Radiation doses for barium enema and barium meal examinations in Ireland: potential diagnostic reference levels

Wide variations in patient dose for the same examinations have been demonstrated by several studies throughout Europe. By investigating patient dose, variations can be acknowledged, causal agents sought and the necessary adjustments made. Diagnostic reference levels (DRLs) provide a framework with which dose levels from individual hospitals are compared, and when exceeded, corrective actions can be taken where appropriate. This study aimed to establish DRLs for barium enema and barium meal examinations in Ireland. Measurements were recorded using a dose-area product meter in 12 hospitals representing 33% of relevant hospitals. Results demonstrated wide mean hospital dose variation, by up to a factor of 7.8 and 4.2 for barium enema and barium meal examinations, respectively. Minimum and maximum individual patient dose values varied by a factor of 45 for barium enemas and 90 for barium meal examinations. Reasons for dose variations were complex, but major factors for both examinations were fluoroscopy time, secondary radiation grid type and level of filtration. Some examination-specific factors were also noted. DRLs, established using the quantity dose-area product, were calculated to be 47 Gy cm(2) for barium enemas and 17 Gy cm(2) for barium meal examinations. Although the DRL value for barium meals was the same as the reference value established in the UK for that examination in 1996, the barium enema DRL in this study was 45% higher than the relevant UK value.     

How to set up and apply reference levels in fluoroscopy at a national level

A nationwide survey was launched to investigate the use of fluoroscopy and establish national reference levels (RL) for dose-intensive procedures. The 2-year investigation covered five radiology and nine cardiology departments in public hospitals and private clinics, and focused on 12 examination types: 6 diagnostic and 6 interventional. A total of 1,000 examinations was registered. Information including the fluoroscopy time (T), the number of frames (N) and the dose-area product (DAP) was provided. The data set was used to establish the distributions of T, N and the DAP and the associated RL values. The examinations were pooled to improve the statistics. A wide variation in dose and image quality in fixed geometry was observed. As an example, the skin dose rate for abdominal examinations varied in the range of 10 to 45 mGy/min for comparable image quality. A wide variability was found for several types of examinations, mainly complex ones. DAP RLs of 210, 125, 80, 240, 440 and 110 Gy cm² were established for lower limb and iliac angiography, cerebral angiography, coronary angiography, biliary drainage and stenting, cerebral embolization and PTCA, respectively. The RL values established are compared to the data published in the literature.     

Evaluation of patient-absorbed doses during coronary angiography and intervention by femoral and radial artery access

The aim of this study was to compare the radiation dose to patients during coronary angiography (CA) and coronary intervention (percutaneous transluminal coronary angioplasty, PTCA) by the femoral or radial artery access routes. A plane-parallel ionisation chamber, mounted on an under-couch X-ray tube (Siemens Coroskop TOP with an optional dose reduction system), recorded the dose-area product (DAP) to the patient from 40 coronary angiographies and 42 coronary interventions by the femoral route. The corresponding numbers for radial access were 36 and 24, respectively. Using a human-shaped phantom, conversion factors between maximum entrance surface dose and DAP were derived for CA and CA plus PTCA, respectively. The dose to the staff was measured with TL dosimeters for 22 examinations. Fluoroscopy time and DAP were significantly (p=0.003) larger using the radial access route for coronary angiography (7.5 min, 51 Gy cm²) than the corresponding values obtained from femoral access route (4.6 min, 38 Gy cm²). For CA plus PTCA the fluoroscopy time and DAP were larger for radial access (18.4 min, 75 Gy cm²) than for femoral access (12.5 min, 47 Gy cm²; p=0.013). In our experience, radial access did significantly prolong the fluoroscopy time and increase the patient doses.     

Dose and image quality in the comparison of analogue and digital techniques in paediatric urology examinations

In paediatric radiology it has been recognised that children have a higher risk of developing cancer from the irradiation than adults (two to three times); therefore, increased attention has been directed towards the dose to the patient. In this study the effect on patient dose and image quality in replacing the exposure in micturating cystourethrography (MCUG) examinations with the stored fluoroscopy image has been investigated. In the intravenous urography (IVU) examination we compared analogue and digital image quality, but the dose measurements were performed on a phantom. Standard clinical X-ray equipment was used. Sixty-eight patients in each of two centres were studied for the MCUG. Doses were measured with a dose-area product (DAP) meter and the image quality was scored. A non-parametric statistical analysis was performed. For the IVU, a phantom was used in the dose measurements but clinical images were scored in the comparison between analogue and digital images. For the MCUG, replacing the exposure with stored fluoroscopy images lowered the DAP value from 0.77 to 0.50 Gy cm². The image quality did not show any difference between the techniques; however, if reflux was to be graded, exposure was needed. For the IVU, the doses could be lowered by a factor of 3 using digital techniques. The image quality showed no statistical difference between the two techniques. There is a potential for a substantial dose reduction in both MUCG and IVU examinations using digital techniques.     

Reference dose levels for patients undergoing common diagnostic X-ray examinations in Irish hospitals

Wide variations in patient dose for the same type of X-ray examination have been evident from various international dose surveys. Reference dose levels provide a framework to reduce this variability and aid in the optimization of radiation protection. The aim of this study was to establish, for the first time, a baseline for national reference dose levels in Ireland for four of the most common X-ray examinations: chest, abdomen, pelvis and lumbar spine. Measurements of entrance surface dose using thermoluminescent dosemeters (TLDs) for these four X-ray examinations were performed on 10 patients in each of 16 randomly selected hospitals. This represented 42% of Irish hospitals applicable to this study. Results have shown wide variation of mean hospital doses, from a factor of 3 for an anteroposterior lumbar spine to a factor of 23 for the chest X-ray. The difference between maximum and minimum individual patient dose values varied up to a factor of 75. Reasons for these dose variations were complex but, in general, low tube potential, high mAs and low filtration were associated with high-dose hospitals. This study also demonstrated lower reference dose levels of up to 40% when compared with those established by the UK and the Commission of the European Communities for four out of six projections. Only the chest X-ray exhibited a similar reference level to those established elsewhere. This emphasizes the importance of each country establishing its own reference dose levels that are appropriate to their own radiographic techniques and practices in order to optimize patient protection.     

A multi institutional comparison of imaging dose and technique protocols for neonatal chest radiography

IntroductionThe focus on paediatric radiation dose reduction supports reevaluation of paediatric imaging protocols. This is particularly important in the neonates where chest radiographs are frequently requested to assess respiratory illness and line placement. This study aims to assess the impact of neonatal chest radiographic protocols on patient dose in four hospitals in different countries.MethodsExposure parameters, collimation, focus to skin distance (FSD) and radiation dose from 200 neonatal chest radiographs were registered prospectively. Inclusion criteria consisted of both premature and full-term neonates weighing between 1000 and 5000 g. Only data from the examinations meeting diagnostic criteria and approved for the clinical use were included. Radiation dose was assessed using dose area product (DAP).ResultsThe lowest DAP value (4.58 mGy cm²) was recorded in the Norwegian hospital, employing a high kVp, low mAs protocol using a DR system. The Canadian hospital recorded the highest DAP (9.48), using lower kVp and higher mAs with a CR system, including the addition of a lateral projection. The difference in the mean DAP, weight, field of view (FOV) and kVp between the hospitals is statistically significant (p < 0.001).ConclusionUse of non-standardised imaging protocols in neonatal chest radiography results in differences in patient dose across hospitals included in the study. Using higher kVp, lower mAs and reducing the number of lateral projections to clinically relevant indications result in a lower DAP measured in the infant sample studied. Further studies to examine image quality based on exposure factors and added filtration are recommended.Implications for practiceReevaluation of paediatric imaging protocols presents an opportunity to reduce patient dose in a population with increased sensitivity to ionising radiation.     

A Nordic survey of patient doses in diagnostic radiology

The aim of this study was to test the applicability of the guidance levels for patient doses cooperatively set by the radiation protection authorities in the five Nordic countries. The kerma-area product (KAP) for five conventional radiological examination types was obtained from several hospitals in each of the Nordic countries. The number of radiographic images and fluoroscopy time were also registered, and the mean values for each examination type and hospital were established based on a representative number of patients (40–100 kg). The results indicate that the situation is very similar in the five Nordic countries, even though some differences were identified. Most of the hospitals demonstrated lower doses than the proposed guidance levels for chest, probably explained by use of faster film/screen combinations during the past decade. An increased use of fluoroscopy for positioning was observed for radiographic examinations of lumbar spine and urography. Large variations in patient doses were found for barium enema depending on the use of fluorospot or 100-mm camera vs full-format film, the range in fluoroscopy times, dose rate, and field size. The guidance levels for lumbar spine (10 Gy × cm²), pelvis (4 Gy × cm²), urography (20 Gy × cm²), and barium enema (50 Gy × cm²) seem to reflect the present quality of X-ray equipment and examination techniques in the Nordic countries. The guidance levels for chest (1 Gy × cm²) should be lowered to 0.6 Gy × cm². Received: 28 February 2000, Revised: 18 May 2000, Accepted: 22 May 2000     

Monitoring neurointerventional radiation doses using dose-tracking software: implications for the establishment of local diagnostic reference levels

Objectives

There is potential for high radiation exposure during neurointerventional procedures. Increasing regulatory requirements mandate dose monitoring of patients and staff, and justification of high levels of radiation exposure. This paper demonstrates the potential to use radiation dose-tracking software to establish local diagnostic reference levels.

Methods

Consecutive neurointerventional procedures, performed in a single institution within a one-year period, were retrospectively studied. Dose area product (DAP) data were collected using dose-tracking software and clinical data obtained from a prospectively generated patient treatment database.

Results

Two hundred and sixty-four procedures met the selection criteria. Median DAP was 100 Gy.cm² for aneurysm coiling procedures, 259 Gy.cm² for arteriovenous malformation (AVM) embolisation procedures, 87 Gy.cm² for stroke thrombolysis/thrombectomy, and 74 Gy.cm² for four-vessel angiography. One hundred and nine aneurysm coiling procedures were further studied. Six significant variables were assessed using stepwise regression analysis to determine effect on DAP. Aneurysm location (anterior vs posterior circulation) had the single biggest effect (p = 0.004).

Conclusions

This paper confirms variable radiation exposures during neurointerventional procedures. The 75th percentile (used to define diagnostic reference levels) of DAP measurements represents a reasonable guidance metric for monitoring purposes. Results indicate that aneurysm location has the greatest impact on dose during coiling procedures and that anterior and posterior circulation coiling procedures should have separate diagnostic reference levels.

Key Points

? Dose-tracking software is useful for monitoring patient radiation dose during neurointerventional procedures? This paper provides a template for methodology applicable to any interventional suite? Local diagnostic reference levels were defined by using the 75th percentile of DAP as per International Commission on Radiological Protection recommendations? Aneurysm location is the biggest determinant of radiation dose during coiling procedures.? Anterior and posterior circulation coiling procedures should have separate diagnostic reference levels.

     

Optimisation of patient dose for the horizontal beam technique in lateral lumbar spine radiographic examinations

In the emergency department, patients undergoing lateral lumbar spine radiography examinations are positioned either lying on their side on an X-ray table with the X-ray beam vertical or lying supine on a trolley with the X-ray beam horizontal. The measured dose–area product (DAP) values were found to differ significantly, typically 1.3 Gy cm² for those patients examined on the X-ray table and 2.7 Gy cm² for those on a trolley. This work investigates the reason for higher DAP values with the horizontal beam technique. The UK’s current recommended national diagnostic reference level (NDRL) for the lateral lumbar spine is 2.5 Gy cm². The measurements of body diameter on volunteers showed that rotating the patients from their side to their back resulted in an increase in tissue thickness of between 2 cm and 9 cm for the lumbar region. X-ray absorption increases exponentially with increasing tissue thickness. An increase of 5 cm in body diameter for a lateral lumbar spine at 93 kV will increase the DAP by more than two-fold. Mathematical modelling and measurements with polymethyl methacrylate provided data to predict the tube potential increase necessary to reduce the DAP. For the horizontal beam technique, the tube potential was increased from 93 kV to 102 kV and the average DAP reduced to 2.3 Gy cm². Radiographic technique should be understood when auditing the dose. Tube potential must be increased to optimise the horizontal beam technique. The 2.5-Gy cm² NDRL relates predominantly to the more common vertical beam technique. Separate local diagnostic reference levels for horizontal and vertical beam techniques are recommended.It is a requirement under the Ionising Radiation (Medical Exposure) Regulations 2000 [IR(ME)R] [1] that hospitals in the UK monitor the dose levels for groups of standard-sized patients undergoing common radiographic examinations. A dose–area product (DAP) meter attached to the X-ray unit provides a quick and easy method to routinely monitor the dose. Guidance on the measurement of the patient dose [2,3] states that data should be collected for a minimum of 10 adult patients with a weight range of between 50 kg and 90 kg. The mean value of the dose from the sample should then be compared against a locally defined diagnostic reference level (DRL) [4]. Where local DRLs still have to be established, it is a common practice to adopt national diagnostic reference levels (NDRLs). The NDRLs are generally taken from the data published by the Health Protection Agency—Radiation Protection Division. Its national database contains dose data submitted from many hospitals across the UK, and summary reports are published every 5 years [5]. It is a requirement of IR(ME)R that, when the mean values of measured doses exceed the DRL, the cause is investigated and corrective action is taken appropriately.     

用胶片法对心脏介入程序中患者峰值皮肤剂量测量研究

目的 采用胶片法对进行心血管介入手术中患者所受峰值皮肤剂量（PSD）进行测量研究,包括冠状动脉血管造影术（CA）和经皮穿刺腔内冠状动脉成形术（PTCA）。方法 选用Gafchromic XR-RV3胶片在两家医院进行患者峰值皮肤剂量的测量。手术时将胶片放在患者身下的诊视床上。记录手术中监视器上显示的kV、mA、透视时间、剂量面积乘积（DAP）、参考点累积剂量等相关信息。采用Epson V750平板扫描仪对胶片进行分析扫描及分析,选用FilmQA软件分别测量图像的红、绿、蓝三色通道的像素值,使用红通道数据计算患者的 PSD。对PSD与设备显示参数进行相关分析,对相关的变量进行多元线性回归分析。结果 共测量CA手术26例,CA+PTCA手术19例。CA手术中,透视时间最高为17.62 min,累积剂量和DAP最大分别为1 498.50 mGy和109.68 Gy ·cm²,PSD最大为361.20 mGy。CA+PTCA手术中,曝光时间最长为64.48 min,累积剂量和DAP最大分别为6 976.20 mGy和5 336.00 Gy ·cm²,17例患者的PSD在1 Gy以内,1例患者PSD在1~2 Gy之间,1例患者PSD超出了发生皮肤损伤2 Gy的阈值,达到了2 195.70 mGy。CA程序中,患者PSD与DAP相关（R²=0.815,P<0.05）,CA+PTCA程序中,患者PSD与累积剂量相关（R²=0.916,P<0.05）。结论 心脏介入放射学程序中部分患者的PSD会超出ICRP建议的发生皮肤确定性效应的2 Gy阈值。DSA设备上显示的剂量相关的参数,只能粗略估算患者PSD的大小。使用XR-RV3胶片精确测量介入手术中患者的峰值皮肤剂量是一种非常快捷、有效的方法。     

Local diagnostic reference levels for skeletal surveys in suspected physical child abuse

IntroductionThe purpose was to determine if an age based, local diagnostic reference level for paediatric skeletal surveys could be established using retrospective data.MethodsAll children below two years of age referred for a primary skeletal survey as a result of suspected physical abuse during 2017 or 2018 (n = 45) were retrospectively included from a large Danish university hospital. The skeletal survey protocol included a total of 33 images. Dose Area Product (DAP) and acquisition parameters for all images were recorded from the Picture Archival and Communication System (PACS) and effective dose was estimated. The 75th percentile for DAP was considered as the diagnostic reference level (DRL).ResultsThe 75th percentile for DAP was 314 mGy1cm², 520 mGy1cm² and 779 mGy1cm² for children <1 month, 1–11 months and 12 < 24 months of age respectively. However, only the age group 1–11 months had a sufficient number of children (n = 27) to establish a local DRL. Thus, for the other groups the DAP result must be interpreted with caution. Effective dose was 0.19, 0.26 and 0.18 mSv for children <1, 1–11 months and 12 < 24 months of age respectively.ConclusionFor children between 1 and 11 months of age, a local diagnostic reference level of 520 mGy1cm² was determined. This may be used as an initial benchmark for primary skeletal surveys as a result of suspected physical abuse for comparison and future discussion.Implications for practiceWhile the data presented reflects the results of a single department, the suggested diagnostic reference level may be used as a benchmark for other departments when auditing skeletal survey radiation dose.     

Dose-area product measurements in a range of common orthopaedic procedures and their possible use in establishing local diagnostic reference levels

There is a national drive towards establishing reference doses for radiological procedures with the aim of optimizing patient doses. Furthermore, the establishment of diagnostic reference level doses became a legal requirement for all hospitals on 13 May 2000. However, to date there are little published data on patient radiation doses from fluoroscopic procedures during orthopaedic surgery. Data relating to patient dose for 492 patients undergoing fluoroscopic examinations during a range of surgical orthopaedic procedures in 1997-1998 have been analysed. Median dose-area product (DAP) readings and interquartile ranges for a variety of common fluoroscopic orthopaedic procedures are presented. In general, the median DAP for procedures on limbs and extremities was quite low (0.04-1.62 Gy cm2), with screening times in the range 0.2-2.0 min, whilst for procedures involving the hips and spine the median DAP was considerably higher (0.4-10.2 Gy cm2), although overall screening times were similar, in the range 0.2-1.4 min. Approximate effective doses have been estimated. For procedures involving the limbs and extremities, the effective dose was generally less than 10 microSv, and for procedures involving the hips and spine it was found that the effective dose could rise to about 1 mSv. Collective doses for each procedure have been calculated to inform prioritization of procedures for local dose reduction strategies.     

A review of factors affecting patient doses for barium enemas and meals

A study of patient doses for barium enema and meal examinations has been carried out for hospitals in the West of Scotland to assess the impact of dose reduction facilities on new X-ray equipment. Dose-area product (DAP) information has been collected on examinations for groups of patients at 20 hospitals and results reviewed together with data on equipment performance measurements. Median DAPs for barium enemas and meals were 15.7 Gy cm(2) and 4.8 Gy cm(2), respectively, and effective doses estimated from the results are 3.5+/-0.7 mSv and 1.5+/-0.5 mSv, respectively. These doses are lower than those reported in earlier studies and in previous surveys in the West of Scotland. The reduction in dose is linked primarily to the low dose facilities available on newer X-ray equipment, such as low dose pulsed fluoroscopy, digital imaging facilities and use of copper filtration. Use of the image intensifier for decubitus images on C-arm units employed for barium enemas also gives a significantly lower dose. Equipment with copper filtration had the lowest doses. The reduction in effective dose will be significantly less than the reduction in DAP for units in which a copper filter is included and the adoption of lower diagnostic reference levels is proposed for units with this facility. It is important that the operators are aware of the low dose imaging options on their equipment in order that techniques can be fully optimized.     

A national patient dose survey and setting of reference levels for interventional radiology in Bulgaria

Objectives

A national study on patient dose values in interventional radiology and cardiology was performed in order to assess current practice in Bulgaria, to estimate the typical patient doses and to propose reference levels for the most common procedures.

Methods

Fifteen units and more than 1,000 cases were included. Average values of the measured parameters for three procedures—coronary angiography (CA), combined procedure (CA?+?PCI) and lower limb arteriography (LLA)—were compared with data published in the literature.

Results

Substantial variations were observed in equipment and procedure protocols used. This resulted in variations in patient dose: air-kerma area product ranges were 4–339, 6–1,003 and 0.2–288 Gy cm² for CA, CA?+?PCI and LLA respectively. Reference levels for air kerma-area product were proposed: 40 Gy cm² for CA, 140 Gy cm² for CA?+?PCI and 45 Gy cm² for LLA. Auxiliary reference intervals were proposed for other dose-related parameters: fluoroscopy time, number of images and entrance surface air kerma rate in fluoroscopy and cine mode.

Conclusions

There is an apparent necessity for improvement in the classification of peripheral procedures and for standardisation of the protocols applied. It is important that patient doses are routinely recorded and compared with reference levels.

Key Points

? Patient doses in interventional radiology are high and vary greatly ? Better standardisation of procedures and techniques is needed to improve practice ? Dose reference levels for most common procedures are proposed     

Evaluation of exposure dose to patients undergoing catheter ablation procedures—a phantom study

The aim of this study was to evaluate entrance skin dose (ESD), organ dose and effective dose to patients undergoing catheter ablation for cardiac arrhythmias, based on the dosimetry in an anthropomorphic phantom. ESD values associated with mean fluoroscopy time and digital cine frames were in a range of 0.12–0.30 Gy in right anterior oblique (RAO) and 0.05–0.40 Gy in left anterior oblique (LAO) projection, the values which were less than a threshold dose of 2 Gy for the onset of skin injury. Organs that received high doses in ablation procedures were lung, followed by bone surface, esophagus, liver and red bone marrow. Doses for lung were 24.8–122.7 mGy, and effective doses were 7.9–34.8 mSv for mean fluoroscopy time of 23.4–92.3 min and digital cine frames of 263–511. Conversion coefficients of dose-area product (DAP) to ESD were 8.7 mGy/(Gy·cm²) in RAO and 7.4 mGy/(Gy·cm²) in LAO projection. The coefficients of DAP to the effective dose were 0.37 mSv/(Gy·cm²) in RAO, and 0.41 mSv/(Gy·cm²) in LAO projection. These coefficients enabled us to estimate patient exposure in real time by using monitored values of DAP.     

Diagnostic reference levels in plain radiography for paediatric imaging: A Portuguese study

ObjectiveTo determine diagnostic reference levels (DRLs) for the most frequent paediatric plain radiography examinations in Portugal (chest, pelvis and abdomen) and to characterise a standard paediatric patient for each age group used in literature.MethodsAnthropometric data was collected from 9935 patients. Each age group (<1, 1–<5, 5–<10, 10–<16, ≥16) was categorised by the median values of weight, height and BMI, to define a standard patient. Exposure parameters, kerma-area product (KAP-mGy cm²) and entrance surface air kerma (ESAK-μGy) were collected. DRLs for KAP and ESAK were defined as the 75th percentile (P75) of dose values and presented by age and weight.ResultsIn each age group the P75 of KAP varied from 11 to 77 mGy cm² for chest; 23–816 mGy cm² for pelvis; 25–979 mGy cm² for abdomen. The P75 of ESAK varied from 49 to 67 μGy for chest; 98–1129 μGy for pelvis and 70–1060 μGy for abdomen.ConclusionThe P75 of dose values determined in this study were lower than those published in literature. When available, weight is the preferred parameter to categorise paediatric patients. The large ranges of dose values found in this study, demonstrates a clear need for the optimisation and harmonisation of practice.     

Method of patient dose evaluation in the angiographic and interventional radiology procedures

PURPOSE: The aim of this study was to evaluate the effective dose in interventional radiology and angiography procedures on the basis of the dose-area product (DAP), either measured or calculated using two different methods. MATERIALS AND METHODS: We studied 2072 examinations carried out on several X-ray systems both in angiography and in interventional radiology. Some of the systems were equipped with an on-board transmission chamber for DAP measurements; for these systems we took direct DAP measurements for each type of examination. For the systems without the dose measurement device, we used a portable transmission chamber, acquiring the data from a set of sampling frames. We then derived the dose values from the systems' dosimetry data and the information about each examination. To this end, the dosimetry of each x-ray system was done by measuring tube output in the different acquisition modes, backscatter factor and field-homogeneity factor. Survey data sheets were filled in after every examination indicating the exposure data (mean Kv, mAs, focus-skin distance and field size). These values combined with the dosimetric data were used to evaluate the DAP for each exam. Where possible, we compared the measured and calculated DAP values by assessing the percentage deviation between each pair of values. A similar comparison was made for the single examinations using a simplified calculation algorithm reported in the literature. For all the examinations for which we had adequate survey data sheets, we estimated the DAP and the entrance dose values and, with the aid of WinODS software, the effective dose. RESULTS: The direct measurements of DAP showed that, in interventional radiology and angiographic procedures, the variability in examination conditions leads to a wide range of possible patient doses even within the same examination type.The comparison between the measured and calculated DAP using our algorithm showed substantial agreement (mean difference 30%, maximum 80%). By contrast, using the algorithm proposed in the literature, we obtained deviations higher than 100%.An estimate of the effective dose for all the recorded examinations (2072) permitted evaluation of both magnitude and variability of patient doses in special radiology procedures such as angiography and interventional radiology. However, it should be noted that evaluations based on calculated DAP values may be as uncertain as those estimated for DAP, and that clearly the evaluations made for the examinations for which direct measurements are available are more accurate.In particularly 'invasive' examinations in terms of entrance dose, where the threshold limits for deterministic effects might possibly be exceeded, the equivalent doses to critical organs were also assessed. This analysis showed that in a small percentage of patients (5%) 2 Gy to the skin was exceeded in the areas exposed with possible transient erythema, while in fewer than 2% of patients, the 3 Gy limit for temporary epilation was exceeded. CONCLUSIONS: Many interventional radiology, especially haemodynamic, examinations have shown to give significant exposure to patients. The direct dose measurement method has shown to be the only method able to provide reliable information on such exposure.However, the authors believe that since the patient dose cannot be established in advance, even in terms of magnitude and since direct dose measurement cannot be performed on all patients, it is nonetheless interesting to be able to assess, at least semiqualitatively, the amount of the above doses.     

Local diagnostic reference levels for typical radiographic procedures

Purpose

To establish local diagnostic reference levels (DRL) for typical radiographic examinations in a fully digital imaging institution.

Methods

The initial survey included 6 standard radiographic projections performed in 19 computed radiography (CR) and digital radiography (DR) rooms. Because of the expected difference in the performance, the local reference levels were analysed separately for those 2 modalities. Data of 226 average size adult patients were included in the analysis. Entrance surface dose (ESD) was calculated from the recorded radiographic techniques and tube radiation output measurements. After observing wide variations in the results of the patient survey, the examinations were repeated by using anthropomorphic phantoms. Initial efforts to understand the reasons for dose variations were focused on CR chest, abdomen, pelvis, and lumbar spine examinations.

Results

The average size patient doses for similar examinations were lower in the DR rooms than in the CR rooms by factors that ranged from 1.2 to 3, with the exception of the chest examination. Standardization of the CR exposure index value allowed us to decrease ESD by 21%-30%. Detector sensitivity had an insignificant effect (2%) on ESD; proper collimation lowered the dose by 17%. However, the major effect, up to 46% difference, was found because of antiscatter grids cutoff.

Conclusion

Modality specific local diagnostic reference levels for standard examinations have been established in a large digital imaging department with hybrid modalities. Typically the local reference values were lower than those recommended in Safety Code 35, except for CR chests. Factors that affect the dose variations have been investigated and determined.     

Contemporary Interventional Radiology Dosimetry: Analysis of 4,784 Discrete Procedures at a Single Institution

PurposeTo report dosimetry of commonly performed interventional radiology procedures and compare dose analogues to known reference levels.Materials and MethodsDemographic and dosimetry data were collected for gastrostomy, nephrostomy, peripherally inserted central catheter placement, visceral arteriography, hepatic chemoembolization, tunneled catheter placement, inferior vena cava filter placement, vascular embolization, transjugular liver biopsy, adrenal vein sampling, transjugular intrahepatic portosystemic shunt (TIPS) creation, and biliary drainage between June 12, 2014, and April 26, 2018, using integrated dosimetry software. In all, 4,784 procedures were analyzed. The study included 2,691 (56.2%) male subjects and 2,093 (43.8%) female subjects with mean age 55 ± 21 years (range: 0-104 years) and with mean weight of 76.9 ± 29.4 kg (range: 0.9-268.1 kg). Fluoroscopy time, dose area product (DAP), and reference dose were evaluated.ResultsTIPS had the highest mean fluoroscopy time (49.1 ± 16.0 min) followed by vascular embolization (25.2 ± 11.4 min), hepatic chemoembolization (18.8 ± 12.5 min), and visceral arteriography (17.7 ± 3.2 min). TIPS had the highest mean DAP (429.2 ± 244.8 grays per square centimeter [Gy·· cm²]) followed by hepatic chemoembolization (354.6 ± 78.6 Gy·· cm²), visceral arteriography (309.5 ± 39.0 Gy·· cm²), and vascular embolization (298.5 ± 29 Gy·· cm²). TIPS was associated with the highest mean reference dose (2.002 ± 1.420 Gy) followed by hepatic chemoembolization (1.746 ± 0.435 Gy), vascular embolization (1.615 ± 0.381 Gy), and visceral arteriography (1.558 ± 1.720 Gy). Of the six procedures available for comparison with the reference levels, the mean fluoroscopy time, DAP, and reference dose for each procedure were below the proposed reference levels.ConclusionAdvances in image acquisition technology and radiation safety protocols have significantly reduced the radiation exposure for a variety of interventional radiology procedures.     

Measurement of the average radiation dose to the local skin and thyroid gland during intracranial aneurysm coil embolization

IntroductionIntracranial aneurysm coil embolisation is a fluoroscopically guided procedure associated with high radiation dose. The increase in the number of coil embolisation procedures raises concern for the amount of radiation and the associated radiation risks to the patients. This research study was conducted to determine the average radiation dose to patients’ thyroid glands and local skin during intracranial aneurysm coil embolisation and to establish preliminary local diagnostic reference levels for this procedure. In this paper, local skin dose refers to the absorbed radiation dose on the areas of the skin exposed to radiation during intracranial aneurysm coil embolisation, namely neck, face and scalp.MethodsThis study employed air-kerma area product meters to determine the local skin dose and diagnostic reference levels during intracranial aneurysm coil embolisation. In addition, thyroid radiation doses were measured using thermo-luminescent dosimeters on a phantom during simulation of embolisation procedures.ResultsThe local skin doses as determined by air-kerma area product ranged between 33 and 125 Gy.cm2. The mean thyroid dose was 9.87 mGy. The established local diagnostic reference level was 52.1 Gy cm², 17.8 min’ fluoroscopy time and 503 image frames.ConclusionThe average air-kerma area product values and the proposed diagnostic reference levels were lower than most published values for intracranial aneurysm coil embolisation.Implications for practiceThe established local diagnostic reference levels are recommended for use as radiation dose optimisation tool at the research site. The findings of this study cannot be generalised or applied to other hospitals. The complexity of the embolisation procedures was not classified for this study. Further research on diagnostic reference levels for intracranial aneurysm coil embolisation, taking into account the complexity of the procedures, is recommended.