and the reason(s) for increased exposure during a case(s). Additionally before the case, during the safety check (or timeout), the fluoroscopy frame rate and cine dose is noted by the radiology technologist and whether the grids are in or out on the detector. As a further safety measure, the technologist announces whenever 500 mGy (total dose, air kerma) is exceeded in one projection. Furthermore, during the catheterization consent process, it is noted that ionizing radiation is used during the procedure, that the total dose is carefully monitored, and if it exceeds a threshold level, the case may be stopped and the child may be asked to return to the hospital to be examined.
Catheterization and Cardiovascular Interventions DOI 10.1002/ccd. Published on behalf of The Society for Cardiovascular Angiography and Interventions (SCAI).
Catheterization and Cardiovascular Interventions DOI 10.1002/ccd. Published on behalf of The Society for Cardiovascular Angiography and Interventions (SCAI).
26
345
138
82
120
52
238
117
366
266
286
38
710
1,224
286
ASD creation
ASD/PFO closure
Aortic valvuloplasty
BAS
Coarctation angioplasty
Coarctation stent
Embolization
Fenestration closure
Pulmonary artery angioplasty
PDA closure
Pulmonary valvuloplasty
PPVI
Myocardial biopsy
Diagnostic cath
PHT study
168 (46–6,832) (481) 504 (34–24,456) (1,917) 340 (14–11,091) (4,982) 85 (1–6,889) (666) 479 (35–19,465) (6,052) 3,292 (149–29,154) 677 (67–31,390) (4,526) 776 (123–9,120) (2,270) 1,091 (42–35,936) (9,543) 254 (38–18,131) (1,120) 163 (22–18,847) (1,066) 12,628 (2,673–93,090) (39,005) 278 (10–8,343) (1,319) 475 (1–33,818) (4,390) 166 (6–6,427) (1,310)
DAP 42 (15–195) (88) 21 (2–367) (63) 42 (8–211) (104) 23 (0–508) (93) 43 (7–447) (139) 80 (13–448) 52 (8–640) (193) 49 (9–516) (111) 102 (8–910) (299) 18 (4–251) (66) 28 (1–345) (104) 191 (60–935) (399) 10 (1–108) (23) 39 (0–9,298) (119) 14 (1–1,100) (49)
DAP/kg
NA
2,827
1,172
88
342
467
427§
34
81c
112
182
138
568
124
a
CCISC (n)
66 (193) 90 (228) 120 (360) 93 (192) 132 (347) 42 (130) 56 (152) 186 (396) 27 (114) 59 (175) NA
72 (247) 41 (118) 80 (192)
DAP/kg
161
671
301
NA
75
92
179§
14
28
NA
86b
37
26
97
13
a
CHOP (n)
900 (343–2,087) 612 (272–2,330) 253 (123–638)
1,747 (674–7,450) 1,772 (1,174–2,347) 2,580 (1,024–7,289) 352 (229–709) 405 (233–1,434) NA
361 (326–1,389) 1,038 (629–2,878) 1,118 (470–6,342) 180 (95–591) 484 (261–1,770) NA
DAP
NA
NA
NA
223
461
547
NA
NA
NA
NA
448b
NA
296
726
NA
C3PO (n)
NA
NA
700 (9,100) 700 (15,800) 23,000 (8,25,000) NA
NA
NA
NA
2,900 (36,700) NA
2,100 (28,400) 1,400 (18,700) NA
NA
DAP
NA
NA
NA
NA
63
140
NA
NA
NA
21
9
NA
30
114
NA
ECH (n)
NA
NA
NA
1,520 (30–21,140) 1,230 (70–14,670) NA
NA
NA
2,370 (1,270–20,270) 27,100 (7,750–1,25,150) NA
2,820 (460–19,020) 2,350 (100–68,620) NA
NA
DAP
Medians (range) and (90%tile when available) for DAP and DAP/kg except for CCISC DAP/kg data which are presented as medians (90%tile) only and C3PO DAP data presented as medians (95%tile). All DAP values are converted to mGy*m2 and DAP/kg data reported as mGy*m2/kg. Bold print represents lowest DAP and DAP/kg per procedure type. Abbrv: HSC: Hospital for Sick Children, CCISC: Congenital Cardiovascular Interventional Study Consortium, CHOP: Children’s Hospital of Philadelphia, C3PO: Congenital Cardiac Catheterization Project on Outcomes, ECH: Evelina’s Children’s Hospital; other abbrev as in Table II. a CCISC data for ASD creation grouped with BAS, CHOP ASD creation reported as ASD stent. b CHOP and C3PO data for coarctation angioplasty and stenting grouped together. c CHOP and CCISC data on embolization is for venovenous embolization; §Pulmonary artery angioplasty and stenting are grouped together in CHOP and CCISC data (proximal PA intervention reported here).
HSC (n)
Comparison of Our Radiation Data With Previously Published Radiation Dose Databases
Procedure type
TABLE IV.
846 Borik et al.
Pediatric Catheterization Radiation Exposure
Fig. 3. Box and whisker plots of the DAP during the three time periods for three common interventional procedure groups. The lower box represents the median, upper box the third quartile, and whiskers represent the range (10–90%) for each interventional type. The 2011–2014 time period, following reduction in fluoroscopy pulse rate to 7.5 pulses/second and broadening the air-gap technique to children
Achievable Radiation Reduction during Pediatric Cardiac Catheterization: How Low Can We Go? Sharon Borik, MD, Sunder Devadas, MRT, Dariusz Mroczek, CVT, BIOMED-ENG, Kyong Jin Lee, MD, FRCPC, Rajiv Chaturvedi, MD, PhD, and Lee N. Benson,* MD, FRCPC, FACC, FSCAI Objectives: To assess the effectiveness of radiation-reduction measures implemented during pediatric catheterization, and provide data on the radiation doses for common interventional and diagnostic procedures, indexed to body weight. Background: Ionizing radiation exposure must be minimized to “as low as reasonably achievable,” by instituting radiation-limiting techniques and knowledge of expected radiation exposure. Methods: Radiation-reduction measures included pulsed-fluoroscopy at 7.5 pulses/ second (0.032–0.045 mGy/pulse), an air-gap magnification technique for children 30 kg, P < 0.001). Dose exposure using radiation-reduction techniques were the lowest reported in the literature for all procedure types compared (e.g. median DAP for pulmonary valvuloplasty 163 mGy*m2 vs. 405 to 1,230 mGy*m2 reported by 3 large centers). Reduction of fluoroscopy acquisition to 7.5 pulses/second nearly halved radiation exposure (P < 0.001). Conclusions: Implementing a radiation dose reduction and awareness program can lead to documented reduction in exposure, across a variety of procedures performed by multiple operators. VC 2015 Wiley Periodicals, Inc. Key words: pediatric catheterization; radiation exposure; interventional cardiology
INTRODUCTION
Over the last three decades the cardiac catheterization laboratory has evolved from an instrument of diagnosis to a modality for therapy. As such, the strategies for management of heart disease have changed and with it the reliance on X-ray based imaging. Parallel with this evolution in therapy is awareness to minimize exposure (both to the patient and laboratory personnel) to ionizing radiation to “as low as reasonably achievable” (the so-called ALARA principle). Detrimental effects of ionizing radiation are well known [1,2], and the exposure burden greatest in children with complex congenital heart disease requiring long and frequently repetitive procedures [3,4]. For these reasons, many pediatric catheterization labs have instituted measures for radiation safety, dose reduction and monitoring [5–9], and recently methods for standardization of radiation dose according to patient weight [7]. In C 2015 Wiley Periodicals, Inc. V
this work, we sought to evaluate our catheterization laboratories’ radiation profile and the techniques used to reduce and monitor exposure, update the existing radiation reference library for various pediatric
Department of Pediatrics, Division of Cardiology, the Labatt Family Heart Centre, the Hospital for Sick Children, the University of Toronto School of Medicine, Toronto, Canada Conflict of interest: Nothing to report. *Correspondence to: L. Benson, MD, The Hospital for Sick Children, 555 University Avenue, Toronto, ON, Canada M5G 1X8. E-mail: [email protected] Received 15 January 2015; Revision accepted 18 April 2015 DOI: 10.1002/ccd.26024 Published online 22 May 2015 in Wiley Online Library (wileyonlinelibrary.com)
842
Borik et al.
diagnostic and interventional procedures, and document the degree of exposure reduction that can be achieved. METHODS Data Collection and Definitions
Radiation data of all diagnostic and interventional cases between July 2007 and May 2014 at the Hospital for Sick Children (HSC), were extracted retrospectively R clinical database (Siemens from the AXIOM SensisV Medical Solutions, Erlangen, Germany), excluding electrophysiology studies, procedural categories with 30 kg. Measurements of total air kerma, DAP, and DAP/kg were compared amongst the weight categories for each of these five interventions.
Median DAP and DAP/kg for specific intervention types previously published were collected from the literature, according to the type of radiation data available [6–9]. This was used to compile a comparison of the radiation doses extracted from our database with other centers’ accessible information. To facilitate comparisons of radiation dose, published DAP values were converted to mGy*m2 as published by Stecker et al [10]. The impact of various changes in radiation protection strategies were assessed during the following time periods: July 2007 through November 2009 representing baseline safety measures; December 2009 through June 2011 the period after implementation of the air-gap technique for children 30 kg (49)
Total air kerma (mGy)
DAP (mGy*m2)
DAP/weight (mGy*m2/kg)
61 (30–128) 41 (5–562) 62 (21–409) 140 (21–2,769) 32 (9–408) 46 (7–273) 59 (19–378) 257 (38–2,019) 40 (4–176) 46 (5–562) 174 (76–425) 377 (101–1,168) 32 (7–420) 54 (12–569) 81 (69–153) 551 (4–2,025) 113 (13–755) 191 (12–2,100) 476 (107–1,932) 1,289 (145–4,328)
291 (178–882) 283 (34–4,268) 471 (193–2,987) 1,270 (193–24,456) 137 (38–1,893) 245 (48–1,238) 411 (91–1,948) 2,087 (294–18,131) 145 (14–709) 48 (5–1,955) 1,472 (738–3,222) 4,454 (805–11,091) 114 (22–1,222) 356 (91–4,039) 748 (549–1,156) 5,090 (87–18,847) 500 (42–3,860) 1,217 (88–16,559) 3,747(642–18,893) 13,343 (1,425–35,936)
31 (22–89) 16 (2–213) 22 (8–136) 23 (6–369) 19 (5–208) 17 (4–86) 17 (4–91) 37 (7–251) 31 (8–125) 42 (9–128) 57 (26–141) 77 (24–211) 27 (6–344) 24 (8–311) 34 (22–42) 99 (1–345) 78 (14–483) 93 (8–910) 167 (30–871) 216 (41–689)
Radiation dose expressed as median (range); P < 0.0001 for variation amongst medians by the Kruskal-Wallis test. Abbrev: As in Table II and Ao valv: aortic valvuloplasty, P valv: pulmonary valvuloplasty, PA dil: pulmonary artery angioplasty.
Fig. 2. Graph of DAP/kg stratified by weight, for 5 common interventions. Bars marked with a black dot above represent a statistically significant difference between this weight group and others.
maintaining diagnostic quality imaging [7]. As both dose-dependent deterministic and thresholdindependent stochastic effects increase in frequency and severity with the total amount of radiation exposure [12,13], it is important to have a reference library of radiation doses from various pediatric cardiac interventions and diagnostic categories [5–9] to ensure that a laboratory’s performance is within acceptable limits. We report here as well, median radiation doses for relatively new procedure types not previously published, such as the hybrid stage I procedure (arterial ductal stenting and bilateral pulmonary artery banding), and post-surgical exit angiography (e.g., following aortic arch reconstruction, cavopulmonary connection, and atrial septectomy, or unifocalization of aortopulmonary
collaterals). Our observations underscore there is substantial radiation exposure during many of these procedures, often performed within the first year of life. Children with complex congenital heart disease will have an increased ionizing radiation burden throughout their lives and as such, attempts to reduce this overall burden, mostly from cardiac catheterization [3,4,14], must be a component of all management strategies. A radiation-safety protocol is an essential component of any quality assurance program [5,13,15–17]. We report in this study the various measures, which have been used in our laboratory over the last several years. Using the exposure database reference values (graphs depicting DAP/kg) it is possible to evaluate performance and patient safety on an individual basis as an ongoing process, to determine if case exposure is greater than expected. In this regard, we review case exposure in a weekly multi-disciplinary meeting to identify outliers and the reason(s) for increased exposure during a case(s). Additionally before the case, during the safety check (or timeout), the fluoroscopy frame rate and cine dose is noted by the radiology technologist and whether the grids are in or out on the detector. As a further safety measure, the technologist announces whenever 500 mGy (total dose, air kerma) is exceeded in one projection. Furthermore, during the catheterization consent process, it is noted that ionizing radiation is used during the procedure, that the total dose is carefully monitored, and if it exceeds a threshold level, the case may be stopped and the child may be asked to return to the hospital to be examined.
Catheterization and Cardiovascular Interventions DOI 10.1002/ccd. Published on behalf of The Society for Cardiovascular Angiography and Interventions (SCAI).
Catheterization and Cardiovascular Interventions DOI 10.1002/ccd. Published on behalf of The Society for Cardiovascular Angiography and Interventions (SCAI).
26
345
138
82
120
52
238
117
366
266
286
38
710
1,224
286
ASD creation
ASD/PFO closure
Aortic valvuloplasty
BAS
Coarctation angioplasty
Coarctation stent
Embolization
Fenestration closure
Pulmonary artery angioplasty
PDA closure
Pulmonary valvuloplasty
PPVI
Myocardial biopsy
Diagnostic cath
PHT study
168 (46–6,832) (481) 504 (34–24,456) (1,917) 340 (14–11,091) (4,982) 85 (1–6,889) (666) 479 (35–19,465) (6,052) 3,292 (149–29,154) 677 (67–31,390) (4,526) 776 (123–9,120) (2,270) 1,091 (42–35,936) (9,543) 254 (38–18,131) (1,120) 163 (22–18,847) (1,066) 12,628 (2,673–93,090) (39,005) 278 (10–8,343) (1,319) 475 (1–33,818) (4,390) 166 (6–6,427) (1,310)
DAP 42 (15–195) (88) 21 (2–367) (63) 42 (8–211) (104) 23 (0–508) (93) 43 (7–447) (139) 80 (13–448) 52 (8–640) (193) 49 (9–516) (111) 102 (8–910) (299) 18 (4–251) (66) 28 (1–345) (104) 191 (60–935) (399) 10 (1–108) (23) 39 (0–9,298) (119) 14 (1–1,100) (49)
DAP/kg
NA
2,827
1,172
88
342
467
427§
34
81c
112
182
138
568
124
a
CCISC (n)
66 (193) 90 (228) 120 (360) 93 (192) 132 (347) 42 (130) 56 (152) 186 (396) 27 (114) 59 (175) NA
72 (247) 41 (118) 80 (192)
DAP/kg
161
671
301
NA
75
92
179§
14
28
NA
86b
37
26
97
13
a
CHOP (n)
900 (343–2,087) 612 (272–2,330) 253 (123–638)
1,747 (674–7,450) 1,772 (1,174–2,347) 2,580 (1,024–7,289) 352 (229–709) 405 (233–1,434) NA
361 (326–1,389) 1,038 (629–2,878) 1,118 (470–6,342) 180 (95–591) 484 (261–1,770) NA
DAP
NA
NA
NA
223
461
547
NA
NA
NA
NA
448b
NA
296
726
NA
C3PO (n)
NA
NA
700 (9,100) 700 (15,800) 23,000 (8,25,000) NA
NA
NA
NA
2,900 (36,700) NA
2,100 (28,400) 1,400 (18,700) NA
NA
DAP
NA
NA
NA
NA
63
140
NA
NA
NA
21
9
NA
30
114
NA
ECH (n)
NA
NA
NA
1,520 (30–21,140) 1,230 (70–14,670) NA
NA
NA
2,370 (1,270–20,270) 27,100 (7,750–1,25,150) NA
2,820 (460–19,020) 2,350 (100–68,620) NA
NA
DAP
Medians (range) and (90%tile when available) for DAP and DAP/kg except for CCISC DAP/kg data which are presented as medians (90%tile) only and C3PO DAP data presented as medians (95%tile). All DAP values are converted to mGy*m2 and DAP/kg data reported as mGy*m2/kg. Bold print represents lowest DAP and DAP/kg per procedure type. Abbrv: HSC: Hospital for Sick Children, CCISC: Congenital Cardiovascular Interventional Study Consortium, CHOP: Children’s Hospital of Philadelphia, C3PO: Congenital Cardiac Catheterization Project on Outcomes, ECH: Evelina’s Children’s Hospital; other abbrev as in Table II. a CCISC data for ASD creation grouped with BAS, CHOP ASD creation reported as ASD stent. b CHOP and C3PO data for coarctation angioplasty and stenting grouped together. c CHOP and CCISC data on embolization is for venovenous embolization; §Pulmonary artery angioplasty and stenting are grouped together in CHOP and CCISC data (proximal PA intervention reported here).
HSC (n)
Comparison of Our Radiation Data With Previously Published Radiation Dose Databases
Procedure type
TABLE IV.
846 Borik et al.
Pediatric Catheterization Radiation Exposure
Fig. 3. Box and whisker plots of the DAP during the three time periods for three common interventional procedure groups. The lower box represents the median, upper box the third quartile, and whiskers represent the range (10–90%) for each interventional type. The 2011–2014 time period, following reduction in fluoroscopy pulse rate to 7.5 pulses/second and broadening the air-gap technique to children
