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NACP-RPC course
Södersjukhuset, Stockholm, September 27th-29th, 2017
Final programme
Abstracts
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Welcome to Stockholm!
It is with great pleasure we welcome you to Stockholm, Sweden for this year’s NACP-RPC
(Nordic Association for Clinical Physics – Radiological Physics Committee) course. This year
the course is dedicated to occupational dosimetry in hospitals, and for the first time the
course is arranged in collaboration with the NACP-NMPC group (Nuclear Medicine Physics
Committee).
The purpose of the course is to take a deeper look into the biological basis of the dose limits
we are operating with in hospitals, as well as understand how working technique, protocol
optimization and shielding equipment can influence radiation exposure to the staff. Nordic
guidelines for occupational dosimetry, trends from dose registries and principles of good
practices will also be discussed.
There will be a course dinner Thursday the 28th of September for those who registered for
this.
We hope you will enjoy the course and your time in Stockholm.
Local organizing committee
Sofi Wickström and Cecilia Lundmark
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Contents
Committees and invited lecturers ........................................................................................................... 4
Practical information ............................................................................................................................... 5
Sponsors .................................................................................................................................................. 8
Final programme ..................................................................................................................................... 9
Abstracts ................................................................................................................................................ 12
Biological basis for occupational dosimetry and dose limits ............................................................ 12
Key issues of occupational radiation protection in interventional procedures ................................ 13
Requirements for protection of exposed workers in the Nordic countries ...................................... 14
Occupational doses in interventional radiology, cardiology and nuclear medicine: comparisons,
conclusions and trends from dose registries .................................................................................... 15
Technical basis of occupational dosimetry ....................................................................................... 16
Implementing guidelines for occupational dosimetry in a hospital .................................................. 17
The use of Active personal dosimeters in hospitals .......................................................................... 18
Shielding methods and equipment and their degree of protection ................................................. 19
Radiation protection of the eyes ....................................................................................................... 20
General principles of good practices: How do these affect staff doses? .......................................... 21
Optimum techniques and use of shielding to reduce staff dose in interventional radiology
procedures ........................................................................................................................................ 22
Optimum techniques and use of shielding to reduce staff dose in interventional cardiology
procedures ........................................................................................................................................ 23
Staff doses and good practices in CT guided interventional radiology procedures .......................... 24
Staff doses and good practices in surgical use of radiation (with movable X-ray equipment) ......... 25
Factors influencing dose to nuclear medicine staff .......................................................................... 26
Internal contamination and dosimetry for personnel in nuclear medicine ...................................... 27
Shielding and operational dosimetry in nuclear medicine staff ....................................................... 28
The patient as a radiation source: Nuclear Medicine Diagnostics and Therapy ............................... 29
Radiation protection and radiation safety in production and delivery of PET radiopharmaceuticals
........................................................................................................................................................... 30
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Committees and invited lecturers
Invited lecturers
Lecturer Country Email
Klaus Trott Germany [email protected]
Maaret Lehtinen Finland [email protected]
Pedro Ortiz-López Austria [email protected]
Antti Kosunen Finland [email protected]
Rune Hafslund Norway [email protected]
Filip Vanhavere Belgium [email protected]
Christoffer Granberg Sweden [email protected]
Tanja Østgård Holter Norway [email protected]
Joanna Sierpowska Finland [email protected]
Jonas Andersson Sweden [email protected]
Sören Mattsson Sweden [email protected]
Sigrid Leide Svegborn Sweden [email protected]
Disa Åstrand Sweden [email protected]
Eleonor Vestergren Sweden [email protected]
Mikael Jensen Denmark [email protected]
Torsten Cederlund Sweden [email protected]
Aoife Gallagher Ireland [email protected]
Lennart Johansson Sweden [email protected]
Hannu Järvinen Finland [email protected]
Program committee
Name Country Email
Daniel A. Aadnevik Norway [email protected]
Hannu Järvinen Finland [email protected]
Ahmed Jibril Abdi Denmark [email protected]
Lennart Johansson Sweden [email protected]
Erik Tesselaar Sweden [email protected]
Local Committee
Name Country Email
Sofi Wickström Sweden [email protected]
Cecilia Lundmark Sweden [email protected]
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Practical information
The venue of the course is Södersjukhuset in the auditorium Ihre. Södersjukhuset is located
at Södermalm. The address to Södersjukhuset is Sjukhusbacken 10.
The easiest way to travel from Stockholm City to Södersjukhuset is by public transportation,
rail (commuter train, pendeltåg, see the green line in the map below), to Stockholms södra
(Södra station (exit Rosenlundsgatan). It´s a 5 minutes’ walk from Stockholms södra to
Södersjukhuset.
Hilton Stockholm Slussen
Scandic Malmen
Hotell Årstaviken Clarion Hotel Stockholm
Venue
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The venue at Södersjukhuset is located at the entrance plan, plan 0. At the main entrance,
you will take left at the ATM (cash machine), at the end of the corridor take left again, pass
hiss P, and turn right. You will find the auditorium Ihre down the corridor on your left.
Hotell Årstaviken =
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WELCOME RECEPTION
The welcome reception will be held outside the auditorium Ihre.
COURSE DINNER
M/S Blue Charm will take us on a 3 h dinner cruise through the Stockholm archipelago.
We meet 18.30 at M/S Blue Charm, Kajplats 17 Strandvägen.
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Sponsors
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Final programme
Wednesday September 27th, 2017
Time Topic Speaker
08:30 – 09:00
Registration
Introduction
09:00 Introduction: Purpose of the course Daniel Aadnevik (Bergen, Norway)
09:05 Practical information on course activities Sofi Wickström (Stockholm, Sweden)
Session 1: Joint topics – Guidelines and technical basis
Moderators: Heli Larjava (Finland) and Ahmed Jibril Abdi (Denmark)
09:10 Biological basis for occupational dosimetry and dose limits
Klaus-Rüdiger Trott (Munich, Germany)
09:40 Key issues of occupational radiation protection in interventional procedures – Recommendations from the ICRP
Pedro Ortiz López (Vienna, Austria)
10:10 Requirements for protection of exposed workers in the Nordic countries
Torsten Cederlund (Stockholm, Sweden)
10:40 Occupational doses in interventional radiology, cardiology and nuclear medicine: comparisons, conclusions and trends from dose registries
Maaret Lehtinen (Helsinki, Finland)
11:10 Discussion
11:30 COFFEE BREAK
11:50 Technical basis of occupational dosimetry: dosimetric quantities, types of dosimeters, dosimeter calibrations, measurement uncertainties
Antti Kosunen (Helsinki, Finland) presented by Hannu Järvinen
12:20 Implementing guidelines for occupational dosimetry in a hospital
Rune Hafslund (Bergen, Norway)
12:50 Discussion
13:00 – 14:30
LUNCH BREAK AND EXHIBITION (dosimeter vendors)
Session 2: Interventional radiology and cardiology: Technical issues
Moderator: Hannu Järvinen (Finland)
14:30 The use of active personal dosimeters in hospitals Filip Vanhavere (Mol, Belgium)
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15:00 Shielding methods and equipment and their degree of protection
Christoffer Granberg (Umeå, Sweden)
15:30 Discussion
15:40 COFFEE BREAK
16:00 Radiation protection of the eyes Klaus-Rüdiger Trott (Munich, Germany)
16:30 Discussion
16:45 WELCOME RECEPTION
Thursday September 28th, 2017
Session 3: Interventional radiology and cardiology – Clinical issues
Moderators: Daniel Aadnevik (Norway) and Erik Tesselaar (Sweden)
09:00 General principles of good practices: How do these affect staff doses?
Hannu Järvinen (Helsinki, Finland)
09:30 Optimum techniques and use of shielding to reduce staff dose in interventional radiology procedures
Tanja Østgård Holter (Oslo, Norway)
10:00 Optimum techniques and use of shielding to reduce staff dose in interventional cardiology procedures
Joanna Sierpowska (Helsinki, Finland)
10:30 Discussion
10:50 COFFEE BREAK
11:10 Staff doses and good practices in CT guided interventional procedures
Jonas Andersson (Umeå, Sweden)
11:40 Staff doses and good practices in surgical use of radiation (with movable x-ray equipment)
Aoife Gallagher (Dublin, Ireland)
12:10 Discussion
12:30 – 14:00
LUNCH BREAK AND EXHIBITION
Session 4: Sponsor presentations
14:00 – 15:00
Sponsor presentations
Plenum presentation of dosimetry equipment (active and real-time), shielding equipment etc.
18:30 COURSE DINNER
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Friday September 29th, 2017
Session 5: Nuclear Medicine (NM) – Technical and clinical issues
Moderators: Andreas Österlund (Sweden) and Lennart Johansson (Sweden)
08:30 Factors influencing dose to nuclear medicine staff Lennart Johansson (Sweden)
09:00 Internal contamination and dosimetry for personnel in nuclear medicine
Sören Mattsson (Lund, Sweden)
09:30 Shielding and operational dosimetry in nuclear medicine staff
Sigrid Leide Svegborn (Lund, Sweden)
10:00 Discussion
10:20 COFFEE BREAK
10:40 Patient as a radiation source: Nuclear Medicine Diagnostics
Eleonor Vestergren (Guthenburg, Sweden)
11:00 Patient as a radiation source: Radionuclide therapy
Disa Åstrand (Stockholm, Sweden)
11:20 Radiation protection and radiation safety in production and delivery of PET radiopharmaceuticals
Mikael Jensen (Roskilde, Denmark)
Closing session
12:00 Discussion
12:30 SUMMARY AND CLOSING
12:45 End of course
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Abstracts
Biological basis for occupational dosimetry and dose limits
Klaus-Rüdiger Trott, Professor, UCL Cancer Institute, University College London, UK
The recommendations issued by ICRP in 1977 in their publication 26 worked well. Yet, modifications of numbers (correction factors, risk factors etc.) did not heal the intrinsic faults of the 40 years old concept of effective dose. In an age of “personalized medicine”, the averaging procedures inherent in the current concepts of radiation protection need to be remedied. At different ages, different organs are at risk or not at risk for developing radiation-induced cancer. Pooling results from all age groups will inevitably underestimate the risk for some people and overestimate it for others. Important examples are the female breast and the thyroid, in both organs differences of radiosensitivity amount to orders of magnitude. Moreover, the sensitivity of different organs to develop radiation-induced malignant diseases differ significantly between males and females, not only for the breast. The main problem, however, is the distinction between stochastic and deterministic effects which is no longer in line with radiobiological and epidemiological evidence.
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Key issues of occupational radiation protection in interventional procedures
Pedro Ortiz López, PhD, International Atomic Energy Agency, Vienna, Austria
The number of interventions guided by radiological imaging is increasing steeply in both developed and developing countries. New types of interventions are also of increased complexity, thus requiring extensive use of x-ray imaging and raising new issues of occupational radiation protection. Patient exposure is closely related to occupational exposure and most actions to protect the patient protect also the staff, since by reducing patient dose or irradiated volume scattered radiation is reduced in a similar proportion. The opposite is not true: actions and devices to specifically protect the staff do not protect the patient. These include protective apron and collar, ceiling-suspended shield, protective eyewear, table-top suspended protective curtains, shielding drapes on the patient, staying on the image receptor side rather than on the side of the x-ray tube and stepping back to increase distance from the patient whenever possible. According to recent evidence, if no protective measures for the eyes are used, personnel with a typical workload will receive doses to the lens of the eye that could exceed the current dose limit, and over time could result in lens opacities. Interventionalists should make use of ceiling-suspended. Two dosimeters, one shielded by the apron (under apron) and one unshielded (over apron) at collar level, provide the best estimate of effective dose and continues to be the primary recommendation. The under-apron dosimeter also provides confirmation that the apron has been actually worn and that its attenuation is sufficient to keep the dose under the apron low. Adequate resources should be allowed for the purchase, testing, quality control and replacement of protective garments. A comprehensive quality assurance programme should be established by the organisation. The programme should include appropriate audits to ensure that personnel adhere to procedures, especially related to wearing of dosimeters, protective devices and methods of protection.
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Requirements for protection of exposed workers in the Nordic countries
Torsten Cederlund, PhD, Swedish Radiation Safety Authority, Stockholm, Sweden
The new European Directive 2013/59/Euratom, laying down basic safety standards (BSS) for protection against the dangers arising from exposure to ionizing radiation has to be transposed into national legislation, of the Member States of the European Union, by 6 February 2018. The directive take into account the new recommendations of the International Commission on Radiological Protection (ICRP) and are revised in the light of new scientific evidence and operational experience. Relevant changes compared to the previous directive are mainly regarding patients. The most important change for protection of exposed workers is the new dose limit for the eye lens.
Due to the new directive the Nordic countries has or are in the process of reviewing their regulations. The presentation will cover categorization of workers and workplaces, training, dose limits, protection of pregnant and breast feeding women, monitoring and reporting of individual radiation doses.
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Occupational doses in interventional radiology, cardiology and nuclear medicine: comparisons, conclusions and trends from dose registries
Maaret Lethinen, MSc, Principal Advisor, STUK – Radiation and Nuclear Safety Authority, Helsinki, Finland
Dose data is collected in different levels: globally, European level and national level. When information is gathered from a wider area, the more assumptions have been made and the data is more averaged.
The Finnish dose register includes exposure data for all workers engaged in radiation work (nuclear energy, use of radiation and natural radiation exposure) from year 1963 until present. It serves as both an updated data bank and a long-term archive and can be used for regulatory control of use of radiation and nuclear energy as well as to epidemiological research. Regulatory control targets to ensure that dose limits are not exceeded, radiation exposure is optimized and working routines are appropriate.
Globally the medical workers are most significant group exposed to artificial sources from collective dose point-of-view. The situation is the same in European level, but the difference with other fields of activity is not so clear.
In Finland, collective dose for cardiologists increased measurably during the 90’s and then remained at the level reached at the end of the 90s. The collective dose for interventional radiologists were at its highest in the 90s and is now again at almost the same level. There are several reasons affecting to the exposure of cardiologists and interventional radiologists, for example number and difficulty of procedures, available technique, use of the protective clothing and training.
In nuclear medicine it is not only the effective dose but also extremity dose for fingers which should be aware of. Even if the effective dose is comparatively low, the hands might be exposed measurably. During the first decade of 2000’s the collective dose for fingers almost tripled when some new nuclides were introduced. After the methods have been partly automatized, the exposure for workers has started to decrease.
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Technical basis of occupational dosimetry
Antti Kosunen, PhD, Radiation and Nuclear Safety Authority - STUK, Helsinki, Finland
A general review on technical and physical aspects of individual dose monitoring by personal dosimeters is presented. Dosimetry concepts and principles are introduced with definitions and relations of physical, operational and protection quantities. Operational quantity used in personal dosimetry is personal dose equivalent Hp(d) and is defined at different depths in soft tissue. Accuracy of personal dose equivalent as an estimate of protection quantity of effective dose is considered.
Basic technical principles of common passive photon dosimeters such as thermoluminescence (TLD), optically stimulated luminescence (OSL), glass dosimetry and direct ion storage (DIS) are described. Characteristics of active dosimeters are introduced by examples. The technical requirements by international standards and recommendations for personal dosimeters are discussed.
Calibration methods of personal dosimeters are described and concepts of measurement traceability and measurement uncertainty are introduced in perspective of metrology of ionizing radiation. Radiation circumstances on calibration of dosimeters can differ from those existing during use of dosimeters and the effects of these differences on the achieved accuracy are pointed out. Uncertainty evaluations for measurement of personal dose are discussed relative to accuracy requirements.
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Implementing guidelines for occupational dosimetry in a hospital
Rune Hafslund, PhD, Radiation Protection Officer, Haukeland University Hospital, Bergen, Norway
As radiation safety officer (RSO) at Haukeland University Hospital in Bergen, I am responsible for central guidelines within all fields related to ionizing and non-ionizing radiation.
Approximating 12.000 people are employed at this hospital, of which 1800 are occupational exposed to radiation. One third of these have a personal dosimeter for radiation monitoring.
Employees find guidelines for use of radiation in a document based on our radiation risk assessment and include all relevant regulations, both governmental directions and approvals and internal instructions. All guidelines related to personal occupational dosimetry are based on a professional consensus among the RSO at hospitals in Western Norway.
The challenge with these guidelines is how to present them and how to make the employees understand and comply with them.
The lecture will explain how this challenge is solved in our hospital by showing an overview of the organization, the functions and responsibilities of defined radiation workers and radiation assistants. We have defined main goals for use of radiation, and we have instructions related to all our barriers measures based on our radiation risk report. Among these instructions are those related to the use of personal dosimeters.
Conclusion: Revised guidelines, dedicated for internal use in our hospital, was published in our system for central documents on July 1th this year. The revision is based on new national/ European rules, and are systemized in order to fit our users and our organization. In the revised document we have tried to be precise on whom should or should not use a personal dosimeter built on professional basis. It is too early to conclude if the employees trust the new guidelines and if they will feel safe in working with radiation.
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The use of Active personal dosimeters in hospitals Filip Vanhavere, PhD, Head of expert group Radiation Protection Dosimetry and Calibration,
Belgian Nuclear Research Centre SCK•CEN, Moi, Belgium
In most of the European countries, passive dosimetry systems are used to verify compliance with regulatory dose limits. Active personal dosimeters (APD) are frequently used as alarm dosimeters in potential high dose areas, and help in the application of the ALARA principle.
In a few countries APDs can be accepted as legal dosimeter and no passive dosimeter is used anymore. In such cases it is important that a quality assurance system is carefully installed and that regular quality control checks and calibrations are performed. Approval by the national authorities will also be required, and a dosimetry service still has a role to play in this issue.
APDs are also increasingly used in occupational dosimetry in medicine. A very recent survey from EURADOS Working Group 12 concluded that in hospitals often the calibration of APDs is not adequately addressed.
Another study from EURADOS showed that the APDs have achieved a technological level that is similar or even better than the passive dosimeters. Also, the level of reliability has become comparable or even better than for passive devices. Still, the results showed that few devices can detect low energy radiation fields and none of them were specially designed for working in pulsed radiation fields. Some years later, an extensive test programme has been performed during the ORAMED project with continuous and pulsed fields. Different existing APDs have been tested for the first time under conditions that are representative of the conditions met in clinical practice. This lead to specific guidelines for the use of APDs in hospitals. More recently APDs have been tested in standardised pulsed fields by EURADOS WG12. This showed again clearly the limitations of the APDs, mainly when high instantaneous dose rates are encountered (above several Sv/h). Tests in real hospital fields however showed that in most normal situations, the APDs perform well because the operators are mostly exposed to the lower intensity scattered field alone.
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Shielding methods and equipment and their degree of protection
Christoffer Granberg, PhD, Institute of Radiation Sciences, Umeå University, Sweden
Consideration of occupational radiation protection is important during interventional radiology and cardiology procedures since medical personnel working near the patient may be exposed to scattered radiation levels beyond regulatory dose limits.
There exist a wide range of radiation protection methods to reduce occupational exposure and most are covered in the draft of ICRP publication “Occupational Radiological Protection in Interventional Procedures”. Most methods are dependent on radiation protection equipment of which there are multiple vendors and models. However, radiation protection equipment lacks a standardized and easy to understand metric of efficiency. Furthermore, there are no clear guidelines on how to combine different types of radiation protection equipment for optimal reduction of occupational exposure.
The efficiency of different radiation protection methods has been summarized by literature review, in-house measurements and conclusions from the ICRP publication daft. The talk will be focused on technical performance of radiation protection methods, together with dependencies on user handling and examples of situations where radiation protection equipment may be detrimental or redundant.
Regulatory dose limits should not be exceeded if medical personnel in interventional radiology and cardiology employ presently available occupational radiation protection equipment and methods.
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Radiation protection of the eyes
Klaus-Rüdiger Trott, Professor, UCL Cancer Institute, University College London, UK
The eyes have very long been classified as being particularly radiosensitive. The first description of radiation damage goes back to 1897! Different types of eye diseases have been described, all of which depend on dose, dose rate and follow-up. Lens exposure may lead to cataract, lacrymal gland exposure may lead to radiation damage relatively early and thus to the dry eye syndrome and loss of vision within 1 year associated with severe pain requiring enucleation, optic nerve exposure may lead to secondary neuropathy, retina exposure may cause retinopathy as a consequence of microvascular radiation damage after 3 or more years. Cataracts are an unwelcome effect of radiation exposure but in contrast to all other potential health effects of low dose radiation exposure they can be treated well with minimal morbidity and excellent long-term wellbeing. This has to be considered in the inclusion of cataracts into the system of radiation protection (e.g. dose limits for workers). Radiation cataract is arguably the most published field in radiation protection research, as it is so easy to do. ICRP 118 emphasizes that, it should be recognized that the purpose of radiation protection is to prevent tissue-damaging effects of clinical significance. The gold standard studies in the A-bomb survivors with >50 years follow-up and individual dosimetry show a linear no-threshold dose effects relationship for clinically significant cataract and a relative risk of 1.4 at 1 Gy, however, also a relative risk of 1.5 at 1 Gy for retinopathy. The implications of these findings for radiation protection will be discussed.
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General principles of good practices: How do these affect staff doses?
Hannu Järvinen, PhD, Principal Advisor for Radiation in Health Care at STUK, Helsinki, Finland
Many of the good practices for the radiation protection of the patient in interventional radiology are also beneficial for the protection of the staff; the good practices reducing patient dose will generally result also in the reduction of staff dose. The whole body dose to staff is mainly caused by the radiation scattered from the patient and therefore, the most important parameters for good practices on point of view of radiation protection are the distances, x-ray beam directions, and properly located radiation shields. The two first parameters are also key factors in reducing the patient dose. Overall, the selections of the following parameters have often an impact also on the staff dose: the arterial access site in cardiac catheterization (transradial vs. transfemoral), radiation shields on the patient, imaging programs and techniques, x-ray beam directions (tube angulations), proposition of fluoroscopy and cine modes, field sizes (collimation) and the use of magnification, frame rate and pulse rate. The impact of good practices in the selection of all these parameters on the staff dose are briefly summarized in this lecture.
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Optimum techniques and use of shielding to reduce staff dose in interventional radiology procedures
Tanja Holter, MSc, Radiation Protection Coordinator, Oslo University Hospital, Norway
After the recent changes in Norwegian radiation protection regulations (valid from 01.01. 2017), the need for staff dose-monitoring has increased. Especially considering the dose limit to the eyelense, which was lowered from 150 mSv to 20 mSv. Different protective equipment has been tested during the last year, with varying results. Properly used protective tools can potentially reduce occupational dose dramatically. This presentation submits some experiences from Oslo University Hospital.
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Optimum techniques and use of shielding to reduce staff dose in interventional cardiology procedures
Joanna Sierpowska, MSc, Hospital Physicist, North Karelia Central Hospital, Joensuu, Finland
At present, the use of ionising radiation is unavoidable in interventional cardiology. The aging population increases the demand for this kind of procedures. In particular, in Finland they increase 10 % a year. The improvements in angiography system technology enable good image quality with relatively low patient dose. This directly translates to staff dose, however it is in itself not enough to satisfy ALARA principle. The staff dose optimisation techniques are similar to those used in other interventional procedures (such as lead aprons, mobile lead barriers, table shields or minimizing the amount of staff in the operational theatre), however their application may vary depending on a cardiological procedure. The staff dose optimization techniques in several cardiological procedures (such as coronary angiography, percutaneous coronary intervention, or Transcatheter Aortic Valve Implantation (TAVI) procedures) are explored. Radiation protection during resuscitation is presented. The issues concerning protection of pregnant workers and outside visitors to the cardiological ward are pondered.
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Staff doses and good practices in CT guided interventional radiology procedures
Jonas Andersson, PhD, Department of Radiation Sciences, Umeå University, Sweden
Interventional radiology (IR) is most commonly performed with conventional X-ray fluoroscopy. However, in recent years such equipment has evolved to include Cone Beam Computed Tomography (CBCT) functionality for increased versatility. Furthermore, some IR procedures, mainly biopsies, are increasingly being performed on clinical CT systems due to superior 2D and 3D image quality.
General radiation protection concerns; i.e. shielding equipment, basic methods for decreasing staff dose and measurement of scatter radiation, do not differ between conventional X-ray equipment and CT. However, due to the potential high output of CT scanners, with associated risk of high staff doses, the manufacturers of CT scanners have added dedicated functionality for radiation protection. Such functionality includes e.g. modulation of the X-ray beam during rotation to reduce radiation exposure of hands.
A complication for the estimation of both staff and patient dose in CT guided IR procedures is that the patient is commonly not placed at isocentre due to practical considerations.
This talk will include a review of staff doses from CT guided procedures and good practices, both from the literature and experiences from the University Hospital of Umeå, Sweden.
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Staff doses and good practices in surgical use of radiation (with movable X-ray equipment)
Aoife Gallagher, MSc, Principal Physicist, Medical Physics and Bioengineering Dept., St. James’s Hospital, Dublin, Ireland
Mobile C-arm imaging technology is primarily used in areas outside the Radiology Department. This presentation considers the factors which differentiates these areas from the Radiology Department from a radiation protection perspective. In addition best practice recommendations which when implemented will minimise occupational exposures are discussed.
A number of incidents involving the use of mobile C-arm imaging equipment are presented. Actions to minimise the opportunity for recurrence of these and similar incidents are explored.
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Factors influencing dose to nuclear medicine staff
Lennart Johansson, Professor, Department of Radiation Sciences, Umeå University, Sweden
Unsealed radiation sources which are used in nuclear medicine requires different methods and strategies for controlling the occupational exposure to the staff. The radionuclide may be contained in vials or syringes, but also the patient may be a source of exposure of the personnel as well as of the general public. The patients may be subject for diagnostic studies, or they may have received a radioactive substance for the purpose of radiotherapy. Technetium-99m is the dominating radionuclide used, but in recent years PET is becoming increasingly popular, thus the use of positron emitting radionuclides, particularly 18F, increases. For therapy 131I is the most common radionuclide.
Open sources implicate a risk for contamination and a program for monitoring this including smear tests together with measurement of internal contamination, is needed. Also the risk of contamination from radioactivity in patient excreta should be considered. This is of special importance for radionuclides with a half-life of more than a few hours, particularly 131I when it is given for therapy. Furthermore preparing, dispensing and injecting the radioactive solutions will result in total body exposure, and for some tasks, the absorbed dose to the fingers needs special attention.
Radionuclides used for PET emit annihilation radiation, two photons with an energy of 0.511 MeV. This leads to an exposure rate from an unshielded vial which is seven times higher for 18F than for 99mTc, and for shielding about 20 times more lead is needed to reduce the exposure to 1/10 of the initial exposure. Installing a PET-camera thus requires a thorough design of the facilities considering the exposure rates to the personnel, due to radiation from the patients. If equipment for production and labelling of PET radionuclides is installed specially designed radiation shielded facilities are required.
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Internal contamination and dosimetry for personnel in nuclear medicine
Sören Mattsson, PhD, Medical Radiation Physics Malmö, Department of Translational Medicine, Malmö, Sweden
For most personnel in nuclear medicine, the major part of exposure is from external radiation. The sources are accelerator targets, radionuclide generators, radioactive solutions, patients and waste. Unique for nuclear medicine is that the personnel also can be contaminated from these sources, including patients´ urine, faeces and exhaled air, as well as eating and drinking utensils, bed linen, saliva, sweat and vomit. Primarily there is a contamination of the staff's skin, especially on fingers and hands, on the hair, and through inhalation. Radionuclides on fingers and hands then enter the body at eating and smoking.
The need for monitoring of internal contamination will depend on the quantity and type of radioactive material present, it’s physical and chemical form, containment used, operations performed and general working conditions. IAEA recommends that individual contamination control should be performed when it is likely that the committed effective dose from an annual intake is expected to exceed 1 mSv. The measurement strategy is dependent on the physical half-life of the radionuclide.
For gamma-emitting radionuclides, the body content can be determined in whole or partial body counters. A measurement using a gamma camera without collimator is a good alternative. Smaller detectors can be used to localize and quantify uptake for example in the thyroid. For pure beta- and alpha-emitting radionuclides, urine and/or faeces analysis have to be done. Detection limits for the different techniques will be discussed.
The dose assessments, which follow the ICRP system, involve numerical solutions of reference biokinetic models, yielding the time-dependent number of nuclear transformations in various source regions. These solutions are then coupled with reference data on nuclear decay information, target tissue masses, and fractions of emitted energy released from source regions that are deposited in target regions as defined in the ICRP/ICRU reference adult phantoms.
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Shielding and operational dosimetry in nuclear medicine staff
Sigrid Leide Svegborn, Associate professor, Department of Radiation Physics, Skånes University Hospital, Malmö, Sweden
The personnel are subject to radiation exposure from various tasks in nuclear medicine practice such as radiopharmaceutical preparation, administration of the radioactive substance, taking care of the patient and during waste management. Especially the fingers are exposed to radiation since a major part of the daily duties is performed using the hands. While the individual effective dose for these workers, estimated from measurements with dosemeters located at the thorax, shows annual values notably lower than the effective dose limit, 20 mSv per year, it is possible that the dose equivalent to the fingers exceeds the annual dose limit of 500 mSv for hands. In particular, this is the case when using radionuclides for positron emission tomography (PET), such as F-18 or Ga-68. The 511-keV photons emitted from these radionuclides require special radiation protection routines.
Measurement of doses to the hands of workers should be carried out routinely, and is preferably performed by use of thermoluminescent dosemeters or by electronic monitoring.
There are several factors affecting the magnitude of the dose to the staff. The time in the radiation field and the amount of activity plays a major role. The skills and the experience of the worker influences the time and thus the dose. Also various dispensing techniques result in different doses. Furthermore, the usage of radiation shielding, such as syringe shielding and radiation shielding of the glass vials, has an apparent effect on the dose. For photon radiation, lead or tungsten shielding is recommended. The larger the distance between the fingers and the radiation source, the lower the absorbed dose. The dose can easily be reduced by increasing the distance, i.e. by using distance tools like forceps and pincers. The radiation dose from the administration of PET-radionuclides may be significantly reduced by means of automatic infusion systems.
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The patient as a radiation source: Nuclear Medicine Diagnostics and Therapy Eleonor Vestergren, PhD, Sahlgrenska University Hospital, Gutenberg, Sweden and Disa Åstrand, MSc, Karolinska University Hospital, Stockholm, Sweden
Patients undergoing nuclear medicine examinations or radionuclide therapies will be radioactive sources that are difficult to shield. Radiation from the patient can cause external doses to staff, relatives and the general public. In Sweden, a group initiated by the Swedish Society of Nuclear Medicine has developed national recommendations on when and how to provide restrictions to patients after nuclear medicine examinations in order to minimize doses to relatives and to the general public. The results from the report will also be applied to radiation safety recommendations for staff. The recommendations in the report are developed from calculations based on measurements on patients and occupancy factors. The recommendations in the report are given for adult patients but the lecture will also give some examples of radiation doses from children undergoing nuclear medicine examinations.
Radionuclide therapies are known to generate increased doses to relatives and to the general public since these patients receive large amounts of radioactive substances with relatively long half-lives. Patients are often hospitalized in order to prevent increased doses to relatives and the general public. The lecture provides insight into some of the most common radionuclide therapies and how they affect the dose load to the staff, relatives and the general public.
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Radiation protection and radiation safety in production and delivery of PET radiopharmaceuticals Mikael Jensen, Professor of Applied Nuclear Physics, The Hevesy Laboratory, DTU-Nutech, Roskilde, Denmark
PET has grown explosively from being a rare, expensive and exclusive research modality embedded in large research units at big medical centers into a widespread, widely requested clinical modality.
The growth is definitely not over. The differences in dissemination even among the Nordic countries show that we are far from steady state. Clinical PET is growing by number of doses and by number of tracers.
To supply this success we need safe, compliant and efficient supply of the PET radiopharmaceuticals. Tools and practices do exist, but the radiation safety of these operations is far from trivial. Conflicting regulations and demands from radiation safety and pharmaceutical safety makes carefully selected compromises necessary. The practice implies potential large radiation doses from an unusual array of sources: high energy gamma, neutrons and intense beta radiation, and carries the risk of introducing long lived radioactive waste and contamination into the medical environment.
From 30 years of personal experience with PET tracer production and distribution both as radiation safety officer and as QP, I will try to describe the present practice and possible developments (dispensing, auto-injectors, point of demand cyclotrons, theranostic use and new more demanding regulations) from the radiation safety point of view.
