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Submitted by Lynne Fairobent, AAPM
   Commenting on behalf of the organisation
Document Diagnostic Reference Levels in Medical Imaging
 
Page/line# Reviewer Name Type of comment Comments Proposed change
  AAPM General There are a few instances in the document where Siemens-specific CT terminology is used where generic words would likely be preferred. For example: Glossary, page 13, Line 26: Constancy testing – this term is ONLY used by Siemens. I’m not sure this needs to be in the glossary at all. Perhaps a search on this term will show where it is used in the document? If a periodic test more complete than a daily QC (such as an annual CT survey) is meant, this phrasing should be used instead of ‘constancy testing.’ and  Page 88, line 18 AND page 110, line 22: ‘topogram’ or ‘topogram/scout’ – both of these are manufacturer’s terms (Siemens topogram and GE scout). The generic term ‘localizer radiograph’ should be used instead of topogram or scout image.  
44/19 AAPM Technical Although the MPPS can send data to HIS/RIS based on the IHE REM Profile this is not the preferred method for obtaining dose attributes.  The RDSR is the preferred method and the dose attributes within the MPPS may be retired based on this change in the DICOM Standard. More emphasis should be made to utilize the RDSR so accurate data on output from devices is recorded.  The RDSR has been successfully used to send data to dose registries.  An issue with this has been known to be the mapping of the dose indexes to appropriate procedure code.  This makes utilization of any dose index for development of DRL problematic if the mapping is done inconsistently.
44/29 AAPM General Statement: "Exposure data recorded in the RDSR, MPPS or the DICOM header can be transmitted to the PACS" does not provide the detail to assist in understanding the benefits and limitations of using the IHE REM Profile and DICOM data. The IHE REM Profile can be referenced at http://wiki.ihe.net/index.php/
Radiation_Exposure_
Monitoring and a discussion on the use of the REM Profile should be included.   
71/26 AAPM Technical For CT-guided interventional procedures, DLP may not be a suitable DRL quantity because the CT imaging required typically takes place over a narrow range of scan lengths (L) and may result in a DLP value that is unusually low in comparison with "standard" CT acquisitions.  "the Commission recommends that DRLs be established for CTDIvol, the number CT sequences obtained, and CT fluoroscopy time." 
80/8 AAPM General The entire paragraph from lines 8 to 16 discusses PKA and Ka,e but not Ka,i. Note that the "2014 American College of Radiology ACR-AAPM Practice Parameter for Diagnostic Reference Levels and Achievable Doses in Medical X-ray Imaging" recommends using Ka,i as the suitable DRL for (projection) radiography. A discussion of Ka,I is warranted, specifically it''s relevance as a DRL quantity in projection radiography.
83/10 AAPM   There is a statement that says if CTDIvol is not displayed, then it will have to be calculated from CTDIw and pitch. Pitch is always displayed, but if CTDIvol is not displayed then it is VERY unlikely that CTDIw will be displayed or be otherwise readily available. I’m not sure that this guidance is very helpful without explaining how one would be expected to find CTDIw.   
83/13 AAPM General The paragraph makes reference to a "standard-size" patient, but the section does not appropriately describe or define what "standard-size" is for setting CT DRL''s. Recommend modifying the sentence that begins in line 16 as follows: "DRL values are designed to help determine whether the amount of ionising radiation applied for a medical imaging procdure in a representative sample of patient size ranges (note: bold font added only for emphasis of recommended change.), for a defined clinical task, is too high or too low."
83/13 AAPM General The "2014 American College of Radiology ACR-AAPM Practice Parameter for Diagnostic Reference Levels and Achievable Doses in Medical X-ray Imaging" recommends the use if CTDIvol as the suitable DRL for CT, paired with the use of "Patient Lateral Dimension" to accommodate the impact of patient size on developing a procedure-specific DRL. Recommend modifying the sentence that begins in line 20 as follows: "It is therefore necessary to ensure that the survey data reflect values for appropriate patient size ranges." (note: bold font added only for emphasis of recommended change.)
83/21 AAPM   Although it would be ideal if only ‘standard-size’ patients were used for a DRL survey, the idea that any patient could be identified as ‘standard-size’ is difficult to understand. ‘Standard-size’ patients would be represented by a range of sizes (however that is defined), and identifying the cut-off points for that range would be fairly arbitrary. If there is a standard way to do this, can it be explained? In CT especially, automatic exposure control is heavily used which is completely dependent on patient habitus. DRLs for CT are heavily influenced by patient population characteristics.  
84/34 AAPM Technical Although it is somewhat implicit based on reading the preceding paragraphs, DRL''s for planar nuclear medicine does not explicitly state that it should also take into account the radiopharmaceutical used.  In the PET section of the document (page 89, lines 14-16) it clearly states that "DRL values have to be set for each radiopharmaceutical". Recommend modifying the sentence that begins in line 37 as follows: "The Commission recommends the establishment of weight-based administered activities (MBq/kg), set for each radiopharmaceutical (note: bold font added only for emphasis of recommended change) for all types of nuclear medicine investigations except for those where the radiopharmaceutical is concentrated predominantly in a single organ ..."
85/4 AAPM Technical Similar to the comment above for page 84 line 219, DRL''s for SPECT imaging procedures should also explicitly take into account the radiopharmaceutical used. Recommend modifying the sentence that begins in line 4 as follows: "The Commission recommends the establishment of weight-based administered activities (MBq/kg), set for each radiopharmaceutical (note: bold font added only for emphasis of recommended change)."
92/16 AAPM Technical Collimation is also very important for pediatric fluoroscopic imaging, especially for interventional fluoroscopic procedures. Recommend modifying the sentence that begins in line 16 as follows: "For projection radiography, fluoroscopy, and interventional fluoroscopy, (note: bold font added only for emphasis of recommended change) the relevance of appropriate collimation is higher in pediatrics."
92/30 AAPM Technical Although it is true that CTDIvol and DLP are based on a 16 cm phantom for head examinations for both adult and pediatric procedures, CTDIvol and DLP are not always based on a 32 cm phantom for body examinations, particularly for pediatric body examinations. Some vendors utilize a 16 cm phantom for pediatric body examinations. In addition, the American College of Radiology CT Accreditation Program as well as the "2014 American College of Radiology ACR-AAPM Practice Parameter for Diagnostic Reference Levels and Achievable Doses in Medical X-ray Imaging" requires the use of a 16 cm phantom for pediatric body examinations. Recommend modifying the sentence that begins in line 30 as follows: "For CT, the DRL quantities are CTDIvol and DLP. These DRL quantities are based on calibration with a 16 cm phantom for head examinations, for both adult and pediatric examinations. These DRL quantities are based on calibration with a 32 cm phantom for adult body examinations, but may be based on either a 32 cm or 16 cm phantom for pediatric body examinations." (note: bold font added only for emphasis of recommended change)
113/^7-8 AAPM   This sentence does not seem to be complete: “When CT protocols are set up, the process should take into account how the interaction of the different variables that can be set.” Perhaps a better version is:  “When CT protocols are set up, the process should take into account of the interactions of the different variables that can be set.” (Underline added to point out the suggested changes.)  
118/20-22 AAPM   The meaning of this statement is not clear. Could an example or two be provided to help convey the intended meaning?  
124/5 and 8 AAPM   The term ‘clinical audit’ is used but has not been described or defined previously.  Is this meant to be the same as a DRL survey? Similarly on line 9 the term ‘annual survey’ is used without a clear definition.