Conversion factors for effective dose and organ doses with the air kerma area product in patients undergoing percutaneous transhepatic biliary drainage and trans arterial chemoembolization

Effective and organ doses in patient undergoing interventional neuroradiology procedures: A multicentre study

PURPOSE

Radiation doses to adult patients submitted to cerebral angiography and intracranial aneurysms treatments were assessed by using DICOM Radiation Dose Structured Reports (RDSR) and Monte Carlo simulations. Conversion factors to estimate effective and organ doses from Kerma-Area Product (PKA) values were determined.

METHODS

77 cerebral procedures performed with five angiographic equipment installed in three Italian centres were analyzed. Local settings and acquisition protocols were considered. The geometrical, technical and dosimetric data of 16,244 irradiation events (13305 fluoroscopy, 2811 digital subtraction angiography, 128 cone-beam CT) were extracted from RDSRs by local dose monitoring systems and were input in MonteCarlo PCXMC software to calculate effective and organ doses. Finally, conversion factors to determine effective and organ doses from PKA were determined. Differences between centres were assessed through statistical analysis and accuracy of dose calculation method based on conversion factors was assessed through Bland-Altman analysis.

RESULTS

Large variations in PKA (14-561 Gycm2) and effective dose (1.2-73.5 mSv) were observed due to different degrees of complexity in the procedures and angiographic system technology. The most exposed organs were brain, salivary glands, oral mucosa, thyroid and skeleton. The study highlights the importance of recent technology in reducing patient exposure (about fourfold, even more in DSA). No statistically significant difference was observed in conversion factors between centres, except for some organs. A conversion factor of 0.09 ± 0.02 mSv/Gycm2 was obtained for effective dose.

CONCLUSIONS

Organ and effective doses were assessed for neuro-interventional procedures. Conversion factors for calculating effective and organ doses from PKA were provided.

Cumulative radiation exposure from radiological imaging in patients with Hodgkin and diffuse large b-cell lymphoma not submitted to radiotherapy

OBJECTIVE

To assess the cumulated exposure to radiation due to imaging in Hodgkin (HL) and diffuse large B-cell (DLBCL) lymphoma patients who were not submitted to radiotherapy.

METHODS

The study population included 51 and 83 adult patients with HL and DLBCL, with a follow-up duration >1 year. The cumulated exposure was expressed using patient-specific data as cumulated effective dose (CED).

RESULTS

Fifty-one HL patients (median age 47 years) were followed for a median of 3.5 years. The median total CED per subject was 104 mSv. CT and PET/CT examinations accounted for 75 and 25% of the total CED, respectively. 26 patients (49%) had a total CED ≥ 100 mSv and the maximum CED was 302 mSv. Eighty-three DLBCL patients (median age 66 years) were followed for a median of 3.7 years. The median total CED per subject over the study period was 134 mSv. CT and PET/CT for 86% and 13% of the total CED, respectively. 56 patients (67%) had a total CED ≥100 mSv. The maximum CED was 557 mSv.

CONCLUSION

Our study demonstrated the large number of imaging procedures performed for patients with lymphoma. Overall, 61% of the patients accrued a CED ≥ 100 mSv. Imaging policies were only in a partial agreement with current international guidelines.

ADVANCES IN KNOWLEDGE

The cumulated exposure radiation exposure may be of concern in HL patients and the contribution of CT procedures to the total CED is significant. The standardisation of clinical guidelines for managing patients with lymphoma is warranted.

A systematic review of conversion factors between kerma-area product and effective/organ dose for cardiac interventional fluoroscopy procedures performed in adult and paediatric patients

The aim of this systematic review is to undertake a critical appraisal of the evidence in the published literature concerning the conversion factors between kerma-area product (P KA) and effective/organ dose (DCED_PKA, DCHT_PKA) for cardiac interventional fluoroscopy procedures performed in adults and paediatric patients and to propose reference conversion factors to help standardize dose calculations. A search strategy utilizing MeSH headings in three databases identified 59 (adult) and 37 (paediatric) papers deemed eligible for the review. Exclusion criteria were adopted to select data only from publications which established DCED_PKA in patients using the ICRP 103 tissue weighting factors. A time restriction from January 2007 was introduced in the search to capture the evolving trends of utilization of fluoroscopy-guided intervention technologies only in recent years. The suggested DCED_PKA and DCHT_PKA were synthesized by calculating the weighted averages of the values reported by the authors with weights corresponding to the study sample size. Eighteen studies for both adult (9) and paediatric (9) patients matching the search terms fulfilled the inclusion criteria. The suggested value for DCED_PKA in adult patients amounts to 0.24 mSv Gy−1cm−2. The suggested values for DCHT_PKA ranged from a minimum of 0.15 mSv Gy−1cm−2 for the female breast to a maximum of 0.97 mSv Gy−1cm−2 for the lungs. The suggested values for DCED_PKA in paediatric patients ranged from 3.45 mSv Gy−1cm−2 for the new-born to 0.49 mSv Gy−1cm−2 in the 15 years age class. The suggested values for DCHT_PKA ranged from a minimum of 0.33 mSv Gy−1cm−2 for bone marrow in the 15 years age class to a maximum of 11.49 mSv Gy−1cm−2 for the heart in the new-born. To conclude, values of DCED_PKA/DCHT_PKA were provided for calculating effective/organ doses in cardiac interventional procedures. They can be useful for standardizing dose calculations, hence for comparison of the radiation detriment from different imaging procedures and in the framework of epidemiologic studies.

Local dose reference levels during transarterial chemoembolization procedure

The aim of this study was to develop local diagnostic reference levels (LDRL) during Transarterial chemoembolization (TACE). This cross-sectional study reports radiation dose indicators of 108 patients in a Mexican hospital, obtained over a period of 35 months. Kerma-area product (P_KA), air-kerma at the reference point (K_{a, r}), and descriptive statistical analysis were examined according to sociodemographic characteristics of the sample patients. The LDRL obtained were then compared to a similar international framework. The present study contributes to the establishment of a TACE LDRL and identifies significant correlations among radiology factors and dosimetric quantities obtained.

Monte Carlo study of patient and medical staff radiation exposures during interventional cardiology

The aim of this study is to assess the radiation exposure of the patient and the medical staff during interventional cardiology procedures. Realistic exposure scenarios were developed using the adult reference anthropomorphic phantoms adopted by the International Commission on Radiological Protection (ICRP110_Male and ICRP110_Female), and the radiation transport code Geant4 (version 10.3). The calculated equivalent and effective doses were normalised by the simulated Kerma-Area Product (KAP), resulting in two conversion coefficients H_T/KAP and E/KAP. To properly evaluate the risk of exposure, several dose-dependent parameters have been investigated, namely: radiological parameters (tube kilovoltage peak (kVp), type of projection, field size (FOV)), and operator positions. Four projections (AP,PA,LAO25° and RAO25°) were simulated for three X-ray energy spectra (80,100 and 120 kVp) with four different values of FOV (15×15 cm²,20×20 cm²,25×25 cm² and 30×30 cm²). The results showed that the conversion coefficients values increase with increasing tube voltage as well as the FOV size. Recommended projection during the interventional cardiology procedures, whenever possible, should be the PA projection rather than AP projection. The most critical projection for the patient and the main operator is the RAO25° projection and the LAO25° projection respectively. The comparison of our results with the literature data showed good agreement allowing their use in the dosimetric characterization of interventional cardiology procedures.

Conversion factors for effective dose and organ doses with the air Kerma area product in hysterosalpingography

Histerosalpingography (HSG) remains the dominant diagnostic tool for investigation of infertility in women. Conversion factors used to estimate effective (E) and organ doses (H_T) from air Kerma area product (KAP) are needed to estimate patient doses in HSG, performed with state-of-the-art fluoroscopic X-ray systems with digital detectors. In this study, estimates of E and H_T for six critical organs/tissues, were derived on an individual basis in 120 HSG procedures and in 1410 irradiation events, performed on two X-ray systems from information available through the radiation dose structured report using Monte Carlo methods. Mean values of E and H_ovaries were1.0 ± 0.9 mSv and 5.6 ± 5.4 mGy. E/KAP conversion factors of 0.13; 0.18; 0.28 and 0.35 mSv Gy^-1cm^-2 were established for irradiation events with a Cu filtration of 0.0; 0.1; 0.4 and 0.9 mm. A high agreement was obtained between E estimated through Monte Carlo methods and E/KAP conversion factors accounting separately for the different modes of fluoroscopy and the radiography component of HSG, with a systematic error of 0 mSv and lower/upper limits of agreement of -0.6 and 0.5 mSv. On the contrary, the use of a single coefficient of conversion did not provide accurate estimates of E, showing a bias of -0.4 mSv and lower and upper limits of agreement of -1.9 and 1.2 mSv. An algorithm for the estimation of effective and organ doses from KAP has been established in HSG procedures depending on the Cu filtration in the X-ray irradiation events.