Multi detector computed tomography statistics

 

Below is a summary of the data submitted to the NDRLS since 2011. If you would like more information on how the DRLs were developed, please see our paper published in March 2020.

If you are conducting a publicly funded research project and would like to gain access to an anonymised version of the NDRLS MDCT dataset, please contact the NDRLS team.

NDRLS MDCT survey participation

Facility registrations

Figure 1 and Figure 2 show the date that facilities currently registered with the NDRLS first registered. The colours in Figure 1 and Figure 2 categorise the facilities by state/territory and facility type respectively.

Figure 1: Area plot showing the number of facilities registered with the NDRLS MDCT survey, categorised by state

Figure 2: Area plot showing the number of facilities registered with the NDRLS MDCT survey, categorised by the type of facility

Number of surveys submitted

Table 1 shows the number of surveys submitted to the NDRLS between April 2011 (the start of the service) and the end of 2022, categorised by protocol and age group.

Table 1: Number of surveys submitted to the NDRLS MDCT survey, categorised by age group, protocol and year

Age group	Protocol	2011	2012	2013	2014	2015	2016	2017	2018	2019	2020	2021	2022	Total
Adult (15+ years) surveys submitted	Head	56	113	166	147	202	284	465	591	712	729	555	599	4619
	Neck	30	57	80	76	141	192	358	131	-	-	-	-	1065
	Soft-tissue neck	-	-	-	-	-	-	-	259	453	530	353	396	1991
	Cervical spine	-	-	-	-	-	-	-	315	565	597	459	508	2444
	Chest	44	78	112	113	177	258	422	542	652	682	514	568	4162
	Chest abdomen pelvis	40	68	100	93	135	200	368	467	559	621	444	493	3588
	Abdomen pelvis	51	100	150	128	194	274	442	575	676	693	549	583	4415
	Kidney ureter bladder	-	-	-	-	-	-	-	256	479	521	408	462	2126
	Lumbar spine	34	75	116	105	156	237	419	517	659	672	516	554	4060
	Total	255	491	724	662	1005	1445	2474	3653	4755	5045	3798	4163	28470
Child (5-14 years) surveys submitted	Head	0	28	26	19	22	22	16	10	10	10	10	7	180
	Chest	0	7	8	7	8	9	13	5	3	6	4	3	73
	Abdomen pelvis	0	3	6	4	6	5	6	2	2	4	3	4	45
	Total	0	38	40	30	36	36	35	17	15	20	17	14	298
Baby (0-4 years) surveys submitted	Head	0	20	23	18	17	20	13	10	6	8	9	5	149
	Chest	0	3	5	4	3	4	6	3	3	3	3	2	39
	Abdomen pelvis	0	0	2	2	1	2	2	1	2	2	2	2	18
	Total	0	23	30	24	21	26	21	14	11	13	14	9	206

FRL distributions

The curves below show the cumulative distributions for the DLP and CTDI_vol from adult abdomen pelvis DRL surveys submitted in 2022. The y-axis displays the percentage of facilities that achieved an FRL below the dose specified on the x-axis.

The blue curve represents all of the submitted data, the orange curve represents the surveys where iterative reconstruction (IR) was used and the green curve represents the surveys where filtered back projection (FBP) was used. The national DRL was derived from data submitted in earlier years and, consequently, the DRLs do not match the 75^th percentile of the plotted distributions.

View similar plots for the other protocols.

 

Figure 3: Cumulative dose distributions for abdomen pelvis scans conducted on adult patients. The y-axis provides the percentage of facilities that achieved an FRL below the dose specified on the x-axis. The blue, orange and green curves represent all data, data from scans that used iterative reconstruction (IR) and scans that used filtered back projection (FBP) respectively.

FRL distribution variation over time

Figure 4 shows the change in the median of the FRL distribution since the beginning of 2012 for adult abdomen pelvis scans. The graph has been generated by examining the surveys submitted during a moving 12-month period, where the start and end points of the window have been shifted by daily intervals. The x-axis is the end date of the 12-month interval, the blue line is the median of the corresponding FRL distribution, the red line denotes the current DRL and the light blue region indicates the 25^th – 75^th percentile range.

View similar graphs for the other adult FRL distributions.

Figure 4: Change in the 75^th percentile (P₇₅) of the DLP and the CTDI_vol for abdomen pelvis scans. The date along the x-axis denotes the end of the 12-month window of data used to calculate the percentile. The red line represents the current DRL.

Impact of iterative reconstruction

The reductions in the 75^th percentile of the FRL distribution can be partially attributed to the increased adoption of iterative reconstruction (IR) techniques. Figure 5 shows the number of surveys submitted since April 2013, categorised by the use of IR.

Figure 5: Number of surveys submitted since April 2013, categorised by the use of iterative reconstruction (IR) or filtered back projection (FBP)

The change in dose distributions is represented in Figure 6 below. The metric plotted is the 75^th percentile of the submitted FRLs, where the FRL has been expressed as a fraction of the relevant DRL. The date along the x-axis represents the end of a 12-month period for which the percentile has been calculated. The plot only includes data for protocols where data has been collected from 2013 to 2022 (inclusive).

Figure 6: Change in the 75^th percentile for the original MDCT protocols that are still in use. The FRL has been calculated as a fraction of the DRL. The blue, orange and green curves represent all data, data from scans that used Iterative Reconstruction (IR) and scans that used Filtered Back Projection (FBP) respectively. The 95% confidence intervals (CI) for each curve are also shown - the 95% CI gives an indication of the number of surveys submitted (a wider CI suggests fewer surveys).