National Diagnostic Reference Levels: 22 January 2016 to 14 November 2018
Updated 15 November 2018
© Crown copyright 2018
This publication is licensed under the terms of the Open Government Licence v3.0 except where otherwise stated. To view this licence, visit nationalarchives.gov.uk/doc/open-government-licence/version/3 or write to the Information Policy Team, The National Archives, Kew, London TW9 4DU, or email: psi@nationalarchives.gov.uk.
Where we have identified any third party copyright information you will need to obtain permission from the copyright holders concerned.
This publication is available at https://www.gov.uk/government/publications/diagnostic-radiology-national-diagnostic-reference-levels-ndrls/national-diagnostic-reference-levels-ndrls
1. Introduction
The following tables list the National Diagnostic Reference Levels (NDRLs) for the UK. These values should be considered by employers when settings their local DRLs as required by the Ionising Radiation (Medical Exposure) Regulations 2000 (as amended).
These NDRLs supersede those previously published by the Department of Health.
The NDRLs are based on National Reference Doses (NRDs) previously published by Public Health England (PHE). For details of how these values were obtained please refer to the PHE reports referenced below.
The values for CT examinations are taken from PHE-CRCE-013: Doses from computed tomography (CT) examinations in the UK (2011 Review).
The values for radiography, fluoroscopy and dental radiography are taken from HPA-CRCE-034: Doses to patients from radiographic and fluoroscopic x-ray imaging procedures in the UK (2010 review).
These reports contain additional dose information which may be of use for setting local DRLs for radiographic procedures where there was insufficient data to formally recommend a NDRL.
The NDRLs will be regularly reviewed and updated by PHE, in collaboration with a working party on national dose surveys and DRLs with representation from PHE, the radiology professional bodies and the Department of Health. Data for future NDRLs will be considered from national dose surveys undertaken by PHE and from other appropriate studies.
Enquires for diagnostic radiology should be sent to the PHE Medical Dosimetry group at medicalradiationdoses@phe.gov.uk.
For nuclear medicine studies, the ARSAC Notes for Guidance provide diagnostic reference levels for the most common examinations.
Further information can be found on the ARSAC website www.gov.uk/arsac.
2. National DRLs for CT examinations
2.1 Adult CT examinations
| Examination | Clinical indication | Scan region/technique | CTDIvol per sequence (mGy) | DLP per complete examination (mGy cm) |
|---|---|---|---|---|
| Head | Acute stroke | Post fossa | 80 | |
| Cerebrum | 60 | |||
| Brain (whole) | 60 | |||
| All sequences | 970 | |||
| Cervical spine | Fracture | All sequences | 28 | 600 |
| Chest 1 | Lung cancer | All sequences | 12 | 610 |
| Chest – high resolution 1 | Interstitial lung disease | Axial | 4 | 140 |
| Helical | 12 | 350 | ||
| Chest-abdomen-pelvis 1 | Cancer | All sequences | * | 1000 |
| CT Angiography (CTA) 1 | Abdominal aorta/blood vessels | All sequences | 15 | 1040 |
| CT Pulmonary Angiography (CTPA) 1 | Pulmonary embolism | All sequences | 13 | 440 |
| Abdomen 1 | Liver metastases | All sequences | 14 | 910 |
| Abdomen and pelvis 1 | Abscess | All sequences | 15 | 745 |
| Virtual colonoscopy 1 | Polyps/Tumour | All sequences | 11 | 950 |
| Kidney-ureters-bladder 1 | Stones/Colic | All sequences | 10 | 460 |
| Urogram 1 | Tumour /Stones/ Colic | All sequences | 13 | 1150 |
* Insufficient data were available to set a reliable national DRL in relation to this particular examination. Report PHE-CRCE-013 provides further information.
Values taken from PHE-CRCE-013: Doses from computed tomography (CT) examinations in the UK (2011 Review).
2.2 Paediatric CT examinations
| Examination | Clinical indication | Scan region/ technique | CTDIvol per sequence (mGy) | DLP per complete examination (mGy cm) |
|---|---|---|---|---|
| Paediatric head: 0–1 y | Trauma | All sequences | 25 | 350 |
| Paediatric head: >1–5 y | Trauma | All sequences | 40 | 650 |
| Paediatric head: >5 y | Trauma | All sequences | 60 | 860 |
Values taken from PHE-CRCE-013: Doses from computed tomography (CT) examinations in the UK (2011 Review).
3. National DRLs for General Radiography and Fluoroscopy
3.1 Individual radiographs on adult patients
| Radiograph | ESD per radiograph (mGy) | DAP per radiograph (Gy cm 2) |
|---|---|---|
| Abdomen AP | 4 | 2.5 |
| Chest AP | 0.2 | 0.15 |
| Chest LAT | 0.5 | |
| Chest PA | 0.15 | 0.1 |
| Cervical spine AP | 0.15 | |
| Cervical spine LAT | 0.15 | |
| Knee AP | 0.3 | |
| Knee LAT | 0.3 | |
| Lumbar spine AP | 5.7 | 1.5 |
| Lumbar spine LAT | 10 | 2.5 |
| Pelvis AP | 4 | 2.2 |
| Shoulder AP | 0.5 | |
| Skull AP/PA | 1.8 | |
| Skull LAT | 1.1 | |
| Thoracic spine AP | 3.5 | 1.0 |
| Thoracic spine LAT | 7 | 1.5 |
Values taken from HPA-CRCE-034: Doses to patients from radiographic and fluoroscopic x-ray imaging procedures in the UK (2010 review).
3.2 Diagnostic examinations on adult patients
| Examination | DAP per exam (Gy cm 2 | Fluoroscopy time per exam 2 (minutes) |
|---|---|---|
| Abdomen | 4.4 | |
| Barium (or water soluble) enema | 21 | 2.6 |
| Barium small bowel enema | 23 | 8.9 |
| Barium follow through | 8.4 | 2.0 |
| Barium meal | 12 | 2.6 |
| Barium meal & swallow | 10 | 2.3 |
| Barium (or water soluble) swallow | 7.5 | 2.1 |
| Barium swallow (video) | 3.4 | 3.5 |
| Chest | 0.3 | |
| Coronary angiography 3 | 31 | 4.3 |
| Coronary graft angiography 3 | 47 | 13 |
| Femoral angiography | 56 | 5.9 |
| Fistulography | 8 | 6.7 |
| Hysterosalpingography | 2 | 0.7 |
| Intravenous Urography (IVU) | 14 | |
| Lumbar spine | 6 | |
| Micturating Cystourethrography (MCU) | 7 | 1.6 |
| Nephrostography | 9 | 3.9 |
| Proctography | 14 | 1.3 |
| Sialography | 2.8 | 1.5 |
| Sinography | 7 | 1.7 |
| T-tube cholangiography | 5 | 1.8 |
Values from HPA-CRCE-034: Doses to patients from radiographic and fluoroscopic x-ray imaging procedures in the UK (2010 review).
3.3 Interventional procedures on adult patients
| Interventional procedure | DAP per exam (Gy cm 2) | Fluoroscopy time per exam 2 (minutes) |
|---|---|---|
| Biliary intervention | 43 | 14 |
| Facet joint injection | 6 | 1.4 |
| Hickman line insertion | 3 | 1.5 |
| Nephrostomy | 13 | 6.7 |
| Oesophageal stent | 13 | 5 |
| Pacemaker (permanent) | 7 | 6 |
| Percutaneous transluminal coronary angioplasty (PTCA) (single stent) 3 | 40 | 11.3 |
Values from HPA-CRCE-034: Doses to patients from radiographic and fluoroscopic x-ray imaging procedures in the UK (2010 review).
3.4 Diagnostic examinations on paediatric patients
| Examination | Standard age (y) | DAP per examination (Gy cm 2) |
|---|---|---|
| Micturating cystourethrography (MCU) | 0 | 0.1 |
| 1 | 0.3 | |
| 5 | 0.3 | |
| 10 | 0.4 | |
| 15 | 0.9 | |
| Barium meal | 0 | 0.1 |
| 1 | 0.2 | |
| 5 | 0.2 | |
| 10 | 0.7 | |
| 15 | 2.0 | |
| Barium swallow | 0 | 0.2 |
| 1 | 0.4 | |
| 5 | 0.5 | |
| 10 | 1.8 | |
| 15 | 3.0 |
Values from HPA-CRCE-034: Doses to patients from radiographic and fluoroscopic x-ray imaging procedures in the UK (2010 review).
4 National DRLs for dental radiography
| Radiograph | Patient entrance dose (PED) per radiograph (mGy) | |
|---|---|---|
| Intra-oral mandibular molar | Adult | 1.7 |
| DAP per radiograph (mGy cm2) | ||
| Panoramic | Adult | 93 |
| Child | 67 |
Values from HPA-CRCE-034: Doses to patients from radiographic and fluoroscopic x-ray imaging procedures in the UK (2010 review).