X-ray Doses in Relation to Body Mass, Indication, and Substrate During Pediatric Electrophysiological Procedures on the Heart

The main goal of this study is to determine typical values of dose area product (DAP) and difference in the effective dose (ED) for pediatric electrophysiological procedures on the heart in relation to patient body mass. This paper also shows DAP and ED in relation to the indication, the arrhythmia substrate determined during the procedure, and in relation to the reason for using radiation. Organ doses are described as well. The subjects were children who have had an electrophysiological study done with a 3D mapping system and X-rays in two healthcare institutions. Children with congenital heart defects were excluded. There were 347 children included. Significant difference was noted between mass groups, while heavier children had higher values of DAP and ED. Median DAP in different mass groups was between 4.00 (IQR 1.00-14.00) to 26.33 (IQR 8.77-140.84) cGycm2. ED median was between 23.18 (IQR 5.21-67.70) to 60.96 (IQR 20.64-394.04) µSv. The highest DAP and ED in relation to indication were noted for premature ventricular contractions and ventricular tachycardia-27.65 (IQR 12.91-75.0) cGycm2 and 100.73 (IQR 53.31-258.10) µSv, respectively. In arrhythmia substrate groups, results were similar, and the highest doses were in ventricular substrates with DAP 29.62 (IQR 13.81-76.0) cGycm2 and ED 103.15 (IQR 60.78-266.99) µSv. Pediatric electrophysiology can be done with very low doses of X-rays when using 3D mapping systems compared to X-rays-based electrophysiology, or when compared to pediatric interventional cardiology or adult electrophysiology.

Management of pregnant or potentially pregnant patients undergoing diagnostic and interventional radiology procedures: Investigation of clinical routine practice

It is well known that foetuses are highly sensitive to ionising radiation and special attention to justification and optimisation of radiological procedures involving a pregnant patient is required. A task to review, validate and compare different approaches to managing the pregnant patient and to estimating the associated foetal doses arising from a diagnostic or interventional radiology (DIR) procedure was designed in the framework of EURADOS working group 12. As a first step, a survey of radiation protection practice including dosimetry considerations among EURADOS members was performed using online questionnaire. Then, to evaluate the possible differences in the estimated foetal doses, a comparison of assessed dose values was made for three cases of pregnant patients that underwent different CT procedures. More than 120 professionals from 108 institutions and 17 countries that are involved in managing pregnant patients undergoing DIR procedures answered the questionnaire. Most of the respondents use national or hospital guidelines on the management of pregnant patients undergoing DIR procedures. However, the guidelines differ considerably among respondents. Comparison of foetal dose assessments performed by dosimetry experts showed the variety of methods used as well as large variability of estimated foetal doses in all three cases. Although European and International commission on radiation protection guidelines already exist, they are more than 20 years old and, in some aspects, they are obsolete. This paper shows that there is a need to revise and update these guidelines.

Assessment of computed tomography simulators used in radiotherapy treatment planning in Serbia, Croatia, and Bosnia and Herzegovina

The purpose of this work was to evaluate computed tomography simulators used in radio-therapy treatment planning in Serbia, Croatia, and Bosnia and Herzegovina. A survey of quality assurance programmes of 24 computed tomography simulators in 16 facilities was conducted. A dedicated CT-to-ED phantom was scanned at 120 kV and 140 kV, to obtain CT-to-ED conversion curves as well as CTDIvol. Thoracal phantoms were scanned in the standard and extended field of view to evaluate the dosimetric effect on treatment planning and delivery. The mean age of the measured scanners was 5.5 years. The mean water HU value was ?6.5 (all scanners, all voltages) and air HU value was ?997. Extended field of view computed tomography data differ from the standard field of view and differences between conversion curves have significant dosimetric impact. The CTDI data showed a large range of values between centers. Better quality assurance of computed tomography simulators in all countries is recommended. The CT-to-ED curve could be used as default at one voltage and per manufacturer. Extended field of view imaging can be used, but treatment planning should be avoided in the regions out of the standard field of view.

National survey to set diagnostic reference levels in nuclear medicine single photon emission imaging in Croatia

PURPOSE

In order to introduce the concept of diagnostic reference levels (DRLs) in the national nuclear medicine practice a survey was proposed and completed through all nuclear medicine departments in Croatia. An additional aim was to increase the awareness of importance and full implementation of a comprehensive quality program that includes devices used in the nuclear medicine chain.

METHODS

Data were collected for more than 30 nuclear medicine single photon emission procedures. National DRLs (NDRLs) as administered activity and also as administered activity per unit mass were calculated in accordance to International Commission on Radiological Protection (ICRP) recommendations. Additionally, effective doses were estimated using conversion factors published by the ICRP.

RESULTS

NDRLs for nuclear medicine single photon emission procedures were proposed. For procedures performed in only one department typical values were presented as reference. Effective doses related to applied radiopharmaceuticals were calculated to estimate radiation risk related to respective nuclear medicine procedure in more detail.

CONCLUSION

This work presents results of the first national survey on DRLs of nuclear medicine single photon emission procedures and proposes reliable NDRLs that represent an actual status of nuclear medicine practice in Croatia. Results have motivated departments to introduce and set their own typical values to be used, as one of the tools, for further optimization process. One of the drawbacks of the DRL concept in nuclear medicine is the lack of the image quality parameters involved. For this reason, a quantity that considers both radiation protection and image quality should be introduced.

IAEA survey of dental cone beam computed tomography practice and related patient exposure in nine Central and Eastern European countries

OBJECTIVES

Cone beam CT (CBCT) in dentistry and maxillofacial surgery is a widely used imaging method for the assessment of various maxillofacial and dental pathological conditions. The objective of this study was to summarize the results of a multinational retrospective-prospective study that focused on patient exposure in this modality.

METHODS

The study included 27 CBCT units and 325 adult and paediatric patients, in total. Data on patients, clinical indications, technical parameters of exposure, patient dose indicator, or, alternatively, dose to phantom were collected. The dose indicator used was air kerma-area product, P_KA.

RESULTS

In most scanners operators are offered with a variety of options regarding technical parameters, especially the field of view size. The median and the third quartile value of P_KA for adult patients in 14 different facilities were 820 mGy cm² and 1000 mGy cm² (interquartile range = 1058 mGy cm²), and 653 mGy cm² and 740 mGy cm² (interquartile range = 1179 mGy cm²) for children, as reported by four different institutions. Phantom dose data were reported from 15 institutions, and median P_KA ranged from 125 mGy cm² to 1951 mGy cm². Median P_KA values varied by more than a 10-fold between institutions, mainly due to differences in imaging protocol used, in particular field of view and tube current-exposure time product.

CONCLUSIONS

The results emphasize the need for a cautious approach to using dental CBCT. Imaging only when the clinical indications are clear, accompanied with the appropriate radiographic techniques and the optimum imaging protocol, will help reduce radiation dose to patients.

Dose area product in estimation of effective dose of the patients undergoing dental cone beam computed tomography examinations

OBJECTIVE

To investigate the relationship of the effective dose and dose area product (DAP) in dental cone beam computed tomography (CBCT) examinations and to propose conversion factors for estimation of effective doses of the patients using DAP. Dependence of organ doses on DAP was also investigated.

MATERIALS AND METHODS

Different exposure geometries in Cranex3Dx CBCT device were simulated using Monte Carlo simulation and computational anthropomorphic phantom. Then organ doses and effective dose for every exposure geometry was compared to DAP and analysed.

RESULTS

The effective dose in all simulated CBCT protocols and positions with 180° tube rotation ranged from 5 μSv for 50 × 50 mm² field of view (FOV) localised on one tooth using lowest resolution to 265 μSv for the largest FOV and highest resolution. In case of 360° tube rotation the effective dose ranges from 6 to 332 μSv for the same FOV sizes and positions as well as resolutions as in 180° tube rotation.

CONCLUSIONS

Though the DAP introduces a large uncertainty in the risk measure in dental CBCT, it represents the dose and FOV size which are the most important scanning parameters affecting the dose. To decrease uncertainty in the risk measure, the effective dose has to be estimated for usual clinical positions of the FOV.

Estimated collective effective dose to the population from nuclear medicine diagnostic procedures in Croatia: A comparison of 2010 and 2015

OBJECTIVE

This study presents national surveys of patient exposure from nuclear medicine (NM) diagnostic procedures in 2010 and 2015 in the Republic of Croatia.

METHODS

The survey was performed according to the European Commission Dose DataMed (DDM) project methodology. 28 most frequent NM diagnostic procedures were identified. Data about frequencies of procedures and average administered activities of radioisotopes used in those procedures were collected. Average administered activities were converted to effective doses according to the dose conversion coefficients. Then the collective effective dose to the population and an effective dose per capita were calculated based on the number of the most frequent NM diagnostic procedures and the average effective dose per procedure.

RESULTS

In 2010, 41200 NM diagnostic procedures led to 146.7 manSv collective effective dose to the population and in 2015, 42000 NM diagnostic procedures led to 146.8 manSv collective effective dose to the population. The frequencies of NM diagnostic procedures were 9.7 and 9.8 annually per 1000 population with 34.1 μSv and 34.2 μSv effective dose per capita for 2010 and 2015, respectively. The main contributors to the annual collective dose from NM in Croatia are examinations of the bone, heart, thyroid and PET/CT tumour diagnostic. Average administered activities have not changed considerably from 2010 to 2015. Nevertheless, within the frequency of some of the procedures, significant changes were found in five-year period.

CONCLUSIONS

Frequencies, average administered activities and collective effective dose to the population from NM diagnostic procedures in Croatia are comparable to the values reported by other European surveys. Changes were found between 2010 and 2015 and we intend to perform this study periodically to identify possible trends, but also to raise awareness about the potential dose optimization.

A study to establish international diagnostic reference levels for paediatric computed tomography

The article reports results from the largest international dose survey in paediatric computed tomography (CT) in 32 countries and proposes international diagnostic reference levels (DRLs) in terms of computed tomography dose index (CTDI vol) and dose length product (DLP). It also assesses whether mean or median values of individual facilities should be used. A total of 6115 individual patient data were recorded among four age groups: <1 y, >1-5 y, >5-10 y and >10-15 y. CTDIw, CTDI vol and DLP from the CT console were recorded in dedicated forms together with patient data and technical parameters. Statistical analysis was performed, and international DRLs were established at rounded 75th percentile values of distribution of median values from all CT facilities. The study presents evidence in favour of using median rather than mean of patient dose indices as the representative of typical local dose in a facility, and for establishing DRLs as third quartile of median values. International DRLs were established for paediatric CT examinations for routine head, chest and abdomen in the four age groups. DRLs for CTDI vol are similar to the reference values from other published reports, with some differences for chest and abdomen CT. Higher variations were observed between DLP values, based on a survey of whole multi-phase exams. It may be noted that other studies in literature were based on single phase only. DRLs reported in this article can be used in countries without sufficient medical physics support to identify non-optimised practice. Recommendations to improve the accuracy and importance of future surveys are provided.

IAEA survey of paediatric computed tomography practice in 40 countries in Asia, Europe, Latin America and Africa: procedures and protocols

OBJECTIVE

To survey procedures and protocols in paediatric computed tomography (CT) in 40 less resourced countries.

METHODS

Under a project of the International Atomic Energy Agency, 146 CT facilities in 40 countries of Africa, Asia, Europe and Latin America responded to an electronic survey of CT technology, exposure parameters, CT protocols and doses.

RESULTS

Modern MDCT systems are available in 77 % of the facilities surveyed with dedicated paediatric CT protocols available in 94 %. However, protocols for some age groups were unavailable in around 50 % of the facilities surveyed. Indication-based protocols were used in 57 % of facilities. Estimates of radiation dose using CTDI or DLP from standard CT protocols demonstrated wide variation up to a factor of 100. CTDI(vol) values for the head and chest were between two and five times those for an adult at some sites. Sedation and use of shielding were frequently reported; immobilisation was not. Records of exposure factors were kept at 49 % of sites.

CONCLUSION

There is significant potential for improvement in CT practice and protocol use for children in less resourced countries. Dose estimates for young children varied widely. This survey provides critical baseline data for ongoing quality improvement efforts by the IAEA.