Interventional radiology (IR) is becoming more relevant in patient care and is associated with increased patient radiation exposure and radiation-induced adverse effects. Diagnostic reference levels (DRLs) are crucial for radiation control. There is a paucity of published DRLs for IR in South Africa and sub-Saharan Africa.
This study aimed to determine local DRLs for fluoroscopically-guided IR procedures and compare the achieved DRLs with published local and international DRLs.
Retrospective, descriptive, single-centre study. Kerma air product (KAP), reference point air kerma (Ka,r) and fluoroscopy time (FT) were collected for patients (12 years and older) who underwent IR procedures at a university hospital from 01 January 2019 to 31 December 2019. The 75th percentile of the distribution of each dose parameter (KAP, Ka,r and FT) per procedure was calculated and taken as the local diagnostic reference levels (LDRL). The established LDRLs were compared to published DRLs.
A total of 564 cases were evaluated. The 13 most frequent procedures (with 15 or more cases) represented 86.1% (487/564). Percutaneous transhepatic biliary drainage was the most common procedure (
The LDRLs for diagnostic cerebral angiogram, interventional cerebral angiogram and UAE exceeded published international DRL ranges. These procedures require radiation optimisation as recommended by the International Commission on Radiological Protection (ICRP).
In addition to informing radiation protection practices at the level of the institution, the established LDRLs contribute towards Regional and National DRLs.
Use of interventional radiology (IR) in patient care is increasing,
Radiation control is achieved through optimisation, justification and dose limitation without compromising image quality.
There is limited published data on DRLs in South Africa and sub-Saharan Africa. This is true for low- and middle-income countries (LMICs) in comparison to high-income countries. In 2015, less than one-quarter of the 135 LMICs had any form of published DRL data.
As far as the authors are aware, there are only two articles establishing DRLs for IR in sub-Saharan Africa. The most recent study is from South Africa by Malan et al.
This study sought to address the paucity of DRL data for IR procedures in South Africa. The aim was to establish local DRLs for fluoroscopically-guided IR procedures and compare the achieved DRL to published local and international DRLs.
The study was designed as a retrospective, descriptive, single-centre study. The study population included consecutive patients (adolescents over the age of 11 years and adults) who underwent fluoroscopically-guided IR procedures (diagnostic or therapeutic) at Chris Hani Baragwanath Academic Hospital (CHBAH) from 01 January 2019 to 31 December 2019. The period was chosen to reflect pre-coronavirus disease 2019 (COVID-19) figures. Chris Hani Baragwanath Academic Hospital is located in Soweto in Gauteng, South Africa. It is a tertiary-level 3400-bed (the third largest in the world) hospital and is the main teaching hospital for the University of the Witwatersrand medical school.
The kerma air product (KAP), reference point air kerma (Ka,r) and fluoroscopy time (FT) were automatically generated by the fluoroscopy unit at the conclusion of each procedure. Radiographers recorded this data in logbooks, from which the researchers acquired it. The department at the time of the study used two fluoroscopy units, the Philips Allura Xper FD20/20 (biplane) and the Philips Allura Xper FD20 (monoplane), which were both installed in 2010.
The dose area product (DAP) – indirect dose parameters – was provided by built-in software for the biplane system. The KAP is the integral of air kerma (the energy extracted from an X-ray beam per unit mass of air in a small irradiated air volume; for diagnostic X-rays, the dose delivered to that volume of air) across the entire X-ray beam emitted from the X-ray tube.
The distribution of IR procedures in this sample was tabled using the frequency function on Microsoft Excel. The most frequent procedures were identified (15 or more cases) and included in the analysis. Conversely, procedures with fewer than 15 cases were excluded from the analysis. The KAP, Ka,r and FT for the included procedures were captured. The mean, median (50th percentile) and 75th percentile of the distribution of each radiation exposure parameter were determined for each procedure. The 75th percentile of data distribution for the DAP and Ka,r of each IR procedure was taken as the LDRL. The LDRLs were compared with published local and international DRLs.
Ethical approval to conduct this study was obtained from the University of the Witwatersrand Human Research Ethics Committee (ref. no. M220320).
The total number of IR cases performed during the study period was 564. The 13 most frequent procedures (each with 15 or more cases) represented 86.1% (
The total number of interventional radiology cases performed during the study period was 564. The 13 most frequent procedures (each with 15 or more cases) representing 86.1 % (
Dosimetry data for Chris Hani Baragwanath Academic Hospital.
Procedure | Total cases (n) | Kerma air product (Gy/cm2) |
Reference point air kerma (mGy) |
Fluoroscopy time (min) |
|||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Median | IQR | 75th percentile | 75th:50th | Median | IQR | 75th percentile | 75th:50th | Median | IQR | 75th percentile | 75th:50th | ||
Percutaneous transhepatic biliary drainage (PTBD) | 146 | 11 | 19 | 24 | 2.2 | 64 | 100, 8 | 131.8 | 2.1 | 3.3 | 4, 5 | 6.2 | 1.8 |
Bronchial artery embolisation (BAE) | 57 | 76 | 70 | 131 | 1.7 | 215 | 197 | 343 | 1.6 | 21.5 | 18, 4 | 33.5 | 1.6 |
Pigtail insertion | 44 | 3.5 | 6, 5 | 7.5 | 2.1 | 19 | 31 | 37 | 1.9 | 1.1 | 1, 8 | 2.4 | 2.1 |
Nephrostomy (unilateral) | 42 | 2 | 8 | 10 | 5 | 20 | 28 | 26 | 1.8 | 1.7 | 2, 6 | 3.4 | 2.1 |
Nephrostomy (bilateral) | 37 | 5.5 | 7 | 10 | 1.8 | 33 | 41 | 62 | 1.9 | 3.6 | 3, 6 | 6.3 | 1.8 |
Selective abdominal vessels-interventional angiogram | 26 | 385 | 600, 3 | 776 | 2 | 1208 | 1819, 5 | 2227.8 | 1.8 | 19.7 | 17, 2 | 28.3 | 1.4 |
Diagnostic cerebral angiogram | 26 | 157.5 | 117, 3 | 209.3 | 1.3 | 598.5 | 420, 8 | 868.5 | 1.5 | 18.8 | 15, 9 | 28.4 | 1.5 |
PICC | 25 | 1 | 1, 0 | 2 | 2 | 2 | 4, 0 | 5 | 2.5 | 1.8 | 3, 2 | 4 | 2.2 |
PTBD internalisation | 20 | 38 | 32, 3 | 57 | 1.5 | 181.5 | 166, 8 | 259 | 1.4 | 13.4 | 9, 25 | 16.7 | 1.2 |
Uterine artery embolisation (UAE) | 18 | 602.5 | 1071 | 1463.8 | 2.4 | 1339 | 3070, 8 | 4019 | 3 | 12.3 | 17, 6 | 24.8 | 2 |
Unilateral antegrade ureteric stent | 16 | 14 | 17 | 23 | 1.6 | 44 | 94 | 118.5 | 2.7 | 9.5 | 11, 5 | 15.2 | 1.6 |
Percutaneous transhepatic cholangiogram (PTC) | 15 | 6 | 6 | 9 | 1.5 | 21 | 20, 5 | 28.5 | 1.4 | 0.4 | 0, 4 | 0.7 | 1.8 |
Interventional cerebral angiogram | 15 | 107 | 242 | 275 | 2.6 | 1502 | 987, 5 | 1744 | 1.2 | 26.3 | 18, 0 | 34.1 | 1.3 |
IQR, interquartile range; PICC, peripherally inserted central catheter.
The ratio of the 75th to 50th centile is used as a measure of the variation with a dose parameter (
Comparison with published data on kerma air product and diagnostic reference levels.
Procedure | CHBAH, 2022 | DRL range | Papanastassiou et al. |
Schegerer et al. |
Malan et al. |
Rizk et al. |
Koir et al. |
Etard et al. |
Ruiz-Cruces et al. |
Heilmaier et al. |
Erskine et al |
Zotovia et al. |
---|---|---|---|---|---|---|---|---|---|---|---|---|
Country | South Africa | - | Greece | Europe | South Africa | Lebanon | Kenya | France | Spain | Switzerland | Australia | Bulgaria |
Percutaneous transhepatic biliary drainage (PTBD) | 24 | 23–145 | 53.8 | 23 | 46 | 145 | 56 | 33.5 | 30 | 60.5 | - | 56 |
Bronchial artery embolisation (BAE) | 131 | 73–131.4 | - | - | 73 | - | - | 131.4 | - | - | - | - |
Pigtail insertion | 7.5 | N/A | - | - | - | - | - | - | - | - | - | - |
Nephrostomy (Unilateral) | 10 | 10–47 | - | - | 10 | 40 | 47 | - | - | 12.6 | 10.8 | - |
Nephrostomy (Bilateral) | 10 | N/A | - | - | 9 | - | - | - | - | - | - | - |
Selective abdominal vessels-interventional angiogram | 776 | N/A | - | - | 170 | - | - | - | - | - | - | - |
Diagnostic cerebral angiogram | 209.3 | 55-87.5 | 70.2 | - | 55 | 71 | - | 87.5 | - | - | 82.6 | - |
Peripherally inserted central catheter (PICC) | 2 | N/A | - | - | - | - | - | 1.2 | - | - | - | - |
PTBD internalisation | 57 | N/A | - | - | - | - | - | - | - | - | - | |
Uterine artery embolisation (UAE) | 1463.8 | 118.4–214 | - | - | - | - | - | 174.4 | 214 | 118.4 | 191 | - |
Unilateral antegrade ureteric stent | 23 | N/A | - | - | - | - | - | - | - | - | - | - |
Percutaneous transhepatic cholangiogram (PTC) | 9 | N/A | 34.4 | - | - | - | - | - | - | - | - | - |
Interventional cerebral angiogram | 275 | 63–233.4 | - | - | 63 | 197 | - | 233.5 | - | - | 152.9 | 41 |
CHBAH, Chris Hani Baragwanath Academic Hospital; DRL, diagnostic reference level; N/A, not applicable.
Comparison with published data on reference point air kerma and diagnostic reference levels.
Procedure | CHBAH, 2022 | DRL range | Papanastassiou et al. |
Schegerer et al. |
Malan et al. |
Rizk et al. |
Koir et al. |
Etard et al. |
Ruiz-Cruces et al. |
Heilmaier et al. |
Erskine et al |
Zotovia et al. |
---|---|---|---|---|---|---|---|---|---|---|---|---|
Country | South Africa | - | Greece | Europe | South Africa | Lebanon | Kenya | France | Spain | Switzerland | Australia | Bulgaria |
Percutaneous transhepatic biliary drainage (PTBD) | 13.8 | 195–1406 | 399.8 | 195 | 227 | 1406 | 320 | 253 | - | 580 | 320 | - |
Bronchial artery embolisation (BAE) | 343 | 259–827 | - | - | 259 | - | - | 827 | - | - | - | - |
Pigtail insertion | 37 | N/A | - | - | - | - | - | - | - | - | - | - |
Nephrostomy (Unilateral) | 26 | 63–412 | - | - | 63 | 412 | - | - | - | 80 | 245 | - |
Nephrostomy (Bilateral) | 62 | N/A | - | - | 56 | - | - | - | - | - | - | - |
Selective abdominal vessels-interventional angiogram | 2227.8 | N/A | - | - | 877 | - | - | - | - | - | - | - |
Diagnostic cerebral angiogram | 868.5 | 289–628 | 494.0 | - | 289 | 596 | - | 628 | - | - | - | - |
Peripherally inserted central catheter (PICC) | 5 | 1.0–4.0 | - | - | - | - | - | 4 | 1 | - | - | - |
PTBD internalisation | 259 | N/A | - | - | - | - | - | - | - | - | - | - |
Uterine artery embolisation (UAE) | 4019 | 729–1240 | - | - | - | - | - | 729 | 168.9 | 1240 | - | - |
Unilateral antegrade ureteric stent | 118.5 | N/A | - | - | - | - | - | - | - | - | - | - |
Percutaneous transhepatic cholangiogram (PTC) | 28.5 | N/A | 194.0 | - | - | - | - | - | - | - | - | - |
Interventional cerebral angiogram | 1744 | 505–2993.5 | - | - | 505 | 2583 | - | 2993.5 | - | - | - | - |
CHBAH, Chris Hani Baragwanath Academic Hospital; DRL, diagnostic reference level; N/A, not applicable.
Comparison with published data on fluoroscopy time and diagnostic reference levels.
Procedure | CHBAH, 2022 | DRL range | Papanastassiou et al. |
Schegerer et al. |
Malan et al. |
Rizk et al. |
Koir et al. |
Etard et al. |
Ruiz-Cruces et al. |
Heilmaier et al. |
Erskine et al |
Zotovia et al. |
---|---|---|---|---|---|---|---|---|---|---|---|---|
Country | South Africa | - | Greece | Europe | South Africa | Lebanon | Kenya | France | Spain | Switzerland | Australia | Bulgaria |
Percutaneous transhepatic biliary drainage (PTBD) | 6.2 | 10–22.9 | 22.9 | 10 | 20 | 20 | 23 | 15.7 | 17.3 | - | - | 12.2 |
Bronchial artery embolisation (BAE) | 33.5 | 37.4–38 | - | - | 38 | - | - | 37.4 | - | - | - | - |
Pigtail insertion | 2.4 | N/A | - | - | - | - | - | - | - | - | - | - |
Nephrostomy (Unilateral) | 3.4 | 3.5–18 | - | - | 4 | 11 | 18 | - | - | - | 3.5 | - |
Nephrostomy (Bilateral) | 6.3 | N/A | - | - | 4 | - | - | - | - | - | - | - |
Selective abdominal vessels-interventional angiogram | 28.3 | N/A | - | - | 29 | - | - | - | - | - | - | - |
Diagnostic cerebral angiogram | 28.4 | 8–10.3 | 9.2 | - | 14 | 8 | - | 10.3 | - | - | 6.25 | - |
Peripherally inserted central catheter (PICC) | 4 | N/A | - | - | - | - | - | 1 | - | - | - | - |
PTBD internalisation | 16.7 | N/A | - | - | - | - | - | - | - | - | - | - |
Uterine artery embolisation (UAE) | 24.8 | 28.7–31 | - | - | - | - | - | 28.7 | 31 | - | - | - |
Unilateral antegrade ureteric stent | 15.2 | N/A | - | - | - | - | - | - | - | - | - | - |
Percutaneous transhepatic cholangiogram (PTC) | 0.7 | N/A | 14.2 | - | - | - | - | - | - | - | - | - |
Interventional cerebral angiogram | 34.1 | 9.2–32 | - | - | 25 | 28 | - | 62.9 | - | - | 32 | 9.2 |
CHBAH, Chris Hani Baragwanath Academic Hospital; DRL, diagnostic reference level; N/A, not applicable.
The procedure type with the most DRL published data were PTBD with published DRLs from 9/10 studies reviewed. Dose parameter with the most published data was KAP with 34 DRLs across all procedures. Regarding published DRLs, the highest recorded across all parameters was for interventional cerebral angiogram (KAP-233.5 Gy/cm2, Ka,r–2993.5 mGy and FT-62.9 min). The lowest was for PICC insertion (KAP-1.2 Gy/cm2, Ka,r–1 mGy and FT-1).
The study identified the current scope of IR procedures carried out at a single institution while simultaneously determining procedures not performed or those performed with low frequency. Hepatobiliary (liver and pancreas) IR has room for growth through adding procedures such as TIPS, portal vein embolisation, transarterial chemo-embolisation (TACE), radio-embolisation with radioactive microspheres and radiofrequency ablation, a similar outcome to what another local study
Uterine artery embolisation recorded the highest DAP doses (selective abdominal vessel interventional angiogram was the second highest), in keeping with findings from other studies. Based on published literature, abdominal and pelvic angiographic interventions
This study showed a relationship between KAP and Ka,r. Generally, high KAP corresponds to high Ka,r. The relationship between KAP and FT is not as strong. This is consistent with findings from local
Unilateral percutaneous nephrostomy (PCN) had the widest variation in KAP (75th:50th percentile ratio of 5) and wide, although not the widest, variation in Ka,r (1.8) and FT (2.1). This is consistent with findings from other published studies.
Regarding neurological procedures, there was no consistency in the degree of dose variation. Diagnostic cerebral angiogram had the narrowest variation in KAP and Ka,r, whereas interventional cerebral angiogram had the second widest variation in dose. Both these procedures were performed by two highly experienced specialist radiologists. This shows that dose variation is a factor of more than just skill level but rather several factors, including but not limited to patient factors and lesion or pathology factors. Many studies have assessed the effect of the degree of lesion complexity on patient radiation.
This study did not use patient weight as a dose parameter. The link between body mass index (BMI) and patient radiation dose has long been established for digital radiography and fluoroscopically-guided injections.
Diagnostic cerebral angiogram (all parameters), interventional cerebral angiogram (FT) and UAE (KAP and Ka,r) exceeded published local and international DRL ranges. As such, these procedure types need to be reviewed and optimised in accordance with the recommendations of the ICRP so that they are aligned with published DRLs.
As a retrospective study, a limited number of parameters that impact dose were evaluated. Parameters such as patient weight (body mass index [BMI]) and lesion complexity could not be included, as this information was not available. Going forward, such information should be recorded to improve the quality of future studies. Although the number of cases for calculating DRLs with a reasonable 95% confidence interval as suggested by Miller et al.
There is a need for standardisation of the terminology used for IR procedures. As with Malan et al.,
This study is in line with international radiation protection initiatives. At an institution level, it contributes to patient radiation optimisation and nationally to establishing national interventional radiology DRLs. The LDRLs for diagnostic cerebral angiogram, interventional cerebral angiogram and UAE exceeded international ranges in this study. These procedures must be reviewed for radiation optimisation. A suggestion is to include patient weight and complexity of lesions as input parameters.
The authors declare that they have no financial or personal relationships that may have inappropriately influenced them in writing this article.
O.S was the principal investigator and N.M. was the supervisor of the study.
This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.
Data supporting the findings of this study are available from the corresponding author, N.M., on request. The authors confirm that the data supporting the findings of this study are available within the article (
The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of any affiliated agency of the authors.