IRS LTD – Integrated Radiological Services Limited Diagnostic Reference Levels (DRL) - IRS LTD
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Diagnostic Reference Levels

The following tables show DRL data collected from the North West (NW) of England for multiple examination modalities. This data has a number of uses, described below:

  1. As a starting point for establishing local diagnostic reference levels (DRLs).

    • It is a requirement under IRMER that DRLs are established for common examinations. Dose values should be audited and compared with published data and the results of any previous audits by the local Medical Physics Expert (MPE).
    • For the most common examinations, European and National data sets are available that can be used to inform a patient dose audit. IRS’s data set expands on this functionality by making available a regional data set for the NW. Additionally, IRS has extended the data set with additional examinations.
  2. As a reference for research studies.
    • These data sets can also be used to help inform the MPE when establishing dose constraints for research studies, which is a key IRMER requirement. As the data contains more than the standard common examinations, the MPE could use these values as a guide to typical doses for a larger range of examinations.

Additionally the data shows that it is possible to collate large amounts of data from specific geographical areas, modalities, examination types, etc., using information from hospital Radiology Information Systems (RIS) and established statistical methods.

CT DRLs (2011-2012)

ExaminationsRecordsMean DLPStdDev DLPMaxMinSEMMedian
CT Abdomen1808694.35509.87157712111.9912581.4
CT Abdomen Biopsy31393.622371.9561577.0191.866.8052269.11
CT Abdomen Colon Enhanced218611.73229.7981332.9178.715.5639622.5
CT Abdomen Drainage22882.611657.7552389.4767140.234730.04
CT Abdomen Pelvis8881715.287477.724602563.65.06928583
CT Adrenals41654.486585.1882052.0161.9891.3911383.75
CT Angiogram25792.184686.8253405145.3137.365719.5
CT Angiogram Aorta559940.345691.862619291.629.2626758.32
CT Angiogram Aortic Arch Carotids279523.19245.873179414414.7201494
CT Angiogram Intracranial5161059.56534.178481111223.51591019.1
CT Angiogram Lower Limbs6221169.28597.9393988133.523.97521074
CT Angiogram Pulmonary3158467.676299.5754367295.33088417.34
CT Angiogram Renal Abdominal124833.047650.735414117058.4377662
CT Angiogram Upper Limbs16558.136380.8241410116.4595.2059428.4
CT Ankle Either208163.32889.1292851476.17999140.2
CT Aorta Thoracic24805.517685.9813051.1262140.025546.7
CT Aorta Whole24987.821616.1482695.499.7125.771914
CT Aorta Whole Enhanced402989.001554.732338412127.6675881.5
CT Brain Perfusion Study103420.471298.8859691947410.7413488
CT Brain Volume636820.09306.072349.814512.1365850.4
CT Calcaneum Either48121.886109.366739.3741.615.785792.2
CT Cardiac Angiogram Coronary550680.681532.78732572522.7181486.45
CT Cardiac Cor Artery Calcium Scoring630151.693244.1681520149.7278952
CT Cardiac Multiple Gated Acquisition161301.658285.72116626422.518215.5
CT Chest4593439.025391.816944814.85.78141348.41
CT Chest Abdomen2983767.492449.493426470.58.22993677.39
CT Chest Abdomen Pelvis8091967.788548.4466202103.76.09723850.7
CT Chest Biopsy167266.305247.9751939.860.119.1889208.63
CT Chest High Resolution2005249.934271.5024425176.06338191.2
CT Chest Liver80520.003294.082164618132.8794428.7
CT Chest Liver Enhanced2850708.814346.0365200736.48184693.2
CT Chest Low Dose583116.574122.798933315.0857981.7
CT Clavicle Either28329.307188.661904114.335.6536266.05
CT Colon237574.021285.647189117218.5548455.61
CT Colonoscopy (Virtual)2723761.135723.27993883413.8606600.8
CT Elbow Either157304.98274.9091925.8328.421.9401190.66
CT Face27304.249113.8364749321.9077355.6
CT Facial Bones109393.555287.5331404.132.9127.5407342.5
CT Foot Either229165.93149.9711726449.91034132.6
CT Guided Biopsy184369.054402.7673234.3529.6923231.65
CT Guided Biopsy Lung109157.009117.25410442911.2309130
CT Guided Biopsy Pelvis16393.794239.477992.5646.0359.8693356.545
CT Guided Brain Biopsy321210.86276.967187484948.96131124.2
CT Guided Drainage98610.684830.8087039.35.383.9242396.5
CT Guided Epidural Injection112315.604137.53394012412.9956273
CT Hand Either37114.75558.0443335.424.59.5424295.72
CT Head22131775.391240.6943456.73641.61795729.61
CT Head Neck71932.201409.1512156.728748.5573996.8
CT Hip Either194448.348275.5841810.7117.6919.7858378.9
CT Hips172408.681270.699145689.620.6406337.95
CT IAM67611.761734.795612040.389.7695456
CT Internal Auditory Meatus Both24395.645278.517963.4141.2956.852227.78
CT Kidneys Ureter Bladder680451.565176.4415001616.76615442.33
CT Knee Either225219.803167.2291607.165.411.1486187
CT Liver3041076.28758.8274802120.843.5217864.05
CT Liver Triple Phase241710.551206.935559.2203.52246.3641506.585
CT Long Leg Measurement26179.631164.02736.119.332.1669199.7
CT Lower Leg Either52329.342444.9443326.665.461.7027246.49
CT Mandible101209.57223.2211076.684.122.2113127.8
CT Mastoid Both17238.093236.452879.144257.3481181.55
CT Maxilla968.5667118.738363.74.139.57949.6
CT Neck283541.544365.0921644421.7024418.09
CT Neck Chest161752.459413.39519948632.5801678
CT Neck Chest Abdomen90993.158418.661961.9268.4744.1306949
CT Neck Chest Abdomen Pelvis5631203.7580.7083741.57141.624.47391099.72
CT Oesophagus16673.781132.83814.441733.2074728.75
CT Orbit Both125366.693333.642279757.429.8419310
CT Pancreas399820.027608.8794408.5143.9530.4821621
CT pancreas Dual Phase48931.546528.9353038.524876.3453855.865
CT Pelvis263517.604499.9657043.238130.8292413
CT Pituitary22722.3337.1351292.27214.871.8775741.09
CT Radiotherapy Planning Scan Head311318.22316.7311877.473756.88661204
CT Renal1158394.292416.3612953.83612.2353207.05
CT Shoulder Either206413.321280.45519386319.5402352.75
CT Sinuses1431106.159112.092966.5232.9631680.4
CT Spine Cervical809391.804287.230303610.0974328.4
CT Spine Cervical Myelogram31725.006549.312581.626198.6589482.7
CT Spine Lumbar458538.63377.5553449.823.417.642418.75
CT Spine Lumbar Myelogram46631.837625.747380417492.2614461.5
CT Spine Thoracic147565.589407.6292203.3103.533.6207420
CT Temporal Bones318202.062184.9210242910.3698128.8
CT Temporomandibular Joint Both18204.572128.88543.49330.3772178.9
CT Thoracic Aorta Enhanced274594.777341.075241911320.6051554.85
CT Upper Arm Either18556.279321.3881236.7882.575.7518595.35
CT Upper Leg (Thigh) Either26691.721393.09514769877.0924581.555
CT Urinary tract1491685.775482.474506289.912.495565.1
CT Urogram7751045.84569.9213218116.2620.4722941
CT Venogram281094.34507.383251922195.88641026.5
CT Venogram Cerebral341142.66578.5752486.617899.22491043
CT Whole Spine421017.57572.192766.485.788.2909844.7
CT Wrist Either211100.08169.723556511.584.7999679


Radiographic DRLs (2013)

Abdomen AP1085583303.380.156.30.522.633.364.42
Chest AP10991119190.130.0030.
Chest LAT106654580.470.031.350.12340.410.52
Chest PA10992354280.130.0040.
L spine AP1064150225.390.198.512.344.045.316.54
L spine LAT1064167259.590.4922.
Pelvis AP1074357372.710.085.21.352.282.613.21
Skull AP/PA10364121.850.123.710.431.341.792.25
Skull LAT10486321.280.082.990.160.931.271.56
T spine AP107062013.570.177.031.432.43.554.38
T spine LAT106965167.060.4517.21.623.946.739.6


Extremity DRLs (Clarks 2014)

Exam NameESD/ExamBody part
Hand – DP/PA0.058 mGyUpper Limb
Hand – Anterior oblique (DP oblique)0.060 mGyUpper Limb
Hand Lateral 0.081 mGyUpper Limb
Finger - DP0.054 mGyUpper Limb
Finger – lateral 0.054 mGyUpper Limb
Thumb - Lateral0.067 mGyUpper Limb
Thumb - AP0.064 mGyUpper Limb
Thumb - PA0.064 mGyUpper Limb
Scaphoid - PA0.072 mGy Upper Limb
Scaphoid – anterior oblique0.072 mGyUpper Limb
Scaphoid – posterior oblique 0.072 mGyUpper Limb
Scaphoid – lateral 0.082 mGyUpper Limb
Wrist - PA0.072 mGyUpper Limb
Wrist – lateral 0.082 mGyUpper Limb
Forearm - AP0.13 mGyUpper Limb
Forearm – lateral 0.13 mGyUpper Limb
Elbow – lateral 0.13 mGyUpper Limb
Elbow – AP 0.12 mGy Upper Limb
Humerus - AP0.28 mGyUpper Limb
Humerus – Lateral 0.35 mGyUpper Limb
Humerus – neck (AP)0.35 mGyUpper Limb
Humerus neck - supero-inferior 0.58 mGyUpper Limb
Supero- inferior (Axial)0.58mGyShoulder
Clavicle – PA - ERECT0 .099mGyShoulder
Clavicle – AP – Supine 0.097mGyShoulder
Scapula- lateral – Y projection 0.73mGyShoulder
Foot - DP0.075mGyLower Limb
Foot DP Oblique0.076mGyLower Limb
Foot – lateral 0.092mGyLower Limb
Toes - DP0.076mGyLower Limb
Toes – DP oblique 0.076mGyLower Limb
Ankle – AP 0.11 mGyLower Limb
ANKLE – Lateral 0.11 mGyLower Limb
Calcaneum – lateral 0.14mGyLower Limb
Calcaneum – axial 0.2mGyLower Limb
Tibia and Fibula – AP 0.15 mGyLower Limb
Tibia and Fibula – lateral 0.16 mGyLower Limb
Knee – Skyline 0.28 mGyLower Limb
Femur – shaft - AP1.42 mGyLower Limb
Femur – shaft – Lateral 1.42 mGyLower Limb
Hip - AP2.83 mGy            HIP, Pelvis and SI joints
Hip – Lateral 8.12 mGy            HIP, Pelvis and SI joints
Sacrum - AP2.9 mGyHIP, Pelvis and SI joints
SACRUM – Lateral 8.1 mGyHIP, Pelvis and SI joints


Mammography DRL (2014)

ExaminationMeanCountStdDevMaxMinStdError of MeanMedian
OBL 50-60mm1.35mGy5170.53.490.650.711.22

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