Current Australian national diagnostic reference levels for multi detector computed tomography

Australian Adult (15+ years) MDCT DRLs

The current DRLs for MDCT scans on adult patients are shown below (Table 1) and were last updated in March 2021. Information relating to the development of the DRLs and on transitional arrangements for the most recent update can be found on the 2021 MDCT update and the MDCT statistics pages.

Table 1: Multi detector computed tomography diagnostic reference levels for adults
Scan region [1] Description (e.g. indication) [2] CTDIvol (mGy) [3] DLP (mGy.cm) [3]
Head Non-contrast brain (trauma/headache) 52 880
Cervical spine Non-contrast (trauma) 21 470
Soft-tissue neck Post contrast (oncology) 15 450
Chest Post contrast (oncology) 10 390
Abdomen-pelvis Post contrast (oncology) 13 600
Kidney-ureter-bladder Non-contrast (suspected renal colic) 10 460
Chest-abdomen-pelvis Post contrast (oncology) 11 940
Lumbar spine Non-contrast (degenerative pain) 26 670

Notes:

  1. Diagrams of the scan regions and additional protocol information are available from the before you enter data page.
  2. The scans included in a dose comparison do not necessarily have to be for the listed phase/indication; however, the exposure parameters of the included scans must match what would be used for the listed phase/indication.
  3. Dose indices for the Head region are based on the 16 cm reference phantom. Dose indices for all other scan regions are based on the 32 cm reference phantom.

Adult (15+ years) MDCT reference level quartiles

The following tables provide additional information on the observed distributions of facility reference levels (FRLs). An FRL is the median dose reported in a survey of patient dose for a specific scan region, on a specific scanner, at a specific facility. These tables are provided for information only – there is no regulatory requirement for facilities to compare their FRLs to them.

Table 2 shows the rounded 25th and 50th percentiles of the FRL distributions and compares them to the national DRLs. Facilities can use this additional information to gain a better understanding of how their FRLs compare to those of other facilities. If your FRL is near the 50th percentile you are approximately consistent with most other sites. If your FRL is below the 25th percentile you are amongst the lowest dose sites. It is important to ensure that the image quality in your scans is sufficient for the clinical task.

Table 2: FRL distribution percentiles and diagnostic reference levels (DRLs)
Scan region Description (e.g. indication) CTDIvol (mGy) DLP (mGy.cm)
25th 50th DRL 25th 50th DRL
Head Non-contrast brain (trauma/headache) 36 43 52 640 770 880
Cervical spine Non-contrast (trauma) 13 16 21 260 340 470
Soft-tissue neck Post contrast (oncology) 9.1 12 15 270 350 450
Chest Post contrast (oncology) 6.0 7.7 10 230 300 390
Abdomen-pelvis Post contrast (oncology) 7.7 9.8 13 380 480 600
Kidney-ureter-bladder Non-contrast (suspected renal colic) 5.5 7.6 10 260 360 460
Chest-abdomen-pelvis Post contrast (oncology) 7.0 8.7 11 580 740 940
Lumbar spine Non-contrast (degenerative pain) 16 20 26 430 540 670

Footnote: The percentiles are derived from data submitted to the ARPANSA National Diagnostic Reference Level Service (NDRLS) in 2017, except in the case of cervical spine, soft-tissue neck, and kidney-ureter-bladder scans where the percentiles are derived from data submitted in 2019. Analysis of the most recent data can be found on the MDCT Statistics page.

Tables 3 and 4 show the quartiles of the FRL distributions but with the surveys categorised by their use of iterative reconstruction. Table 3 shows the quartiles where iterative reconstruction was used and Table 4 shows the quartiles for surveys that did not use iterative reconstruction (which ARPANSA assumed were reconstructed using filtered back projection). Table 5 compares the 75th percentiles from Tables 3 and 4 with the national DRLs.

Table 3: Iterative reconstruction FRL distribution percentiles
Scan region Description (e.g. indication) CTDIvol (mGy) DLP (mGy.cm)
25th 50th 75th 25th 50th 75th
Head Non-contrast brain (trauma/headache) 35 41 48 620 740 840
Cervical spine Non-contrast (trauma) 12 16 21 260 340 430
Soft-tissue neck Post contrast 9.1 11 15 270 340 430
Chest Post contrast (oncology) 5.9 7.5 9.3 230 290 370
Abdomen-pelvis Post contrast (oncology) 7.4 9.4 12 370 460 580
Kidney-ureter-bladder Non-contrast (suspected renal colic) 5.3 7.3 9.4 250 350 460
Chest-abdomen-pelvis Post contrast (oncology) 6.8 8.4 10 550 700 920
Lumbar spine Non-contrast (degenerative pain) 16 19 25 420 530 660
Table 4: Filtered back projection FRL distribution percentiles
Scan region Description (e.g. indication) CTDIvol (mGy) DLP (mGy.cm)
25th 50th 75th 25th 50th 75th
Head Non-contrast brain (trauma/headache) 44 52 61 770 870 990
Cervical spine Non-contrast (trauma) 12 16 21 250 330 460
Soft-tissue neck Post contrast (oncology) 11 15 19 320 400 510
Chest Post contrast (oncology) 7.9 10 13 290 370 460
Abdomen-pelvis Post contrast (oncology) 9.6 12 14 450 570 630
Kidney-ureter-bladder Non-contrast (suspected renal colic) 8.0 10 11 370 430 510
Chest-abdomen-pelvis Post contrast (oncology) 9.0 11 13 730 910 1000
Lumbar spine Non-contrast (degenerative pain) 19 25 32 500 620 810
Table 5: Comparison of the diagnostic reference levels (DRLs) and the 75th percentile of the FRL for surveys conducted using filtered back projection (FBP) and iterative reconstruction (IR)
Scan region Description (e.g. indication) 75th CTDIvol (mGy) DLP (mGy.cm)
75th FBP 75th IR DRL 75th FBP 75th IR DRL
Head Non-contrast brain (trauma/headache) 61 48 52 990 840 880
Cervical spine Non-contrast (trauma) 21 21 21 460 430 470
Soft-tissue neck Post contrast (oncology) 19 15 15 510 430 450
Chest Post contrast (oncology) 13 9.3 10 460 370 390
Abdomen-pelvis Post-contrast (oncology) 14 12 13 630 580 600
Kidney-ureter-bladder Non-contrast (suspected renal colic) 11 9.4 10 510 460 460
Chest-abdomen-pelvis Post contrast (oncology) 13 10 11 1000 920 940
Lumbar spine Non-contrast (degenerative pain) 32 25 26 810 660 670

Australian child (5-14 years) MDCT DRLs

Child protocol CTDIvol (mGy) DLP (mGy.cm)
Head 35 600
Chest 5 110
Abdo Pelvis 10 390

For more information see the MDCT statistics page.

Australian baby/infant (0-4 years) MDCT DRLs

Baby protocol CTDIvol (mGy) DLP (mGy.cm)
Head 30 470
Chest 2 60
Abdo Pelvis 7 170

For more information see the MDCT statistics page.