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Our Responsibility for Medical Radiation Dose Determinations
Volume 23 䡲 Number 4 䡲 April 䡲 2012
451
INVITED COMMENTARY
Our Responsibility for Medical Radiation Dose Determinations Donald P. Frush, MD ABBREVIATION DAP ⫽ dose-area product
The article by Govia et al (1) entitled “Estimates of Effective Dose to Pediatric Patients Undergoing Enteric and Venous Access Procedures” is provocative for several reasons. This work (i) upholds the growing mandate for accurate radiation dose estimation across modalities and the archiving/reporting of these dose estimates, (ii) conveys some challenges with respect to accurate dose estimation and archiving/reporting, and (iii) reveals essential admonitions as accountability for doses delivered expands. Together, these realizations underscore our fundamental responsibility as imaging experts to take ownership for patient care beyond the traditional elements such as equipment and examination/procedure performance, interpretation, and communication: we must understand and account for the radiation doses we deliver to our patients. This article addresses directly or indirectly a number of critical issues confronting radiologists. First, radiation is a necessary component of many imaging modalities, and relatively high radiation doses do have biologic risks. We have a responsibility for managing radiation risks, as we do for other risks of interventional procedures such as infection, bleeding, thrombosis, drug interactions, and other iatrogenic consequences, many of which are documented in databases. This responsibility is more than patient radiation protection during the procedure and is aimed at accounting for the radiation against which we cannot protect. Part of this responsibility is to understand the dose potentially delivered for a spectrum of procedures performed. This responsibility also implies some consensus representation of dose that is useful, relatively easily obtained, and ar-
From the Division of Pediatric Radiology, McGovern–Davison Children’s Health Center; and Department of Radiology, Duke University Medical Center, Box 3808, Erwin Road, Durham, NC 27710. Final revision received and accepted January 13, 2012. Address correspondence to D.P.F.; E-mail: [email protected] The author has not identified a conflict of interest. © SIR, 2012 J Vasc Interv Radiol 2012; 23:451– 452 DOI: 10.1016/j.jvir.2012.01.063
chived, serving for a specific patient-based cumulative record as well as overall procedural doses for the portfolio of imaging procedures for quality assessment and improvement (ie, protocol and procedural modification in situations in which these doses may be relatively high). This availability of procedural dose estimations would provide reference levels, and, with multiinstitutional participation, dose information would function as a benchmark against which to assess practice performance. This investigation (1) also demonstrates the importance of assessing doses to our patient population for procedures other than computed tomography (CT), which has more often been a focus of attention when it comes to radiation, potential radiation risks such as cancer, and medical imaging. The investigators also emphasize that we should be looking at common procedures (in this case, venous catheter placements and enteric procedures), for which the conclusions would have the most sweeping impact. Moreover, dose estimations were explored in the pediatric population, which has unique and intensified considerations with respect to radiation exposure and risk for familiar reasons. Finally, multidisciplinary participation in this project is a model that is critical in investigative design and performance, and in interpretation yielding consensus recommendations for dose estimations. Given these contributions from this investigation (1), there are also equally important challenges. First, providing dose estimations across patient sizes/ages is time- and resource-consuming. Metal oxide semiconductor field-effect transistor technology and anthropomorphic phantoms are costly to purchase and to maintain. Dose estimation data may have limited application. In this investigation (1), data were gathered for a single phantom representing a 5-yearold child. In addition, many dose-determining variables (including the operator) will exist for interventional procedures, and surrogate measures such as fluoroscopic times may not represent the range of exposures. In addition to collimation, magnification, and fluoroscopic time, the projection and number of cine sequences can also substantially affect the dose delivered. In addition, if there is some agreed-upon measure of dose estimation for fluoroscopy/ angiography (eg, dose-area product [DAP]), how is this to
452 䡲 Commentary: Our Responsibility for Radiation Dose Determinations
be recorded? Only in picture archiving and communications system? In the patient report or in the medical record elsewhere? What should be contained in a report? Which information should be recorded—a DAP dose measure (eg, Gy·m2), effective dose (in mSv), or conversion of a dose estimate to risk estimation? Notably, for what would any of this information be used in a patient report? The fundamental question is whether it would be helpful. Would these data be used for decision making, such as limiting further fluoroscopic evaluation in cases with a history of a relatively high cumulative radiation dose? Would dose/dose risk information be used differently for a child versus an adult? A female versus a male subject? Physicists, radiologists, regulatory or governmental organizations, and patients might all have different needs when considering the “what,” “how,” and “why” of dose recording. If this were to happen with interventional procedures, should not it happen with other ionizing imaging modalities such as fluoroscopy outside of the interventional suite, radiography, and CT? If we are recording this, it must be seen as important. Should consent be required to include dose risk discussion? There are obvious complexities when it comes to signed informed consent to radiation risks from diagnostic imaging levels of radiation (2). Many imaging experts currently believe we need to move away from effective dose as a measure of risk (3). Current work in CT is beginning to offer patient-specific organ doses and more accurate effective dose estimations (4). These models can be applied to other modalities. Despite these challenges, investigations such as this one by Govia and colleagues (1) in the pediatric population are taking necessary and important steps, embarking on the course of dose estimations and accountability for these doses from interventional procedures. Finally, several admonitions arise from work such as this. First, the study (1) provides not individual patient dose but an estimation of dose, and methodologic caveats addressed in the study note this. In addition, we must be careful to continue to promote the advantages of what we do—the value of both diagnostic and interventional radiology evaluation. The evocative first sentence (1) and the fraternal use of the phrase and term “imaging radiation” and “cancer,” I believe, should be sculpted to provide a more proper context of value and risk. We must promote the good by reminding ourselves and those we serve that these procedures have, as a rule, very large and often likely potential benefit. Finally, we must be mindful of the scope of our
Frush 䡲 JVIR
diverse “customer” base (eg, patients, referring clinicians, administrators, regulators) and be sure that the information we provide, if in a report, is appropriate. I advocate for a simple and general statement of (re)assurance indicating that the equipment, personnel, and program (eg, CT, interventional radiology, fluoroscopy, nuclear medicine, conventional radiography) meet standards of excellence for expertise, safety (including radiation protection), and quality (ie, American Society of Radiologic Technologists and American Board of Radiology certification, modality/program accreditation). Further information can be subsequently layered in the report. For example, information on dose estimation for the equipment or for the specific procedure or protocol, radiation dose estimations in general for medical imaging, or radiation risks can be linked to established and authoritative sites (eg, those of the Radiological Society of North America, American College of Radiology, National Council on Radiation Protection and Measurements, International Atomic Energy Agency, Food and Drug Administration, or National Cancer Institute; or Image Gently or Image Wisely) for those who wish to find more detailed information. This general statement would be equivalent to the Good Housekeeping seal. Most customers do not care, for example, what ingredients are in their toothpaste (perhaps an analogue to the DAP) but simply want the reassurance that some respected organization has emblematic approval of the product. Understanding the challenges, admonitions, and opinions on how we, as a profession, might proceed with dose estimations and recording, the investigation by Govia et al (1) begins to provide this more defined information for interventional radiologic procedures in children. If we do not take ownership of this, someone will tell us how to do it—with unfortunate consequences, both expected and unforeseen.
REFERENCES 1. Govia K, Connolly BL, Thomas KE, Gordon CL. Estimates of effective dose to pediatric patients undergoing enteric and venous access procedures. J Vasc Interv Radiol 2012; 23:443– 450. 2. Nievelstein RJ, Frush DP. Should we consent patients for radiation? AJR Am J Roentgenol 2012 (in press). 3. Martin CJ. Effective dose: how should it be applied to medical exposures? Br J Radiol 2007; 80:639 – 647. 4. Li X, Samei E, Frush D, et al. Patient-specific radiation dose and cancer risk estimation in CT: part II. Applications to patients. Med Phys 201; 38:408 – 419.
451
INVITED COMMENTARY
Our Responsibility for Medical Radiation Dose Determinations Donald P. Frush, MD ABBREVIATION DAP ⫽ dose-area product
The article by Govia et al (1) entitled “Estimates of Effective Dose to Pediatric Patients Undergoing Enteric and Venous Access Procedures” is provocative for several reasons. This work (i) upholds the growing mandate for accurate radiation dose estimation across modalities and the archiving/reporting of these dose estimates, (ii) conveys some challenges with respect to accurate dose estimation and archiving/reporting, and (iii) reveals essential admonitions as accountability for doses delivered expands. Together, these realizations underscore our fundamental responsibility as imaging experts to take ownership for patient care beyond the traditional elements such as equipment and examination/procedure performance, interpretation, and communication: we must understand and account for the radiation doses we deliver to our patients. This article addresses directly or indirectly a number of critical issues confronting radiologists. First, radiation is a necessary component of many imaging modalities, and relatively high radiation doses do have biologic risks. We have a responsibility for managing radiation risks, as we do for other risks of interventional procedures such as infection, bleeding, thrombosis, drug interactions, and other iatrogenic consequences, many of which are documented in databases. This responsibility is more than patient radiation protection during the procedure and is aimed at accounting for the radiation against which we cannot protect. Part of this responsibility is to understand the dose potentially delivered for a spectrum of procedures performed. This responsibility also implies some consensus representation of dose that is useful, relatively easily obtained, and ar-
From the Division of Pediatric Radiology, McGovern–Davison Children’s Health Center; and Department of Radiology, Duke University Medical Center, Box 3808, Erwin Road, Durham, NC 27710. Final revision received and accepted January 13, 2012. Address correspondence to D.P.F.; E-mail: [email protected] The author has not identified a conflict of interest. © SIR, 2012 J Vasc Interv Radiol 2012; 23:451– 452 DOI: 10.1016/j.jvir.2012.01.063
chived, serving for a specific patient-based cumulative record as well as overall procedural doses for the portfolio of imaging procedures for quality assessment and improvement (ie, protocol and procedural modification in situations in which these doses may be relatively high). This availability of procedural dose estimations would provide reference levels, and, with multiinstitutional participation, dose information would function as a benchmark against which to assess practice performance. This investigation (1) also demonstrates the importance of assessing doses to our patient population for procedures other than computed tomography (CT), which has more often been a focus of attention when it comes to radiation, potential radiation risks such as cancer, and medical imaging. The investigators also emphasize that we should be looking at common procedures (in this case, venous catheter placements and enteric procedures), for which the conclusions would have the most sweeping impact. Moreover, dose estimations were explored in the pediatric population, which has unique and intensified considerations with respect to radiation exposure and risk for familiar reasons. Finally, multidisciplinary participation in this project is a model that is critical in investigative design and performance, and in interpretation yielding consensus recommendations for dose estimations. Given these contributions from this investigation (1), there are also equally important challenges. First, providing dose estimations across patient sizes/ages is time- and resource-consuming. Metal oxide semiconductor field-effect transistor technology and anthropomorphic phantoms are costly to purchase and to maintain. Dose estimation data may have limited application. In this investigation (1), data were gathered for a single phantom representing a 5-yearold child. In addition, many dose-determining variables (including the operator) will exist for interventional procedures, and surrogate measures such as fluoroscopic times may not represent the range of exposures. In addition to collimation, magnification, and fluoroscopic time, the projection and number of cine sequences can also substantially affect the dose delivered. In addition, if there is some agreed-upon measure of dose estimation for fluoroscopy/ angiography (eg, dose-area product [DAP]), how is this to
452 䡲 Commentary: Our Responsibility for Radiation Dose Determinations
be recorded? Only in picture archiving and communications system? In the patient report or in the medical record elsewhere? What should be contained in a report? Which information should be recorded—a DAP dose measure (eg, Gy·m2), effective dose (in mSv), or conversion of a dose estimate to risk estimation? Notably, for what would any of this information be used in a patient report? The fundamental question is whether it would be helpful. Would these data be used for decision making, such as limiting further fluoroscopic evaluation in cases with a history of a relatively high cumulative radiation dose? Would dose/dose risk information be used differently for a child versus an adult? A female versus a male subject? Physicists, radiologists, regulatory or governmental organizations, and patients might all have different needs when considering the “what,” “how,” and “why” of dose recording. If this were to happen with interventional procedures, should not it happen with other ionizing imaging modalities such as fluoroscopy outside of the interventional suite, radiography, and CT? If we are recording this, it must be seen as important. Should consent be required to include dose risk discussion? There are obvious complexities when it comes to signed informed consent to radiation risks from diagnostic imaging levels of radiation (2). Many imaging experts currently believe we need to move away from effective dose as a measure of risk (3). Current work in CT is beginning to offer patient-specific organ doses and more accurate effective dose estimations (4). These models can be applied to other modalities. Despite these challenges, investigations such as this one by Govia and colleagues (1) in the pediatric population are taking necessary and important steps, embarking on the course of dose estimations and accountability for these doses from interventional procedures. Finally, several admonitions arise from work such as this. First, the study (1) provides not individual patient dose but an estimation of dose, and methodologic caveats addressed in the study note this. In addition, we must be careful to continue to promote the advantages of what we do—the value of both diagnostic and interventional radiology evaluation. The evocative first sentence (1) and the fraternal use of the phrase and term “imaging radiation” and “cancer,” I believe, should be sculpted to provide a more proper context of value and risk. We must promote the good by reminding ourselves and those we serve that these procedures have, as a rule, very large and often likely potential benefit. Finally, we must be mindful of the scope of our
Frush 䡲 JVIR
diverse “customer” base (eg, patients, referring clinicians, administrators, regulators) and be sure that the information we provide, if in a report, is appropriate. I advocate for a simple and general statement of (re)assurance indicating that the equipment, personnel, and program (eg, CT, interventional radiology, fluoroscopy, nuclear medicine, conventional radiography) meet standards of excellence for expertise, safety (including radiation protection), and quality (ie, American Society of Radiologic Technologists and American Board of Radiology certification, modality/program accreditation). Further information can be subsequently layered in the report. For example, information on dose estimation for the equipment or for the specific procedure or protocol, radiation dose estimations in general for medical imaging, or radiation risks can be linked to established and authoritative sites (eg, those of the Radiological Society of North America, American College of Radiology, National Council on Radiation Protection and Measurements, International Atomic Energy Agency, Food and Drug Administration, or National Cancer Institute; or Image Gently or Image Wisely) for those who wish to find more detailed information. This general statement would be equivalent to the Good Housekeeping seal. Most customers do not care, for example, what ingredients are in their toothpaste (perhaps an analogue to the DAP) but simply want the reassurance that some respected organization has emblematic approval of the product. Understanding the challenges, admonitions, and opinions on how we, as a profession, might proceed with dose estimations and recording, the investigation by Govia et al (1) begins to provide this more defined information for interventional radiologic procedures in children. If we do not take ownership of this, someone will tell us how to do it—with unfortunate consequences, both expected and unforeseen.
REFERENCES 1. Govia K, Connolly BL, Thomas KE, Gordon CL. Estimates of effective dose to pediatric patients undergoing enteric and venous access procedures. J Vasc Interv Radiol 2012; 23:443– 450. 2. Nievelstein RJ, Frush DP. Should we consent patients for radiation? AJR Am J Roentgenol 2012 (in press). 3. Martin CJ. Effective dose: how should it be applied to medical exposures? Br J Radiol 2007; 80:639 – 647. 4. Li X, Samei E, Frush D, et al. Patient-specific radiation dose and cancer risk estimation in CT: part II. Applications to patients. Med Phys 201; 38:408 – 419.