Advanced equine diagnostics – developments in computed tomography

Advancement in veterinary imaging technologies to assess pathology in the horses has been greatly improved since the development of computed tomography in the 1970s. These technical innovations have enabled faster acquisition times, lower patient doses of radiation and easier care of the patient during scanning. A wide range of computed tomography scanners are now available to the veterinary market, from companies providing second hand refurbished scanners, to those tailoring computed tomography scanners to the veterinary market. In turn, this makes the price of purchase, or rental, much more feasible to the industry. The financial implications of purchasing a scanner need to be reviewed to ensure viability, as well as identifying maintenance costs, space, specialist staffing and case load. However, even with access to advanced imaging devices such as computed tomography, imaging the equine patient comes with its own complexities and limitations. Owing to their size and anatomy, passing the relevant structures through the gantry can be difficult in itself, often requiring the administration of general anaesthetic to acquire suitable images, which comes with its own set of risks and additional costs. Therefore, there is an ongoing need to further develop the skills and abilities needed for standing computed tomography.

Comparison of methods for calculating effective doses for children during CT examinations of the chest organs

Computed tomography is associated with high patient doses. CT is actively used for pediatric, however, currently there is no reliable data on the pediatric patient doses in the Russian Federation. The current study presents the data on the anthropometric characteristics of 5, 10 and 15-year-old pediatric patients, as well as the results of a comparative assessment of the effective doses of these patients during CT-examinations of chest, considering their anthropometric data. The effective doses were calculated using three methods: based on the actual guidelines (MU 2.6.1.3584-19) using the age specific conversion coefficients; using the conversion coefficients considered patient body mass and effective diameter; using a specialized software NCICT 3.0. The difference between effective doses according to actual guidelines and considering patient body mass and effective diameter was about 7.1 % (max-65 %). High deviations were observed in patients with abnormally large or abnormally low body mass. Effective doses calculated using NCICT 3.0 were higher compared to doses calculated according to actual guidelines on average by 18 % (max — 53 %). Such differences are explained by the fact that in MU 2.6.1.3584-19 conversion coefficients are presented for the most common CT-scan parameters of protocols, and in NCICT 3.0 the calculation considers individual scan parameters for each patient. The difference between effective doses according to NCICT 3.0 and considering patient body mass and effective diameter was about 32 % (max-70 %). This difference can be explained by the differences in the anthropometric data of some patients, and by the use of different types of phantoms: a stylized phantom (Golikov et al) and a voxel phantom in NCICT 3.0.

Patient doses in endovascular and hybrid revascularization of aortoiliac segment

Objectives: Constantly increasing number of procedures performed – endovascular or hybrid in patients with aortoiliac occlusive disease during the last decades finds its explanation in the lower morbidity and mortality rates, compared to bypass surgery. The purpose of the current survey was to estimate patients’ radiation exposure in aortoiliac segment after endovascular or hybrid revascularization and to study the main factors which have direct contribution. Methods: A retrospective study of 285 procedures conducted with the help of a mobile C-arm system in 223 patients was performed. Procedures were grouped according to criteria such as: type of intervention, vascular access, level of complexity and operating team. Different analyses were performed within the groups and dose values. Results: The median values of kerma–air product (KAP), the number of series and the peak skin dose (PSD) significantly increase with the increasing number of vascular accesses: for one access (16.68 Gy.cm2, 6 and 336 mGy), for two (56.93 Gy.cm2, 11 and 545 mGy), and for three (102.28 Gy.cm2, 15 and 781 mGy). Significant dependence was observed in the case of single access site between the type of access and the dose values: hybrid and retrograde common femoral artery/superficial femoral artery (CFA/SFA) endovascular accesses, 10.06 Gy.cm2/301 mGy and 13.23 Gy.cm2/318 mGy respectively, in contrast with the contralateral CFA and left brachial access, 33 Gy.cm2/421 mGy and 38.33 Gy.cm2/448 mGy respectively. Conclusion: The results demonstrate that the most important factors increasing the dose values are number and type of vascular accesses, followed by the combination and number of implanted stents with the complexity of the procedure. The PSD values for a single procedure were between 2 and 12 times lower than those IAEA proposed as trigger levels for radiation-induced erythema. This study shows that trigger levels were not reached even for patients with repeated procedures in the same segment in 1-year period. Advances in knowledge: The study gives important understanding and clarity on the growing awareness for dose-modifying factors during endovascular and hybrid revascularization of aortoiliac segment.

Labelling via [Al18F]2+ Using Precomplexed Al-NODA Moieties

Over the past 20 years, 68Ga-labelled radiopharmaceuticals have become an important part in clinical routine. However, the worldwide supply with 68Ge/68Ga generators is limited as well as the number of patient doses per batch of 68Ga radiopharmaceutical. In the recent years, a new technique appeared, making use of the ease of aqueous labelling via chelators as with 68Ga but using 18F instead. This technique takes advantage of the strong coordinative bond between aluminium and fluoride, realized in the aqueous cation [Al18F]2+. Most applications to date make use of one-pot syntheses with free Al(III) ions in the system. In contrast, we investigated the labelling approach split into two steps: generating the Al-bearing precursor in pure form and using this Al compound as a precursor in the labelling step with aqueous [18F]fluoride. Hence, no free Al3+ ions are present in the labelling step. We investigated the impact of parameters: temperature, pH, addition of organic solvent, and reaction time using the model chelator NH2-MPAA-NODA. With optimized parameters we could stably achieve a 80% radiochemical yield exerting a 30-min reaction time at 100 °C. This technique has the potential to become an important approach in radiopharmaceutical syntheses.

Ac-EAZY! Towards GMP-Compliant Module Syntheses of 225Ac-Labeled Peptides for Clinical Application

The application of 225Ac (half-life T1/2 = 9.92 d) dramatically reduces the activity used for peptide receptor radionuclide therapy by a factor of 1000 in comparison to 90Y, 177Lu or 188Re while maintaining the therapeutic outcome. Additionally, the range of alpha particles of 225Ac and its daughter nuclides in tissue is much lower (47–85 μm for alpha energies Eα = 5.8–8.4 MeV), which results in a very precise dose deposition within the tumor. DOTA-conjugated commercially available peptides used for endoradiotherapy, which can readily be labeled with 177Lu or 90Y, can also accommodate 225Ac. The benefits are lower doses in normal tissue for the patient, dose reduction of the employees and environment and less shielding material. The low availability of 225Ac activity is preventing its application in clinical practice. Overcoming this barrier would open a broad field of 225Ac therapy. Independent which production pathway of 225Ac proves the most feasible, the use of automated synthesis and feasible and reproducible patient doses are needed. The Modular-Lab EAZY is one example of a GMP-compliant system, and the cassettes used for synthesis are small. Therefore, also the waste after the synthesis can be minimized. In this work, two different automated setups with different purification systems are presented. In its final configuration, three masterbatches were performed on the ML EAZY for DOTA-TATE and PSMA-I&T, respectively, fulfilling all quality criteria with final radiochemical yields of 80–90% for the 225Ac-labeled peptides.

Sistem Pemantauan Dosis (Dose Monitoring System) Dalam Upaya Meningkatkan Kualitas Pelayanan Radiologi Diagnostik dan Intervensional

X-ray-based medical imaging has become one of the most popular imaging modalities today. Computed tomography (CT) and interventional procedures can result in higher radiation exposure for patients compared to other radiographic examinations. There has been an increase in the effective dose of > 100 mSv from some procedures. Recent studies have shown that multiphase CT imaging and repeated imaging provide larger radiation doses in some patients. In considering the effective dose (E) for each patient, it is essential to note that the risk per Sv tends to be greater on average in pediatric patients than in adults. In addition, E can be used to describe the possible risk to the patient. Dose management is essential in monitoring and controlling patient doses. Consistent and systematic monitoring of radiation dose is needed to improve the quality of diagnostic and interventional radiology services. Dose monitoring activities include performance control, optimization of protocols used, corrective actions against non-standard practices, and raising awareness for radiation workers to minimize risks. The use of a dose monitoring system (Dose Monitoring System) responds to concerns about the radiation risk that comes from diagnostic imaging modalities, particularly Computed Tomography (CT) and fluoroscopy in interventional procedures. The dose monitoring system (Dose Monitoring System) has developed into a requirement in monitoring and controlling patient doses and is one of the applications of radiation safety culture that can improve diagnostic and interventional radiology services. Keywords: Computed tomography (CT), effective dose, interventional procedure

Proposals for the Russian quality assurance program in computed tomography

To ensure the quality assurance of CT-examinations, it is necessary to obtain the high-quality diagnostic information and maintain the optimal exposure levels of patients and medical staff. This paper is focused on the requirements and main aspects of quality assurance of CT-examinations, which include quality control of the equipment, methods of CT-image quality control, optimization of radiation protection, as well as management of the unintended and accidental medical exposure. The paper contains recommendations on quality control of diagnostic equipment, methods for monitoring the quality control of CT-images, values of diagnostic reference levels for the detection of abnormally high patient doses and optimization of the radiation protection of patients, as well as the recommendations for management of radiation and non-radiation accidents. All main sections of the paper represent an unified quality assurance system in computed tomography.

Évaluation de la dose aux patients lors de l’examen du thorax de face à Abidjan, Côte d’Ivoire

Our study aims to evaluate medical practices in order to reduce patient doses for frontal examination of the thorax in postero-anterior view. Thus, in five (5) radiological rooms of five (5) most frequented hospitals in Abidjan, thirty (30) patients per medical center, meaning a total of one hundred and fifty (150) patients, providing chest examination reports were followed. Using a DAP- meter consisting of an ionization chamber attached to the outlet of the tube and an electrometer, the dose in air (Dair) was measured. Then by calculating the entry dose (De) for each patient was determined. Thus, from the statistical method of the 75th percentile we determine the level of diagnostic references (DRL) in each room as well as in all the rooms of our study. The inlet dose averages (Dem) in each room and in all rooms were calculated. The couples (NRD, Dem) per room expressed in mGy (0.252, 0.226), (0.249, 0.213), (0.164, 0.159), (0.128, 0.117) and (0.234, 0.211) respectively at the CHU of Cocody, CHU of Yopougon, HMA, ICA and PISAM. By comparing the NRD value of De to that of Dem in each radiological room, we found Dem values lower than the NRD. This indicates that the doses are optimized in the rooms of our study, likewise, for all the rooms in Abidjan (0.220, 0.177). However, the average values of the voltage 104.04 kV and the load 4.55 mAs tell us that efforts can be made in the rooms of our study, increasing the voltage and reducing the load, to avoid unneeded doses of X-rays.

High filtration in interventional practices reduces patient radiation doses but not always scatter radiation doses

Objectives: In fluoroscopy-guided interventional practices, new dose reduction systems have proved to be efficient in the reduction of patient doses. However, it is not clear whether this reduction in patient dose is proportionally transferred to operators’ doses. This work investigates the secondary radiation fields produced by two kinds of interventional cardiology units from the same manufacturer with and without dose reduction systems. Methods: Data collected from a large sample of clinical procedures over a 2-year period (more than 5000 procedures and 340,000 radiation events) and the DICOM radiation dose structured reports were analysed. Results: The average cumulative Hp(10) per procedure measured at the C-arm was similar for the standard and the dose reduction systems (452 vs 476 μSv respectively). The events analysis showed that the ratio Hp(10)/KAP at the C-arm was (mean ± SD) 5 ± 2, 10 ± 4, 14 ± 4 and 14 ± 6 μSv·Gy−1·cm−2 for the beams with no added filtration, 0.1, 0.4 and 0.9 mm Cu respectively and suggested that the main cause for the increment of the ratio Hp(10)/KAP vs the “standard system” is the use of higher beam filtration in the “dose reduction” system. Conclusion: Dose reduction systems are beneficial to reduce KAP in patients and their use should be encouraged, but they may not be equally effective to reduce occupational doses. Interventionalists should not overlook their own personal protection when using new technologies with dose reduction systems. Advances in knowledge: Dose reduction technology in interventional systems may increase scatter dose for operators. Personal protection should not be overlooked with dose reduction systems.