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ICRP: Free the Annals!

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Submitted by Keith J. Strauss, Alliance for Radiation Safety During Pediatric Imaging (ImageGently)
   Commenting on behalf of the organisation
Document Diagnostic Reference Levels in Medical Imaging
 
ICRP Ref 4836-8337-6684
Annals of the ICRP Publication 1XX:  DRLs in Medical Imaging
Last Name First Name Page # Line # Comment
Frush Don 6 16 " . . . this tool, application of the DRL . . ."
         
Frush Don 6 17 newer imaging technologies, and additional difficulties in pediatric practice expecially due to the wide variety of patient sizes."
Frush Don 6 18 guidance on these issues. A corrective action plan should be impemented and documented without undue delay to determine possible reasons.
Frush Don 12 6 . . . Appropriate.  Variation in patient radiation dose for two paediatric patients that are the same size when the area of anatomy irradiated is the same for the same clinical indication is not appropriate if it is due . . .
Strauss Keith 17 18 may include SSDE conversion factors from CTDIvol based on attenuation data of the patient acquired during the projection scan(s) of the scanned patient (AAPM, 2011).
Strauss Keith 70 14 . . .performed.  While data can be found in the literature that provides Ka,r, PKA, or fluoroscopy time at multiple sites for adult interventional fluoroscopic procedures, this type of data has only been published recently for paediatric examinations and the number of cases in these studies typically are more limited than desired. (A)
Strauss Keith     A. Strauss KJ, Racadio JM, Johnson N, et.al. Estimates of diagnostic reference levels for pediatric peripheral and abdominal fluoroscopically guided procedures.  AJR2015; 204:W713-W719.  Doi:102214/AJR.14.13630
         
Strauss Keith 81 25 " . . . Range), the LAT or AP dimension of the actual patient is easily determined by a radiological technologist equiped with a standard caliper  designed to measure patient thickness, or to utilize . . . "
         
Strauss Keith 82 6 "estimates (SSDE) may be a better choice as a recommended CT DRL quantity when DRLs are established for patient sizes with attenuation characteristics that are not reasonably modeled by one of the two standard CTDI phantoms, e.g.the vast majority of pediatric patients and adult patients larger than standard size.
         
Strauss Keith 83 21 "data reflect values for more than one standard-sized patient.
         
Strauss Keith 92 8 imaging.  Ideally, seven or more size ranges should be established between premature infants (< 2 kg) and teenages, ~ 60 kg, that are smaller than standard sized adults.
         
Strauss Keith 92 16 " . . . Paediatrics.  For CT, precise definition of the scan length that excludes primary irratiation of unnecessary regions of the paediatric body is extremely important in managing the patient''s DRL.
         
Strauss Keith 92 20 ". . . Indicator. While the thickness of the body region imaged (easily measured with standard calipers) provides the most accurate classification of paediatric patient size, the current weight of the patient is the next best substitute if available.
         
Strauss Keith 92 24 ". . . Measure.  The most accurate classification of patient size is based on the thickness of the patient body region imaged.
         
Strauss Keith 92 30 " . . . The typical DRL quantities . . . "
         
Strauss Keith 92 36 " . . . Quantities to provide a more accurate estimate of paediatric patient dose as a function of patient size as opposed to typical DRL quantities that estimate the dose delivered to standard phantoms that poorly model the attenuation characteristics of paediatric patients."
         
Strauss Keith 93 10 ". . . (ICRP, 2013). The geometry and spacing of the three sensors of AEC systems are designed for an adult-sized body which limits the application of AEC controlled exposures for paediatric patients.  The small size of the trunk of the smallest patients and of the limbs of most paediatric patients require manual as opposed to AEC controlled exposures because small bodies cannot adequately cover the entire area of the individual AEC sensors."                                     SHORT EXPOSURE TIMES ARE NOT AN ISSUE.  THE TUBE CURRENT SHOULD BE LOWERED FOR SMALL PATIENTS SO THE EXPOSURE TIME RANGES BETWEEN 5 - 10 MILLISECONDS.
         
Frush Don 93 15  ''. . .dose may occur for two similar sized patients undergoing the same type of clinical exam, due to inappropirate technique . . ."
         
Strauss Keith 93 24 " . . . apply for children which must recognize the unique design characteristics of a given manufacturer''s fluoroscopic unit and configure the unit in a manner to take advantage of the unit''s strengths while minimizing the effects of its design weaknesses."
         
    93 28 ". . . premature infant (< 1 kg) to that of an obese . . ."
         
Frush Don 94 4 ". . . entail radiation risk.  Independent of variation in patient size, establishment of DRLs should involve a broad scope of practice types.  Routine patient doses in academic centers may be different than typical patient doses in non academic practices due to differences in confidence levels/familiarity with paediatric diseases and body sizes."
         
Strauss Keith 94 10 ". . . Available measure. While the thickness of the body region imaged (easily measured with standard calipers) provides the most accurate classification of paediatric patient size, the current weight of the patient is the next best substitute if available. In the future, the equivalent thickness of the patient based on the physical thickness of the patient and attenuation characteristics of the  anatomy as determined by the CT scanner may result in the automated calculation and display of SSDE on the display of the CT scanner.
         
Strauss Keith 94 28 ". . . grouping survey data into attenuation-bands, i.e., small ranges of patient thickness which results in a small change of the total attenuation of the x-rays between the smallest and largest patient within a given group of patient sizes."
         
Strauss Keith 94 29 "For radiography and fluoroscopy, weight can be used to group paediatric patients into size groups for the purpose of determining DRL values and evaluating local practice.
         
Frush Don 94 36  . . . in most hospitals, compared to the number of adult examinations, data collection . . ."
         
Frush Don 96 21 Phantom size does not address the variability in size of children or adults, and patient size has a . . .
         
Strauss Keith 96 25 " . . . standard coefficients.  While the thickness of the body region imaged (LAT dimension easily measured with standard calipers) provides the most accurate classification of paediatric patient size, the current weight of the patient is the next best substitute if available. In the future, the equivalent thickness of the patient based on both the physical thickness of the patient and attenuation characteristics of the  anatomy as determined by the CT scanner may result in the automated calculation and display of SSDE on the display of the CT scanner.
         
Strauss Keith 96 30 " . . . its effect on patient dose could be accounted for."
         
Strauss Keith 96 36 ". . . Reduce patient doses. Likewise, if iterative reconstruction is available and used by the operator at a given strength, the properly revised CT scan protocols may reduce patient dose.
         
         
         
Strauss Keith 97 10 to age (ICRU, 2005). This type of data (AP and LAT size) is also suppled by Kleinman et.al (2010) allowing calculation of effective diameter as a function of age. 
         
Frush Don 97 16 " . . . Procedures.  The DRL metrics recommended for adults . . ."
         
Strauss Keith 97 19 "paediatric DRLs. For radiography and fluoroscopy, weight can be used to establish paediatric patient group "sizes".  However, this can be performed more accurately by measuring the thickness of the patient anatomy that will be directly irradiated with a set of calipers .  This is particularly applicable to radiography performed with digital detectors during which numerous variables make it a challenge to deliver the correct entrance air kerma to the image receptor as a function of wide variation of paediatric patient size. Any variable that can be eliminated by a simple measurement, such as patient thickness with a calipers, helps to standardize the dose used for a given size patient and allows more accurate development of DRLs as a function of patient size.  
         
Strauss Keith 107 3 . . . future.  Additional information on the audit process and steps that can be taken to improve the acquisition process for pediatric patients can be found elsewhere. (B)
        B.  IAEA Human Health Series No. 24 Dosimetry in Diagnostic Radiology for Paediatric Patients.  2013, Vienna, Austria, 159 pp.
         
Strauss Keith 108 18  . . . subsections and elsewhere. (B) When medium to large adult patients are imaged, the challenge for the equipment manufacturer is producing radiation at a high rate to reduce the exposure time required to acquire the image and freeze the motion within the patient''s body.  In the case of imaging the small bodies of paediatric patients steps are required to address the significantly reduced necessary air kerma rate at the entrance plane of the patient. The imaging equipment manufacturer may not be aware of the need for this type of reconfiguration of acquisition parameters when imaging the small paediatric patient.
         
Strauss Keith 110 7 . . . dose.  This is especially true when imaging the small trunk or head of the young paediatric patient or the extremities of any patient, paediatric or adult sized.
         
Strauss Keith 112 14 . . . Protection, especially for paediatric examinations.  For the majority of  procedures, adult or paediatric, technique . . .
Strauss Keith 112 21  . . . This may be more of a problem for manufacturer suggested protocols for paediatric examination than for adult examinations. As discussed in Section . . . 
         
Strauss Keith 112 26 . . . identical models running identical revisions of system software.
         
Strauss Keith 113 10 . . . patients.  One should not assume that acceptable noise levels for CT image of small and average sized adults will be acceptable for small paediatric patients.  Typically, lower levels of quantum mottle are required in paediatric images of the smallest patients which requires unique settings of image quality indicators as a function of patient size.
         
Strauss Keith 113 19 . . . area.  If the scanner manufacturer''s application specialists do not have recommendations for changes to adult protocols for paediatric patients performed on their scanner, universal protocols for paediatric patients based on the protocols recommended on the Image Gently website should be helpful in establishing reference CTDIvol, DLP, or SSDE values as a function of patient size.(C) Once reference dose indices as a function of patient size are determined by a particular site, the radiologists, technologists, and medical physicist(s) at the site should work in collaboration with application specialists and other resource individuals from the manufactuer to ensure that the necessary modifications to paediatric protocols have been made to deliver the desired image quality and patient radiation dose.
Strauss Keith     C. Strauss KJ. Dose indices: Everybody wants a number. Pediatr Radiol (2014) 44 (Suppl 3):pp. S450-S459.
         
Strauss Keith 115 35 . . . testing is necessary to confirm that this is not the case must be completed and analyzed prior to first clinical use of the chnages.
         
Strauss Keith 119 3 . . . being evaluated, to the specific study being performed, and to the specific size of the patient.
         
Strauss Keith 119 28 . . . (SSDE) provides more accurate estimates of paediatric patient doses, than CTDIvol or DLP which are both indices of the dose to standardized phantoms.
         
Strauss Keith 121 24 or different paediatric patient sizes
         
Strauss Keith 122 28 . . .DRLs.   This requires adjustment for the varying sizes of different patients.The method illustrated in Figure 6.1 may be a reasonable way to present the limited paediatric data.
         
Strauss Keith 123 34 examination and the actual size of the of the paediatric patient irradiated.