Contribution of CT scan to patient's radiation exposure in parathyroid SPECT/CT scintigraphy.

INTRODUCTION: Dual phase technetium-99mTc-methoxy isobutyl isonitrile (MIBI) single-photon emission computed tomography with computed tomography (SPECT/CT) may be the most accurate conventional imaging approach for localization of enlarged parathyroid gland (EPG). The imaging is based on the radiopharmaceutical (RP) retention in EPG compared to washout from normal thyroid and normal parathyroid glands. This study aimed to estimate and optimize the contribution of computed tomography (CT) scan and scan range to effective dose (ED) in dual-phase MIBI SPECT/CT parathyroid scintigraphy. METHODS: The study included seventy-four patients; thirty-seven with reduced and thirty-seven with extended CT scan range. The ED caused by the CT scan was calculated using Dose Length Product (DLP) data and estimated using the Imaging Performance Assessment of CT scanners (ImPACT) calculator. RESULTS: For all patients, the contribution of CT to the ED in a combined SPECT/CT examination was 2.62 ± 0.29 mSv (48%). The contribution of CT to the total ED was 1.8 ± 0.18 mSv (33%) when using reduced and 3.44 ± 0.23 mSv (64%) when using extended scan range. The DLP and ED were statistically significantly different between the reduced and extended CT scan range (p < 0.001) in the first and second phases. The individual organ dose was reduced from 8% to 94%. CONCLUSION: The hybrid SPECT/CT improves the interpretation of nuclear medicine images and also increases the radiation dose to the patient. An adequately defined CT scan range on SPECT/CT imaging, can significantly reduce a patient's ED. IMPLICATIONS FOR PRACTICE: The research findings showed that knowledge of anatomy, pathology and technology can provide optimising diagnostic procedures and reduce patient ED after SPECT/CT scans.

Risk of deterministic effects during endovascular aortic stent graft implantation.

Since the 1990s, stent graft implantation for aortic pathology has become an alternative to extensive surgical procedures in some patients. Indeed, many patients with such pathology are now treated endovascularly. Only limited data concerning the risk of a deterministic effect during aortic stent graft implantation are available Accordingly, 179 consecutive patients treated in our institute between October 2002 and July 2008 with endovascular aortic stent grafts were included in this study. Dosimetric data (kerma area product (KAP) and cumulative dose at the interventional reference point (CD(irp))) from radiograph reports were analysed for 172 patients. On a group of 19 patients, GAFCHROMIC XR type dosimetric films were also used to verify the automatic measurements. Readings from the integrated KAP meter were found to be too high and were therefore corrected - KAP to dose area product (DAP) and CD(irp) to entrance skin dose (ESD). Median DAP was 153 Gy cm² (35-700 Gy cm²) and median ESD was 0.44 Gy (0.12-2.73 Gy). Recorded dosimetric quantities were found to be good predictors of the skin dose and highlighted 4 patients (2.3%) who received skin doses that might cause possible deterministic effects. Endovascular stent graft implantation is less invasive than a surgical procedure and is widely used; mid-term results are encouraging. In a small number of patients, deterministic effects can occur even in departments with well-trained staff. Operators should inform the patients of possible skin injury after receiving high doses of ionising radiation and proper support must be available should that occur.

Patient peak skin doses from cardiac interventional procedures.

Interventional cardiac procedures not only lead to significant effective doses for the patient but also can potentially cause deterministic effects on the patient's skin. Information about the peak (maximal) skin doses (PSD) received by patients during percutaneous transluminal coronary angioplasty procedures were collected from three cardiac catheter rooms. Cumulative dose at the interventional reference point (CD(IRP)) was collected for 161 patients and for 16 patients PSD was determined using Gafchromic dosimetry films. The comparison showed that CD(IRP) readings give a useful but conservative estimation of patient peak skin dose as it can lead to a significant overestimation. The median and third quartile values of CD(IRP) were 0.64 and 0.92 Gy, respectively. The 2 Gy threshold for deterministic effects was exceeded in nine patients. A good correlation was found between CD(IRP) and kerma area product measurements while the correlation with fluorography time was very weak.

Is digital better in dental radiography?

In Slovenia, dental radiography was the first field in which projection x-ray imaging using digital detectors was done. At present around 30% of intraoral dental x-ray units use digital detectors. Annual test results were analysed to compare digital systems with film-based ones. The survey results show significantly lower doses of exposure in digital systems. In our opinion digital systems are especially suitable for practitioners who perform a low number of x-ray examinations (e.g. private dentists), because of problems that may arise due to developing a limited number of films. The problem with digital systems could be the ease of deleting an image and performing another examination, the extent of which was not investigated.

Development of training syllabi for radiation protection and quality assurance of dual-energy X-ray absorptiometry (DXA) systems.

The use of dual-energy X-ray absorptiometry (DXA) scanners for measuring bone mineral density (BMD) is on the increase. A single DXA scan is a relatively low-dose diagnostic X-ray examination; however, radiation protection (RP) issues should not be trivialised. One objective of the EU 6th Framework SENTINEL co-ordination action was to develop training syllabi in RP and quality assurance (QA) for BMD, and this study presents the results. An EU-wide survey was carried out which confirmed that there was a need for an accredited DXA RP training course in many EU states. There is also limited published guidance on acceptance testing/QA for DXA. Two training syllabi were developed: one on RP and one on QA of DXA systems. A training course was delivered in Ireland in 2006 by the Medical Physics & Bioengineering Department of St James's Hospital, Dublin. Following the training course, a PC-based training CD was developed and will be made available. A harmonised approach to training will promote consistent approaches to radiation safety across the EU.

European survey of dental X-ray equipment.

The implementation of an X-ray Quality Assurance (QA) program is a legal requirement in Europe as stipulated in the EU Council Directive 97/43/EURATOM (MED). A review of the literature has identified that European countries are performing some level of QA testing of their dental X-ray equipment, although the type and level to which testing is performed can differ. The European SENTINEL co-ordination action proposed to collate a survey of equipment data for both conventional and digital dental X-ray installations among the SENTINEL partners. The European QA results confirm that systems can be operated below tolerance, and in some cases significantly so, while still in clinical use. This can occur despite servicing of equipment. The results have emphasised the fact that there is a requirement for the medical physics/engineering professions to become more closely involved in the management of dental radiology equipment. This also includes their involvement in the development and delivery of appropriate training courses for dentists and suppliers of dental radiology equipment.

Staff dosimetry in interventional cardiology: survey on methods and level of exposure.

In interventional cardiac procedures, staff operates near the patient in a non-uniformly scattered radiation field. Consequently, workers may receive, over a period, relatively high radiation doses. The measurement of individual doses to personnel becomes critical due to the use of protective devices and, as a consequence of the large number of methods proposed to assess the effective dose, great variability in monitoring programmes is expected among European countries. SENTINEL consortium has conducted a survey on staff dosimetry methods and on the level of staff exposure in 12 European cardiac centres demonstrating the urgent need to harmonise dosimetry methods. From the dosimetry survey, constraint annual effective dose of 1.4 mSv and Hp(0.07) over the protective apron of 14 mSv are proposed for the optimisation the exposure the most-exposed operator.

Development of a quality assurance programme for external personal dosimetry in Slovenia.

In order to improve the quality of individual monitoring and to achieve harmonisation with the new international standards, important components of a quality assurance system are considered and are presented as a result of cooperation of different institutions. The components are quality assurance and routine quality control of monitoring systems, and the creation of a central state dose register of workers.