Medical Interventional Procedures Research Articles

Pilot study to assess the feasibility of self-administered, low-dose methoxyflurane for cystoscopic procedures

Introduction: Methoxyflurane (MEOF) (Penthrox™) is an inhaled, self-administered, non-opioid analgesic approved by Health Canada for the short-term relief of moderate to severe acute pain associated with trauma or interventional medical procedures. In this pilot study, we evaluated the feasibility of using MEOF as an anesthetic agent in 11 patients undergoing outpatient cystoscopic procedures. Methods: The average duration of the procedure was 24 (range 20–35) minutes and this included 10 minutes of administration time of the drug and five minutes of wait time before the procedure. The average monitoring time from start to end of the procedure was 23 (range 20–35) minutes and this included 15 minutes of monitoring post-procedure. On a scale of 0–10, patients on average rated the pain 4/10 (standard deviation [SD] 2.6). Results: Global performance was on average 3/4 (SD 1.3) for the patients and 3/4 (SD 1.1) for the operator. Of the 11 patients, four reported adverse events; two experienced euphoria, one experienced dizziness, and one was unable to tolerate the medication. Two patients noted their adverse events to be of moderate intensity, while the other two were of mild intensity. None of the adverse events was deemed serious. Conclusions: Our findings in this pilot study provide proof of principle for the design of a randomized control trial to evaluate MEOF as an anesthetic in an outpatient cystoscopic procedural setting. As more urologic procedures are being performed in an outpatient setting, this may offer significant clinical benefit.

Autonomous medical needle steering in vivo.

The use of needles to access sites within organs is fundamental to many interventional medical procedures both for diagnosis and treatment. Safely and accurately navigating a needle through living tissue to a target is currently often challenging or infeasible because of the presence of anatomical obstacles, high levels of uncertainty, and natural tissue motion. Medical robots capable of automating needle-based procedures have the potential to overcome these challenges and enable enhanced patient care and safety. However, autonomous navigation of a needle around obstacles to a predefined target in vivo has not been shown. Here, we introduce a medical robot that autonomously navigates a needle through living tissue around anatomical obstacles to a target in vivo. Our system leverages a laser-patterned highly flexible steerable needle capable of maneuvering along curvilinear trajectories. The autonomous robot accounts for anatomical obstacles, uncertainty in tissue/needle interaction, and respiratory motion using replanning, control, and safe insertion time windows. We applied the system to lung biopsy, which is critical for diagnosing lung cancer, the leading cause of cancer-related deaths in the United States. We demonstrated successful performance of our system in multiple in vivo porcine studies achieving targeting errors less than the radius of clinically relevant lung nodules. We also demonstrated that our approach offers greater accuracy compared with a standard manual bronchoscopy technique. Our results show the feasibility and advantage of deploying autonomous steerable needle robots in living tissue and how these systems can extend the current capabilities of physicians to further improve patient care.

Ultrasound image formation in the deep learning age

The success of diagnostic and interventional medical procedures is deeply rooted in the ability of modern imaging systems to deliver clear and interpretable information. After raw sensor data is received by ultrasound and photoacoustic imaging systems in particular, the beamforming process is often the first line of software defense against poor quality images. Yet, with today’s state-of-the-art beamformers, ultrasound and photoacoustic images remain challenged by channel noise, reflection artifacts, and acoustic clutter, which combine to complicate segmentation tasks and confuse overall image interpretation. These challenges exist because traditional beamforming and image formation steps are based on flawed assumptions in the presence of significant inter- and intrapatient variations.In this talk, I will introduce the PULSE Lab’s novel alternative to beamforming, which improves ultrasound and photoacoustic image quality by learning from the physics of sound wave propagation. We replace traditional beamforming steps with deep neural networks that only display segmented details, structures, and physical properties of interest. I will then transition to describing a new resource for the entire community to standardize and accelerate research at the intersection of ultrasound beamforming and deep learning. This resource includes the first internationally crowd-sourced database of raw ultrasound channel data and integrated beamforming and evaluation code (see https://cubdl.jhu.edu/ & https://pulselab.jhu.edu/ for more details).

Generation of annotated multimodal ground truth datasets for abdominal medical image registration

PurposeSparsity of annotated data is a major limitation in medical image processing tasks such as registration. Registered multimodal image data are essential for the diagnosis of medical conditions and the success of interventional medical procedures. To overcome the shortage of data, we present a method that allows the generation of annotated multimodal 4D datasets.MethodsWe use a CycleGAN network architecture to generate multimodal synthetic data from the 4D extended cardiac–torso (XCAT) phantom and real patient data. Organ masks are provided by the XCAT phantom; therefore, the generated dataset can serve as ground truth for image segmentation and registration. Realistic simulation of respiration and heartbeat is possible within the XCAT framework. To underline the usability as a registration ground truth, a proof of principle registration is performed.ResultsCompared to real patient data, the synthetic data showed good agreement regarding the image voxel intensity distribution and the noise characteristics. The generated T1-weighted magnetic resonance imaging, computed tomography (CT), and cone beam CT images are inherently co-registered. Thus, the synthetic dataset allowed us to optimize registration parameters of a multimodal non-rigid registration, utilizing liver organ masks for evaluation.ConclusionOur proposed framework provides not only annotated but also multimodal synthetic data which can serve as a ground truth for various tasks in medical imaging processing. We demonstrated the applicability of synthetic data for the development of multimodal medical image registration algorithms.

Eye Lens Doses Received by Radiation Workers in Interventional Medical Procedures

The International Commission on Radiological Protection (ICRP) has recently recommended that the occupational dose limit for the eye lens be reduced to 20 mSv per year, averaged over defined periods of 5 years, with no single year exceeding 50 mSv. ICRP clearly states that the recommendations are chiefly based on epidemiological evidence that suggested the eye lens dose threshold for cataract induction revised downwards from 2-5 Gy to about 0.5 Gy. Interventional medical workers are at greater health risk from radiation exposure to eyes as a result of the procedures they undertake than most other medical specialists. An extensive study has been carried out to measure the eye lens doses received by 373 interventional medical radiation workers in twelve large hospitals in Indonesia. Measurements were made using Thermo Scientific Harshaw thermoluminescence dosimeter (TLD) chip (size 3.2 mm × 3.2 mm × 0.15 mm) put inside an EYE-D holder placed in the worker’s temple. The procedures performed are grouped based on classification made by the UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation). The results showed that in general the measured data are in an agreement with some published data, even though a large range of doses was observed. The highest mean eye lens dose of 0.2378 mSv per procedure was received by interventionists who worked in the abdominal interventions procedure. Overall, from the results of measurement, it can be concluded that most interventionists might receive eye lens dose exceeding the dose limit if the procedures are carried out on daily basis, and the abdominal interventions procedures were found to be the ones that give the highest risk to the eye lens of workers as it delivered the highest dose to this particular organ. 14.00 Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";}

New Reconstruction Method for Needle Contrast Optimization in B-Mode Ultrasound Image by Extracting RF Signal Parameters in Frequency Domain

Ultrasound-guided needle insertion has become standard in medical interventional procedures. Regardless of its advantages, it still has crucial problems related to needle visibility. Some technical factors affect the visibility with non-linear characteristic, i.e. frequency, insertion angle and depth. Here, backscattered signal parameters from measurement were compared to a simulation of a resonance scattering model. Raw radio frequency (RF) data were reconstructed with a new method to represent unique information on total backpropagation from the needle, which consists of non-resonance and resonance scattering components. The result suggests that reconstruction of the needle in B-mode images should be derived from the maximum power spectral density and the energy spectral density to optimize the contrast of the needle. In measurements with the center frequency at 1.87 MHz, the effect of resonance scattering on the total backpropagation around critical angles could be observed more clearly with this method than with standard reconstruction based on the signal envelope. The simulation showed that the fractional bandwidth of the spectrum of the backscattered pressure field centered at 1.87 MHz was relatively optimal at 40% to 100%. So that the simulation of the resonance scattering model can be used to predict the backscattered response from the needle, it must be able to confirm it to the real conditions of RF data with random characteristics. Therefore, extraction of the backscattered pressure field in a simulation with fractional bandwidth should be a concern.

Lens dose and risk of radiation-induced early lens opacities among hospital staff. A cross-sectional study

The main health effect of exposure to ionizing radiation on the eyes is lens opacities and cataracts. Recent findings have raised questions about the pathogenesis of lenticular damage and the exact threshold dose for the onset of this effect. Occupational dose limits for the lens have been therefore recently reduced to 0.02 Gy/year averaged over 5 years with no single year exceeding 0.05 Gy/year. Healthcare workers can be exposed to ionizing radiation during interventional and other medical procedures. The aim of our study was to evaluate the annual dose to the lens in a large group of healthcare workers exposed to ionizing radiation who are working in a university hospital in Rome and to evaluate a dose-response relationship between lens exposure and the onset of lenticular opacities. We reviewed the exposure data of 702 subjects; the average annual dose to the crystalline lens was calculated using a physical algorithm. Moreover, the clinical records of 107 radiation exposed workers were reviewed: the presence of radiation-compatible opacities were assessed for all operators according to the Lens Opacities Classification System (LOCS) III and Merriam-Focht classification. Annual doses exceeding 0.02 Gy were found in 2.1% of the exposed population. Incipient lenticular opacities were observed in 18.6% of the study population. The presence of alterations was associated with higher lens dose (>0.0092 Gy). Based on our results, optimization of procedures and protection of the lens from ionizing radiation by means of personal protection equipment are strongly recommended in higher exposure scenarios.

P129: A phase IV real world study on the use of low dose methoxyflurane (PENTHROX™) for the treatment of moderate to severe trauma pain in the Canadian emergency department (ADVANCE-ED): an interim report on secondary outcomes

Introduction: Inhaled low dose methoxyflurane (MEOF) was recently approved in Canada for the short-term relief of moderate to severe acute pain associated with trauma or interventional medical procedures in conscious adult patients. ADVANCE-ED is an ongoing phase IV, prospective open label study undertaken to generate real-world evidence to complement the global clinical development program through evaluation of the effectiveness of low dose MEOF in Canadian emergency departments (EDs). Methods: This multi-centre study is enrolling adult (≥18 yrs) patients with moderate to severe acute pain (NRS0-10 ≥ 4) associated with minor trauma. To address limitations from the pivotal study, this study allows patients who were excluded in the pivotal trials: namely, those with severe (≥7) pain, and those using OTC or stably dosed analgesics for other conditions, including chronic pain. Eligible patients receive a single treatment of up to 2 x 3 mL MEOF (2nd 3 mL to be provided only upon request), self-administered by the patient under medical supervision. Rescue medication is permitted at any time, if required. Results: Here we describe the patient demographics and treatment satisfaction (Global Medication Performance, GMP) at 50% enrolment (n = 49). Mean (SD) patient age is 48.0 (17.1) yrs and 55.1% are female. Mean pain (SD) reported at enrolment is 8.3 (1.5), with 73.4% of patients with NRS0-10 ≥ 8. Injuries are overwhelmingly limb trauma (87.8%). The most common type is sprain/strain (40.8%), followed by fracture (32.7%). At 5 minutes post-start of administration (STA) of MEOF, 80.4% of patients reported pain relief; this increased to 91.3% at 15 minutes, and 100% of patients reported pain relief by 30 minutes post-STA. GMP was assessed as “good”, “very good” or “excellent” by ≥80% of patients both 20 minutes post-start of administration (STA) of MEOF (83.3%) and at discharge (85.8%). When asked to what extent their expectation of pain relief had been met, 32.7% responded good, 26.5% responded “very good” and 22.4% responded “excellent”. Three quarters of enrolled patients (75.5%) did not require rescue medication. The most common (≥5%) treatment-related adverse events were dizziness (n = 14, 28.6%) and euphoric mood (n = 4, 8.2%). No serious adverse events have been reported. Conclusion: Based on 50% of the patients enrolled in this prospective, open label study, responses to inhaled low-dose MEOF are within expectation for both effectiveness and tolerability.

Patient Exposure from Radiologic and Nuclear Medicine Procedures in the United States: Procedure Volume and Effective Dose for the Period 2006-2016.

Background Comprehensive assessments of the frequency and associated doses from radiologic and nuclear medicine procedures are rarely conducted. The use of these procedures and the population-based radiation dose increased remarkably from 1980 to 2006. Purpose To determine the change in per capita radiation exposure in the United States from 2006 to 2016. Materials and Methods The U.S. National Council on Radiation Protection and Measurements conducted a retrospective assessment for 2016 and compared the results to previously published data for the year 2006. Effective dose values for procedures were obtained from the literature, and frequency data were obtained from commercial, governmental, and professional society data. Results In the United States in 2006, an estimated 377 million diagnostic and interventional radiologic examinations were performed. This value remained essentially the same for 2016 even though the U.S. population had increased by about 24 million people. The number of CT scans performed increased from 67 million to 84 million, but the number of other procedures (eg, diagnostic fluoroscopy) and nuclear medicine procedures decreased from 17 million to 13.5 million. The number of dental radiographic and dental CT examinations performed was estimated to be about 320 million in 2016. Using the tissue-weighting factors from Publication 60 of the International Commission on Radiological Protection, the U.S. annual individual (per capita) effective dose from diagnostic and interventional medical procedures was estimated to have been 2.9 mSv in 2006 and 2.3 mSv in 2016, with the collective doses being 885 000 and 755 000 person-sievert, respectively. Conclusion The trend from 1980 to 2006 of increasing dose from medical radiation has reversed. Estimated 2016 total collective effective dose and radiation dose per capita dose are lower than in 2006. © RSNA, 2020 See also the editorial by Einstein in this issue.

Robust control of a bevel-tip needle for medical interventional procedures

In minimally invasive surgery, one of the main objectives is to ensure safety and target reaching accuracy during needle steering inside the target organ. In this research work, the needle steering approach is determined using a robust control algorithm namely the Integral sliding mode control &#x0028 ISMC &#x0029 strategy to eliminate the chattering problem associated with the general clinical scenario. In general, the discontinuity component of feedback control input is not appropriate for the needle steering methodology due to the practical limitations of the driving actuators. Thus in ISMC, we have incorporated the replacement of the discontinuous component using a super twisting control &#x0028 STC &#x0029 input due to its unique features of chattering elimination and disturbance observation characteristics. In our study, the kinematic model of an asymmetric flexible bevel-tip needle in a soft-tissue phantom is used to evaluate stability analysis. A comparative study based on the analysis of chattering elimination is executed to determine the performance of the proposed control strategy in real-time needle steering with conventional sliding mode control using vision feedback through simulation and experimental results. This validates the efficacy of the proposed control strategy for clinical needle steering.

Modular Catheter Systems in Minimally Invasive Interventional Medical Procedures: Case Study

Background Medical device catheters that are used in minimally invasive interventional medical procedures all follow the same integrated design and use paradigm. The features and elements of any catheter device are combined in a single unitary construction. A modular approach to the design, construction, and use of these types of interventional catheters may provide significant advantages and benefits not available with an integrated design paradigm. Objective This paper aimed to present the design of a modular catheter system and the findings from an initial veterinary use as a case study for the potential of modular catheter systems in general. Methods A modular catheter system was designed using commercially available angioplasty balloon dilatation catheters as one module in the system and a custom designed scoring adapter as the other module. The scoring adapter incorporates wires to add scoring features to the angioplasty balloon catheter to improve the dilatation performance during a pulmonary valvuloplasty procedure. The scoring adapter also includes a novel attachment mechanism to couple the scoring adapter to any 0.035-inch guidewire–compatible angioplasty balloon catheter. Results The modular catheter system was successfully designed, manufactured, and used in an initial minimally invasive veterinary cardiovascular intervention to treat a case of canine subvalvular pulmonary stenosis. The scoring adapter and angioplasty balloon catheter were successfully combined tableside in the operating room at the time of the procedure and used to successfully dilate the subvalvular obstruction. Conclusions The successful design and use of the presented modular catheter system demonstrates the feasibility and potential advantages of this type of paradigm to enable physicians to create interventional catheter devices at the time of a procedure guided by the procedural needs.

P015: A phase IV protocol for a real world study on the use of low dose methoxyflurane (PENTHROX™) for the treatment of moderate to severe trauma pain in the Canadian emergency department (ADVANCE-ED)

Introduction: Pain is a significant driver of demand in emergency care and 65% of adult patients with trauma also report moderate to severe pain. Inhaled low dose methoxyflurane (MEOF) a rapid-acting patient administered inhalational analgesic was recently approved in Canada for the short-term relief of moderate to severe acute pain associated with trauma or interventional medical procedures in conscious adult patients. This study will generate real-world evidence to complement the global clinical development program through evaluation of the effectiveness of MEOF in Canadian emergency departments. Methods: This is a phase IV, prospective open label, multi-centre study. Approximately 100 adult (≥18 yrs) patients with moderate to severe acute pain (NRS0-10≥4) associated with single system trauma will be enrolled at 5-10 EDs across Canada. Patients will receive a single treatment of up to 2 x 3 mL MEOF (2nd 3 mL to be provided only upon request), self-administered by the patient under medical supervision. Rescue medication will be permitted at any time, if required. Results: Planned Assessments and Outcome Measures: Pain will be assessed using the NRS0-10 at 4 time points: screening/triage, 5 minutes and 20 minutes post-start of administration (STA) of MEOF, and when ready for discharge. Secondary assessments will include the speed of action of analgesia (from STA of MEOF); patient and physician satisfaction with treatment (as assessed through Global Medical Performance (GMP) at 20 minutes post-STA and when ready for discharge); patient and physician fulfilment of pain relief expectations (assessed when ready for discharge); use of rescue medication and treatment-emergent adverse events. Exploratory outcomes will include the time to disposition, time to readiness for discharge and responder analysis. The primary outcome measure will be the change in pain intensity over 20 minutes from the start of administration of MEOF as measured on the NRS0-10. Conclusion: We report on the methodology of a phase IV, prospective open label, multi-centre study, evaluating the use of MEOF for the management of acute traumatic pain in Canadian Emergency Departments.

Self-Administered Low-Dose Inhaled Methoxyflurane (Penthrox) during Administration of OnabotulinumtoxinA for Chronic Migraines: A Real World Case Series

POSTER ABSTRACTThe intramuscular administration of onabotulinumtoxinA (onabotA) has been well established as an effective preventative treatment for chronic migraines (CM). Though generally well tolerated, the procedure-related pain can be a large limitation of the treatment for patients with comorbidities such as fibromyalgia.Inhaled low-dose methoxyflurane (MEOF) is a proven analgesic that has been used for over 30 years with more than 5.6 million administrations worldwide. MEOF was recently approved in Canada for moderate-severe pain related to trauma or interventional medical procedures in adults. MEOF as an analgesic for onabotA injections for CM has not been previously reported.This case series describes the use of MEOF as a procedural analgesic during intramuscular onabotA injections for CM.Ten patients who previously experienced significant pain (NRS >8) and associated moderate-severe anxiety with onabotA injections were treated with MEOF. Immediately post-procedure, patients rated their pain and anxiety. Adverse events (AE) were recorded andpatient satisfaction was assessed by asking “Are you satisfied with the treatment?” and “Would you use MEOF again?”.Post-procedure, average reported pain score was 3 and the average anxiety level was “mild”. All patients were “satisfied” with MEOF and confirmed that they would use it again. Most common AEs were dizziness and somnolence and AEs were transient (resolved within 5 minutes post administration). To our knowledge, this is the first report of the use of MEOF to facilitate intramuscular onabotA injections.

Accelerating multi-modal image registration using a supervoxel-based variational framework

For the successful completion of medical interventional procedures, several concepts, such as daily positioning compensation, dose accumulation or delineation propagation, rely on establishing a spatial coherence between planning images and images acquired at different time instants over the course of the therapy. To meet this need, image-based motion estimation and compensation relies on fast, automatic, accurate and precise registration algorithms. However, image registration quickly becomes a challenging and computationally intensive task, especially when multiple imaging modalities are involved.In the current study, a novel framework is introduced to reduce the computational overhead of variational registration methods. The proposed framework selects representative voxels of the registration process, based on a supervoxel algorithm. Costly calculations are hereby restrained to a subset of voxels, leading to a less expensive spatial regularized interpolation process. The novel framework is tested in conjunction with the recently proposed EVolution multi-modal registration method. This results in an algorithm requiring a low number of input parameters, is easily parallelizable and provides an elastic voxel-wise deformation with a subvoxel accuracy.The performance of the proposed accelerated registration method is evaluated on cross-contrast abdominal T1/T2 MR-scans undergoing a known deformation and annotated CT-images of the lung. We also analyze the ability of the method to capture slow physiological drifts during MR-guided high intensity focused ultrasound therapies and to perform multi-modal CT/MR registration in the abdomen. Results have shown that computation time can be reduced by 75% on the same hardware with no negative impact on the accuracy.

Sliding mode control of a shape memory alloy actuated active flexible needle

SUMMARYIn medical interventional procedures such as brachytherapy, biopsy and radio-frequency ablation, precise tracking through the preplanned desired trajectory is very essential. This important requirement is critical due to two major reasons: anatomical obstacle avoidance and accurate targeting for avoiding undesired radioactive dose exposure or damage to neighboring tissue and critical organs. Therefore, a precise control of the needling device in the unstructured environment in the presence of external disturbance is required to achieve accurate target reaching in clinical applications. In this paper, a shape memory alloy actuated active flexible needle controlled by an adaptive sliding mode controller is presented. The trajectory tracking performance of the needle is tested while having its actual movement in an artificial tissue phantom by giving various input reference trajectories such as multi-step and sinusoidal. Performance of the adaptive sliding mode controller is compared with that of the proportional, integral and derivative controller and is proved to be the effective method in the presence of the external disturbances.

EYE LENS RADIATION EXPOSURE OF WORKERS DURING MEDICAL INTERVENTIONAL PROCEDURES AND SURGERY.

To evaluates the eye-lens radiation exposure of workers during medical interventional procedures and surgery in a military hospital as well as of the equine veterinarians. The measures represent the exposure in a normal workload schedule of ninety randomly selected workers over a 3-month period, extrapolated to 1 year. The eye-lens dosemeters were placed near the eye closest to the radiation source (Carinou, E., Ferrari, P., Bjelac, O. C., Gingaume, M., Merce, M. S. and O'Connor, U. Eye lens monitoring for interventional radiology personnel: dosemeters, calibration and practical aspects of H p (3) monitoring. A 2015 review. J. Radiol. Prot. 2015;35(3): R17-R34). Three models of eye-lens dosemeters (Dosilab, Landauer and IRSN) were assessed in term of ergonomics. The annual estimation of eye-lens doses did not reach the annual dose limit of 20 mSv revised by the ICRP, ranged from 0.00 to 18.12 mSv with a mean of 0.96 ± 2.28 mSv. However, these results cannot be representative of a heavy workload or incident situations for which radiation exposure to the eye-lens could exceed this limit. The IRSN dosemeter model was considered the most convenient.

Monte Carlo Study of 3D Stray Radiation during Interventional Procedures

In interventional medical procedures, other than the highly important issue of optimizing image quality and patient exposure using the primary beam, there remains a continuing need for the study of staff exposure from the scattered radiation. Herein, investigation is made of the 3D stray-radiation distribution, the simulation being made of a realistic interventional scenario through use of the Monte Carlo code Geant4 (version 10.3). The simulation is conducted based on the high definition reference Korean-man (HDRK-man) computational phantom and a GE Infinia 3/8” C-arm machine, focusing on the effect of variation of kVp and field of view (FoV) on the scattered particles’ spatial distribution. With direct measurement of the absorbed dose remaining challenging, not least in respect of the organs at risk, we computed the scatter fractions, defined as the ratio of the air kerma free-in-air to the entrance surface air kerma (ESAK), which are both easily quantifiable. Scatter fraction distributions were simulated for X-ray tube outputs (and half-value layers, HVL) of 60 kVp (2.3 mm Al), 80 kVp (3.2 mm Al) and 120 kVp (4.3 mm Al) and FoV of 15, 20, 25 and 30 cm. The distributions are obtained for different height levels, corresponding to the lens of the eye, and the lung and prostate, all radiosensitive organs. Investigations are made for eight likely locations around the patient. At fixed FoV results reveal an inverse relationship between ESAK and kVp, also that change in kVp from 60 to 80 has a greater effect than from 80 to 120. For change in FoV at fixed kVp, the scatter fraction remains constant. The particular staff locations are found to be optimal in seeking mitigation of dose. Moreover, the combined usage of numerical human model and Monte Carlo simulation can be considered as an added value to the radiation safety research field, especially to the interventional radiology staff and to the patient.

Chapter 26 - Safety of blood, blood derivatives, and plasma-derived products

There has been concern for several decades around the possibility that prion diseases may be transmissible by blood components and / or plasma products. Whilst the evidence in respect of transmission of sporadic Creutzfeldt-Jakob disease (CJD) is largely circumstantial, the identification of variant CJD gave rise to increased concern due to the evidence of prion accumulation in peripheral lymphoid tissue at the time of clinical disease. A series of studies of appendix tissues in the United Kingdom revealed prion accumulation in around 1 / 2000 of the individuals tested and raised further concern that there may be a significant proportion of the healthy population with subclinical infection posing an increased risk of transmission by substances of human origin (blood, plasma, tissues, organs) and interventional medical and surgical procedures. The former risk was realized with transmission of variant CJD infection to four individuals becoming evident between 2004 and 2006. These concerns precipitated significant changes to donor selection criteria internationally, to blood processing in the United Kingdom with the introduction of universal leucodepletion, and to the use of UK plasma for fractionation to plasma products. Considerable effort has also been invested in the development of peripheral blood assays for subclinical variant CJD and of prion reduction filters for blood components, though to date these technologies have not achieved routine clinical implementation. Whilst the variant CJD outbreak appears to be receding, continued vigilance is required in respect of the risks posed by all prion diseases to blood safety.

Dosage Estimation in Mammography for Quality Assurance and Quality Control Using Adult Mammograms

Any form of X-ray exposure should be carefully monitored and controlled, so that the patient is only exposed to safe amounts. Even though X-ray users are extremely careful when exposing their patients to diagnostic tests, where radiation is involved, it is important to bear in mind how low the risks really are, especially when compared to other forms of radiation exposure. As with any kind of medical procedure, X-rays are safe when they are used properly. When clinically indicated, properly conducted imaging with the smallest risk should be performed. In this study, the optical densities, OD, of adult mammograms, undergoing X-ray exposures was measured from the radiology department of the University of Benin Teaching Hospital (UBTH), Benin City, Edo State, Nigeria, with the aid of a densitometer, model MA 5336. The measured optical densities were used to estimate the X-ray radiation dose to patients, undergoing mammography, for the purpose of Quality Assurance (QA) and Quality Control (QC), in diagnostic and screening. A total of fifty (50) adult mammograms were collected for use in the radiology department of the hospital. The optical densities were measured five times at different spots across the image of each of the mammograms and the mean were obtained, in other to estimate the absorbed dose. The results obtained showed that the mean dose was 0.48 mGy, minimum dose 0.04 mGy, maximum dose 1.07 mGy, range of dose 1.03 mGy, SD 0.24, kurtosis 2.77, 1^st Q 0.34 and 3^rd Q 0.66. These results were in agreement with those of the International Atomic Energy Agency (IAEA), guidance levels in X-ray guided medical interventional procedures.

A Systematic Review of the Causes and Management of Ischaemic Stroke Caused by Nontissue Emboli.

Introduction The inadvertent or purposeful introduction of foreign bodies or substances can lead to cerebral infarction if they embolize to the brain. Individual reports of these events are uncommon but may increase with the increased occurrences of their risk factors, for example, intra-arterial procedures. Method We searched EMBASE and MEDLINE for articles on embolic stroke of nontissue origin. 1889 articles were identified and screened and 216 articles were ultimately reviewed in full text and included in qualitative analysis. Articles deemed relevant were assessed by a second reviewer to confirm compatibility with the inclusion criteria. References of included articles were reviewed for relevant publications. We categorized the pathology of the emboli into the following groups: air embolism (141 reports), other arterial gas embolisms (49 reports), missiles and foreign bodies (16 reports), and others, including drug embolism, cotton wool, and vascular sclerosant agents. Conclusion Air and gaseous embolism are becoming more common with increased use of interventional medical procedures and increased popularity of sports such as diving. There is increasing evidence for the use of hyperbaric oxygen for such events. Causes of solid emboli are diverse. More commonly reported causes include bullets, missiles, and substances used in medical procedures.