Current Australian national diagnostic reference levels for multi detector computed tomography

Australian Adult (15+ years) MDCT DRLs

The DRLs below were introduced on 1 July 2018 and supersede the DRLs published in 2012. Information relating to the development of the current DRLs and on the transition from the 2012 DRLs can be found on the 2018 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) 23 470
Soft-tissue neck Post contrast (oncology) 17 450
Chest Post contrast (oncology) 10 390
Abdomen-pelvis Post contrast (oncology) 13 600
Kidney-uterer-bladder [4] Non-contrast (suspected renal colic) 13 600
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.
  4. Kidney-ureter-bladder (KUB) is a new category. Provisional DRLs for this category have been set using the data for abdomen-pelvis. This choice is expected to be conservative; facilities should not be overly concerned if their FRL is well below the DRL. Data will be reviewed within 2 years to set specific DRLs that reflect current practice.

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; the included FRLs are those from surveys submitted to the NDRLS during 2017. 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 17 23 270 350 470
Soft-tissue neck Post contrast (oncology) 9.5 12 17 290 350 450
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-uterer-bladder Non-contrast (suspected renal colic) - - 13 - - 600
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

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 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 22 270 350 450
Soft-tissue neck Post contrast 9.1 12 14 280 330 420
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-uterer-bladder Non-contrast (suspected renal colic) - - - - - -
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) 17 24 31 340 460 510
Soft-tissue neck Post contrast (oncology) 15 19 23 390 500 590
Chest Post contrast (oncology) 7.9 10 13 290 370 460
Abdomen-pelvis Post contrast (oncology) 9.6 12 14 450 570 630
Kidney-uterer-bladder Non-contrast (suspected renal colic) - - - - - -
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) 31 22 23 510 450 470
Soft-tissue neck Post contrast (oncology) 23 14 17 590 420 450
Chest Post contrast (oncology) 13 9.3 10 460 370 390
Abdomen-pelvis Post-contrast (oncology) 14 12 13 630 580 600
Kidney-uterer-bladder Non-contrast (suspected renal colic) - - 13 - - 600
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 DLP (mGy.com) CTDIvol (mGy)
Head 600 35
Chest 110 5
AbdoPelvis 390 10

For more information see the MDCT statistics page.

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

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

For more information see the MDCT statistics page.