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Delivery: <= 8 days. True-PDF full-copy in English will be manually translated and delivered via email. GB/T 16137-2021: Methods for estimation of examinee’s organ doses in X-ray diagnosis Status: Valid GB/T 16137: Historical versions
Basic dataStandard ID: GB/T 16137-2021 (GB/T16137-2021)Description (Translated English): Methods for estimation of examinee��s organ doses in X-ray diagnosis Sector / Industry: National Standard (Recommended) Classification of Chinese Standard: C57 Word Count Estimation: 62,674 Issuing agency(ies): State Administration for Market Regulation, China National Standardization Administration GB/T 16137-2021: Methods for estimation of examinee’s organ doses in X-ray diagnosis---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.(Method of radiation of subject's organ in X-ray diagnosis) ICS 13.280 CCSC57 National Standards of People's Republic of China Replace GB/T 16137-1995 Method of Estimating Organ Dose of Subject in X-ray Diagnosis Released on 2021-05-21 2021-12-01 implementation State Administration of Market Supervision and Administration Issued by the National Standardization Management Committee Table of contentsForeword Ⅰ 1 Scope 1 2 Normative references 1 3 Terms and definitions 1 4 Organ dose conversion coefficient method 3 5 Monte Carlo simulation calculation method for organ dose 6 6 Estimation of the effective dose of the subject 6 Appendix A (informative) The backscatter factor under different illumination conditions 8 Appendix B (Informative) The air kerma kinetic energy rate at 1m away from the X-ray source 11 Appendix C (Informative) Organ Dose Conversion Coefficient for Ordinary X-ray Photography Subject 12 Appendix D (informative) Common X-ray fluoroscopy subjects’ organ dose conversion coefficient 37 Appendix E (informative) X-ray mammography subjects organ dose estimation parameters 43 Appendix F (informative) X-ray computed tomography (CT) subject organ dose conversion factor 51 Appendix G (informative) Effective dose conversion factor for commonly used X-ray photography subjects 55 Appendix H (Informative) Commonly used X-ray computed tomography (CT) subjects effective dose conversion factor 57 Reference 58 Method of Estimating Organ Dose of Subject in X-ray Diagnosis1 ScopeThis document specifies the exposure dose of the main organs (or tissues) of the subject under specific irradiation conditions in common medical X-ray diagnosis Estimation method and related parameters. This document is suitable for receiving general X-ray photography, X-ray fluoroscopy, X-ray mammography and X-ray computed tomography (CT) Of subjects.2 Normative referencesThere are no normative references in this document.3 Terms and definitionsThe following terms and definitions apply to this document. 3.1 OrdinaryX-rayradiography Including traditional X-ray photography, digital X-ray photography (DR) and computer X-ray photography (CR) that use screen/film as the image receiver. 3.2 Incident air kerma Ka,i On the central axis of the ray beam on the surface of the subject or phantom, the measured air kerma kinetic energy generated by the incident beam. Note. Only refers to the incident radiation to the examinee or phantom, does not include backscattered radiation. 3.3 Entrance surface airkerma Ka,e The actual measured air kerma kinetic energy on the axis of the center line of the subject or the surface position of the phantom. Note. Including the radiation incident on the surface of the subject or phantom and its backscattered radiation. 3.4 Back-scattering factor; BSF Quantitatively characterize the scattering coefficient caused by the medium that makes the angle of the radiation or particle travel direction relative to the original direction greater than 90°. Note. The backscattering factor is equal to the ratio of the kerma kinetic energy of the incident surface air to the kerma kinetic energy of the incident air. 3.5 Airkerma-areaproduct PKA In a plane perpendicular to the beam axis, the product of the air kerma and the area of the irradiation field. 3.6 Airkerma-lengthproduct PKL In the plane perpendicular to the beam axis, the product of the air kerma and the length of the irradiation field. 3.7 Volume CT air kerma kinetic energy index volumeCTairkermaindex CVOL The average value of the air kerma in the overall scan volume in an axial scan or spiral scan can be measured to obtain the weighted CT air ratio The ratio of the release kinetic energy index (CW) to the CT spiral factor (p). 3.8 Organ dose DT The average energy of ionizing radiation absorbed by a specific tissue or organ (T) of the human body divided by the total mass of the tissue or organ. 3.9 Average mammaryglandulardose DG The average absorbed dose of the subject's breast caused by mammography. 3.10 Effectivedose The equivalent dose of each tissue or organ of the human body is multiplied by the corresponding tissue weighting factor, and the expression relationship is. E=∑ wT·HT Where. E --- effective dose, the unit is sievert (Sv); wT---Tissue weighting factor; HT---the equivalent dose of tissues or organs, in sievert (Sv). 3.11 Conversion coefficients of organdose CT The absorbed dose of different tissues or organs is normalized to a conversion factor of dosimetry that can be easily measured or calculated. 3.12 Conversion coefficients of effective dose CE The systemic effective dose is normalized to a conversion factor that can be easily measured or calculated. 3.13 Totalfiltration The sum of inherent filtering and additional filtering. Note. Inherent filtering is the equivalent filtering produced by the radiation beam from the X-ray source assembly or its parts before passing through the non-removable material. Attach Filtering is equivalent filtering produced by additional filter plates and other detachable substances between the X-ray source and the patient or a prescribed plane of the radiation beam. 3.14 Half-value layer; HVL When a narrow beam of X-rays with a specific radiation energy or energy spectrum passes through a prescribed substance, the air kerma rate is reduced to that measured without the substance The thickness of the specified substance that is half the value. 3.15 Focus skin distance; FSD The shortest distance from the effective focus of the X-ray tube to the skin surface of the subject. 3.16 Focus to receiver distance focalspottoimagereceptordistance; SID The distance from the reference plane of the effective focus to the intersection point of the reference axis and the image receiver plane. 3.17 Radiationfield The ray beam passes through the range of the phantom vertically after passing through the collimator. Note. Use the cross-sectional size of the phantom surface to indicate the area of the irradiation field.4 Organ dose conversion coefficient method4.1 General X-ray photography 4.1.1 Organ dose calculation formula The organ dose is calculated according to formula (1). DT=CT·Ka,e (1) Where. DT --- the absorbed dose of tissues or organs, in milligrays (mGy); CT ---organ dose conversion coefficient, the unit is milligray per gray (mGy/Gy); Ka,e-the kerma kinetic energy of the air incident on the body surface, in gray (Gy). 4.1.2 Obtaining the kerma kinetic energy of the air on the surface of the incident body 4.1.2.1 The actual measurement results of the kerma (Ka, e) of the incident surface air should be used first. 4.1.2.2 If there is no actual measurement result of the air kerma of the body surface, the PKA value of the area product of the air kerma can be used to estimate according to formula (2) Calculate Ka,e. Ka,e= PKA W·L · SID FSD ·BSF (2) Where. Ka,e --- the kerma kinetic energy of the incident surface air, in gray (Gy); PKA ---The product of air kerma kinetic energy area, in gray square centimeters (Gy cm2); W --- the width of the irradiation field, in centimeters (cm); L --- the length of the irradiation field, in centimeters (cm); SID --- the distance from the focus to the receiver, in centimeters (cm); FSD---focus distance, in centimeters (cm); BSF---Backscattering factor (see Appendix A). 4.1.2.3 If there is neither the actual measurement result of the incident surface air kerma (Ka, e) nor the PKA value, the measured or known distance X can be used. The air kerma rate K at the focal point d of the ray tube (can be selected in the range of 50cm~100cm) a, i and formula (3) to estimate Ka, e. Ka,e=Q·K a,i· FSD ·BSF (3) Where. Ka,e --- the kerma kinetic energy of the incident surface air, in gray (Gy); Q ---The product of current and time, in milliampere second (mA·s); a,i ---The air kerma rate at the focal point d from the tube, in gray per milliamp second [Gy/(mA·s)]; d ---The distance from the focal point of the tube to the measuring point, in centimeters (cm); FSD---focus distance, in centimeters (cm); BSF---Backscattering factor (see Appendix A). 4.1.2.4 If the air kernal energy rate data of the X-ray device under the voltage and current value used is not available, but the total filter thickness is known Degree, you can refer to Figure B.1 in Appendix B to first estimate the air kernal kinetic energy rate K at a distance of 1 m from the focal point of the X-ray tube a, i, then press formula (3) To estimate Ka,e, but this method has a large estimation error. 4.1.3 Organ dose conversion factor 4.1.3.1 Adult organ dose conversion factor. Tables C.1 to C.15 in Appendix C show six common body positions for adult X-ray photography. Test the dose conversion factor of each tissue or organ. 4.1.3.2 Children’s organ dose conversion factor. Table C.16~Table C.30 in Appendix C show two common positions for X-ray photography of 5-year-old and The dose conversion coefficient of each tissue or organ in a 10-year-old child. 4.1.3.3 When estimating the organ dose of a particular subject, if the size and quality of the subject are similar to those listed in Appendix C, Similarly, the corresponding organ dose conversion coefficients in Table C.1~Table C.30 can be used directly. The dose of irradiation field changes to the exposed organs in the irradiation field The impact is negligible, but it has a greater impact on the exposed organs in the field. For the same posture photography, the actual FSD used is the same as in Appendix C The difference in FSD listed has relatively little effect on the dose of organs in the irradiation field. 4.2 X-ray fluoroscopy 4.2.1 The calculation of the subject's organ dose caused by X-ray fluoroscopy can refer to formula (1). 4.2.2 The method of obtaining the kerma kinetic energy of the incident surface air by X-ray fluoroscopy can refer to 4.1.2. 4.2.3 The organ dose conversion coefficients of adult men and women undergoing X-ray fluoroscopy in different positions are as follows. a) For the organ dose conversion coefficients of adult men and women undergoing esophageal fluoroscopy, see Table D.1 to Table D.6 in Appendix D; b) Refer to Table D.7 and Table D.8 of Appendix D for the organ dose conversion coefficients of adult men and women undergoing gastric fluoroscopy; c) For the typical values of the organ dose conversion coefficients for adult men and women receiving cardiovascular angiography, see Appendix D, Table D.9. 4.3 Mammography 4.3.1 Organ dose calculation formula The average breast dose is calculated according to formula (4). DG=CG·Ka,i (4) Where. DG --- average breast dose, in milligrays (mGy); CG ---The average dose conversion coefficient of different targets/filters and different proportions of glands, in milligray per milligray (mGy/mGy); Ka,i-the kerma kinetic energy of incident air, in milligray (mGy). 4.3.2 Obtaining the kerma kinetic energy of incident air 4.3.2.1 The actual measurement results of the kerma (Ka, i) of incident air without the subject or phantom should be used first. 4.3.2.2 If the measured data of the kerma (Ka, e) of the air on the surface of the incident body measured in the presence of the subject or the phantom is used, it can be The backscatter factor BSFG of mammography is used to estimate Ka,i according to formula (5). Ka,i= Ka,e BSFG (5) Where. Ka,i --- kerma kinetic energy of incident air, in milligrays (mGy); Ka,e --- kerma kinetic energy of incident surface air, in milligrays (mGy); BSFG---The backscatter factor for mammography (see Table E.7 in Appendix E). 4.3.3 Breast dose conversion factor Refer to Table E.1~Table E.6 of Appendix E for the average breast dose conversion coefficients of different target/filtered and different proportions of glands. 4.4 Computer Tomography (CT) 4.4.1 Organ dose calculation formula The organ dose is calculated according to formula (6). DT=CCT·nCVOL·PIt (6) Where. DT --- the absorbed dose of tissues or organs, in milligrays (mGy); CCT ---CT-induced organ dose conversion coefficient of the subject, the unit is milligray per milligray (mGy/mGy); nCVOL---Volume CT air kernal energy index in milliampere second, in milligray per milliampere second [mGy/(mA·s)]; PIt ---The milliampere second value of the CT tube rotating one circle, the unit is milliampere second (mA·s). 4.4.2 Obtaining volumetric CT air kerma kinetic energy index 4.4.2.1 It is preferred to read directly from the radiation dose structured report (RDSR) of the CT system. 4.4.2.2 If it cannot be read, the weighted CT dose index CTDIW (equivalent to CT Air kerma kinetic energy index CW), and then use formula (7) to calculate CVOL. CVOL= CW·N·T Δd (7) Where. CVOL---Volume CT air kernal kinetic energy index, the unit is milligray (mGy); CW ---CT air kerma kinetic energy index, the unit is milligray (mGy); N ---The number of slices generated in one scan; T ---CT scan thickness, in millimeters (mm); Δd ---The distance that the CT tube rotates once the diagnostic bed moves, in millimeters (mm). 4.4.3 Organ dose conversion factor 4.4.3.1 Refer to Appendix F Table F.1 for the conversion factor of adult reference human organ dose. 4.4.3.2 For the organ dose conversion coefficients of children of different ages, see Table F.2~Table F.4 in Appendix F. 4.4.3.3 When estimating the organ dose of a specific subject, the manufacturer and model of the CT device used are the same as those listed in Appendix F. When the models are the same, the corresponding organ dose conversion coefficients in Table F.1 to Table F.4 can be used directly. When the manufacturer or model is different, the The organ dose conversion factor will have a greater degree of uncertainty.5 Monte Carlo simulation calculation method of organ dose5.1 Parameter selection 5.1.1 Ray source item. X-ray energy spectrum can use EGSnrc, FLUKA, GEANT, MCNPX, MCNPX. Software such as 1) is obtained by Monte Carlo (MC) simulation calculation, and can also be obtained with the help of X-ray energy spectroscopy that has been publicly released by relevant research institutions at home and abroad. Into software (such as XCOMP5R). The key factors affecting the energy spectrum mainly include the tube voltage and the overall filter setting. 1) The above commercial software is an example of software that can be used to simulate and calculate the X-ray energy spectrum. This information is given for the convenience of users of this document, and Does not indicate an endorsement of these software. If other equivalent software has the same effect, you can use these equivalent software. 5.1.2 Human body model. commonly used voxel (Voxel) model, because of its more detailed description of organs. Non-uniformity based on surface definition can also be used The rational B-spline curve (NURBS) model, which can customize the size and composition of each organ according to the individual, such as adjustable height And body weight, can construct different breast size, shape, ratio of breast to adipose tissue, etc. 5.1.3 Irradiation situation. mainly refers to the relative geometric position of the ray source and the human body model and the geometric size of the irradiation field. 5.2 Calculation method Define the radiation source items and the subject's human body model (age, body type, etc.) of the various X-ray diagnosis in 5.1, according to the specific exposure situation Carry out MC simulation calculation, respectively count the energy deposited in the organ or tissue of interest divided by the mass of the organ or tissue, and calculate The average organ dose can also be calculated directly (DT, MC). By increasing the number of particles (photons) calculated by simulation, Reduce the error of MC simulation calculation. The results of the MC simulation output are normalized to each emitted source particle (photon), and the same situation should be used. The ratio of the actual measured value (VM) and the simulated calculated value (VMC) of a specific physical quantity is converted, and the calculation is shown in formula (8). DT=DT,MC· VM VMC (8) Where. DT --- the estimated value of the absorbed dose of the organ or tissue; DT, MC-MC simulation calculation value of absorbed dose of organ or tissue; VM --- the measured value of a specific physical quantity; VMC --- The simulated calculated value of a specific physical quantity. 5.3 Conversion factor When the MC simulation calculation is carried out according to the methods described in 5.1 and 5.2, the corresponding incident air comma can be obtained at the same time in a simulation Energy and organ dose, the ratio of the two is the organ dose conversion coefficient. However, the conversion factor is only for a specific irradiation situation, if the irradiation situation (Including the equipment source item, the age and size of the subject) changes, the MC method can be used to recalculate the organ dose under different exposure situations Conversion factor.6 Estimation of the effective dose of the subject6.1 The effective dose of ordinary X-ray radiography subjects 6.1.1 Effective dose calculation formula The effective dose is calculated according to formula (9). E=CE·Ka,e (9) Where. E --- effective dose, the unit is millisievert (mSv); CE --- effective dose conversion factor, in millisievert per gray (mSv/Gy); Ka,e-the kerma kinetic energy of the air incident on the body surface, in gray (Gy). 6.1.2 Effective dose conversion factor 6.1.2.1 Refer to Table G.1 in Appendix G for the effective dose conversion coefficients of the six common posture photographic adult reference persons. 6.1.2.2 The effective dose conversion coefficients of two common posture photography for 5-year-old and 10-year-old children are shown in Table G.2 in Appendix G. 6.1.2.3 When estimating the effective dose of a particular subject, if the size and quality of the subject are the same as the adult male, female or adult One of the children's mannequins is similar in size and quality, so you can directly use Table G.1 or Table G.2 in Appendix G. Effective agent The estimation of the amount has a certain influence. When using the effective dose conversion coefficient table, try to take a dose that is close to or larger than the subject's imaging field. Conversion factor. 6.1.2.4 The estimation of the effective dose of ordinary X-ray photography subjects can be used for image quality comparison or optimization, and should not be used directly for radiation hazards risk assessment. 6.2 Effective dose of computed tomography subjects 6.2.1 Effective dose calculation formula The effective dose is calculated according to formula (10). E=CE,CT·PKL,CT (10) Where. E --- effective dose, the unit is millisievert (mSv); CE, CT ---The effective dose conversion coefficient of the subject caused by CT scan, the unit is millisievert per milligy centimeter [mSv/(mGy·cm)]; PKL, CT---CT scan of the air kerma length product, the unit is milligray centimeters (mGy·cm). 6.2.2 Obtaining the product PKL and CT of the length product of air kerma kinetic energy 6.2.2.1 It is preferred to read directly from the radiation dose structured report (RDSR) of the CT system. 6.2.2.2 If it cannot be read, use the method of 4.4.2.2 to obtain CVOL first, and then multiply it by the scan length to calculate PKL and CT. 6.2.3 Effective dose ......Tips & Frequently Asked Questions:Question 1: How long will the true-PDF of GB/T 16137-2021_English be delivered?Answer: Upon your order, we will start to translate GB/T 16137-2021_English as soon as possible, and keep you informed of the progress. The lead time is typically 5 ~ 8 working days. 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