Keith J. Strauss

Image Gently: Ten Steps You Can Take to Optimize Image Quality and Lower CT Dose for Pediatric Patients

AJR:194, April 2010 This article suggests 10 steps that radiologists and radiologic technologists, with the assistance of their medical physicist, can take to obtain good quality CT images while properly managing radiation dose for children undergoing CT. The first six steps ideally should be completed before performing any CT on a pediatric patient. The final four steps address the unique consideration that should be given for each scanned patient.

The 'Image Gently' campaign: increasing CT radiation dose awareness through a national education and awareness program

ALARA (As Low As Reasonably Achievable) has been a guiding principle for pediatric radiologists for decades. The Society for Pediatric Radiology (SPR) has long been a leader in promoting safety in radiology practice in children. However, the ALARA principle has taken on new meaning in the past several years as the number of CT scans in children has skyrocketed. For example, it is estimated that since the 1980s when CT was beginning its ascendancy there has been up to an 800% increase. CT scans in children provide great benefit in patient care when used appropriately. However, increased use requires a team approach to ensure that only indicated exams are performed and at the Pediatr Radiol (2008) 38:265–269 DOI 10.1007/s00247-007-0743-3

Clinical radiation management for fluoroscopically guided interventional procedures.

The primary goal of radiation management in interventional radiology is to minimize the unnecessary use of radiation. Clinical radiation management minimizes radiation risk to the patient without increasing other risks, such as procedural risks. A number of factors are considered when estimating the likelihood and severity of patient radiation effects. These include demographic factors, medical history factors, and procedure factors. Important aspects of the patients medical history include coexisting diseases and genetic factors, medication use, radiation history, and pregnancy. As appropriate, these are evaluated as part of the preprocedure patient evaluation; radiation risk to the patient is considered along with other procedural risks. Dose optimization is possible through appropriate use of the basic features of interventional fluoroscopic equipment and intelligent use of dose-reducing technology. For all fluoroscopically guided interventional procedures, it is good practice to monitor radiation dose throughout the procedure and record it in the patients medical record. Patients who have received a clinically significant radiation dose should be followed up after the procedure for possible deterministic effects. The authors recommend including radiation management as part of the departmental quality assurance program.

Pediatric radiation exposure and effective dose reduction during voiding cystourethrography.

PURPOSE To compare radiation exposure and effective dose in children who underwent voiding cystourethrography (VCUG) performed with grid-controlled variable-rate pulsed fluoroscopy (GCPFL) with radiation exposure and effective dose in children who underwent VCUG performed with continuous fluoroscopy (CFL) and to compare these effective doses with those estimated with radionuclide cystography (RNC). MATERIALS AND METHODS Institutional review board approval was obtained, and the informed consent requirement was waived for this HIPAA-compliant retrospective study. Radiation exposure and fluoroscopy time during VCUG were reviewed in 145 children (75 girls, 70 boys; age range, 3 days to 8 years) who underwent GCPFL or CFL between 2001 and 2002. Children were grouped on the basis of the fluoroscopy unit used and their supine anteroposterior abdominal diameter (group 1, 8.0-8.5-cm diameter; group 2, 10-11-cm diameter; group 3, 12-13-cm diameter). Analysis of variance was used to compare radiation exposure and fluoroscopy time between fluoroscopy units and patient diameter groups. Effective doses were calculated and compared for both fluoroscopes and for estimated RNC dose values. RESULTS GCPFL resulted in a significant reduction in total radiation exposure, which was at least eight times lower than that with CFL in all three groups (P < .001 for all). There was no significant difference in fluoroscopy time (P > .50). Effective radiation doses from GCPFL were approximately one order of magnitude lower than those from CFL but one order of magnitude higher than those from RNC. CONCLUSION In children, VCUG can be performed with a GCPFL unit that delivers radiation exposures that are at least eight times lower than those delivered by a conventional CFL unit. SUPPLEMENTAL MATERIAL http://radiology.rsnajnls.org/cgi/content/full/2492062066/DC1.

The ALARA (as low as reasonably achievable) concept in pediatric interventional and fluoroscopic imaging: striving to keep radiation doses as low as possible during fluoroscopy of pediatric patients—a white paper executive summary

ALARA represents a practice mandate adhering to the principle of keeping radiation doses to patients and personnel As Low As Reasonably Achievable. This concept is strongly endorsed by the Society for Pediatric Radiology, particularly in the use of procedures and modalities involving higher radiation doses such as CT and fluoroscopic examinations of pediatric patients. There is no doubt that medical imaging, which has undergone tremendous technological advances in recent decades, is integral to patient care. However, these technological advances generally precede the knowledge of end-users concerning the optimal use and correct operation of the resulting imaging equipment, and such knowledge is essential to minimizing potential risks to the patients. Current imaging methods must be optimized for radiation dose reduction in pediatric patients who might be as much as ten times more radiosensitive than adults. Unlike straightforward radiographic examinations, radiation dose to the patient during fluoroscopy is dependent on the operator’s training, experience with the fluoroscope, and efficiency in completing a diagnostic study. The range of pediatric radiation doses from fluoroscopy is wide because this examination is performed not only by pediatric radiologists but also by general radiologists who occasionally care for children, interventional cardiologists, gastroenterologists, urologists and others. Thus, a venue where multidisciplinary interaction by this variety of operators can occur serves to improve pediatric patient care. The third ALARA conference organized by the Society for Pediatric Radiology was held in Orlando, Fla., on 11–2 February 2006. It was co-sponsored by the Office of Rare Diseases and the National Cancer Institute of the National Institutes of Health (NCI/NIH). The conference was funded by unrestricted educational grants from three manufacturers of fluoroscopic and interventional equipment (GE, Philips, Siemens) and financial support from the Society for Pediatric Radiology and NCI/NIH. The 22 faculty members consisted of 8 pediatric radiologists, 5 medical physicists, 3 pediatric subspecialists, 3 industry speakers, and 3 radiation epidemiology researchers. A diverse cadre of 74 pediatric radiologists, medical physicists, radiologic technologists, researchers, pediatric subspecialists and vendors met to examine the risk of radiation exposure from fluoroscopic and interventional procedures, identify means by which to reduce ionizing radiation exposure, and explore future technologic modifications that could optimize imaging while further reducing radiation exposures.

Diagnostic Reference Ranges for Pediatric Abdominal CT

PURPOSE To develop diagnostic reference ranges (DRRs) and a method for an individual practice to calculate site-specific reference doses for computed tomographic (CT) scans of the abdomen or abdomen and pelvis in children on the basis of body width (BW). MATERIALS AND METHODS This HIPAA-compliant multicenter retrospective study was approved by institutional review boards of participating institutions; informed consent was waived. In 939 pediatric patients, CT doses were reviewed in 499 (53%) male and 440 (47%) female patients (mean age, 10 years). Doses were from 954 scans obtained from September 1 to December 1, 2009, through Quality Improvement Registry for CT Scans in Children within the National Radiology Data Registry, American College of Radiology. Size-specific dose estimate (SSDE), a dose estimate based on BW, CT dose index, dose-length product, and effective dose were analyzed. BW measurement was obtained with electronic calipers from the axial image at the splenic vein level after completion of the CT scan. An adult-sized patient was defined as a patient with BW of 34 cm. An appropriate dose range for each DRR was developed by reviewing image quality on a subset of CT scans through comparison with a five-point visual reference scale with increments of added simulated quantum mottle and by determining DRR to establish lower and upper bounds for each range. RESULTS For 954 scans, DRRs (SSDEs) were 5.8-12.0, 7.3-12.2, 7.6-13.4, 9.8-16.4, and 13.1-19.0 mGy for BWs less than 15, 15-19, 20-24, 25-29, and 30 cm or greater, respectively. The fractions of adult doses, adult SSDEs, used within the consortium for patients with BWs of 10, 14, 18, 22, 26, and 30 cm were 0.4, 0.5, 0.6, 0.7, 0.8, and 0.9, respectively. CONCLUSION The concept of DRRs addresses the balance between the patients risk (radiation dose) and benefit (diagnostic image quality). Calculation of reference doses as a function of BW for an individual practice provides a tool to help develop site-specific CT protocols that help manage pediatric patient radiation doses.

Image GentlySM: A National Education and Communication Campaign in Radiology Using the Science of Social Marketing

Communication campaigns are an accepted method for altering societal attitudes, increasing knowledge, and achieving social and behavioral change particularly within public health and the social sciences. The Image Gently(SM) campaign is a national education and awareness campaign in radiology designed to promote the need for and opportunities to decrease radiation to children when CT scans are indicated. In this article, the relatively new science of social marketing is reviewed and the theoretical basis for an effective communication campaign in radiology is discussed. Communication strategies are considered and the type of outcomes that should be measured are reviewed. This methodology has demonstrated that simple, straightforward safety messages on radiation protection targeted to medical professionals throughout the radiology community, utilizing multiple media, can affect awareness potentially leading to change in practice.

Estimated pediatric radiation dose during CT

State-of-the-art CT scanners typically display two dose indices: CT dose index (CTDIvol [mGy]) and dose length product (DLP [mGy-cm]) based on one of two standard CTDI phantoms (16- or 32-cm diameter) used in the calculation of CTDIvol. CTDIvol represents the radiation produced by the CT scanner, not the radiation dose to an individual patient. Pediatric radiologists, aware of this discrepancy, have requested a method to estimate the CT patient dose based on the size of the pediatric patient or small adult. This paper describes the method developed by AAPM Task Group 204 to provide a better estimate of CT patient dose. These improved estimates of patient dose provide radiologists with a practical tool to better manage the radiation dose their patients receive. In the future, size-specific dose estimates (SSDE) received by the patient should be included in the patient’s electronic medical record to help radiologists better assess risk versus benefit for their patients.

Patient Size Measured on CT Images as a Function of Age at a Tertiary Care Children's Hospital

OBJECTIVE The purpose of our study was to measure patient size on CT images as a function of age at a large tertiary care childrens hospital to develop current patient size data for modeling optimal x-ray exposure factors in children. MATERIALS AND METHODS Anteroposterior and transverse dimensions of the head, thorax, abdomen, and pelvis were measured on CT examinations of pediatric patients less than 21 years old performed between June and November 2007. Patients with diseases that could affect measurements were excluded. From 1,009 patients, 336 examinations of each of four body regions were selected; 2,688 measurements were made and separated into 21 groups. Statistical model building and prediction equations were established for each region and 95% prediction intervals were used for analyses. RESULTS Rapid growth of the head occurred from birth to approximately 2 years followed by a gradual plateau until 21 years. The thoracic, abdominal, and pelvic regions showed a linear relationship between age and size. Fitted equations showed transverse trunk measurements increased more rapidly than anteroposterior measurements. The anteroposterior trunk size growth rate was relatively region independent; transverse pelvic dimensions grew more rapidly than thoracic or abdominal regions. There was a broad overlap of predicted patient size ranges as a function of age within each region. Excellent interobserver agreement was measured by Pearsons correlation coefficient (r) (all p < 0.0001). CONCLUSION Fitted average patient sizes are age dependent; however, predicted individual patient size does not correlate well with age. Our study suggests that pediatric patient body size should be determined for individual patients before performing diagnostic imaging procedures that entail radiation risks.

Characterization of radiation exposure and effect of a radiation monitoring policy in a large volume pediatric cardiac catheterization lab

Objectives: This study aimed to characterize radiation dose during cardiac catheterization in congenital heart disease and to assess changes in dose after the introduction of a radiation monitoring policy. Background: Minimizing radiation exposure is an important patient safety initiative and relatively few data are available characterizing radiation dose for the broad spectrum of congenital cardiac catheter‐based interventions. Methods: Radiation dose data were reviewed on all cases since 7/1/05 at a single large center. Procedures were classified according to 20 common case types then subdivided into five age categories. Groups with <20 cases were excluded. Radiation dose was estimated by cumulative air KERMA (mGy) and DAP (dose area product, μGym2) which were reported as median and interquartile range (IQR). We also examined differences in radiation dose before and after the implementation of a radiation policy. Results: Between 7/1/05 and 12/10/08, 3,365 cases were identified for inclusion. Radiation dose increased with age and procedural complexity. Patients were characterized into low, medium, and high dose categories relative to each other. “Low” dose cases included isolated pulmonary or aortic valvotomy, pre‐Fontan assessment, and ASD closure. “High” dose cases involved multiple procedures in pulmonary arteries or veins. After introduction of a radiation policy, there was a significant decrease in radiation dose across a variety of case types, particularly among infants and young children. Conclusions: Radiation dose in congenital cardiac catheterization varies by age and procedure type. A radiation monitoring and notification policy may have contributed to reduced radiation dose.