National Diagnostic Reference Levels (NDRLs) from 11 December 2025
Updated 11 December 2025
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Introduction
National Diagnostic Reference Levels (NDRLs) for the UK are listed in the following tables. These include CT, general radiography, some fluoroscopy and interventional procedures, CT as part of SPECT or PET, screening mammography and dental x-rays.
National Dose Reference Levels for radiotherapy imaging (CT and CBCT) are also listed.
National Diagnostic Reference levels for the most common nuclear medicine studies are given in the ARSAC Notes for Guidance. Further information can be found on the ARSAC website.
The NDRL values should be considered by employers when setting their local DRLs as required by the Ionising Radiation (Medical Exposure) Regulations 2017 and the Ionising Radiation (Medical Exposure) Regulations (Northern Ireland) 2018 (as amended).
The UK National DRLs are based on modality, body region and, where appropriate, clinical requirement for the examination. They are generally given as the third quartile value from a spread of values from a national survey.
NDRLs are the starting point for optimisation. It is always advisable to consider the source data for NDRLs when reviewing local values and optimising practice.
The published reports and peer reviewed papers, which contain the source information, are referenced in each section. They are also listed at the end of this page.
Some examinations, which were on earlier lists of NDRLs, have not been included on this page. This could be through insufficient data from the most recent survey or a change in the modality of choice for that investigation. The surveys for these examinations were undertaken a number of years ago and doses are likely to have changed. The previous NDRLs can be found on the archived pages National Diagnostic Reference Levels: 22 January 2016 to 14 November 2018 (archived content).
The source publications include some additional examinations for which insufficient data sets were received to enable formal recommendation of an NDRL, however they are of sufficient value to be included in the publication.
Enquiries regarding NDRLs should be sent to the UKHSA Medical Dosimetry Group medicalradiationdoses@ukhsa.gov.uk
National DRLs for computed tomography
Table 1. Adult CT examinations
| Examination | Clinical Indication | Scan region / technique | CTDI vol per sequence (mGy) | DLP per complete examination (mGy cm) | Year NDRL adopted |
|---|---|---|---|---|---|
| Head(1) | Acute stroke | All sequences | 47 | 790 | 2022 |
| Paranasal sinuses(1) | Sinus disease | All sequences | 12 | 160 | 2022 |
| Cervical spine(1) | Fracture | All sequences | 16 | 400 | 2022 |
| Neck, chest, abdomen and pelvis(1) | Cancer | All sequences | 850 | 2022 | |
| Chest(1) | Lung cancer | All sequences | 8.5 | 290 | 2022 |
| Chest and Abdomen(1) | Lung cancer | All sequences | 470 | 2022 | |
| Chest-high resolution(1) | Interstitial lung disease | Helical | 8 | 300 | 2022 |
| Chest, abdomen, pelvis(1) | Cancer | All sequences | 660 | 2022 | |
| CT Pulmonary Angiography (CTPA)(1) | Pulmonary embolism | All sequences | 9.1 | 310 | 2022 |
| Abdomen and pelvis(1) | Abscess | All sequences | 10 | 530 | 2022 |
| Virtual colonoscopy(1) | Polyps/Tumour | All sequences | 690 | 2022 | |
| Kidneys, ureters, bladder(1) | Stones/Colic | All sequences | 6.3 | 290 | 2022 |
| Urogram(1) | Tumour/Stones/Colic | All sequences | 890 | 2022 | |
| Coronary CT angiography (CTA)(2) | Prospective, no padding | 170 | 2018 | ||
| Prospective, with padding | 280 | 2018 | |||
| Retrospective, with gating | 380 | 2018 |
Note: Doses for the head and paranasal sinus examinations refer to measurements in the 16cm standard CT dosimetry phantom. All other doses refer to measurements in the 32cm standard CT dosimetry phantom.
Caution is required when comparing your local dose values with the NDRL for the chest exam. There are separate NDRLs for ‘chest’ and ‘chest and abdomen’, covering the appropriate body regions. However, the descriptor for the ‘chest’ exam for the previous NDRL (based on the 2011 survey) extended to the liver region, and therefore may not be directly comparable.
Table 2. Paediatric CT examinations
| Examination | Clinical indication | Scan region / technique | CTDIvol per sequence (mGy) | DLP per complete examination (mGy cm) | Year NDRL adopted |
|---|---|---|---|---|---|
| Paediatric head: 0 to <1 y |
Trauma | All sequences | 19 | 290 | 2022 |
| Paediatric head: 1 to <5 y |
Trauma | All sequences | 24 | 420 | 2022 |
| Paediatric head: 5 to <10y |
Trauma | All sequences | 36 | 570 | 2022 |
| Paediatric head: 10 to <15y |
Trauma | All sequences | 46 | 690 | 2022 |
| Paediatric head: 15 to <18y (adult head CT values applied) |
Acute Stroke | All sequences | 47 | 790 | 2022 |
| Paediatric chest: 0 to <5kg |
Query cancer | All sequences | 0.44 | 8 | 2022 |
| Paediatric chest: 5 to <15kg |
Query cancer | All sequences | 0.86 | 18 | 2022 |
| Paediatric chest: 15 to <30kg |
Query cancer | All sequences | 2.0 | 40 | 2022 |
| Paediatric chest: 30 to <50kg |
Query cancer | All sequences | 2.6 | 62 | 2022 |
| Paediatric chest: 50 to <80kg |
Query cancer | All sequences | 3.8 | 110 | 2022 |
Note: Doses for the head examination refer to measurements in the 16 cm standard CT dosimetry phantom. Doses for chest examinations refer to measurements in the 32 cm standard CT dosimetry phantom.
For paediatric head (15 to less than 18 years) adult head values are applied.
For the paediatric chest 0 to less than 5kg and 50 to less than 80kg categories, the values are based on sample sizes smaller than commonly used to set NDRLs. The application of these NDRLs should therefore be carefully considered by the Medical Physics Expert (MPE).
Values taken from ‘Analysis and results from a UK national dose audit of paediatric CT examinations’.
Table 3. Adult CT examinations as part of PET-CT and SPECT-CT examinations
| Examination | Clinical indication | Scan region / technique | CTDIvol per sequence (mGy) | DLP per complete examination (mGy cm) | Year NDRL adopted |
|---|---|---|---|---|---|
| PET half body | attenuation correction and localisation of the nuclear medicine signal | All sequences | 4.3 | 400 | 2018 |
| SPECT bone scan | attenuation correction and localisation of the nuclear medicine signal | All sequences | 4.9 | 150 | 2018 |
| SPECT parathyroid | attenuation correction and localisation of the nuclear medicine signal | All sequences | 5.6 | 170 | 2018 |
| SPECT post-thyroid ablation | attenuation correction and localisation of the nuclear medicine signal | All sequences | 5.9 | 210 | 2018 |
| SPECT mIBG/octreotide | attenuation correction and localisation of the nuclear medicine signal | All sequences | 5.5 | 240 | 2018 |
| SPECT cardiac | attenuation correction | All sequences | 2.1 | 36 | 2018 |
Note: Doses refer to measurements in the 32cm standard CT dosimetry phantom.
Values taken from ‘A national survey of computed tomography doses in hybrid PET-CT and SPECT-CT examinations in the UK’.
National DRLs for general radiography and fluoroscopy
Table 4. Individual radiography projections of adult patients
| Radiograph | DAP per radiograph (Gy cm2) | Year NDRL adopted |
|---|---|---|
| Abdomen AP | 1.7 | 2025 |
| Chest AP | 0.092 | 2025 |
| Chest AP mobile (ward) | 0.11 | 2025 |
| Chest LAT | 0.34 | 2025 |
| Chest PA | 0.077 | 2025 |
| Cervical spine AP | 0.096 | 2025 |
| Cervical spine LAT | 0.11 | 2025 |
| Foot (single) weight bearing DP | 0.023 | 2025 |
| Hand (single) PA | 0.022 | 2025 |
| Hip (single) horizonal beam lateral | 1.6 | 2025 |
| Knee AP | 0.054 | 2025 |
| Knee LAT | 0.056 | 2025 |
| Lumbar spine AP | 1.4 | 2025 |
| Lumbar spine LAT | 2.1 | 2025 |
| Pelvis AP | 1.6 | 2025 |
| Shoulder AP | 0.090 | 2025 |
| Thoracic spine AP | 0.61 | 2025 |
| Thoracic spine LAT | 0.95 | 2025 |
Values taken from ‘Radiographic and simple fluoroscopic X-ray imaging: patient doses’.
Table 5. Diagnostic plain radiography examinations of adult patients
| Examination | DAP per exam (Gy cm2) | Year NDRL adopted |
|---|---|---|
| Abdomen | 2.0 | 2025 |
| Cervical spine | 0.24 | 2025 |
| Chest | 0.12 | 2025 |
| Facial bones | 0.82 | 2025 |
| Foot | 0.049 | 2025 |
| Hip (single) | 2.2 | 2025 |
| Knee (single) | 0.13 | 2025 |
| Lumbar spine | 3.9 | 2025 |
| Pelvis | 1.9 | 2025 |
| Shoulder | 0.20 | 2025 |
| Thoracic spine | 2.0 | 2025 |
Values taken from ‘Radiographic and simple fluoroscopic X-ray imaging: patient doses’.
Table 6. Diagnostic fluoroscopy examinations of adult patients
| Examination | DAP per exam (Gy cm2) | Year NDRL adopted |
|---|---|---|
| Barium swallow | 5.0 | 2025 |
| Water soluble swallow | 5.3 | 2025 |
| Barium swallow (video) | 1.2 | 2025 |
| Water soluble enema | 8.2 | 2025 |
| Hysterosalpingography | 0.55 | 2025 |
Values taken from ‘Radiographic and simple fluoroscopic X-ray imaging: patient doses’.
Table 7. Interventional procedures on adult patients
| Interventional procedure | DAP per exam (Gy cm2) | Year NDRL adopted |
|---|---|---|
| ERCP (diagnostic and interventional) (3) | 6.4 | 2025 |
| Insertion of tunnelled central venous catheter (3) | 0.65 | 2025 |
| Nephrostomy (3) | 1.5 | 2025 |
| Nephrostomy tube replacement (3) | 0.52 | 2025 |
| Pacemaker (single or dual chamber, permanent) (3) | 1.7 | 2025 |
| PICC line insertion (3) | 0.31 | 2025 |
| Radiologically inserted gastrostomy tube (3) | 1.3 | 2025 |
| Stent: ureteric (antegrade and retrograde) (3) | 3.0 | 2025 |
| Endovascular Aneurysm Repair (EVAR) (4) | 160 | 2024 |
| Thoracic endovascular aortic repair (TEVAR) (4) | 180 | 2024 |
| Branched endovascular aneurysm repair (BEVAR) or fenestrated endovascular aneurysm repair (FEVAR) (4) | 270 | 2024 |
Table 8a. Diagnostic radiography examinations on paediatric patients: micturating cystourethrography (MCU)
| Standard age (y) | DAP per examination (Gy cm2) | Year NDRL adopted |
|---|---|---|
| 0 | 0.1 | 2016 |
| 1 | 0.3 | 2016 |
| 5 | 0.3 | 2016 |
| 10 | 0.4 | 2016 |
| 15 | 0.9 | 2016 |
Table 8b. Diagnostic radiography examinations on paediatric patients: barium meal
| Standard age (y) | DAP per examination (Gy cm2) | Year NDRL adopted |
|---|---|---|
| 0 | 0.1 | 2016 |
| 1 | 0.2 | 2016 |
| 5 | 0.2 | 2016 |
| 10 | 0.7 | 2016 |
| 15 | 2.0 | 2016 |
Table 8c. Diagnostic radiography examinations on paediatric patients: barium swallow
| Standard age (y) | DAP per examination (Gy cm2) | Year NDRL adopted |
|---|---|---|
| 0 | 0.2 | 2016 |
| 1 | 0.4 | 2016 |
| 5 | 0.5 | 2016 |
| 10 | 1.8 | 2016 |
| 15 | 3.0 | 2016 |
Values taken from ‘HPA-CRCE-034: Doses to patients from radiographic and fluoroscopic X-ray imaging procedures in the UK (2010 review)’.
National DRLs for dental radiography
Table 9a. National DRLs for intra-oral radiography
| Radiograph | Patient size | Patient entrance dose (PED) per radiograph (mGy) | Year NDRL adopted |
|---|---|---|---|
| Intra-oral mandibular molar | Adult | 1.2 | 2019 |
| Child | 0.7 | 2019 |
Table 9b. National DRLs for panoramic, cephalometric, and CBCT radiography
| Radiograph | Patient size (clinical indication) | DAP per radiograph (mGy cm2) | Year NDRL adopted |
|---|---|---|---|
| Panoramic (full jaw) | Adult | 81 | 2019 |
| Child | 60 | 2019 | |
| Lateral cephalometric | Adult | 35 | 2019 |
| Child | 24 | 2019 | |
| Dental CBCT | Adult (imaging prior to placement of a maxillary molar implant) | 265 | 2019 |
| Child (imaging of an impacted maxillary canine of a 12-year-old child) | 170 | 2019 |
Values taken from ‘Dental radiographic X-ray imaging: dose to patients’.
National DRLs for screening mammography
This value was proposed to the UKHSA NDRL working group by the Breast Screening Physics Clinical Professional Group (formerly National Breast Screening QA Co-ordinating Group for Physics), and the National Co-ordinating Centre for the Physics of Mammography (NCCPM).
Table 10. National DRLs for screening mammography
| Radiograph | Mean glandular dose (MGD) (mGy) | Year NDRL adopted |
|---|---|---|
| Screening mammography | 2.5 | 2022 |
Average mean glandular dose (MGD) for mediolateral oblique breast exposures of a sample of 50mm to 60mm thick breasts using at least 10 patients, 2D full field digital mammography in screening using DR systems. Please note that only DR systems are used in the NHSBSP.
Value based on data from ‘Radiation doses in the United Kingdom breast screening programmes 2016–2019’.
National DRLs for radiotherapy imaging
In radiotherapy, the acronym DRL refers to Dose Reference Level.
NDRLs are presented for adult patients for radiotherapy imaging; for treatment planning with conventional computed tomography (CT), and for radiotherapy verification imaging with cone beam CT (CBCT).
Table 11. National DRLs for radiotherapy planning with conventional CT
| Examination | CTDIvol per sequence (mGy) | DLP per complete examination (mGy cm) | Scan length (mm) | Year NDRL adopted |
|---|---|---|---|---|
| Breast | 10 | 390 | 360 | 2018 |
| Gynaecological | 16 | 610 | 400 | 2018 |
| Lung 3D | 14 | 550 | 390 | 2018 |
| Lung 4D | 63 | 1750 | 340 | 2018 |
| Prostate | 16 | 570 | 340 | 2018 |
| Brain | 50 | 1500 | 290 | 2018 |
| Head and Neck | 49 | 2150 | 420 | 2018 |
Doses for the brain and ‘head and neck’ examinations only refer to measurements in the 16cm standard CT dosimetry phantom. All other doses refer to measurements in the 32cm standard CT dosimetry phantom.
Values taken from ‘IPEM topical report: the first UK survey of dose indices from radiotherapy treatment planning computed tomography scans for adult patients’.
Table 12. National DRLs for radiotherapy verification with CBCT
| Examination | CBDIw (mGy) | Year NDRL adopted |
|---|---|---|
| Brain | 3.5 | 2025 |
| Head and Neck | 4.2 | 2025 |
| Breast | 5.0 | 2025 |
| Lung 3D | 6.0 | 2025 |
| Lung 4D | 12 | 2025 |
| Prostate | 21 | 2025 |
| Gynaecological | 21 | 2025 |
The weighted Cone Beam Dose Index is used (CBDIw) for cone beam CT. Values are taken from table 3 in ‘IPEM topical report: the first UK survey of cone beam CT dose indices in radiotherapy verification imaging for adult patients – IOPscience’.
Large differences in dose values are observed according to model of imaging system. Therefore, for optimisation it is especially important to review local data in conjunction with the referenced report.
References
-
UKHSA. ‘UKHSA-RCE-1 Doses from computed tomography examinations in the UK (2019 review)’
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Castellano IA and others. ‘A prospective national survey of coronary CT angiography radiation doses in the United Kingdom’ Journal of Cardiovascular Computed Tomography 2017: volume 11, pages 268 to 273
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UKHSA. ‘Radiographic and simple fluoroscopic X-ray imaging: patient doses’.
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Tsitsiou Y and others. ‘National UK Survey of Radiation Doses During Endovascular Aortic Interventions’: volume 92, pages 92 to 100
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Radiographic, fluoroscopic and dental x-rays. ‘Patient dose audits’
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Worrall M and others. ‘Analysis and results from a UK national dose audit of paediatric CT examinations’ British Journal of Radiology 2021: volume 95, issue 1129
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Iball GR and others. ‘A national survey of computed tomography doses in hybrid PET-CT and SPECT-CT examinations in the UK’ Nuclear Medicine Communications 2017: volume 38, issue 6, pages 459 to 470
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Loveland J, Young KC, Oduko JM and Mackenzie A. ‘Radiation doses in the United Kingdom breast screening programmes 2016–2019’ British Journal of Radiology 2022: volume 95, issue 1135
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Wood TJ and others. ‘IPEM topical report: the first UK survey of dose indices from radiotherapy treatment planning computed tomography scans for adult patients’ Physics in Medicine and Biology 2018
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Wood TJ and others. ‘IPEM topical report: the first UK survey of cone beam CT dose indices in radiotherapy verification imaging for adult patients - IOPscience’ Phys. Med. Biol. 69 (2024) 225002