Lead Shielding Research Articles

Monte Carlo Simulation of Radiotherapy for Breast Cancer in Pregnant Patients: How to Reduce the Radiation Dose and Risks to Fetus?

This study estimated the fetal dose and risks from radiotherapy for breast cancer with 6 MV X-rays. Breast irradiation was simulated with the MCNP code using two mathematical phantoms corresponding to patients in the early and middle periods of pregnancy. Monte Carlo simulations were performed to determine the appropriate fetal shielding. For a 50-Gy tumor dose, the unshielded fetal dose reached up to 133.1 mGy. Fetal protection with a lead shield of dimensions 30×30×5 cm3 placed besides the treatment couch resulted in maximum doses of 22.0 and 70.3 mGy at the first and second trimesters of gestation, respectively. These shielded fetal doses may be associated with a fatal cancer risk during childhood up to 0.42% and a maximum probability for the appearance of heritable effects of 0.17%. The use of fetal shielding ensures the absence of deterministic effects from radiotherapy during the first 24 weeks of gestation.

86: Using Optical Scanner and 3D Printer Technology to Create Lead Shielding for Radiotherapy of Facial Skin Cancer with Low Energy Photons: An Exciting Innovation

86: Using Optical Scanner and 3D Printer Technology to Create Lead Shielding for Radiotherapy of Facial Skin Cancer with Low Energy Photons: An Exciting Innovation

Poster – 39: Using Optical Scanner and 3D Printer Technology to Create Lead Shielding for Radiotherapy of Facial Skin Cancer with Low Energy Photons

Purpose:Treatment of skin cancers of the face using orthovoltage radiotherapy often requires lead shielding. However, creating a lead shield can be difficult because the face has complex and intricate contours. The traditional process involved creating a plaster mould of the patient's face can be difficult for patients. Our goal was to develop an improved process by using an optical scanner and 3D printer technology.Methods:The oncologist defined the treatment field by drawing on each patient's skin. Three‐dimensional images were acquired using a consumer‐grade optical scanner. A 3D model of each patient's face was processed with mesh editing software before being printed on a 3D printer. Using a hammer, a 3 mm thick layer of lead was formed to closely fit the contours of the model. A hole was then cut out to define the field.Results:The lead shields created were remarkably accurate and fit the contours of the patients. The hole defining the field exposed only a minimally sized site to be exposed to radiation, while the rest of the face was protected. It was easy to obtain perfect symmetry for the definition of parallel opposed beams.Conclusion:We are routinely using this technique to build lead shielding that wraps around the patient as an alternative to cut‐outs. We also use it for treatment of the tip of the nose using a parallel opposed pair beams with a wax nose block. We found this technique allows more accurate delineation of the cut‐out and a more reproducible set‐up.

X-ray Attenuation and Reduction of Backscattered Radiation

This paper reports the comparative study of X-ray attenuation using different materials which can be utilized to design anti-backscattered grids and radiation protection shields. The characteristics of X-ray attenuation in several materials, namely, lead, copper, iron steel, and aluminum, are investigated under diverse exposure parameters to measure their ability to attenuate incident X-ray and their capability to reduce backscattered X-ray. Lead and iron steel shields exhibit the best abilities in attenuating X-ray, whereas aluminum shield shows the least attenuation ability. This study proposes a design of a unique method for assessing the backscatter X-ray dose. The iron steel grid based on iron steel plate provides the best value in reducing backscattered radiation (up to 34.78%) compared with other conventional plate materials.

A Low Background Gamma Ray Spectrometer with Anticosmic Shielding

The article describes a gamma ray spectrometer protected by a lead shield (Model 747E Canberra lead shield) and an active shield made of an 80~cm \(\times\) 80~cm \(\times\) 3~cm plastic scintillator plate in anticoincidence on top of the lead shield. The detector used as low background gamma-spectrometer is a high purity Germanium crystal of model GC2018 Canberra. The background count rate currently achieved (30-2400 keV) is 1.27 cps without anticoincidence. The level of background suppression obtained from the active protection is 0.80 overall and about 0.43 for the 511 keV gamma line. The gamma ray spectrometer is installed and operated in the Nuclear Laboratory, Department of Nuclear Physics, University of Science, HCMC-Vietnam National University.

Determination of 137Cs activity in soil from Qatar using high-resolution gamma-ray spectrometry

With interest in establishing baseline concentrations of 137Cs in soil from the Qatarian peninsula, we focus on determination of the activity concentrations in 129 soil samples collected across the State of Qatar prior to the 2011 Fukushima Dai-ichi nuclear power plant accident. As such, the data provides the basis of a reference map for the detection of releases of this fission product. The activity concentrations were measured via high-resolution gamma-ray spectrometry using a hyper-pure germanium detector enclosed in a copper-lined passive lead shield that was situated in a low-background environment. The activity concentrations ranged from 0.21 to 15.41Bq/kg, with a median value of 1Bq/kg, the greatest activity concentration being observed in a sample obtained from northern Qatar. Although it cannot be confirmed, it is expected that this contamination is mainly due to releases from the Chernobyl accident of 26 April 1986, there being a lack of data from Qatar before the accident. The values are typically within but are sometimes lower than the range indicated by data from other countries in the region. The lower values than those of others is suggested to be due to variation in soil characteristics as well as metrological factors at the time of deposition.

Use of 3D printing for construction of custom bolus in external beam radiotherapy

Aim To create a patient specific mould of a treatment area for bolus fitting using a 3D printer and compare it with conventional bolus. Methods A patient with a right medial Basal Cell Carcinoma (BCC) lesion on the forehead extending to the upper nose was presented for electron external beam radiotherapy (50 Gy in 20#). A conventional custom bolus 0.5 cm thick using Aquaplast™ thermoplastic pellets was made on the treatment area. Following this, a CT simulation using 2.5 mm slice thickness was performed. DICOM image files from the CT simulation for the treatment area were processed using 3D printing software to allow for a solid plastic mould of the patient’s contour to be printed using a 3D printer. The mould was used to fashion form fitting bolus, 1cm thick, with custom lead lens shielding included. The mould and bolus were CT scanned to ensure there were no air gaps and that the lead shielding was in the correct position. Comparison of the dosimetric performance of the conventional bolus and the bolus designed on the 3D printed mould will be presented. A 6 MeV electron plan for each bolus will be performed using electron Monte Carlo algorithm. Conclusion This work has demonstrated the feasibility of the use of 3D printing to assist in the construction of patient specific bolus for the treatment of superficial lesions. The bolus created on the 3D printed mould demonstrated less air gaps which improved the dosimetric performance when compared with a conventional bolus. To create a patient specific mould of a treatment area for bolus fitting using a 3D printer and compare it with conventional bolus. A patient with a right medial Basal Cell Carcinoma (BCC) lesion on the forehead extending to the upper nose was presented for electron external beam radiotherapy (50 Gy in 20#). A conventional custom bolus 0.5 cm thick using Aquaplast™ thermoplastic pellets was made on the treatment area. Following this, a CT simulation using 2.5 mm slice thickness was performed. DICOM image files from the CT simulation for the treatment area were processed using 3D printing software to allow for a solid plastic mould of the patient’s contour to be printed using a 3D printer. The mould was used to fashion form fitting bolus, 1cm thick, with custom lead lens shielding included. The mould and bolus were CT scanned to ensure there were no air gaps and that the lead shielding was in the correct position. Comparison of the dosimetric performance of the conventional bolus and the bolus designed on the 3D printed mould will be presented. A 6 MeV electron plan for each bolus will be performed using electron Monte Carlo algorithm. This work has demonstrated the feasibility of the use of 3D printing to assist in the construction of patient specific bolus for the treatment of superficial lesions. The bolus created on the 3D printed mould demonstrated less air gaps which improved the dosimetric performance when compared with a conventional bolus.

Dose Reduction to the Thyroid Gland in Pediatric Chest Radiography

Background It is remain a main concern that pediatric chest radiographies contribute to the significant radiation exposure to the thyroid gland as a more susceptible organ to radiation induced cancer. The aim of this study was to assessment the entrance surface dose (ESD) of pediatric chest radiography compared to the diagnostic reference levels (DRL) and evaluation the efficacy of the lead (Pb) shield in radiation dose reduction to the thyroid gland. Materials and Methods After assessing each patient against specific inclusion-exclusion criteria, 40 pediatric patients who were undergoing anterior-posterior (AP) projection of the chest x-ray were considered eligible for this study. The ESD of the chest and also ESD of thyroid gland with and without a 1 mm butterfly-shaped lead shield which placed on the thyroid gland were measured using high sensitive thermo luminescent dosimeters (TLD-GR 200). Results The average of ESD for chest radiography was 0.068+ 0.04 mGy (0.021 - 0.232 mGy). The unshielded average thyroid ESD was 0.065+0.053 mGy compared to the shielded average thyroid ESD of 0.001 + 0.034 mGy. The use of Pb-shield produced a statistically significant decrease in the average thyroid dose by about 97% (P< 0.001). Conclusion It seems that the Pb-thyroid shield has potential to reduced radiation dose significantly without compromising image quality. The use of thyroid shield in the AP projection of pediatric chest radiography may be an effective method to reduce patient's radiation risk and its usage should be encouraged. Key Words: chest x-ray, pediatrics, radiation exposure, thyroid gland

Development of a guinea pig cutaneous radiation injury model using low penetrating X-rays

Purpose: A guinea pig skin model was developed to determine the dose-dependent response to soft X-ray radiation into the dermis.Materials and methods: X-ray exposure (50 kVp) was defined to a 4.0 × 4.0 cm area on the lateral surface of a guinea pig using lead shielding. Guinea pigs were exposed to a single fraction of X-ray irradiation ranging from 25–79 Gy via an XRAD320ix Biological Irradiator with the collimator removed. Gross skin changes were measured using clinical assessments defined by the Kumar scale. Skin contracture was assessed, as well as histological evaluations.Results: Loss of dermal integrity was shown after a single dose of soft X-ray radiation at or above 32 Gy with the central 2.0 × 2.0 cm of the exposed site being the most affected. Hallmarks of the skin injury included moist desquamation, ulceration and wound contracture, as well as alterations in epithelium, dermis, muscle and adipose. Changes in the skin were time- and radiation dose-dependent. Full-thickness injury occurred without animal mortality or gross changes in the underlying organs.Conclusions: The guinea pig is an appropriate small animal model for the short-term screening of countermeasures for cutaneous radiation injury (CRI).

SU‐G‐IeP3‐02: Characteristics of In‐Vivo MOSFET Dosimeters for Diagnostic X‐Ray Low‐Dose Measurements

Purpose:To correct in‐vivo metal‐oxide‐semiconductor field‐effect transistor (MOSFET) dosimeters dependence on X‐ray energy, dose and dose rate, and temperature in order to measure doses or exposures on several anatomic points of interest undergoing some routine radiographs.Methods:A mobile MOSFET system (BEST Medical) was carefully calibrated with X‐ray at kVp of 70, 80, 100, 120, and 138 kVp, phantom temperatures at 0, 21, and 43 oC, and exposure range from 0.01 to 10 R confirmed with Raysafe and RadCal dosimeters. The MOSFETS were placed on the midline bladder or uterus, left pelvic iliac artery, left abdominal above iliac crest, abdominal midline anterior at inferior margin of stomach, and left pectoral of a large and a small body‐size cadavers undergoing AP/PA chest and lumber spine radiographs using manual and automatic exposure control (AEC) with and without lead shielding. MOSTFETs and TLD chips were also placed on the stomach, sigmoid, pubic symphysis, left and right pelvic walls of another cadaver for AP pelvic manual or AEC radiography prior to and after a left hip metal implant.Results:Individual MOSFET detectors had various low‐dose limits in ranged from 0.03 to 0.08 R, nonlinear response to X‐ray energy, and significant temperature effect of 15%. By accumulating 10 manual exposures and 20 AEC exposures, we achieved dose measured accuracy of 6%. There were up to 8 fold increases for AEC exposure of spine and chest X‐ray procedure from no shielding to with shielding. For pelvic radiography, exposure to public symphysis was the highest even higher than that of the skin. After hip implant, AEC pelvic radiograph increase exposure by 30 to 200% consistent with results of TLDs.Conclusion:Dependence of energy, temperature and dose limit were accurately corrected. We have found significant exposure for those clinical pr°ocedures and the study provided evidences for developing new clinical procedures.

SU‐F‐I‐72: Evaluation of the Ancillary Lead Shielding for Optimizing Radiation Protection in the Interventional Radiology Department

Purpose:The rising complexity of interventional fluoroscopic procedures has resulted in an increase of occupational radiation exposures in the interventional radiology (IR) department. This study assessed the impact of ancillary shielding on optimizing radiation protection for the IR staff.Methods:Scattered radiation measurements were performed in two IR suites equipped with Axiom Artis systems (Siemens Healthcare, Erlangen, Germany) installed in 2006 and 2010. Both rooms had suspended ceiling‐mounted lead‐acrylic shields of 75×60 cm (Mavig, Munich, Germany) with lead equivalency of 0.5 mm, and under‐table drapes of 70×116 cm and 65×70 cm in the newer and the older room respectively. The larger skirt can be wrapped around the table's corner and in addition the newer suite had two upper shields of 25×55 cm and 25×35 cm. The patient was simulated by 30 cm of acrylic, air kerma rate (AKR) was measured with the 180cc ionization chamber (AccuPro Radcal Corporation, Monrovia, CA, USA) at different positions. The ancillary shields, x‐ray tube, image detector, and table height were adjusted by the IR radiologist to simulate various clinical setups. The same exposure parameters were used for all acquisitions. AKR measurements were made at different positions relative to the operator.Results:The AKR measurements demonstrated 91–99% x‐ray attenuation by the drapes in both suites. The smaller size of the under‐table skirt and absence of the side‐drapes in the older room resulted in a 20–50 fold increase of scattered radiation to the operator. The mobile suspended lead‐acrylic shield reduced AKR by 90–94% measured at 150–170 cm height. The recommendations were made to replace the smaller under‐table skirt and to use the ceiling‐mounted shields for all IR procedures.Conclusion:The ancillary shielding may significantly affect radiation exposure to the IR staff. The use of suspended ceiling‐mounted shields is especially important for reduction of interventional radiologists’ cranial radiation.

TH-CD-201-02: A Monte Carlo Investigation of a Novel Detector Arrangement for the Energy Spectrum Measurement of a 6MV Linear Accelerator

Purpose: Direct measurement of the energy spectrum of a 6MV linear accelerator has not been successful due to the high fluence rate, high energy nature of these photon beams. Previous work used a Compton Scattering (CS) spectrometry setup with a shielded spectrometer for spectrum measurements. Despite substantial lead shielding, excessive pulse pile-up was seen. MCNP6 transport code was used to investigate the feasibility and effectiveness of performing measurements using a novel detector setup. Methods: Simulations were performed with a shielded high-purity germanium (HPGe) semiconductor detector placed in the accelerator vault's maze, with a 2 cm diameter collimator through a 92 cm thick concrete wall. The detector was positioned 660 cm from a scattering rod (placed at isocenter) at an angle of 45° relative to the central axis. This setup was compared with the shielded detector positioned in the room, 200 cm from the scattering rod at the same CS angle. Simulations were used to determine fluence contributions from three sources: (1) CS photons traveling through the collimator aperture, the intended signal, (2) CS scatter photons penetrating the detector shield, and (3) room-scattered photons penetrating the detector shield. Variance reduction techniques including weight windows, DXTRAN spheres, forced collisions, and energy cutoffs were used. Results: Simulations showed that the number of pulses per starting particle from an F8 detector tally for the intended signal decreased by a factor of 102 when moving the detector out of the vault. This reduction in signal was amplified for the unwanted scatter signal which decreased by up to a factor of 109. Conclusion: This work used MCNP6 to show that using a vault wall to shield unwanted scatter and increasing isocenter-to-detector distance reduces unwanted fluence to the detector. This study aimed to provide motivation for future experimental work using the proposed setup.

Cosmogenic and primordial radioisotopes in copper bricks shortly exposed to cosmic rays

Cosmogenic activation is the most common source of radioactivity in copper, being 60 Co the most significant because of its long half-life (5.27 y) and saturation activity at sea level of 1 mBq/kg. Copper bricks, which had been exposed to cosmic rays for 41 days after their casting, were used to replace the internal 10 cm of the lead shielding of a HPGe detector placed at the Canfranc Underground Laboratory. We describe the outcome of the new shielding and the cosmogenic and primordial radioisotopes observed.

MP23-12 INTRAOPERATIVE RADIATION THERAPY DURING GENITOURINARY SURGERY: THE IMPORTANCE OF SPECIMEN MARGIN STATUS IN IMPROVING SURVIVAL

You have accessJournal of UrologySurgical Technology & Simulation: Instrumentation & Technology I1 Apr 2016MP23-12 INTRAOPERATIVE RADIATION THERAPY DURING GENITOURINARY SURGERY: THE IMPORTANCE OF SPECIMEN MARGIN STATUS IN IMPROVING SURVIVAL Meera Chappidi, Max Kates, Zeyad Schwen, Nikolai Sopko, Phuoc Tran, Nita Ahuja, Stephanie Terezakis, Phillip Pierorazio, and Trinity Bivalacqua Meera ChappidiMeera Chappidi More articles by this author , Max KatesMax Kates More articles by this author , Zeyad SchwenZeyad Schwen More articles by this author , Nikolai SopkoNikolai Sopko More articles by this author , Phuoc TranPhuoc Tran More articles by this author , Nita AhujaNita Ahuja More articles by this author , Stephanie TerezakisStephanie Terezakis More articles by this author , Phillip PierorazioPhillip Pierorazio More articles by this author , and Trinity BivalacquaTrinity Bivalacqua More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2016.02.734AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Intraoperative radiation therapy (IORT) is used to provide effective local control (LC) for patients with locally advanced or recurrent tumors. Since 2006, our institution has performed IORT for pelvic and retroperitoneal soft tissue malignancies. We sought to assess outcomes of IORT cases in which there was genitourinary (GU) involvement. METHODS We retrospectively reviewed patients from 2006-2015 who underwent IORT with GU involvement. Case selection for IORT included those in which pre-op EBRT could not obtain LC without excessive toxicity or pre-op imaging suggested difficulty obtaining negative surgical margins due to proximity to vital structures, bladder, or bowel. To provide IORT, the area at risk for local recurrence is measured following tumor resection and an appropriately sized Freiburg flap is created with linear, connected silicone rubbers balls to provide a uniform radiation dose (10-16 Gy) to the targeted area while using lead shields to protect surrounding structures. The primary endpoint was overall survival (OS) with secondary endpoints of recurrence free survival (RFS, defined as local recurrence in the surgical bed), 90-day readmission rate and Clavien grade IV or V complication rates. RESULTS Of the 158 patients who underwent IORT, 87 cases (55.1%) involved GU surgery. The most common procedures were 33 (37.9%) radical cystectomies and 21 (24.1%) radical nephrectomies. With a median follow-up time of 21.6 months, the 2-year OS was 71% [95% confidence interval (CI) 57-81%]. OS for patients with positive and negative margins was 54% [CI 29-73%] vs. 81% [CI 62-91%] (p=0.04) respectively. The 2-year RFS for patients with negative margins was 73% [CI 55-85%]. In a multivariate model controlling for age and receipt of neoadjuvant chemotherapy, margin status was the only predictor of OS [HR=2.10 (1.32-9.95)]. The 90-day readmission rate was 44.2% and 90-day rate of Clavien IV complications was 16.3% with no deaths in the cohort. CONCLUSIONS IORT is a safe and feasible treatment for high-risk patients undergoing complex surgery for sarcomas and other soft tissue malignancies with GU involvement. While IORT can improve LC, it does not serve as a substitute for adequate surgical control as surgical margin is still an important predictor of survival. Effort should be taken to achieve a negative margin in order to maximize the LC achieved with IORT. As this mode of cancer therapy expands into other sectors of urologic oncology, future studies will need to address the benefits of this cancer therapy versus additional local toxicity. © 2016FiguresReferencesRelatedDetails Volume 195Issue 4SApril 2016Page: e266 Advertisement Copyright & Permissions© 2016MetricsAuthor Information Meera Chappidi More articles by this author Max Kates More articles by this author Zeyad Schwen More articles by this author Nikolai Sopko More articles by this author Phuoc Tran More articles by this author Nita Ahuja More articles by this author Stephanie Terezakis More articles by this author Phillip Pierorazio More articles by this author Trinity Bivalacqua More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Röntgenophobia?

Wilhelm Röntgen discovered x-rays (just over 120 years ago), as well as the protective effects of lead shields. Today we still need to use radiography, while protecting growing children. In its clinical report issued last year on the evaluation of suspected child abuse, the American Academy of Pediatrics recommended that a skeletal survey be performed when there is a concern for abuse in all children less than 2 years of age, as well as in older children at the discretion of the treating physician (Pediatrics 2015;135:e1337-54). Should we worry about radiation exposure from a skeletal survey? In this issue of The Journal, Berger et al use a Monte Carlo simulation to derive effective dose from a skeletal survey in an infant. Calculated dose was 0.2 mSv (Sieverts describe tissue absorption better than the legacy exposure unit, Röntgen). Put another way, 0.2 mSv approximates the dose we experience flying across the US by airplane, and is far less than 3 mSv a woman receives from a screening mammogram or the 20 mSv a neonate experiences from computed tomography of the abdomen. Berger et al calculated the risk of exposure-induced cancer death from a skeletal survey to be 2 to 5/100 000/year, close to or slightly above the background mortality rate of childhood cancer. Although a skeletal survey could perhaps double a child's risk of cancer death, or escalate slightly future cancer mortality as an adult, the absolute risk is rather tiny. When there is a reasonable clinical indication for a skeletal survey, with benefits greater than risks, we should avoid röntgenophobia. Article page 310▶ Effective Radiation Dose in a Skeletal Survey Performed for Suspected Child AbuseThe Journal of PediatricsVol. 171PreviewEffective dose of a skeletal survey in infants using digital radiography was estimated to be 0.2 mSv using Monte Carlo simulation. Radiation risk from this procedure is, therefore, low. Radiation concern should not be an overriding factor when deciding whether skeletal survey is needed in cases of possible physical abuse. Full-Text PDF

How Much Does Lead Shielding during Fluoroscopy Reduce Radiation Dose to Out-of-Field Body Parts?

BackgroundFluoroscopy technologists routinely place a lead shield between the x-ray table and the patient's gonads, even if the gonads are not directly in the x-ray field. Internal scatter radiation is the greatest source of radiation to out-of-field body parts, but a shield placed between the patient and the x-ray source will not block internal scatter. Prior nonfluoroscopy research has shown that there is a small reduction in radiation dose when shielding the leakage radiation that penetrates through the collimator shutters. The goal of this in vitro study was to determine if there was any radiation dose reduction when shielding leakage radiation during fluoroscopy. MethodsThis was an in vitro comparison study of radiation doses using different collimation and shielding strategies during fluoroscopy. Ionization chamber measurements were obtained during fluoroscopy of an acrylic block with and without collimation and shielding. Ionization chamber readings were taken in-field at 0 cm and out-of-field at 7.5, 10, and 12.5 cm from beam center. ResultsCollimation reduced 87% of the out-of-field radiation dose, and the remaining measurable dose was because of internal scatter. The radiation dose contribution from leakage radiation was negligible, as there was not any measurable radiation dose difference when shielding leakage radiation, with P value of .48. ConclusionThese results call into question the clinical utility of routinely shielding out-of-field body parts during fluoroscopy.

The effects of device position on the operator's radiation dose when using a handheld portable X-ray device.

Handheld X-ray devices are now offered in dental practice. Handheld X-ray units challenge the concept of a restricted access to the "controlled area" as they are held by the operator. Although an integral lead shield is provided, the distance from the body is variable, dependent on how the device is held. The aim of this article was to investigate the level of operator dose when using a handheld X-ray device in various positions. A NOMAD Pro™ Handheld X-ray system (Aribex Inc., Charlotte, NC) fitted with a remote control and mounted on a tripod was used in this study. A maxillofacial phantom ATOM(®) Max Dental and Diagnostic Phantom, model 711 HN (CIRS Inc., Norfolk, VA) was used to simulate the patient's head position. A mannequin was used to represent the operator. Pre-calibrated thermoluminescent dosemeters (TLDs) (Qados, Agar Scientific, Stansted, UK) were placed on the mannequin close to the eyes and at the level of thyroid, trunk, waist, hand (right finger + left palm) and feet, and three TLDs were used for background radiation. Three test scenarios were investigated; Position 1, close to operators' body and parallel to the ground; Position 2, away from the body with the arms fully extended (approximately 40 cm distance) and parallel to the ground; Position 3, perpendicular to the ground while the arms are partially extended. 30 exposures each of 1 s were performed in each test. Background radiation was measured at 0.0110 mGy. The highest exposure after subtracting background radiation was recorded on the palm of the left hand (0.0310 mGy) at Position 3. The estimated dose to the operator was calculated based on an average workload of 100 intraoral radiographs weekly for a dental practitioner working 46 weeks a year. There is a negligible increase in operator exposure levels using handheld X-ray devices which remain well below the recommended levels of the Ionizing Radiation Regulations 1999. They could however represent an increase from what should be a nil exposure when using a wall-mounted machine. The position of the device relative to the operator has a significant effect on the overall operator's radiation exposure. The use of personal dosemeters is highly recommended to ensure a continuity of low radiation dose exposure. Furthermore, guidance, training and protocols on usage must be in place, strictly adhered to and regular audits are necessary to ensure compliance.

Radiation Protection Awareness and Practices in Cameroon Dental Health Care Facilities

Introduction: Strict adherence to the radiation exposure guidelines is mandatory when using X-rays for disease detection in order to minimize its harmful effects. The objective of this study was to determine the radiation protection awareness and practices in Cameroon Dental Health care facilities. Materials and Methods: This multiregional questionnaire-based study was conducted among dental clinics located in the capitals of the Littoral, Central, South West, and North West regions of Cameroon. Results: The majority 63 (90.0%) of the participants reported awareness of the adverse effects of radiation on patients and dental professionals. Only 22.9% reported awareness of the agency in-charge of X-ray protection and standardization in Cameroon. The majority of the X-ray machine were located inside the operating room of the dental clinic. The most vulnerable group to the effects of radiation reported was pregnant women while the most vulnerable part of the body to the effects of radiation reported was reproductive organs. The lead shield was the dominantly utilized radioprotective device among the participants. Six meters away from the direction of radiation was the most frequently adopted radioprotection positioning among the participants. Conclusion: Data from this study revealed that many aspects of radiation protection in dental radiology is suboptimal; hence, specific training in education and training in radiation protection is deemed necessary among dental health care professionals in Cameroon. It is recommended that Cameroon National Radiation Protection Agency should establish radiation protection guidelines in dental health care delivery.

Determination of the activity concentration levels of the artificial radionuclide137Cs in soil samples collected from Qatar using high-resolution gamma-ray spectrometry

The goal of this study was to establish the first baseline measurements for radioactivity concentration of the artificial radionuclide [Formula: see text]Cs in soil samples collected from the Qatarian peninsula. The work focused on the determination of the activity concentrations levels of man-made radiation in 129 soil samples collected across the landscape of the State of Qatar. All the samples were collected before the most recent accident in Japan, “the 2011 Fukushima Dai-ichi nuclear power plant accident”. The activity concentrations have been measured via high-resolution gamma-ray spectrometry using a hyper-pure germanium detector situated in a low-background environment with a copper inner-plated passive lead shield. A radiological map showing the activity concentrations of [Formula: see text]Cs is presented in this work. The concentration was[Formula: see text]found to range from 0.21 to 15.41 Bq/kg. The highest activity concentration of [Formula: see text]Cs was observed in sample no. 26 in North of Qatar. The mean value was found to be around 2.15 ± 0.27 Bq/kg. These values lie within the expected range relative to the countries in the region. It is expected that this contamination is mainly due to the Chernobyl accident on 26 April 1986, but this conclusion cannot be confirmed because of the lack of data before this accident.

Simple shielding reduces dose to the contralateral breast during prone breast cancer radiotherapy

Our goal was to design a prone breast shield for the contralateral breast and study its efficacy in decreasing scatter radiation to the contralateral breast in a prone breast phantom setup receiving radiation therapy designed for breast cancer. We constructed a prone breast phantom setup consisting of (1) A thermoplastic mask with a left-sided depression created by a water balloon for a breast shape; (2) 2 plastic bags to hold water in the thermoplastic mask depression; (3) 2000mL of water to fill the thermoplastic mask depression to create a water-based false breast; (4) 1-cm thick bolus placed in the contralateral breast holder; (5) 2 lead (Pb) sheets, each 0.1-cm thick for blocking scatter radiation in the contralateral bolus-based false breast; (6) a prone breast board to hold the thermoplastic mask, water, bolus, and lead; (7) 9cm solid water on top of the breast board to simulate body; (8) a diode was used to verify dose for each treatment field of the treated water-based breast; (9) metal–oxide–semiconductor-field effect transistor (MOSFET) dosimeters to measure dose to the contralateral bolus-based breast. The phantom prone breast setup was CT simulated and treatment was designed with 95% isodose line covering the treated breast. The maximum dose was 107.1%. Megavoltage (MV) port images ensured accurate setup. Measurements were done using diodes on the treated water-based breast and MOSFET dosimeters at the medial and lateral sides of the contralateral bolus-based breast without and with the Pb shield. Five treatments were done for each of the 3 data sets and recorded individually for statistical purposes. All treatments were completed with 6MV photons at 200cGy per treatment. The dose contributions from each of the 3 data sets including 15 treatments total without and with the prone lead shield to the medial and lateral portions of contralateral bolus-based breast were averaged individually. Unshielded dose means were 37.11 and 2.94cGy, and shielded dose means were 12.68 and 1.54cGy, respectively. When comparing medial and lateral portions of the contralateral bolus-based doses without and with Pb, the shield significantly reduced dose to both sides of the contralateral breast (medial p = 2.64 × 10−14, lateral p = 4.91 × 10−6). The prone 0.2-cm Pb shield significantly reduced scatter dose to the contralateral breast on the order of 2 to 3 times. Reductions may be clinically relevant for women younger than 45 years by decreasing the risk of contralateral radiation-induced breast cancer in patients receiving radiation therapy for breast cancer. This shield is simple as it would be a part of the prone breast board during treatments, but future studies are warranted for safety and efficacy clinically.