Diagnostic reference levels and complexity indices in interventional radiology: a national programme.

OBJECTIVES: To propose national diagnostic reference levels (DRLs) for interventional radiology and to evaluate the impact of the procedural complexity on patient doses. METHODS: Eight interventional radiology units from Spanish hospitals were involved in this project. The participants agreed to undergo common quality control procedures for X-ray systems. Kerma area product (KAP) was collected from a sample of 1,649 procedures. A consensus document established the criteria to evaluate the complexity of seven types of procedures. DRLs were set as the 3rd quartile of KAP values. RESULTS: The KAP (3rd quartile) in Gy cm2 for the procedures included in the survey were: lower extremity arteriography (n = 784) 78; renal arteriography (n = 37) 107; transjugular hepatic biopsies (THB) (n = 30) 45; biliary drainage (BD) (n = 314) 30; uterine fibroid embolization (UFE) (n = 56) 214; colon endoprostheses (CE) (n = 31) 169; hepatic chemoembolization (HC) (n = 269) 303; femoropopliteal revascularization (FR) (n = 62) 119; and iliac stent (n = 66) 170. The complexity involved the increases in the following KAP factors from simple to complex procedures: THB x4; BD x13; UFE x3; CE x3; HC x5; FR x5 and IS x4. CONCLUSIONS: The evaluation of the procedure complexity in patient doses will allow the proper use of DRLs for the optimization of interventional radiology. KEY POINTS: • National DRLs for interventional procedures have been proposed given level of complexity • For clinical audits, the level of complexity should be taken into account. • An evaluation of the complexity levels of the procedure should be made.

Stochastic risk estimate for barium radiological examinations in Malaga (Spain).

The aim of this research work has been the estimation of the stochastic risk for five barium examinations. The sample was the population attending the Radiological Service of the 'Nuestra Señora de la Victoria' University Hospital, who had been treated with some barium examinations, set in five different groups: oesophagus tract, oesophagus-gastric-duodenal tract, intestinal tract, enteroclysis and double enema. To estimate the stochastic risk, it is necessary to know the organ dose. This can be calculated from the dose-area product which allows us to determine the effective dose using software. The dose-area product is the most suitable quantity to measure in these types of examination. We have evaluated the contribution that each procedure provides to the genetically significant dose, somatically significant dose, collective effective dose, annual effective dose 'per capita' and detriment, which are useful for assessing the population risk of cancer or hereditary effects after x-ray exposure. The contribution to the genetically significant dose is 6.7 microGy, to the somatically significant dose 8.82 mSv-yr, 16.07 person-Sv for the collective effective dose, 0.03 mSv for the 'per capita' annual effective dose and the annual aggregated detriment is 0.33.

Patient dose from barium procedures.

The objective of this work was to estimate patient doses (dose-area product, organ dose, effective dose and entrance surface dose) for barium procedures. A total of 175 procedures, in 175 patients, for five different examination categories was analysed. Dose-area product was determined using a transmission ionization chamber. Organ dose and effective dose were assessed using a knowledge of the examination and the software. For all patients, the contribution of fluoroscopy to the total dose was greater than that from radiography. Dose-area product from double contrast barium enema, enteroclysis and intestinal tract procedures was higher than that obtained for the other procedures. The average effective dose was 1.04 mSv and 13.99 mSv for oesophageal tract and enteroclysis examinations, respectively. Entrance surface dose in the oesophageal tract was 16 mGy, 10 times lower than for the other four procedures. Patient dose reduction in barium procedures may be achieved by improved training of resident radiologists, senior radiologists and other specialists in radiation protection.

Estimation of effective dose in some digital angiographic and interventional procedures.

In general, effective dose values for similar interventional vascular radiology (IVR) procedures are different. This is due to problems with the classification of radiological procedures, which make comparisons difficult. Patient size, examination technique and clinical condition as well as the skill of the medical radiologists also affect effective dose. Currently, there is a broad agreement on the classification of similar procedures so that effective dose estimates can be made from measurements of the dose area product (DAP). Thus, reference dose values may be established and comparative studies between different services and hospitals can be made. The objective of this study is to provide dose data for some digital angiographic and interventional procedures. Values of measured DAP for 143 patients for five types of procedures are presented. Procedures investigated were abdominal angiography, arteriography of lower limbs, biliary drainage, embolization of spermatic vein and nephrostomy. All the procedures were performed using digital equipment. Values of DAP and effective dose were 30 Gy cm2 and 6.2 mSv for arteriography of lower limbs and 150 Gy cm2 and 38.2 mSv for biliary drainage. In each one of these procedures, effective dose values per minute of fluoroscopy and per radiography film have been calculated. It is possible to use this information for the rapid estimation of effective dose.

Organ doses, detriment and genetic risk from interventional vascular procedures in Málaga (Spain).

Nowadays, the radiological risk from simple X-ray procedures is well known. The purpose of this work has been to estimate the population risk from digital angiographic and interventional procedures and to compare it with the one from simple procedures in the same population. The population risk has been estimated according to the following quantities: genetically significant dose, somatic significant dose, collective effective dose, annual per caput effective dose and detriment. These have been estimated from dose area product and organ dose. Organ dose values were estimated with the Eff-Dose software. A population of 605410 people were included in the study. In 1996, 1312 patients were to digital interventional vascular procedures in Malaga, and 159 of them were selected in this research project to obtain the dose area product and organ dose. The results obtained for the quantities evaluated are: genetically significant dose, 4.1 microGy; somatic significant dose, 0.9 mSv; collective effective dose, 11.65 person-Sv: annual per caput effective dose, 0.02 mSv and detriment, 0.65 radiogenic cancers per year. These procedures supply a high radiation dose, so they should have a greater contribution to population dose and risk than simple examinations. However, our results indicate just the opposite.

Organ doses, detriment and genetic risk from simple X-ray examinations in Málaga (Spain).

This work has been carried out with the aim of evaluating, as a reference, some radiological magnitudes which affect patients receiving radiation from X-ray sources. The sample was the population tended by the Radiological Service of the 'Na, Sra, de la Victoria' University Hospital and who have been treated with some of the five simple explorations: chest, abdomen, lumbar spine, hip and pelvis. The primary beam of radiation delivered by the different generators have been measured by means of non-invasive methods, which allows us to estimate the effective dose. Likewise, we have evaluated the dose in gonads and the contribution that each technique provides to the genetically significant dose (GSD = 158.59 microGy) and to the somatic significant dose (SSD = 3.19 mSv-year). Moreover, we have calculated the annual dose per capita (0.15 mSv) and the contribution that performs to the detriment (G) of these tests of conventional radiology. The results obtained are analogous to the reference values proposed in the area of E.C.M. Furthermore, we also include the values of child expectancy and the number of exploration performed in the Health Sanitary Area Malaga-West classified according to type, age and sex of the patient.

Patient dose in radiologically guided interventional vascular procedures: conventional versus digital systems.

PURPOSE: To calculate the difference in the patient radiation dose in radiologically guided interventional vascular procedures between conventional and digital systems and to estimate the effective dose and the energy imparted with the digital system. MATERIALS AND METHODS: A total of 318 procedures (in 318 patients) in 15 different examination groups were analyzed. The dose-area product was determined by using a transmission chamber fitted to an x-ray-tube light-beam diaphragm; the effective dose was determined by using software. RESULTS: Urinary and biliary tract procedures showed small differences in the average dose-area product between conventional and digital systems. The dose-area products in the vascular procedures were higher with the digital than with the conventional system. The average effective dose and energy imparted were 0.88 mSv and 129 mJ, respectively, in the subcutaneous placement of a reservoir for analgesic administration and as much as 25.7 mSv and 829 mJ, respectively, in spermatic vein embolization. CONCLUSION: The dose-area product was higher with the digital system than with the conventional system in 13 of the 15 groups. To reduce the patient dose in vascular interventional radiology procedures, the training of personnel and the frequent use of conventional fluoroscopy and low-dose imaging are required.