Lead Shielding Research Articles

Assessment of Radiation Protection Measures to Minimize Occupational Radiation Exposure from C-arm Fluoroscopy During Common Orthopaedic Surgical Procedures

Background: Modern fluoroscopic C-arms have substantially expanded the use of fluoroscopic C-arms in a variety of orthopaedic surgical procedures. Fluoroscopy professionals who are exposed to radiation for an extended period of time have an increased risk of developing radiation-induced cancer. The study aimed to evaluate the radiation protection precautions taken by theater staff in two selected hospitals to reduce occupational radiation doses during fluoroscopy-guided common orthopaedic surgeries. Methods: After examining the theatre records for three months in two selected hospitals in Sri Lanka, the three major orthopaedic surgeries for both hospitals were selected (Dynamic Hip Screw, Tibial Plateau Fracture, and Distal Radial Fracture). The study used a checklist for an unbiased observation, containing the internationally recommended guidelines for Fluoroscopy inside an interventional suit published in the International Commission on Radiological Protection (ICRP) 139 publication to check whether the theatre personnel followed the radiation protective measures during their procedures. Results: Fluoroscopy technical-based protective measures and the quality assurance-related criteria were satisfied to a 100% level. Both hospitals, A and B, did not have an adequate number of lead shielding devices to be utilized in theatres. A lack of individual exposure monitoring and the use of two dosimeters were identified as the main problems. Conclusions: The staff of both hospitals adhered to the standard international guidelines on radiation protection during C-arm guided orthopaedic surgeries despite the unavailability of a proper personal monitoring system.

Radiological health risks assessment of vegetable and fruit samples taken from the provincial borders of Adıyaman in the south-eastern Anatolia region, in Turkey

In this study, the natural radionuclide activity concentrations such as 238U, 232Th and 4 K were measured in 65 vegetable-fruit samples taken from fields within provincial borders of Adıyaman in the south-eastern Anatolia region of Türkiye. An HPGe detector having the energy resolution of 1.85 keV at 1332.5 keV and 40% relative efficiency, p-type coaxial, covered with 10 cm thick lead shield was used to measure 238U, 232Th, and 4 K radionuclide activity concentrations of the samples of plant and fruit.238U, 232Th and 4 K radionuclide activity concentrations in vegetable and fruit samples are varied from 0.04 -2.39 Bk/kg, 0.08–2.14 Bq/kg and 28–252 Bq/kg, respectively. The mean radionuclide activity concentrations of 238U, 232Th and 4 K measured in fruits (peppers, tomatoes, eggplants, cucumbers, pumpkins, figs, and their stalks) and vegetables (leek, parsley and basil) were also calculated. For 238U and 4 K, the average radionuclide activity concentrations calculated in fruit stalks are generally higher than those calculated in fruits. However, this cannot be said for the 232Th. The measured mean radionuclide activity concentrations are smaller than the Worldwide mean value of 35 Bqkg−1, 30 Bqkg−1 and 400 Bqkg−1 for 238U, 232Th and 4 K, respectively, which is defined by UNSCEAR in 2000 year. The rate of absorbed dose measured in vegetable and fruit samples is much smaller than the World safety limit value defined by the ICRP in 1993. The calculated excess lifetime cancer risk (ELCR) values are higher than the world safe limit value (2.9 × 10−4 mSvy−1). Therefore, it can be said that there is a radiological risk.

EFFECT OF PELVIC LEAD SHIELD ON ORGAN DOSES IN POSTERO-ANTERIOR CHEST RADIOGRAPHY.

Lead shields are commonly used in X-ray imaging to protect radiosensitive organs and to minimise patient's radiation dose. However, they might also complicate or interfere with the examination, and even decrease the diagnostic value if they are positioned incorrectly. In this study, the radiation dose effect of waist half-apron lead shield was examined via Monte Carlo simulations of postero-anterior (PA) chest radiography examinations using a female anthropomorphic phantom. Relevant organs for dose determination were lungs, breasts, liver, kidneys and uterus. The organ dose reductions varied depending on shield position and organ but were negligible for properly positioned shields. The shield that had the largest effective dose reduction (9%) was partly positioned inside the field of view, which should not be done in practice. Dose reduction was practically 0% for properly positioned shields. Therefore, the use of lead shield in the pelvic region during chest PA examinations should be discontinued.

PO09: Treatment of Facial Folliculotropic Mycosis Fungoides with High Dose Rate Brachytherapy in Two Fractions

<h3>Purpose</h3> To describe the treatment and outcomes for the treatment of folliculotropic mycosis fungoides (FMF) with high dose rate (HDR) brachytherapy in the facial area with complex topography. <h3>Materials and Methods</h3> A 68-year-old male with past medical history of morbid obesity status post gastric bypass, diabetes mellitus, hypertension, and atrial fibrillation was diagnosed with FMF of the face, scalp, trunk and extremities. Patient was referred to radiation therapy due to severe burning pain and pruritus of facial lesions on the nose, upper lip, and left temple after no response with UVA therapy. Electron beam therapy was initially chosen with a prescription of 3600 cGy in 20 fractions, but the resulting treatment plans were highly non-conformal with large dose heterogeneity and poor target coverage. HDR brachytherapy was pursued as an alternate treatment option with a prescription dose of 800 cGy in 2 fractions. Patient setup for simulation included a custom Freiburg flap applicator on an Aquaplast mask using 18 catheters to cover all lesions. Patient was scanned with pink bolus in the nostrils, a lead shield under the lip, and a bite block. Treatment planning was performed using Oncentra (Elekta, Stockholm, Sweden). HDR treatment was delivered using an Elekta Flexitron remote afterloader unit. Bilateral internal tungsten eye shields (Civco, Orange City, IA) were placed prior to treatment to reduce ocular dose. <h3>Results</h3> The drawn target was 25.2cc along the upper lip, bilateral nose, right medial canthus, and left temple. Achieved target coverage was V90% = 98.6%, D90% = 100.5%, and D95% = 95.9%. Skin V150% was 0.12cc. Without eye shield placement, right and left eye D0.01cc were 117.9% and 78.2%, respectively. Right and left lens doses were 99.1% and 69.4%, respectively. Average fractional delivery time was 603.5 seconds with an air kerma strength of 39.0 mGy*m²/s (apparent activity 9.7 Ci). Patient tolerated treatment without complications. At two week follow up, patient showed grade 1 dermatitis of the treatment area with erythema and mild desquamation. Patient has been asymptomatic six months post treatment. <h3>Conclusions</h3> Low dose HDR brachytherapy can be an effective treatment for facial FMF lesions with complex topography. It allows for suitable target coverage and normal tissue sparing, a shorter treatment course when compared to electron beam radiotherapy, and is associated with minimal adverse effects and rapid clinical response. It also allows sparing total skin electron therapy for the future in case of disease progression as the volume of tissue receiving radiation is very small. Figure 1a: Oncentra treatment plan in axial, sagittal, and coronal planes, with 3D rendering show in bottom right. Target volume in light blue, right eye in green, and left eye in blue. 1b shows wires outlining the target volume (top); pre-mask setup with pink bolus, bite block, gauze in the nostrils, and bilateral eye shields (middle); and final treatment setup with mask (bottom). 1c shows the pre-treatment lesions, and 1d shows the same area four months post treatment.

PO13: Development of a Risk-Based Workflow to Identify Dosimetric Relevance of Implanted Cardiac Devices (ICDs) for Brachytherapy Patients

<h3>Objective</h3> To develop a risk-based workflow for assessing dosimetric relevance of ICDs (i.e pacemaker/defibrillators) in patients undergoing brachytherapy in our department. <h3>Materials and Methods</h3> In order to conservatively assess possible dose to ICD in clinical brachytherapy situations, worst-case scenarios were generated for brachytherapy procedures performed at our institution. Cases were organized by site and technique: Pelvic HDR [prostate HDR, gynecologic HDR, rectum HDR, pelvic intraoperative (IORT)], pelvic permanent implantations (prostate and other pelvic seed implantations with I-125 and Pd-103), upper abdomen/chestwall/H&N HDR (Esophagus HDR, upper body HDR IORT). Twenty patients were randomly selected among recently treated cases; prescription doses, treatment images (when available) and treatment plan dose distributions (TG43) were used to develop worst-case scenario geometries for each application. Patients did not have ICDs, and theoretical ICD locations were estimated assuming closest reasonable placement to the treatment site. We evaluated the data to set a policy to identify, in advance of treatment, situations in which ICD dose could exceed threshold of 2Gy, and we developed a risk-based workflow. <h3>Results</h3> For pelvis HDR cases, maximal total dose prescription was 28Gy and distance from treatment site to 2Gy threshold was 7cm. For pelvic permanent implantations, maximal total dose prescription was 144Gy using I-125, and distance from treatment site to 2Gy threshold was 5cm. Closest location of ICD to treatment site was estimated to be >>7cm in all pelvic cases, therefore ICD dose for pelvic cases was considered negligible. For upper abdomen/chest wall/H&N HDR cases, maximal total dose prescription was 15Gy and distance from treatment site to 2Gy threshold was 5cm. Worst-case scenario geometries for Esophagus HDR treatments, where applicator location was simulated to be close to the chest wall, predicts a distance to the ICD >5cm, with doses to ICD of 0.5-1Gy. For upper body IORT cases, due to clinical variability, applicator placement can be <5cm from the ICD, thus requiring physical measurements to confirm safety of treatment. Therefore, we proposed a risk-based workflow, taking into account (i) negligible radiation ICD risk for all pelvic cases, (ii) geometric/dosimetric assessment at time of planning for esophagus HDR cases and (iii) intra-operative assessment for IORT cases at or above upper abdomen. For cases (ii) and (iii) the physicist 2^nd checking the plan would review the electronic medical record prior to treatment to identify presence of ICD. For image-guided cases, the ICD should be contoured to evaluate distance from implant site, and dose calculated. For IORT cases, an intraoperative distance measurement from ICD to treatment area would be performed. If distance is ≤5cm, possibility of 2Gy to ICD must be acknowledged. The dose estimate should be recorded in specified form and signed by MD. Sterile lead shielding may be used, if feasible, internally to limit ICD dose. This risk-based workflow is represented in the figure. <h3>Conclusion</h3> We developed a risk-based workflow to evaluate ICD dose for brachytherapy patients. Development of this workflow could help identify patients at clinically relevant risk to ICD perturbation and conversely, reduce unnecessary interventions for negligible risk scenarios. This policy will need to be re-evaluated if new treatment modalities or fractionations are introduced. Dose rate effects were not considered (<<8Gy/min in all situations). Differences between TG43 and physical doses were not systematically explored.

Silicon-Germanium Electronics and Photonics for Space Systems

Space has been aptly called the “final frontier” (thank you, Star Trek!). The application needs of the global space and aerospace communities are predictably many and varied, ranging from a diverse set of communications and imaging satellites, to the GPS constellation, to microwave and millimeter-wave (mmW) remote sensing to support weather forecasting and climate science, to exploration of other worlds, which include: the mighty James Webb Space Telescope (probing the origins of the universe), the shadowed polar craters of the Moon (the search for water ice), Mars surface (colonization?), and Europa (the search for extraterrestrial life in the water ocean beneath the 10 km ice cap).While classically, orbital satellites were massive, tough to launch, and extremely expensive (a few $Bs), the current (and rapidly accelerating) trend has swung decidedly towards using relatively low-cost (a few $M) and easy to launch constellations of single or multi-U CubeSats (1U = 10x10x10 cm3) to cost-effectively address the plethora of emerging needs. These days, this has been increasingly supported by commercial space ventures (e.g., SpaceX, BlueOrigin et al., vs. the old gang—NASA and DoD), which are proliferating rapidly.As appealing as space is for visioning fun new science and slick applications, it remains a decidedly unfriendly place to visit. Space is the quintessential “extreme environment,” bathed in intense radiation from both our Sun (high energy electrons and protons trapped by the Earth’s magnetosphere in radiation belts) and the cosmos (GeV energy galactic cosmic rays from supernovae). By way of level setting, a satellite in the most benign Earth orbit, Low Earth Orbit (LEO – 160-1000 km up from the surface), experiences 100,000 rad of ionizing radiation dose over mission life. In comparison, 500 rad will do a person in! That is, we are asking a lot of our electronics in such systems, and given the extreme cost constraints of launch weight, adding a few inches of lead shielding is not the ideal solution! In addition, it is mighty chilly in space (2.73 K = -455°F, the cosmic background), and when the sunlight shines on you, it gets uncomfortably warm, very quickly (e.g., on the surface of the Moon, from -180°C to +120°C from darkness to light, within a few moments). Yep, space is a tough place to do business.As I have long argued [1], SiGe HBT BiCMOS technology provides a unique solution for many of the needs of these emerging space systems, including: 1) extreme levels of performance (multi-hundred GHz) with the SiGe HBT and high integration levels with on-board CMOS, for realizing compelling system functionality/unit volume, at low cost; 2) the rapid improvement of all electronic circuit relevant performance metrics with cooling, with operational capability down into the mK quantum regime (SiGe HBTs love chilly weather!); 3) the ability to operate robustly up to 150-200°C, with modest performance loss; 4) the ability to operate robustly over wide temperature ranges (in principle from mK to 150-200°C); 5) built-in robustness to multi-Mrad total ionizing dose radiation; and 6) built-in heavy ion induced latchup immunity (read: those pesky GeV cosmic rays).Long ago (1990s), the notion of creating a low-cost Si-based electronic + photonic integrated circuit (EPIC) “superchip” was envisioned (Soref), which brought together advanced SiGe HBTs (analog, RF-mmW), CMOS (digital), and Si integrated photonics (with the possible exception of a laser, which could be flipped onto the die worse case). In essence, EPICs are a low-cost, high-yielding, reliable, highly integrated Si platform for putting electrons and light into the same conversation! Clearly this represents a paradigm shift to business as usual. Now, with even more compelling system functionality/unit volume, at low cost. Such an EPIC superchip could in principle satisfy all-comers-of-new-needs. While photonics has long been used in space (think solar cells, imagers), EPICs are new to that space game, but possess great potential for the emergent needs in this new vision of CubeSat/SmallSat driven space systems, including, thing like: LIDAR (spacecraft-to-spacecraft positioning); deep space and within-constellation optical communications (huge data rate improvement); and on-spacecraft high bandwidth data transport (think data center in the sky for instruments that spew out tons of data that need to get back home quickly). This field of EPICs in space is only a few years old, but already much has been learned, and results look very encouraging.In this invited talk, I will highlight the current status and the future trends of using SiGe electronic and photonics in space systems.[1] J.D. Cressler, Proc. IEEE, vol. 93, pp. 1559-1582, 2005. Figure 1

Development of thermal neutron shield with low radioactivity

The second phase of the Advanced Mo-based Rare process Experiment (AMoRE-II) searches for a neutrino-less double-beta decay of 100Mo. A background level in the region of interest of 3034 ± 10 keV is required to be lower than 10-4 count/(keV kg year). Neutrons can generate background signals by gamma-ray emitting reactions with AMoRE-II detector materials. Thermal neutron shields will be installed inside and outside the lead shield to reduce the neutron flux in the shielding system. The background radioactivity of the inner thermal neutron shield must be low because AMoRE-II requires a low background level. A thermal neutron shield with a high shielding efficiency and low radioactivity was produced by using boric acid powder and silicone rubber. The shielding efficiency was tested to be {99.2 ± 0.25(stat)-0.53 +0.47(syst)}%, and the radioactivities of 40K, 226Ra, 228Ac, and 228Th were measured to be < 9.2 at 90% C.L., 14.2 ± 1.5, < 1.6 at 90% C.L., and 2.83 ± 0.80 mBq/kg, respectively.

Detector optimization to reduce the cosmogenic neutron backgrounds in the TAO experiment

Short-baseline reactor antineutrino experiments with shallow overburden usually have large cosmogenic neutron backgrounds. The Taishan Antineutrino Observatory (TAO) is a ton-level liquid scintillator detector located at about 30 m from a core of the Taishan Nuclear Power Plant. It will measure the reactor antineutrino spectrum with high precision and high energy resolution to provide a reference spectrum for JUNO and other reactor antineutrino experiments, and provide a benchmark measurement to test nuclear databases. Background is one of the critical concerns of TAO since the overburden is just 10 meter-water-equivalent. The cosmogenic neutron background was estimated to be ∼10% of signals [1]. With detailed Monte Carlo simulations, we propose several measures in this work to reduce the neutron backgrounds, including doping Gadolinium in the buffer liquid, adding a polyethylene layer above the bottom lead shield, and optimization of the veto strategy. With these improvements, the neutron background-to-signal ratio can be reduced to ∼2%, and might be further suppressed with pulse shape discrimination.

Personalized Superficial HDR Brachytherapy-Dosimetric Verification of Dose Distribution with Lead Shielding of Critical Organs in the Head and Neck Region.

Background: Surface brachytherapy, usually characterized by a high dose gradient, allows the dose to be precisely deposited in the irradiated area while protecting critical organs. When the lesion is located in the nasal or ocular region, the organ of vision must be protected. The aim of this study was to verify the dose distributions near critical organs in the head and neck region during a brachytherapy procedure using lead shielding of the eye. Methods: Anthropomorphic phantom using 3D-printing technology was prepared. The doses deposited at a point in the lens of the eye and on the surface of the eyelid, directly under the lead shield were calculated and measured using EBT3 radiochromic films. Comparison of doses planned in the treatment planning system using the TG-43 formalism, TG-186 formalism, and measured were also performed. Results: Comparing the planned and calculated doses with TG186 formalism it can be assumed that the use of lead shields is a method for protecting the organ of vision from the adverse effects of ionizing radiation. Conclusions: The decision to use a lead shield during facial surface brachytherapy procedures should be made on a patient-by-patient basis and based on model-based calculation methods recommended by TG186.

Evaluation of the effectiveness of testicular shielding in rectal cancer radiotherapy

This study aimed to investigate the effect of local shielding on the reduction of the dose received by the male sexual organs in pelvic radiation therapy. For this purpose, a clinical case, and its corresponding simulation with the Monte Carlo Geant4 toolkit were studied. Here, the 15 MV photon mode of a medical LINAC was used to irradiate the pelvic region of three patients with rectal cancer. Using thermoluminescent dosimeter (TLD) 100, the doses received by the testes, seated out of the field, were measured in two situations, i.e., with and without a testicular shield. After benchmarking the simulation setup by comparing the simulated and experimental PDDs (Percentage Depth Dose) and lateral profiles in a water phantom, the simulation corresponding to the clinical case has been done. Afterward, the desired quantities such as absorbed dose, total equivalent dose, and neutron equivalent dose have been calculated. The results indicate that the local placement of a spherical lead shield leads to a decrease in the absorbed dose received by the testes with a coefficient greater than 2. It was also observed that shielding had a minimal contribution to the production of secondary neutrons and was not seen any sensible change in neutron equivalent dose, whereas a decrease in the total equivalent dose by a factor of 2.2 for the testes was observed. These observations imply that the risk of secondary cancers decreased proportionately, as well as a reduction in the risk of permanent infertility for young men.

Transit dose measurements using alanine and diode-based dosimeters

The growing interest in low-dose (&lt; 100 Gy) radiation processing applications has raised concerns about accurately measuring the absorbed dose in irradiated materials. Depending on the irradiator design, the transit time due to the radioactive source movement (or the product itself) until the stable irradiation position might affect the predicted absorbed dose. This work aims to evaluate the transit dose in a 60Co Gammacell 220-Nordion irradiator, which has radioactive sources settled at the bottom of a lead shielding. When the facility is on, the product and the dosimeter are mechanically guided down to the irradiation position, and hereafter the selected exposure time starts to be counted. At the end of irradiation, both product and dosimeter rise to the initial position enabling them to be gathered by the operator. The product is continuously irradiated at different dose rates during its fall and rise movement, preventing the transit dose from being obtained straightforward. The experimental approach adopted is to assess the transit time, and thus the transit dose, using an online diode-based dosimetry system previously calibrated against reference standard alanine dosimeters. The agreement between the transit doses attained with the diode (0.41 ± 0.02) Gy and alanine ((0.38 ± 0.01) Gy validates the method herein proposed.

Positron Emission Tomography and Computed Tomography Contributions to Patient Dose and Personnel Exposure to Radiation during PET/CT-Guided Tumor Ablations

This study sought to quantify the positron emission tomography (PET) and computed tomography (CT) components of patient radiation doses and personnel exposure to radiations during PET/CT-guided tumor ablations and assess the utility of a rolling lead shield for operator protection. Two operators performed 21 PET/CT-guided ablations behind a customized, 25-mm-thick lead shield with midchest-to-midthigh coverage. The mean patient radiation dose per procedure was 3.90 mSv ± 1.13 (11.3%) from PET and 30.51 mSv ± 19.05 (88.7%) from CT. The mean primary and secondary operator exposure outside neck-level thyroid shields was 0.05 and 0.02 mSv per procedure, respectively. The radiation exposure levels behind the rolling lead shield, inside the primary operator’s thyroid shield, and on the other personnel were below the measurable threshold cumulatively over 21 procedures. The mean PET exposure level at continuous close proximity to patients was 0.02 mSv per procedure. The PET radiation doses to the patients and personnel were small. Thus, the rolling lead shield provided limited benefit.

Abstract 6279: Combination of metformin and local irradiation efficiently provokes abscopal effects in a murine rectal cancer model

Abstract Introduction; Neoadjuvant chemoradiation therapy (CRT) for locally advanced rectal cancer is effective for the reduction of local recurrence and improvement of postoperative QOL. However, CRT has little effects for metastatic lesions in distant organs and does not prolong the prognosis. Abscopal effect refers to a phenomenon of tumor regression at a distant tumor away from the irradiated primary tumor, presumably through the host immune system. Metformin, a widely used drug for the treatment of type 2 Diabetes Mellitus, has been shown to elicit anti-cancer effects partly through the activation of host immunity. However, how metformin modulates the abscopal effects of local radiation (RT) and metformin has not been well investigated. Method; Mice were subcutaneous inoculated by 1x106 cells of LuM1, a highly murine lung metastatic subclone of colon 26, at right flank of 7 weeks female BALB/c mice which were treated with metformin and/or RT. In RT groups, 4Gy X-ray was selectively given to subcutaneous tumors using lead shield under general anesthesia at day 13 and 15. Metformin hydrochloride (1mg/ml) were orally administrated from day13 continuously. At 28 days, mice were sacrificed, and we evaluated the weight of primary subcutaneous (s.c) tumor and the number of lung metastases. The phenotypes of splenocytes and blood were examined by flowcytometric analysis. Results: Local RT (4Gy x 2) suppressed the growth of s.c tumor to approximately half of control group although not statistically significantly (p=0.067). Metformin alone did not significantly suppress the tumor growth. However, when combined with RT, tumor weight at day28 was markedly reduced as compared with control group (p&amp;lt;0.01). Many lung metastases developed in all control group mice (Median (M)=120, 22-188) which was not changed by the treatment of metformin alone. The number of metastases tended to be reduced in RT group, although not significant (M=34, 3-78, p=0.12). In comparison, when metformin was combined to RT, the number of lung metastasis was markedly decreased (M=13, 0-70, p&amp;lt;0.01) with no metastases detected in 3 in 10 mice. The ratios of CD4(+) or CD8(+) T cells tended to be reduced in mice treated with RT alone, while increased in mice treated with RT and Metformin. CD49b(+)CD335(+) activated natural killer (NK) cells was significantly increase in combination group (1.1%±0.19% vs 2.6%±1.0%, p&amp;lt;0.05). The ratios PD-1(+) cells tended to be reduced, whereas those of IFN-γ (+) cells in T cell subpopulations after stimulation were significantly increased in mice treated with RT and metformin as compared with those in control group (CD4; 6.8±2.4% vs 10.4%±1.3%, p&amp;lt;0.05; CD8; 24.1±3.6% vs 40.4%±7.2%, p&amp;lt;0.01) Conclusion;Metformin restores T cell exhaustion and increase the number of activated NK cells in irradiated mice which may suppress the growth of lung metastases as abscopal effects. Citation Format: Mineyuki Tojo, Hideyo Miyato, Koji Koinuma, Hisanaga Horie, Hidenori Tsukui, Akira Saito, Yuki Kimura, Yuki Kaneko, Hideyuki Ohzawa, Hironori Yamaguchi, Alan Kawarai Lefor, Naohiro Sata, Joji Kitayama. Combination of metformin and local irradiation efficiently provokes abscopal effects in a murine rectal cancer model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6279.

A software-based approach for calculating spatially resolved radiation exposure for structural radiation protection in nuclear medical imaging

The objective of the work described is the development of a software tool to provide the calculation routines for structural radiation protection from positron and gamma emitters, for example, 18F. The calculation of the generated local annual dose in the vicinity of these radioactive sources supports the engineering of structural measures necessary to meet regulatory guidelines. In addition to accuracy and precision, a visual and intuitive presentation of the calculation results enables fast evaluation. Finally, the calculated results are presented in a contour plot for design, evaluation, and documentation purposes. A python program was used to provide the calculation routines for structural radiation protection. For simplicity, the radiating sources can be considered as point sources. The attenuation of structural elements can be specified or, in the case of lead, calculated by virtue of its thickness. The calculated attenuation for the lead shielding is always slightly underestimated, which leads to a marginally higher calculated local dose rate than would be physically present. With the conservatively determined value, the structural radiation protection can be optimised in accordance with the general rule of as low as reasonably achievable. The pointwise comparison between the software results and the standard procedure for calculating the dose of points in space leads to similar values. In comparison with the general approach of calculating single representative points in the radiation protection area, the visual and intuitive presentation of the results supports the design and documentation of the measures required for structural radiation protection. In the present version of the software, the local dose rate and local annual dose are overestimated by a maximum of 4.5% in the case of lead shields. The proposed software, termed RadSoft, was successfully used to develop the structural radiation protection of a controlled area for hybrid magnetic resonance - positron emission tomography imaging, with the focus herein being on the requirements for PET.

Enhancing the detection sensitivity of a high-resolution β − γ coincidence spectrometer

A high-resolution β − γ coincidence spectrometry system has been set-up and calibrated at the UK CTBT Radionuclide Laboratory (known as GBL15) at AWE. The system has been configured specifically to measure the signatures of radioxenon isotopes that can be indicative of a nuclear explosion. The high purity germanium (HPGe) and PIPSBox detectors have been placed in an ultra-low-background lead shield to reduce the background count-rate and new software allows the combination of signals from four detectors (two HPGe detectors and two silicon-based detectors) to cover a larger solid angle. Measurements of samples of radioxenon isotopes are used to realise an improved detection efficiency and background acquisitions have demonstrated the achievable detection limits to reach 1.3 mBq for 133Xe and ≤0.3 mBq for the metastable isomers 131mXe and 133mXe. Due to the improved energy resolution in both photon and electron detectors, the detection sensitivity remains high in the presence of interfering signals from other radioxenon isotopes, such as those that may be present due to the significant levels of atmospheric radioxenon in parts of the world. This paper summarises the detector setup, efficiency calibration measurements and determination of the limits of detection. This work demonstrates the benefits of high-resolution coincidence detector systems for re-measurement of samples from the CTBT International Monitoring System (IMS) – improved detectability of metastable isomers 131mXe and 133mXe in the presence of 133Xe, compared to the current laboratory system.

Ultrasound Can Determine Joint Distraction During Hip Arthroscopy but Fluoroscopic-Guided Portal Placement Is Superior

PurposeTo compare joint distraction measured on ultrasound (US) with joint space width (JSW) measured on fluoroscopy in hip arthroscopy and to determine whether ultrasound guidance is as safe and effective as fluoroscopy, the current gold standard, for establishing arthroscopic portals.MethodsCadaveric whole-body specimens were positioned supine and subjected to 60 lbs. of unilateral axial traction using a distal femoral Steinman pin. Joint distraction was measured via JSW on fluoroscopic and ultrasound images. A single, fellowship-trained orthopaedic surgeon established anterolateral arthroscopy portals via ultrasound or fluoroscopic guidance in a randomized sequence. Total procedure time, number of times the spinal needle pierced the capsule, and iatrogenic chondral or labral injury were recorded.ResultsTwelve full-body specimens (20 hips) underwent distraction, and 17 hips underwent portal placement with fluoroscopic (n = 8) or ultrasound (n = 9) guidance. JSW measured on ultrasound was significantly less laterally (13.0 vs 9.2 mm, P < .001), apically (16.7 vs 9.2 mm, P < .001), and medially (17.9 vs 9.2 mm, P < .001). Successful portal entry was achieved in every specimen. Average procedure time was 133 ± 51 seconds for the fluoroscopy group and 371 ± 260 seconds for the ultrasound group (P = .026). Fluoroscopic guidance required significantly less needle insertion attempts at 1.13 compared with 3.33 attempts for ultrasound (P = .022). Labral damage was greater in the ultrasound group at 66.67% compared with 12.50% for fluoroscopy (P = .0497).ConclusionsJoint distraction measured on ultrasound can be used to subjectively determine if the joint is adequately distracted in hip arthroscopy. Ultrasound-guided portal placement was associated with more needle insertion attempts, iatrogenic injury of the labrum, and overall procedure time in comparison to fluoroscopic guidance.Clinical RelevanceFluoroscopy is the gold standard to confirm adequate joint distraction, aid in establishing arthroscopy portals, and evaluate resection of the femoral head during hip arthroscopy but exposes the patient to ionizing radiation, requires additional operators in the operating room, and involves the need for a heavy lead shield. Alternatives to fluoroscopy are needed, but ultrasound has not proven superior in our cadaveric model.

Sentinel Node Biopsy Imaging in Breast Cancer: Scatter Reduction Using 3-Dimensionally Printed Lead Shields.

BackgroundPoint of injection scatter (SPI) confounds breast cancer sentinel lymph node detection. Round flat lead shields (FLSs) incompletely reduce SPI, requiring repositioning. We designed lead shields that reduce SPI and acquisition time.MethodsTwo concave lead shields, a semioval lead shield (OLS) and a semispherical lead alloy shield (SLS), were created with a SICNOVA JCR 1000 3D printer to cover the point of injection (patent no. ES1219895U). Twenty breast cancer patients had anterior and anterior oblique imaging, 5 minutes and 2 hours after a single 111 MBq nanocolloid in 0.2 mL intratumoral or periareolar injection. Each acquisition was 2 minutes. Absolute and normalized background corrected scatter counts (CSCs) and scatter reduction percentage (%SR) related to the FLS were calculated. Repositionings were recorded. Differences between means of %SR (t test) and between means of CSC (analysis of variance) with Holm multiple comparison tests were determined.ResultsMean %SR was 91.8% with OLS and 92% using SLS in early images (P = 0.91) and 87.2%SR in OLS and 88.5% in late images (P = 0.66). There were significant differences between CSC using FLS and OLS (P < 0.001) and between FLS and SLS (P < 0.001), but not between OLS and SLS (P = 0.17) in early images, with the same results observed in delayed studies (P < 0.001 in relation to FLS and P = 0.1 between both curved lead shields). Repositioning was required 14/20 times with FLS, 4/20 times with OLS, and 2/20 times with SLS.ConclusionsWe designed 2 concave lead shields that significantly reduce the SPI and repositioning with sentinel lymph node lymphoscintigraphy.

Investigation and ANN-based prediction of the radiation shielding, structural and mechanical properties of the Hydroxyapatite (HAP) bio-composite as artificial bone

This paper focuses on the radiation shielding, structural and specifically mechanical features of the Hydroxyapatite (HAP) bio-composites which can be used instead of the bone and tooth tissues in the human body via FLUKA Monte Carlo Code (FMCC), Phy-X: PSD software, and an analytical method. Since HAP bio-composites are so brittle, their use is limited instead of bone in the human body. This challenging issue persuaded the scientists and researchers to solve the problem by inserting various oxide or dioxide materials into HAP bio-composites. Thus, in this work, TiO2 and CeO2 with different ratios of x = 0, 3, 7.5, 10 wt.% and y = 0, 2, 6, 7.5 wt.% are inserted into HAP bio-composites and thus eight types of S (S1, S2, S3, and S4) and B (B1, B2, B3, and B4) samples are produced. Using Artificial Neural Network (ANN), this study predicts and demonstrates the system's behavior. Outcomes reveal that increasing the TiO2 and CeO2 concentrations in the (100-x) HAP + xTiO2 and (100-y) HAP + yCeO2 bio-composites will improve the gamma photon shielding performance of the S and B samples. Furthermore, the photon and electron spatial maps for simulated geometries related to the S4 sample are extracted by the FLUKA Monte Carlo Code and are represented graphically. The produced electrons with the highest energy are monitored in lead volumes due to various interactions of gamma photons with lead shields. In addition, sharp peaks are reported for Zeff curves related to the B samples which may be due to the K-edge absorption of the Ce in HAP samples. The FLUKA results are in full agreement with the predicted targets via the ANN algorithm. Moreover, increasing the CeO2/TiO2 concentrations in HAP bio-composites will enhance the rigidity of the chosen S and B samples. The rising percentage of the mechanical moduli related to the S and B series vary between 30% and 90% which may be due to the relationship between the density of the selected HAP bio-composites and mechanical moduli.

Evaluation of thyroid radiation dose during abdominal Computed Tomography procedures and dose reduction effectiveness of thyroid shielding

IntroductionDuring abdominal Computed Tomography (CT) studies, vicinity organs receive a dose from scatter radiation. The thyroid is considered an organ at greater risk due to high radiosensitivity. MethodsThe primary objective of this study was to determine the entrances surface dose (ESD) to the thyroid during abdominal CT studies and to evaluate the efficiency of dose reduction by lead shielding. The calibrated thermoluminescence dosimeter (TLD) chips were used to measure the ESD during 180 contrast-enhanced (CE) and non-contrast-enhanced (NC) abdominal CT studies in the presence and absence of lead shielding. ResultsThyroid shielding reduces the ESD by 72.3% (0.55 mGy), 86.5% (2.95 mGy) and 64.0% (2.24 mGy) during NC, 3–phase and 4–phase abdominal CT scans. Also, the patient height was identified as a parameter that inversely influenced the thyroid dose, proving that the taller patients receive less dose to the thyroid. Regardless, the scan parameters such as time and display field of view (DFOV) positively impact the thyroid dose. ConclusionLead shielding can prevent the external scatter reaching the thyroid region by 64%–87% during the non-vicinity scans such as abdomen CT. However, the actual dose saving lies between 0.2% and 0.4%, compared to the total effective dose of the whole CT procedure. Implications for practiceThe thyroid shield can effectively reduce external scatter radiation during abdominal CT procedures. However, the dose saving is insignificant compared to the total effective dose from the whole examination. Therefore, the use of thyroid shielding should be carefully evaluated during CT abdomen procedures.

Effect of 3D Printing Material and Thickness on CT Image Quality and Shielding

In order to proceed with an accurate CT examination and to prevent unnecessary exposure during CT examination, the need for an appropriate fixing device and shielding device is required. In this study, 3D printing technology, a next-generation technology, is applied to radiation science to investigate the effect on CT images and shielding effects through filaments that can be easily obtained using a general 3D printer of the melt-stacking modeling method. Using a 3D printer, a phantom made of four materials: PLA (Poly Lactic Acid), Bronze, Carbon, and eSteel was produced cylindrical shape. Statistical analysis was performed using a non-parametric test method, and the significance level (α) was set to 0.05 (5%). As a result of the measurement, the PLA filament material had the least effect on the CT image quality. After placing the dosimeter inside the phantom, when the shielding rate was measured for each material through scanning, the eSteel material had the highest shielding rate and showed a shielding rate equivalent to or higher than that of the lead shielding device currently used in clinical practice.