Radiation Protection Requirements Research Articles

Radiation protection relevant to nuclear chemistry in the light of recent international recommendations

The paper discusses the requirements for radiation protection in nuclear chemistry which are related to the recent recommendations of the International Commission on Radiological Protection. These recommendations have been incorporated into the updated International Basic Safety Standards issued by the International Atomic Energy Agency as well as into new relevant Directives of the European Union based on which the legislation of the EU Member States has to be updated. The new international requirements are aimed at the further improvement of strict control of radiation sources, their safety and security as well as the minimization of exposure to workers and members of the public. It would be appropriate for the nuclear chemistry community to become familiar with the changes in radiation protection so that it would be easier for nuclear chemists to adopt new requirements in their everyday practical work.

Protección radiológica a trabajadores y público en instalaciones que operan radioisotopos industriales

En este trabajo se verifica el cumplimiento que las tasas de dosis, en los alrededores de una instalación que opera radioisótopos de uso industrial con actividades de hasta 50 Ci. También se verifica si cumple con los requisitos exigidos por los protocolos internacionales para la protección radiológica de trabajadores y público en general. En este caso se validó la instalación del Laboratorio de Radiaciones Nucleares de la Universidad Pedagógica y Tecnológica de Colombia. El procedimiento consistió en construir la geometría de la instalación siguiendo las dimensiones y materiales usados en la construcción mediante levantamiento topográfico. Haciendo uso del código de simulación MCNPX, se ubicaron detectores en diversos puntos dentro y fuera de la instalación, los que permitieron calcular la fluencia de fotones que atravesaba las diferentes barreras de contención diseñadas para este propósito. Usando los respectivos coeficientes de conversión establecidos por la comisión Internacional de Protección Radiológica (ICRP-74, 1997), para la conversión de fluencia a dosis, se consiguió calcular las diferentes tasas de dosis en dichos puntos, las que fueron comparadas con mediciones experimentales. Los resultados encontrados corroboran que la instalación cumple con los requisitos en cuanto a protección radiológica y lo mas importante, sugieren algunas recomendaciones de tipo preventivo.

New Requirements for Radiation Protection in X-Ray Surgery

New ways to reduce the radiation load on patients and medical personnel during X-ray-monitored surgery are suggested.

Scatter radiation intensities around full-field digital mammography units.

The aim of this study was to investigate the scatter radiation intensity around digital mammography systems and apply these data to standard shielding calculations to reveal whether shielding design of existing breast screening rooms is adequate for the use of digital mammography systems. Three digital mammography systems from GE Healthcare, Hologic and Philips were employed in the study. A breast-equivalent phantom was imaged under clinical workload conditions and scatter radiation intensities around the digital mammography systems were measured for a range of angles in three planes using an ionisation chamber. The results were compared with those from previous studies of film-screen systems. It may be deduced from the results that scattering in the backward direction is significant for all three systems, while scattering in the forward direction can be significant for some planes around the GE and Hologic systems. Measurements at typical clinical settings on each system revealed the Philips system to have markedly lower scatter radiation intensities than the other systems. Substituting the measured scattered radiation intensity into shielding calculations yielded barrier requirements similar to those already in place at the screening centres operating these systems. Current radiation protection requirements based on film-screen technology remain sufficient when applied to rooms with digital mammography installations and no alteration is required to the structural shielding.

WE‐B‐213CD‐02: NCRP‐168 as a Training and Operational Resource

NCRP Report 168 provides guidance on facilities as well as on patient and worker radiation safety during fluoroscopically guided interventions (FGI). Fluoroscopy is widely used in surgical settings in ways that can be comparable to its use in other FGI procedures. Surgical fluoroscopes range from simple mobile analog C‐arms, heavy mobiles with most of characteristics of a fixed system, to state of the art fixed systems. Patient and worker radiation safety concerns along with training, credentialing, and privileging of surgical staff are similar to those for all other FGI procedures. Recommendations relevant to the surgical setting will be reviewed. Two key recommendations are: An FGI procedure shall be performed or supervised only by a physician or other medical professional with fluoroscopic and clinical privileges appropriate to the specific procedure. An FGI procedure shall be performed or supervised only by a physician or other medical professional with fluoroscopic and clinical privileges appropriate to the specific procedure. Other topics such as responsibilities of all workers for their own radiation protection, those of the attending surgeon for patient dose management and follow‐up, and those of the facility for providing necessary resources will also be briefly discussed.Learning Objectives:1. To understand the responsibilities of surgeons and others working in a FGI environment toward patient and worker radiation safety.2. To understand radiation protection requirements and actions necessary for personal safety while radiation is in use in a surgical environment3. To gain familiarity with the knowledge base needed to safely perform or supervise FGA procedures in the surgical environment.

Development of two mobile laboratories for a routine and accident monitoring of internal contamination

To provide medical surveillance of workers exposed to risk of internal contamination, IRSN (French Institute for Radiological Protection and Nuclear Safety) has developed two mobile laboratories for on-site monitoring. The laboratories are unique in Europe. They meet the new radiation protection requirements for nuclear medicine departments and radiological emergency response. Details of the design, calibration procedures and performance characteristics of these systems in measurements of various types of organs (thyroid, lung and whole body) are described. The sensitivity of the measurements is very close to that achieved in a heavily shielded stationary laboratory.

Design Features of ITER Cooling Water Systems to Minimize Environmental Impacts

ITER is a joint international fusion facility which is being built in France to demonstrate the scientific and technological feasibility of fusion power. ITER will pave the way for the commercial exploitation of nuclear fusion to meet the ever increasing energy needs of mankind. Fusion power at ITER is generated using a Tokamak machine in which burning plasma inside the vacuum vessel at temperatures in excess of 150 million °C is confined by magnetic fields. The heat energy generated from the Tokamak and the auxiliary systems is removed by the Cooling Water System (CWS). The cooling water system is designed to remove the total peak heat load of about 1100 MW to the atmosphere by circulating approximately 25,000 m3 of water of diverse chemical specifications in multiple loops.The design of the cooling water systems considers occupational health and safety, nuclear safety, radiation protection, and environmental protection requirements. Minimizing environmental impact is a major factor in demonstrating the viability of fusion energy as a future energy source. This paper presents the features in the design of CWS for making it environmentally friendly.

TH-C-211-01: International Perspectives on Radiation Protection

There are some actions which require international cooperation. An example of good cooperation can be found in the largely seamless international use of credit cards and ATM machines. Conversely, an example where international cooperation has not been effective can be found in the diversity of electricity plugs and sockets in different countries. In the area of radiation protection, there are also examples of good and bad cooperation. The global acceptance of concepts and principles of radiation protection as developed by the International Commission on Radiological Protection (ICRP) such as justification, optimization and dose limitation is a good example. Conversely, there are quite a few examples of non-agreement or partial agreement of issues in the field of radiation protection, such as dose limits for workers and members of the public, and acceptance of SI units e.g. Sv and Gy against rem and rad. When it comes to radiation protection of patients, there is Universityersal agreement that there should be no dose limits and that the concept of diagnostic reference levels (DRLs) should be used with flexibility. International actions are needed not only to create harmonization of concepts but also to give impetus to some areas, raise awareness about emerging issues and forewarn about upcoming dangers if actions are not initiated by countries well in time. The talk will cover “How does the International System of Radiation Protection work” and inform about an International Action Plan on Radiation Protection of Patients of the IAEA. Is the international system binding or national systems are?. How harmonization is achieved through the work of the IAEA. Ultimately, the role medical physicists and health physicists in implementing the radiation protection requirements for staff and patient protection shall be discussed. Learning Objectives: 1. To understand the system of radiation protection in international and national context 2. To become familiar with international action plan on radiation protection of patients 3. To become familiar with international organizations in the area of medical radiation protection 4. To understand the potential role you can play in international activities

A transportable fast neutron and dual gamma-ray system for the detection of illicit materials

A transportable FNGR radiography system has been simulated using the MCNPX Monte Carlo code. The system is envisaged to be applied to the material characterisation of a suspicious bulky object, in view of identifying illegal materials. The system combines a neutron and two gamma-ray sources achieving characterisation of the material of the object through two ratios, namely 137Cs/DD and 60Co/DD. Hence, the system discriminates materials of similar or even the same of either of the two ratios. The proposed unit complies with radiation protection requirements achieving a safe occupational environment.

Equipment performance and radiation protection status in X-ray fluoroscopy units in Sudan

The number of fluoroscopy and fluoroscopically guided procedures has been substantially growing in developing countries at the same time advanced and sophisticated equipment are used in some hospitals. However, radiation protection requirements are not necessarily well adopted. In this study nine fluoroscopy X-ray units in Sudan were examined for compliance with international standards. The tests included: beam quality, entrance surface air kerma, image quality and radiation field measurements. Staff radiation protection tools such as lead aprons and eye glasses were also visually examined to find out whether international recommendations were fulfilled and to determine the level of staff awareness. The measured peak tube voltage deviation exceeded the recommended tolerance level in 30 % of the measurements. The results of patient doses measurements exceeded the recommended reference dose levels in 43 % of the measurements; however image quality and radiation field generally fulfilled the requirements for most units. The study revealed that a considerable number of fluoroscopy units were not performing according to the international standards and highlights the need of optimisation of radiation protection.

Reusable shielding material for neutron- and gamma-radiation

Abstract At neutron research facilities all around the world radiation shieldings are applied to reduce the background of neutron and gamma radiation as far as possible in order to perform high quality measurements and to fulfill the radiation protection requirements. The current approach with cement-based compounds has a number of shortcomings: “Heavy concrete” contains a high amount of elements, which are not desired to obtain a high attenuation of neutron and/or gamma radiation (e.g. calcium, carbon, oxygen, silicon and aluminum). A shielding material with a high density of desired nuclei such as iron, hydrogen and boron was developed for the redesign of the neutron radiography facility ANTARES at beam tube 4 (located at a cold neutron source) of FRM-II. The composition of the material was optimized by help of the Monte Carlo code MCNP5. With this shielding material a considerable higher attenuation of background radiation can be obtained compared to usual heavy concretes.

On the use of HDR source with the MammoSite® Radiation Therapy System

This work summarizes Monte Carlo results in order to evaluate the potential of using HDR 60Co sources in accelerated partial breast irradiation (APBI) with the MammoSite applicator. Simulations have been performed using the MCNP5 Monte Carlo Code, in simple geometries comprised of two concentric spheres; the internal consisting of selected concentrations, C, of a radiographic contrast solution in water (Omnipaque 300) to simulate the MammoSite balloon and the external consisting of water to simulate surrounding tissue. The magnitude of the perturbation of delivered dose due to the radiographic contrast medium used in the MammoSite applicator is calculated. At the very close vicinity of the balloon surface, a dose build-up region is observed, which leads to a dose overestimation by the treatment planning system (TPS) which depends on Omnipaque 300 solution concentration (and is in order of 2.3%, 3.0%, and 4.5%, respectively, at 1 mm away from the balloon - water interface, for C=10%, 15%, and 20%). However, dose overestimation by the TPS is minimal for points lying at the prescription distance (d=1 cm) or beyond, for all simulated concentrations and radii of MammoSite balloon. An analytical estimation of the integral dose outside the CTV in the simple geometries simulated shows that dose to the breast for MammoSite applications is expected to be comparable using HDR 60Co and 192Ir sources, and higher than that for 169Yb. The higher enegies of 60Co sources result to approximately twice radiation protection requirements as compared to 169Ir sources. However, they allow for more accurate dosimetry calculation with currently used treatment planning algorithms for 60Co sources, compared to 169Ir.

Assessment of dosimetric quantities for patients undergoing X-ray examinations in a large public hospital in Brazil--a preliminary study

The introduction of routine patient dosimetry to Brazilian radiological institutions is very necessary in order to meet national and international standard requirements for radiation protection. This work presents a survey of the air kerma-area product (P(KA)), the entrance surface air kerma (K(e)) and the effective dose (E) in common radiographic examinations during the routine of a large public hospital in the city of Belo Horizonte, Brazil. Results draw attention to the use of field sizes larger than the cassette dimension, the lack of both the collimation X-ray beam and the standardisation of the exposure parameters by radiology technicians.

Radiation doses to normal tissues and organs outside the target volume during radiotherapy

Public Health Codes more and more require that any information relevant to the estimation of the high doses delivered within the target volumes and low doses delivered outside should be recorded. In this context, the availability for each radiotherapy patient of the magnitude of the unavoidable low doses delivered outside the target-volumes becomes an important issue. However, to date, Treatment Planning Systems (TPS) are not designed for this issue. Therefore, we have developed a new version of the ISOgray TPS which can provide, in addition to the doses distributions in the fields, the magnitude of the doses to distant healthy tissues in the course of common radiotherapeutic procedures. Our strategy involves 3 modules: A library of adjustable whole-body patient models in treatment position which allows different patient anatomies to be simulated; A multi-sources beam model, which allows the description of the irradiation field to be extended to the whole body; A dose calculation engine producing the distributions of doses in the fields and in any organ outside. This paper describes the principles of the system and provides data on doses distributions to distant organs for various common radiotherapeutic procedures. At this stage of development, the agreement of measured and calculated doses reaches ±3% in the radiation field and is better than ±15% outside. In the case of a 17 years aged girl treated for Hodgkin's disease using two 6MV opposite photon beams, when a dose of 20 Gy was delivered to the target volume, outside the beam, the dose to the brain was 0.37 Gy (1.85% of the tumor dose), the kidney 0.06 Gy (0.30%) and the ovaries below 0.02 Gy (<0.1%). Although the development of our system is still in progress, these preliminary results are encouraging. Allowing the realization of whole-body dose evaluations for each patient in the course of radiation therapy treatment planning, our approach must provide relevant information required to meet the current requirements of patient radiation protection and radiation therapy benefit-risk management purposes. The systematic evaluation of low doses outside the radiation therapy fields creates new opportunities in quality assurance of radiation therapy and prospective studies of long-term risks of radiation modern radiotherapeutic procedures.

Qualitätskontrolle von Röntgenthoraxaufnahmen bei Kindern in diagnostischen Zentren mit und ohne kinderradiologische Kompetenz

Radiation protection in pediatric radiology is very important because of the particular sensitivity of radiosensitive organs in younger patients. Optimized image quality supports radiation protection and should be targeted. In our study we examined the quality of pediatric chest X-rays at diagnostic centers (university hospitals and other large clinics). We then evaluated differences in image quality in departments without pediatric competence (R) and departments with pediatric competence (PR). Our study was based on 313 conventional chest X-rays from 207 patients (192 p. a./a. p. and 121 lateral, 43 from R, 258 from PR and 12 neither from R nor KR) and 38 digital chest X-rays from 26 patients (25 p. a./a. p. and 13 lateral, 1 from R and 37 from PR). All patients (age 0 - 18 years) are from Nephroblastoma-Study SIOP-93/01-GPOH. We examined all initial chest X-rays, which were sent to us for evaluation upon request between 4/3/2002 and 6/14/2002. The examined parameters were: exposure, centering of the X-rays/patient positioning, collimation and sharpness. The X-rays were evaluated on a scale from 1 (best result) to 5 (worst result), resulting in an overall score of A = optimum, B = minor problems, C = major problems, or D = unusable. The optical density, the center of the image and the relative field size were also measured. Statistical tests (Mann-Whitney-U and log regression) were carried out on the conventional images. The study was performed retrospectively. The exposure, sharpness and optical density of the digital X-rays were not analyzed. In the case of all conventional X-rays, the quality of the centering of the X-rays/patient positioning and collimation was moderate (average scale value: 2.4 and 2.8), and the quality of the exposure and sharpness was good and very good (average scale value: 1.9 and 1.5). The quality of the chest X-rays in departments with additional pediatric radiological expertise was better mainly in the case of younger patients (younger than 5 years) than departments without additional pediatric radiological expertise (average scale value in age group 0 - 1 month: PR = 1.7; average scale value in age group 2 months - 2 years: R = 2.4 and PR = 1.8; average scale value in age group 3 - 5 years: R = 2.5 and PR = 1.8). Despite the good overall image quality, the quality of the centering of the X-rays/patient positioning and collimation was insufficient in both examiner groups (R and PR). For this reason, some radiation protection requirements could not be fulfilled. X-rays from PR were higher quality than X-rays from R in this special study group. Day-to-day quality checks are necessary for pediatric chest X-rays in order to achieve a high quality standard.

PET/CT

Clinical studies demonstrate a gain in diagnostic accuracy by employing combined PET/CT instead of separate CT and PET imaging. However, whole-body PET/CT examinations result in a comparatively high radiation burden to patients and thus require a proper justification and optimization to avoid repeated exposure or over-exposure of patients. This review article summarizes relevant data concerning radiation exposure of patients resulting from the different components of a combined PET/CT examination and presents different imaging strategies that can help to balance the diagnostic needs and the radiation protection requirements. In addition various dose reduction measures are discussed, some of which can be adopted from CT practice, while others mandate modifications to the existing hard- and software of PET/CT systems.

The requirement for energy imparted in radiation protection practice

The lifetime probability of an 'excess' cancer for an individual is assumed by the ICRP to be a linear function of dose, without threshold. This linear-no-threshold (LNT) model is not based on firm data, but on conservative estimates which provide simplifying guidelines for individual values for lifetime risk. Yet, such values are currently used as the basis for radiation protection. However, the present authors do not accept the ICRP assumptions with regard to the LNT model, and instead use the A-Bomb human carcinogenesis data as a basis for recommending an alternative method for determining exposure limits for radiation workers. A change in the radiation protection system is recommended in which absorbed dose is replaced with energy imparted. Alternative reporting requirements for radiation protection are also suggested.

A study of scatter in diagnostic X-ray rooms.

An important part of determining the radiation protection requirements during X-ray room design is the calculation of the amount of scatter inside and outside the planned locations of the shielding barriers. In this work, a Monte Carlo code has been developed to calculate the percentage scatter so that the current data can be consolidated and new data can be provided as required. Calculations have been compared with measurements to show that they are representative of scatter found in X-ray rooms. Scatter from the dose-area product meter and the collimator system were found to provide large contributions to the measured scatter. A fluoroscopy room containing a C-arm X-ray set was modelled with the Monte Carlo code. The scatter dose was calculated at an X-ray room entrance behind the protective screen, acting as a secondary barrier, at the radiographer's console. The variation of scatter with the position of the protective screen was studied. An empirical calculation, which provided reasonable agreement with the Monte Carlo calculations, was found by using new data for the variation of scatter from concrete with field size. If a door was placed in the X-ray room entrance behind the protective screen, the results showed that it would not need to be lead lined.

CONSIDERATIONS ABOUT TENORM: A STUDY CASE ON NIOBIUM FACILITIES

Two niobium mining facilities located at two different geological settings were selected as case studies for assessing the radiological impacts associated with mining and milling activities. The impacts were assessed both for operational and post-operational (future unrestricted use of the area) scenarios. The work methodology encompassed sampling and analysis of different materials along the operational process, including wastes, effluents and by-products, mass balance calculations, and dose assessment. The exposure scenario considered during the operational phase included the land use by hypothetical groups of members of the general public. In the case of post-operational phase the possible occupation of contaminated areas was considered. The results pointed out that during the operational phase of the investigated industries no relevant impacts could be attributed to them. However, in the case of the potential occupation of the contaminated areas where the wastes are being deposited, the unrestricted use of these areas cannot be accepted in terms of the relevant radiation protection requirements.

Physical and technical quality assurance and radiation protection in transperineal interstitial permanent prostate brachytherapy with 125-iodine seeds

Early stage prostate cancer can be treated successfully by interstitial brachytherapy with 125-iodine seeds. A quality-assurance programme is presented that was designed for this purpose for internal clinical use. Furthermore the requirements of the new German Ordinance Governing Radiation Protection (StrlSchV) that came into force on August 1, 2001, are taken into account. For the 125-iodine monotherapy of the prostate we used RAPID STRANDS (Amersham Health, Braunschweig, Germany). According to the guidelines of the new Ordinance Governing Radiation Protection, the determination of the body dose of the staff is made to rely on the new measurement quantities H(p) (10) and H(p) (0.07). The nominal air kerma rate of the seeds is measured with a calibrated well-chamber of the type HDR 1000 Plus and an electrometer of the type MAX 4000 (Standard Imaging Inc., USA). The ultrasound images of the prostate are produced by an ultrasound device of the type Falcon 2101 (B-K Medical, Denmark). For treatment planning the programme VariSeed (Varian, Darmstadt, Germany) was employed. Correct loading of the needles is controlled by autoradiography before implantation. After the implantation radiation-protection measurements in the operating room are carried out. As regards the personnel, for the depth personal dose equivalent Hp(10) and relating to two applications each, measurement values between 0 microSv and 14 microSv resulted. The control of the radiation exposure of the hands revealed superficial personal dose values H(p) (0.07) of up to 1 mSv. The nominal air kerma rates of the RAPID STRANDS were all lying within the 95% confidence interval guaranteed by the producer. The autoradiographs documented -- except for one case -- the correct loading of the needles. The interstitial transperineal prostate implantation of the 125-iodine seeds succeeded as planned with all patients. Until now no contamination of the operating room was detected by the radiation-protection measurements. The physical-technical quality assurance programme presented here covers the whole physical-technical range of the internal clinical quality assurance and could be integrated into the course of the treatment without any problems. It has th following advantages: The autoradiographic documentation of the correctly loaded needles serves as proof that the prerequisite for the production of the prescribed physical dose distribution is fulfilled. The internal clinical determination of the nominal air kerma rate is the basis for a correct dose application.