Image Gently – Back to Basics:

Image Gently – Back to Basics:
Ten steps to help manage radiation dose in pediatric digital radiography There is a potential for a gap in knowledge for those used to working with analog screen-film technology who are now working with digital radiography. The gap occurs when technology advances faster than education resources. This talk addresses facts and challenges related to performing digital radiography. While many of the basic concepts have stayed the same, digital radiology requires new knowledge. The basic fact that patient thickness of the anatomical part being imaged is a critical consideration when determining technique is discussed. This requires going back to the basics of patient measuring and utilizing accurate exposure combinations to produce x-rays. The new technology requires an understanding of how the digital radiographic image is produced and what is the significance of the exposure index. We hope this talk will be helpful in bridging this potential education gap. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

The Alliance for Radiation Safety in Pediatric Imaging
The image gently campaign

What is Image Gently An education, awareness and advocacy campaign
To improve radiation protection for children worldwide Alliance for Radiation Safety in Pediatric Imaging >70 health care organizations/agencies >800,000 radiologists radiology technologists medical physicists worldwide Before we begin, we would like to take a minute and discuss the sponsors of this talk….. The Image Gently campaign. what is Image Gently? Image Gently is an education and awareness program whose goal it is to improve radiation protection for children both nationally and internationally. There are 70 healthcare organization and agencies who have signed on to “ take the pledge” and work together towards this goal. The Alliance represents over 800,000 health care professionals worldwide. We are currently receiving inquiries from medical societies wanting to support this worthwhile endeavor. Another unique aspect of the campaign is that since its inception, the critical triad of radiologist, physicists and technologists have worked hand in hand for this common goal. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

The Alliance for Radiation Safety in Pediatric Imaging
The Image Gently Alliance is a coalition of health care organizations dedicated to providing safe, high quality pediatric imaging worldwide. The primary objective of the Alliance is to raise awareness in the imaging community of the need to adjust radiation dose when imaging children. The ultimate goal of the Alliance is to change practice. What is the mission of the Alliance… the mission is to provide safe high quality pediatric imaging focused on raising awareness in the imaging community on the need to adjust dose when imaging children…. And our ultimate goal is to change practice locally to improve care for children. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Objectives Raise awareness of opportunities to lower radiation dose while maintaining diagnostic image quality when imaging children Address methods to standardize the approach to pediatric digital radiography Highlight challenges related to the technology when used with patients of widely variable body size Digital radiography has become the norm in hospitals within the United States. The ability to immediately view images, post-process and transmit the images system–wide are its distinct advantages. Yet, these technical advances have created many challenges for the radiology community, including the need to re-educate its workforce and prevent unnecessary radiation exposure. This education process is even more important in children, where maintaining diagnostic image quality at a properly managed dose is critical for patient care. As children are more sensitive than adults to the potential effects of ionizing radiation, particular attention to technique and its relationship to patient dose is most important. This PowerPoint presentation emphasizes the need for attention to the basics of radiography and the importance of a standard approach in pediatric digital radiography. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Imaging Statistics Radiography is the most common type of exam in diagnostic imaging 74% of all imaging exams Represents 85% of all ionizing radiation studies in children During a three-year radiography study: 40% children had 1 study 22% had 2 14% had >3 Projection radiography is the most common type of examination performed in diagnostic imaging. The 2006 National Council on Radiation Protection and Measurements Report No. 160 stated that 74% of all imaging examinations in radiography are projection radiographs [1]. In a survey of five large healthcare markets, projection radiography represents 85% of all ionizing radiation imaging examinations in children [2]. During the three-year period from that survey, 40% of the children had at least one projection radiographic examination, 22% had 2 examinations and 14% had three or more examinations. When combining all ionizing radiation examinations, a child will receive more than 7 studies by 18 years of age. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Changing of Technology
Digital radiography has largely replaced screen-film (SF) radiography throughout the United States Imaging community is responsible for understanding technology changes Exposure creep – increase in technique factors over time Digital radiography has largely replaced screen-film (SF) radiography throughout the United States. Radiologists, technologists, and medical imaging physicists are responsible for understanding and properly using digital radiography. Although digital images can be acquired with low dose, without careful attention, the exposure factors can increase over time, resulting in overexposure to patients, termed “exposure creep” [3]. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Exposure Creep Image processing compensates for underexposure and overexposure Radiologists prefer noise-free images Overexposure common 40% of adult digital radiographs overexposed 43% of pediatric digital radiographs overexposed References 26 and 29.

Step 1. Understand the basics of digital radiography
Digital radiography encompasses both computed radiography (CR) and direct digital radiography (DR) Computed Radiography (CR) Readout process Separate laser reader from the image receptor Readout availability in seconds Image Receptors Photostimulable-phosphor plate Needle phosphor plate (CsBr) Digital radiography (Table 1) is the term that encompasses both computed radiography (CR) and direct digital radiography (DR). These technologies digitally capture an x-ray image, replacing analog screen-film cassettes as image receptors. CR uses a photostimulable storage-phosphor imaging plate that absorbs energy from the x-rays exiting a patient’s body to form an invisible image. The cassette is then placed in a laser reader, which scans the plate, creating a visible digital image on a monitor in seconds. Powder phosphor imaging plates are the most common type of CR. More recently, needle phosphors composed of Cesium Bromide (CsBr), have been developed that have improved physical properties [4] that permits reduced exposure to the patient [5]. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Direct Digital Radiography (DR) Readout process Thin-film transistor layer bonded with image receptor Readout availability in less than 10 seconds Image Receptors Two types depending on method of converting x-ray to image 1. Direct converts x-rays to electrical charge Selenium most common type of receptor 2. Indirect converts x-rays to light which then produces electrical charge CsI and Gadolinium Oxysulfide most common types DR uses x-ray sensors bonded onto thin-film transistor integrated circuits to instantaneously convert the image stored on the sensor to a visible digital image, eliminating the need for a separate scanning step. DR can use either direct detection (converting x-rays into electronic charge) or indirect detection (first converting x-rays into light, which is then converted to electronic charge), resulting in readouts that are much faster (typically less than 10 seconds) than CR. Selenium is the most common type direct conversion DR. CsI and Gadolinium Oxysulfide are the most common types of indirect conversion DR. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Digital radiography advantages over traditional SF radiography Latitude of exposure ~ 100 times greater Image manipulation (processing) Electronic images can be stored and distributed anywhere Point-of-care image access Digital radiography has several advantages over traditional SF radiography. It has a latitude of exposure is approximately 100 times greater than screen-film radiography [6] , reducing the number of repeat examinations due to underexposure and overexposure. Image manipulation (processing) is possible to change the appearance of the image thereby making subtle characteristics in the image more apparent. The electronic images can be stored and distributed anywhere within the hospital network [7], providing point-of-care access of the images within minutes after exposure. While spatial resolution (sharpness) of the digital image is typically less than a SF image, the superior contrast and other improvements in image quality, including image processing available only in the digital image, results in superior clinical studies with digital radiography [4]. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Digital radiography performance Characterized by spatial resolution and noise Sharpness/Modulation Transfer Function (MTF) Noise Level/Noise Power Spectrum (NPS) Characteristics determine efficiency of the system in converting x-rays into an image Described as Detective Quantum Efficiency (DQE) The performance of a digital imaging system can be characterized by its spatial resolution (sharpness, Modulation Transfer Function [MTF]) and noise level (Noise Power Spectrum [NPS]), which together determine the efficiency of system in converting x-rays into an image described by the Detective Quantum Efficiency (DQE) [8]. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Detective Quantum Efficiency (DQE) Function of spatial frequency Ideal detector has a DQE of 1.0 For lower beam energies used in pediatric radiology, experiments show that DR with CsI can achieve higher DQE than CR and SF radiography The higher the DQE, less radiation exposure is needed to achieve the same image quality The performance of a digital imaging system can be characterized by its spatial resolution (sharpness, Modulation Transfer Function [MTF]) and noise level (Noise Power Spectrum [NPS]), which together determine the efficiency of system in converting x-rays into an image described by the Detective Quantum Efficiency (DQE) [8]. DQE is a function of spatial frequency with an ideal detector having a DQE of 1.0 across all spatial frequencies. The value DQE at zero line pairs is commonly quoted to describe the efficiency of the detector. Due to its high spatial resolution and sensitivity at higher energies, screen-film systems can achieve a relatively high DQE compared with CR and DR for high beam energies [9]. For lower beam energies, such as those commonly used in pediatric radiology, experiments show that DR with the newest columnar CsI phosphor can achieve higher DQE than CR and SR [10]. The higher the DQE, less radiation exposure is needed to achieve the same image quality. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Radiologists, technologists, and medical physicists must leverage the strengths and weaknesses of each of their detectors to optimize exposure factors and reduce doses, especially when imaging children Radiologists, technologists, and medical physicists must leverage the strengths and weaknesses of each of their detectors to optimize exposure factors and reduce doses, especially when imaging children. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Step 2. Understand challenges associated with digital imaging
Screen-film radiography provided immediate and direct feedback regarding overexposure or underexposure Overexposed image was too black Underexposed image was too white Optical density was directly coupled to the exposure technique In the past, SF radiography provided radiologists and radiologic technologists with immediate and direct feedback as to overexposure or underexposure. An overexposed image was too black, and an underexposed image was too white. The SF radiograph’s optical density was directly coupled to the exposure technique. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Digital radiography is fundamentally different Optical density feedback is lost Image processing adjusts grayscale images to the correct brightness despite underexposure or overexposure Digital radiography is fundamentally different; the optical density feedback to the radiologists and radiologic technologist is lost [11]. Image processing is designed to produce adequate grayscale images of the correct brightness despite underexposure or overexposure. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Underexposed digital images Fewer x-rays absorbed by the detector Results in increased quantum mottle The image appears noisy or grainy Increased exposure in digital imaging Reduction in quantum mottle Overexposure may go unnoticed Results in needless overexposure and potential harm to the patient Underexposed images have fewer x-rays absorbed by the detector, resulting in increased quantum mottle. If the underexposure is large, radiologists will recognize and object to the significant noisy/grainy appearance, and may request a repeat image. As with CT, increased exposure reduces noise. The radiologist may not notice this subtle reduction in grainy appearance in the image. Thus, overexposed images may go unnoticed, resulting in needless overexposure and potential harm to the patient. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Image acquisition process varies Depends on vendor and equipment type Techniques may be different than SF Requires technologists to adjust techniques Different detectors may require different techniques due to differences in efficiency (DQE) The image acquisition process varies depending on specific vendors and equipment type, which requires technologists to adjust techniques accordingly. Techniques required to achieve optimal radiographic imaging in digital radiography probably will be different from those used for SF radiography. Further, different digital detectors may require different techniques, due to differences in the efficiency (quantitated by DQE). Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Need for a standard approach Differences in technique amongst digital systems may cause confusion Result in varying levels of image quality Approach must be based on: 1. Feedback provided from exposure indicator 2. Individual image quality analysis The differences in technique amongst digital systems may cause confusion and result in varying levels of image quality at facilities where more than one vendor or detector system is in use. Operators should determine a standard approach to producing consistent, high-quality digital radiographic imaging, based not on image brightness on the monitor, but on feedback provided from detector exposure indicator and individual image quality analysis. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Step 3. Learn new exposure terminology standards
Proprietary Exposure Indicator Terminology Method for estimating exposure to image receptor May be linear or logarithmic Directly or inversely related to plate exposure Hospitals frequently have more than one detector type from more than one vendor Difficult to familiarize with all of the proprietary exposure terminology Causes confusion Each manufacturer has a proprietary method of estimating exposure to the image receptor, which can be used to indicate adequacy of radiographic technique factors [11]. When only a small number of manufacturers existed, it was relatively easy to learn and use the proprietary language. Now more than 15 manufacturers of digital radiographic equipment are in the market. Hospitals frequently have more than one detector type from more than one vendor; it is much more difficult for technologists and radiologists to become familiar with all of the proprietary exposure terminology.

Solution to the exposure terminology problem 2004 ALARA conference in digital radiography AAPM and IEC Developed standardized terminology designed to eliminate proprietary terminology in the installed equipment in the future Medical Imaging and Technology Alliance (MITA) Publically agreed to adopt the IEC standard Espoused by the 2004 ALARA conference in digital radiography [3], as well as the medical physics community, both the International Electrotechnical Commission (IEC) [12], a standards writing body, and the American Association of Physicists in Medicine [13], independently developed standardized terminology designed to eliminate proprietary terminology in the installed equipment in the future. In part due to the advocacy that occurred at the Image Gently Digital Radiography Summit in 2010 [14], the manufacturers through the Medical Imaging and Technology Alliance (MITA) publicly agreed to adopt the IEC standard [15]. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

IEC standard terms to learn: Target exposure index (EIT) Exposure index (EI) Deviation index (DI) Radiologists, radiologic technologists, and medical physicists have three important terms to learn from the new IEC standard: Target exposure index (EIT), exposure index (EI), and deviation index (DI) [16]. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Target exposure index (EIT) Ideal exposure at the image receptor Can be set by: Manufacturer User facility The EIT represents the ideal exposure at the image receptor. The EIT is set for each anatomical study and imaging equipment. It can be set by either the manufacturer or the user facility. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Exposure index (EI) Image receptor radiation exposure Measured in relevant region Direct, linear with respect to mAs Doubling the mAs will double the EI Value depends on: Body part selected and body part thickness, kVp and any added filtration Type of detector EI it is NOT an individual patient dose metric The EI is a direct, linear with respect to mAs, measure of radiation exposure at the image receptor in the relevant region of the image; it is not a patient dose metric. The EI depends on the body part selected, the body part thickness, the kVp, the added filtration in the x-ray beam, and the type of detector, among other factors. With the same patient, body part, kVp and filtration selected, doubling the mAs will double the EI. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Deviation index (DI) Indicates how much the EI deviates from the EIT The DI is defined as: DI= 10×log10 (EI/EIT) The DI indicates to the technologist and the radiologist by how much the EI for the imaging study deviates from the EIT. The DI is defined as: DI= 10×log10 (EI/EIT) Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

The meaning of DI An ideal situation where EI is equal to the EIT, the DI is zero (DI =0) If the exposure index is higher than the EIT (overexposed), the DI is positive, and if it is lower than the EIT (underexposed), the DI is negative A DI of -1 is 20% below the appropriate exposure, while +1 is a 26% overexposure A DI of ±3 indicates halving or doubling of the exposure relative to the EIT In an ideal situation where EI is equal to the EIT, the DI is zero. If the exposure index is higher than the EIT (overexposed), the DI is positive, and if it is lower than the EIT (underexposed), the DI is negative. A DI of -1 is 20% below the appropriate exposure, while +1 is a 26% overexposure. Further, a DI of ±3 indicates halving or doubling of the exposure relative to the EIT. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

{ { Deviation Index Percentage (%)
Step 3. Learn new exposure terminology standards Deviation Index Percentage (%) -3.0 50 -1.0 80 100 +1 126 +3 200 { Underexposure The ideal exposure (DI=0) means that the x-ray used to correct exposure combination: this yielded 100% accurate exposure based on body part thickness. The DI of -1 means the body part was 20% underexposure: -3 means the part was 50% underexposured as compared to the EIT (Exposure Indicator Target) value. The DI of +1 yields 26% overexposure and +3 would result in 100% overexposure (equivalent to exposing the part twice). Ideal { Overexposure

The importance of DI Immediate feedback Indicates the adequacy of the exposure Goal -1 < DI > +1 Few studies DI > +3 or <-3 Standardized terminology will reduce confusion from proprietary terminology The DI serves as immediate feedback number to both the technologist and interpreting radiologist indicating the adequacy of the exposure. The goal is DI values in the range from -1 to +1, with very few images greater than 3 or less than - 3. The new standard will reduce the confusion resulting from the current proprietary terminology. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Deviation Index is only one factor in image quality: To assure image quality, checks should be made for : positioning, patient motion, collimation, and appropriate use of grids Image noise levels for underexposure and saturation with overexposure should also be monitored The Image Gently Campaign encourages radiologists and technologists to go “Back to BASICS” with digital radiography It is, however, only one factor in image quality, the presence of noise in the image. Proper positioning, elimination of patient motion, collimation, and appropriate use of grids will need to be checked on each examination to ensure appropriate image quality. The Image Gently Campaign encourages radiologists and technologists to go “Back to BASICS” with digital radiography. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Step 4. Establish technique charts using a team approach
Automatic exposure control (AEC) sensors, commonly used in adults, is often problematic in children For smaller children the imaged area of anatomy may be smaller than the single central sensor The trio of automatic exposure control (AEC) sensors, commonly used in adults, is often problematic in children if the body part is smaller than the trio of AEC sensors [17]. In some cases, the AEC may be used on children if only the center sensor is activated and the child’s body part is positioned to completely cover the entire single sensor. However, for smaller children the imaged area of anatomy may be smaller than the single central sensor. Thus, manual techniques may be most appropriate for small children. Goske, M. J., E. Charkot, et al.(2011). Pediatr Radiol 41(5): Reused with permission. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Manual techniques may be most appropriate for small children Team approach: Physician, technologist, medical physicist, vendor Start with limited exams: Chest, abdomen, small parts May need detector-specific technique charts Thus, manual techniques may be most appropriate for small children. To use a manual technique, one must develop pediatric-specific technique charts. Establishing technique charts for common examinations in digital radiology is similar to CT, where one uses size, weight, or body part circumference-generated technique charts to appropriately “size” the mAs and kVp used for each patient. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Image processing is different for pediatric patients and adults Review and adjust anatomically programmed radiography techniques Appropriate values must be included for both AEC and manual technique selection Pre-programmed adult techniques used for pediatric imaging may not result in the appropriate image quality or patient dose As noted previously, the AEC can be used when the body part to be imaged will completely cover the AEC sensor. Many vendors have different processing programs for children and adults for the same body part. It is well known that image processing is different for pediatric patients than adult, especially for chest radiographs [9, 18]. The anatomically programmed radiography techniques must be reviewed and adjusted to assure that appropriate values are included for both AEC and manual technique selection. Pre-programmed adult techniques used for pediatric imaging may not result in the appropriate image quality or patient dose. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Step 5. Measure body part thickness
X-ray absorption/transmission depends on the composition of the body part being imaged Body part thickness is the most important technique determinant One cannot reliably use patient age as a guide for techniques The largest 3-year old’s abdomen thickness is the same as the smallest 18-year old X-ray absorption/transmission depends on the composition of the body part being imaged and its thickness. Patient age is a poor substitute for thickness. As with any projection radiograph, body part thickness is the most important determinant for the technique. Kleinman has shown that the abdomens of the largest 3 year olds are the same size as the abdomens of the smallest 18 year old [19]. One cannot reliably use patient age as a guide for techniques [19]. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Step 5. Measure body part thickness
Revert “Back to Basics” The goal is for reproducible, consistent images for children with a body part of the same size Use calipers to measuring patients Ensures standardized technique is selected One then selects kV, filtration, and mAs for that specific study to “child size” the examination Reverting “Back to Basics” by measuring patients with calipers will ensure that a standardized technique is selected. Knowing the body part and its thickness, one can then set the kV, filtration, and mAs for that specific study to “appropriately size” the examination for the child. The goal is for reproducible, consistent images for children with a body part of the same size. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Step 6. Use grids only when body part thickness is > 12 cm
Anti-scatter grids remove scatter from the image Grids improve the subject contrast Scatter degrades image when the body part is >12 cm of water-equivalent thickness Air containing structures greater than 12 cm thickness can be imaged without a grid Example: chest radiographs The main purpose of anti-scatter grids is to remove scatter from the image to improve the subject contrast in the image. Scatter starts to significantly degrade subject contrast in the image when the body part is at least cm of water-equivalent thickness [10, 20]. Structures that are greater than 12 cm thickness containing air, especially chest radiographs, can be successfully imaged without a grid. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Step 6. Use grids only when body part thickness is > 12 cm
Grids may double or triple the exposure factors necessary to obtain an adequate image Removing the grid when it is not necessary greatly reduces patient exposure Guidelines for digital radiography have stated that grids should be used sparingly in pediatrics Depending on the grid selected, anti-scatter grids double or triple the exposure factors necessary to obtain an adequate image [21]. Thus, removing the grid when it is not necessary greatly reduces patient exposure. Both the ACR-SPR[22] and the ACR-AAPM-SIIM[23] guidelines for digital radiography have stated that grids should be used sparingly in pediatrics. Both guidelines argue that grids should not be routinely used for extremity work and body part thickness ≤10-12 cm. Furthermore, in some areas of the body that contain highly attenuating structures such as bone, grid use with lower kVp techniques may not be necessary [21]. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Step 7. Collimate prior to the exposure
It is unacceptable to open the collimators, then manipulate and electronically crop the image after the exposure ASRT survey: 50% of the technologists use electronic cropping of the image after the exposure 75% of the time Radiologists may not be aware that cropping is occurring, yet radiologists are responsible for the image before cropping occurs With the advent of digital radiography, it is possible to open the collimators, then manipulate and electronically crop the image after the exposure. In a recent American Society of Radiologic Technologist’s survey of digital radiology trends, almost 50% of the technologists report using electronic cropping of the image after the exposure 75% of the time [24]. Radiologists may not be aware that cropping is occurring (Figure 3), yet radiologists are responsible for the image before cropping occurs. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

The cropped portions of the body are exposed to unnecessary radiation It is better to properly immobilize patient and collimate appropriately before the exposure The cropped portions of the body are exposed to unnecessary radiation. While opening the collimators may be necessary occasionally for inclusion of anatomy such as an arm in a percutaneously inserted central venous catheter, under the best of circumstances it is better to immobilize the patient and collimate appropriately before the exposure rather than crop the image after the exposure [17]. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Benefits of collimation: Reduces the area exposed and lowers the dose-area product (DAP) Reduces scatter radiation, which will improve image quality Improves the accuracy of the image processing Provides more accurate exposure indicator Collimation is necessary to eliminate x-ray exposure to body parts not affecting the clinical diagnosis, reducing the area exposed and lowering the dose-area product (DAP). Collimation also reduces scatter radiation, which improves image quality [25]. A well-collimated field improves the accuracy of the image processing. Extraneous structures outside the area of interest, such as shields, are excluded and prevented from negatively impacting the applied image processing. Open collimators may also affect the exposure indicator of the system, giving a false reading of adequacy of the technique [17]. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Step 8. Display technique factors for each image
Require that the kVp, mAs, EI and, especially, DI are present on the displayed image Ideally DAP meter results and image processing program should also be displayed These displayed values provide important feedback to the radiologist and technologists The radiologist should become familiar with technique factors used for common examinations. This requires that the kVp, mAs, added beam filtration, the exposure indicators including the EI and, especially, the DI are present on the displayed image. Pediatric radiologists and physicists have been advocating this position since the ALARA conference in 2004 [3]. Ideally DAP meter results should also be displayed. (Currently DAP meters are not required in the United States but are required in Europe.) The image processing organ program (such as portable chest, abdomen, hand, etc.) should also be displayed. These displayed values provide feedback to the radiologist and can be used to help solve problems when an image is not acceptable Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Image Courtesy of Ann & Robert H. Lurie Children’s Hospital of Chicago

Step 9. Accept noise level appropriate to clinical question
Radiologists prefer images that have little noise However, noise intolerance can lead to exposure creep Must work to understand the relationship between exposure indicators and the visual appearance of noise in an image Routinely monitoring the appropriateness of the technique based on the level of image noise along with the DI, exposure creep be avoided Radiologists prefer images that have little noise [26]; however, noise intolerance can lead to exposure creep. To avoid exposure creep radiologists need to become familiar with the exposure indicators for their equipment and understand the relationship between exposure indicators and the visual appearance of noise in an image. Once this relationship is understood, an appropriate target exposure value (EIT) can be established and the Deviation Index (DI) can be calculated and displayed on the interpreting workstation. By routinely monitoring the appropriateness of the technique based on the level of image noise along with the DI, exposure creep be avoided. Radiologists may be tolerant of more noise in some body tissues than in others. For example, noise does not affect the visualization of high-resolution structures, such as bone detail, or the endotracheal tube or chest tube [26]. The ability to identify disease processes, such as surfactant deficiency disease/respiratory distress syndrome of the premature newborn and low contrast structures, are more noise sensitive [27, 28]. As users become more comfortable with the technique/noise relationship of digital radiography, lower-dose follow-up studies (such as a follow-up study after adjusting line placement) tailored to answer a specific question may become more common. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Step 10. Develop a quality assurance program
It is critical that radiologists, radiographers, and physicists develop standards for their institution, utilizing a team approach to assure diagnostic image quality at a properly managed dose for pediatric patients. It is critical that radiologists, radiographers, and physicists develop standards for their institution, utilizing a team approach to assure diagnostic image quality at a properly managed dose for pediatric patients. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Importance of QA program 40% of the digital radiographs obtained from one adult center are overexposed 43% of radiographs in a pediatric center were reported as overexposed By recording and monitoring exposure indicators, an individual hospital can control and reverse exposure creep Recent literature has shown that up to 40% of the digital radiographs obtained from one adult center are overexposed [29]. This same center noted that exposure creep was occurring in ICU studies. Exposures in 43% of radiographs in a pediatric center using computed radiography were also reported to be overexposed [26]. By recording and monitoring exposure indicators, an individual hospital can control and reverse exposure creep [29]. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Analyzing the percentage of images that fall within and outside of an acceptable range can be used to educate technologists and decrease the variation while improving image quality goals of the department Analyzing the percentage of images that fall within and outside of an acceptable range can be used to educate technologists and decrease the variation while improving image quality goals of the department. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Utilizing digital imaging resources DICOM headers contain information that can be exported and used in QA programs IHE REM profiles make additional information available Common IEC standard terminology can also be used With the advent of digital imaging, much information is contained in the header of the digital imaging and communications in medicine (DICOM) image, which can be exported and used in a Quality Assurance Program. Integrating the Healthcare Enterprise (IHE) radiation exposure monitoring (REM) profile also makes additional information available [30]. This is an easy method to get routine evaluation of the performance metrics of digital radiography for analysis by the quality assurance team. Coupled with the new IEC standard, there is a common terminology that can be used for an individual hospital to develop its own quality assurance program. Cohen et al. used the new IEC standard for monitoring EI in an individual neonatal intensive care unit over a 3-month period, and showed no tendency for exposure creep [31]. With the advent of DICOM structured reports and the IHE REM program, groups of hospitals with similar image receptors will be able to collaborate on their techniques and exposure indicator ranges. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Likely in the future: National diagnostic reference levels to compare digital radiographic techniques ACR Dose Index Registry program for Pediatric Digital Radiography registry has been approved Diagnostic reference levels likely will be developed from this data based on detector type and body part It is likely in the future there will be national standards to help provide diagnostic reference levels for radiology departments to compare their digital radiographic techniques. The ACR has a Dose Index Registry [11] program for which a Pediatric Digital Radiography registry has been approved [14]. It is likely that diagnostic reference levels will be developed from this data based on detector type, body part. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Conclusion Knowledge in digital radiography will provide radiologists and technologists the basis for standardizing their approach to imaging pediatric patients Education will reduce the tendency for exposure creep The “Back to Basics” Image Gently® campaign is a reminder to standardize procedures to improve image quality while properly managing radiation dose during pediatric imaging Pediatric digital radiography, while an imaging modality that uses less ionizing radiation compared with CT, is commonly performed in both adult and pediatric-centered facilities. Increased knowledge in this versatile and efficient technology will provide radiologists and technologists the basis for standardizing their approach to imaging pediatric patients, thereby reducing the tendency for excess radiation through exposure creep. The new Image Gently campaign, “Back to Basics”, is a reminder that a consistent approach to technique factors based on body part thickness, elimination of grids when not needed, appropriate collimation, and a rigorous quality assurance program that tracks the new exposure indicators, should improve image quality while properly managing the radiation dose during pediatric imaging. Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

References 1.Ionizing Radiation Exposure of the Population of the United States. Bethesda, MD: National Council on Radiation Protection and Measurements, Dorfman AL, Fazel R, Einstein AJ, et al. Use of medical imaging procedures with ionizing radiation in children: a population-based study. Archives of pediatrics & adolescent medicine 2011;165: Willis CE, Slovis TL. The ALARA concept in pediatric CR and DR: dose reduction in pediatric radiographic exams – A white paper conference Executive Summary. Pediatric Radiology 2004;34:S162-S164 4.Korner M, Weber CH, Wirth S, Pfeifer KJ, Reiser MF, Treitl M. Advances in digital radiography: physical principles and system overview. Radiographics 2007;27: Cohen M, Corea D, Wanner M, et al. Evaluation of a New Phosphor Plate Technology for Neonatal Portable Chest Radiographs. Academic Radiology 2011;18: Willis C. Computed radiography: a higher dose? Pediatric Radiology 2002;32: Hillman BJ, Fajardo LL. Clinical assessment of phosphor-plate computed radiography: equipment, strategy, and methods. J Dig Imag 1989;2: Medical electrical equipment – Characteristics of digital X-ray imaging devices – Part 1: Determination of the detective quantum efficiency International Electrotechnical Commission (IEC), international standard IEC , Geneva, Switzerland Monnin P, Gutierrez D, Bulling S, Lepori D, Valley J-F, Verdun FR. Performance comparison of an active matrix flat panel imager, computed radiography system, and a screen-film system at four standard radiation qualities. Medical Physics 2005;32: Bertolini M, Nitrosi A, Rivetti S, et al. A comparison of digital radiography systems in terms of effective detective quantum efficiency. Medical Physics 2012;39: Seibert JA, Morin RL. The standardized exposure index for digital radiography: an opportunity for optimization of radiation dose to the pediatric population. Pediatr Radiol 2011;41: Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

References 12.Medical electrical equipment - Exposure index of digital X-ray imaging systems - Part 1: Definitions and requirements for general radiography International Electrotechnical Commission (IEC), international standard IEC , Geneva, Switzerland.2008. 13.Shepard SJ, Wang J, Flynn M, et al. An exposure indicator for digital radiography: AAPM Task Group 116 (Executive Summary). Medical Physics 2009;36: 14.Don S, Goske MJ, John S, Whiting B, Willis CE. Image Gently pediatric digital radiography summit: executive summary. Pediatr Radiol 2011;41: 15.Vastagh S. Statement by MITA on behalf of the MITA CR-DR group of the X-ray section. Pediatr Radiol 2011;41:566 16.Don S, Whiting BR, Rutz LJ, Apgar B. New Exposure Indicators for Digital Radiography Simplified for Radiologists and Technologists Am J Roentgenol 2012 (accepted for publication) 17.Goske MJ, Charkot E, Herrmann T, et al. Image Gently: challenges for radiologic technologists when performing digital radiography in children. Pediatr Radiol 2011;41: 18.Don S, Whiting BR, Ellinwood JS, Foos DH, Kronemer KA, Kraus RA. Neonatal chest computed radiography: image processing and optimal image display. AJR American journal of roentgenology 2007;188: 19.Kleinman PL, Strauss KJ, Zurakowski D, Buckley KS, Taylor GA. Patient Size Measured on CT Images as a Function of Age at a Tertiary Care Children's Hospital. American Journal of Roentgenology 2010;194: 20.Kalender W. Monte Carlo calculations of x-ray scatter data for diagnostic radiology. Physics in medicine and biology 1981;26: 21.Cartlon RR, Adler AM. The Grid. In: Principles of radiographic imaging : an art and a science Clifton Park, NY: Delmar Cengage Learning, 2013 22.ACR-SPR Practice Guideline for General Radiography. American College of Radiology. Reston, VA, 2008 Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

References 23.ACR–AAPM–SIIM Practice Guidelime for Digital Radiography. American College of Radiology. Reston, VA, 2007 24.Morrison G, John SD, Goske MJ, et al. Pediatric digital radiography education for radiologic technologists: current state. Pediatr Radiol 2011;41: 25.Curry T, Dowdey J, Murry R. In: Christensen's Physics of Diagnostic Radiology. Philadelphia: Lea & Febiger, 1990:93-98 26.Don S. Radiosensitivity of children: potential for overexposure in CR and DR and magnitude of doses in ordinary radiographic examinations. Pediatric Radiology 2004;34:S167-S172 27.Don S, Hildebolt CF, Sharp TL, et al. Computed radiography versus screen-film radiography: detection of pulmonary edema in a rabbit model that simulates neonatal pulmonary infiltrates. Radiology 1999;213: 28.Roehrig H, Krupinski EA, Hulett R. Reduction of patient exposure in pediatric radiology. Academic Radiology 1997;4: 29.Gibson DJ, Davidson RA. Exposure Creep in Computed Radiography: A Longitudinal Study. Academic Radiology 2012;19: 30.O'Donnell K. Radiation exposure monitoring: a new IHE profile. Pediatr Radiol 2011;41: 31.Cohen MD, Cooper ML, Piersall K, Apgar BK. Quality assurance: using the exposure index and the deviation index to monitor radiation exposure for portable chest radiographs in neonates. Pediatr Radiol 2011;41: 32.Cohen MD, Markowitz R, Hill J, Huda W, Babyn P, Apgar B. Quality assurance: a comparison study of radiographic exposure for neonatal chest radiographs at 4 academic hospitals. Pediatr Radiol 2011 Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

imagegently.org We hope this presentation has been helpful. For more educational materials on promoting radiation protection for children got he the image gently website and sign up and take the pledge! Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

Thanks to Digital Radiography Committee Members:
Steven Don, M.D. Robert MacDougall, MSc Keith Strauss, MSc, FAAPM, FACR Quentin Moore, MPH, R.T.(R)(T)(QM) Marilyn J. Goske, M.D., FAAP Mervyn Cohen, M.D., MBChB Tracy Herrmann, MEd, R.T.(R) Susan D. John, M.D Lauren Noble, Ed.D., R.T.(R) Greg Morrison, MA, R.T.(R), CNMT, CAE Lois Lehman, R.T.(R)(CT) Coreen Bell Ceela McElveny Loren Stacks Shawn Farley Steven Don, MD Electronic Radiology Laboratory Mallinckrodt Institute of Radiology St. Louis Children’s Hospital Washington University School of Medicine 510 South Kingshighway St. Louis, Missouri 63110 Robert MacDougall, MSc Department of Medical Imaging Ann and Robert H. Lurie Children’s Hospital of Chicago Chicago, IL Keith Strauss, MSc Cincinnati Children’s Hospital Clinical Professor of Radiology and Pediatrics University of Cincinnati Department of Radiology, ML 5031 3333 Burnet Avenue Cincinnati, OH 45229 Quentin T. Moore, MPH, R.T.(R)(T)(QM) Mercy College of Ohio 2221 Madison Ave. Toledo, Ohio 43604 Marilyn J. Goske, M.D., FAAP Chair, Alliance for Radiation Safety in Pediatric Imaging The Corning Benton Chair for Radiology Education Professor of Radiology Cincinnati Children’s Hospital Medical Center 3333 Burnet Ave. Cincinnati, Ohio Mervyn Cohen, M.D., MBChB Department of Radiology, Riley Hospital for Children, 702 Barnhill Drive, Rm. 1053, Indianapolis, IN 46202, USA Tracy Herrmann, M.Ed., R.T.(R) Radiologic Technology Program Director University of Cincinnati Raymond Walters College, Blue Ash, OH, USA Susan D. John, MD Radiologist in Chief The University of Texas Medical School, Houston Department of Radiology 6431 Fannin Houston, TX 77030 Lauren Noble, Ed.D., R.T.(R) Radiologic Technology Program University of North Carolina at Chapel Hill Chapel Hill, NC Greg Morrison, MA, RT(R), CNMT, CAE Chief Operating Officer American Society of Radiologic Technologists 15000 Central Ave SE Albuquerque, NM Lois Lehman, R.T(.R)(CT) Assistant Director of Radiology Texas Scottish Rite Hospital for Children Dallas, TX 75219 Bruce R Whiting, PhD Radiology Department University of Pittsburgh 3362 Fifth Ave. Pittsburgh PA 15213 Copyright 2012 Alliance for Radiation Safety in Pediatric Imaging All Rights Reserved

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