Radiation dose rates from adult patients undergoing nuclear medicine investigations

Adult patients undergoing nuclear medicine investigations may subsequently come into close contact with members of the public and hospital staff. In order to expand the available dosimetry and derive appropriate recommendations, dose rates were measured at 0.1, 0.5 and 1.0 m from 80 adult patients just before they left the nuclear medicine department after undergoing one of eight 99Tcm studies, an 123I thyroid, an 111In leucocyte or a 201Tl cardiac scan. The maximum departure dose rates at these distances of 150, 30 and 7.3 microSv h-1 were greater than those found in similar published studies of adult and paediatric patients. To limit the dose to an infant to less than 1 mSv, an 111In leucocyte scan is the only investigation for which it may be necessary to restrict close contact between the infant and a radioactive parent, depending on the dose rate near the surface of the patient, the parent's habits and how fretful is the infant. It is unlikely that a ward nurse will receive a dose of 60 microSv in a working day if caring for just one radioactive adult patient, unless the patient is classified as totally helpless and has undergone a 99Tcm marrow, bone or brain scan. The data and revised calculations of effective exposure times based on a total close contact time of 9 h in every 24 h period should allow worst case estimates of radiation dose to be made and recommendations to be formulated for other circumstances, including any future legislative changes in dose limits or derived levels.     

The Fukushima nuclear accident temporarily increased patients reluctance for nuclear medicine investigations

Only mentioning the word "nuclear" already creates anxiety and distress. We attempted to assess the impact of the media hype about the Fukushima event on patients admitted in nuclear medicine units to undergo diagnostic investigations. The number of patients denying scintigraphic studies over half a year after the Fukushima accident was compared with the same period of the 2 previous years 2009 and 2010. Data were separately analyzed into thyroid vs. other organ scintigraphies. Physicians' referrals to nuclear medicine showed no decline. Patients undergoing various organ scintigraphies asked questions related to the accident but only few of them denied the investigation. Questioning and denial for nuclear medicine tests were more frequent in females as compared to males and especially in child-bearing females. Among patients referred in the initial post-event phase for thyroid function tests, more than 10% denied thyroid scintigraphy and 2.75% questioned this test. Again, questioning and denial was higher with females, especially in child-bearing age. In conclusion, this study showed that nuclear accidents and perhaps irresponsible media reports may affect behaviour of patients referred for nuclear medicine studies and in particular for thyroid scintigraphy even if these accidents had no radioactive effect to them.     

Dose to patients through nuclear medicine procedures in a department in northern Greece

Diagnostic nuclear medicine procedures in a large hospital in northern Greece during 1984–1988 have been surveyed in order to estimate the radiation burden to the patients. The mean effective dose equivalent (EDE) was found to be 1.96 mSv/examination and 2.46 mSv/patient, allowing for the fact that a number of patients underwent more than one examination. Apart from EDE, absorbed dose has been calculated for bone marrow, thyroid, gonads, kidneys and bladder. Patients undergoing multiple examinations have been used to calculate true patient dose distribution as well as patient time-weighted dose distribution. Because of the predominance of renal examinations, 8.5 fatal renal malignancies are expected per 100000 patients.     

Dose to patients through nuclear medicine procedures in a department in northern Greece

Diagnostic nuclear medicine procedures in a large hospital in northern Greece during 1984-1988 have been surveyed in order to estimate the radiation burden to the patients. The mean effective dose equivalent (EDE) was found to be 1.96 mSv/examination and 2.46 mSv/patient, allowing for the fact that a number of patients underwent more than one examination. Apart from EDE, absorbed dose has been calculated for bone marrow, thyroid, gonads, kidneys and bladder. Patients undergoing multiple examinations have been used to calculate true 'patient dose distribution' as well as 'patient time-weighted dose distribution'. Because of the predominance of renal examinations, 8.5 fatal renal malignancies are expected per 100,000 patients.     

Radiation dose rates from paediatric patients undergoing 99Tcm investigations.

Infants or children undergoing nuclear medicine investigations may subsequently come into close contact with nurses or parents responsible for their care. In order to estimate the radiation dose to these individuals, and to formulate appropriate recommendations, dose rates were measured at distances of 0.1, 0.5 and 1.0 m from 148 paediatric patients who had undergone one of 12 99Tcm studies. The maximum dose rates of 70, 14 and 5 microSv h-1 at these distances were not greater than the corresponding maximum values found in an earlier study of adult patients. However, the maximum dose rates per unit activity of 0.5, 0.2 and 0.1 microSv h-1 MBq-1 were greater than the corresponding maximum 99Tcm adult values, consistent with a general increase of dose rate per unit activity with decrease of body weight observed in the paediatric measurements. A parent caring for and feeding a young infant is most unlikely to receive a dose equivalent of 1 mSv, and a nurse attending to one young radioactive patient is most unlikely to receive a dose equivalent in a working day of 60 microSv. The data obtained should allow radiation doses to be estimated and appropriate recommendations to be formulated for other circumstances, including any future legislative changes in dose limits or derived levels.     

Quality assurance and harmonisation of nuclear medicine investigations in Europe

A survey of all member societies of the European Association of Nuclear Medicine has shown that a satisfactory degree of harmonisation exists for the quality assurance of the preparation and handling of radio-pharmaceuticals and the performance of nuclear medicine instrumentation. However, variations were found in acquisition protocols, data analysis and the interpretation and presentation of clinical results. Harmonisation of these areas of a nuclear medicine investigation would help ensure the overall quality. A European initiative is proposed to collect and collate procedures in these areas in order to produce a reference framework of good practice for the acquisition, analysis and interpretation of nuclear medicine investigations. This would involve collaboration between national societies and exchange of information with and support from European organisations, taking into account relevant international activities. The reference framework should be compatible with quality management guidelines.     

Dose rate measurements from radiopharmaceuticals: implications for nuclear medicine staff and for children with radioactive parents

Following the introduction of a number of radiopharmaceuticals, we assessed the dose received by staff working in the nuclear medicine department and also by children who may be in close contact with a radioactive parent. We measured departure dose rates (microSv.h-1) at distances of 0.1, 0.5 and 1.0 m from the skin surface at the level of the thyroid, chest and bladder of patients undergoing the following nuclear medicine procedures: MUGA scans using 99Tcm-labelled red blood cells, myocardial perfusion scans using 99Tcm-labelled radiopharmaceuticals, lymphoscintigraphy using colloidal 99Tcm (Re) sulphide, bone scans using 99Tcm-labelled oxidronate, 111In-octreotide scans, 111In-labelled leukocyte studies and cardiac reinjection studies using 201Tl. The maximum dose rates at 0.1 m were those from MUGA studies (167.3 microSv.h-1) and myocardial perfusion studies (one-day protocol = 391.7 microSv.h-1, two-day protocol = 121.8 microSv.h-1). The implications of these dose rates on both technical and nursing staff are assessed. Also, the dose received by an infant in close contact with a parent following a nuclear medicine investigation was estimated.     

Radiation risk to patients from nuclear medicine in Poland (1981)

This paper presents the method and results of an estimation of radiation risk to the patients subjected to in vivo diagnostic radio-isotopic procedures in Poland in 1981. The qualitative and quantitative structure of these examinations is also presented. The estimation of an expected number of the stochastic effects caused by the internal exposure to ionizing radiation from the administered radionuclides have been performed for the patients according to ICRP recommendations. The conclusion was that 33 fatal radiation induced cancers, caused mainly by thyroid procedures with 131I, may be expected in the future in the population of about 80,000 patients who were subjected to radioisotopic procedures in Poland in 1981.     

Exposure of critical groups to nuclear medicine patients

When a radiopharmaceutical has been administered to a patient, assessment of the risk to critical groups from emitted photon radiation is by measurement of the integral dose received by an individual, or by measurements of the dose rate external to the patient coupled with appropriate occupancy factors. Estimations have been made from the available data of the dose to critical groups exposed to patients who have undergone diagnostic or therapeutic procedures. These dose estimations can be used to assess the impact of the proposed changes in statutory requirements, and to allow appropriate recommendations to be formulated. Two areas for consideration are that pregnant staff exposed to nuclear medicine patients will require an abdominal surface dose limit lower than 2 mSv to restrict their foetal dose to 1 mSv, and the current UK restrictions for the behaviour of patients who have undergone ¹³¹I treatment are either already adequate or can even be relaxed in order to restrict the exposure of members of the public to the proposed lower dose limits. Agreement is needed on the value (e.g. 95th percentile) from a study of the dose to a number of individuals which should serve as the basis for radiation protection recommendations.     

Information for patients and staff concerning nuclear medicine.

Providing information to patients and staff is an important part of the practice of nuclear medicine. To assist in improving the standard of communications, guidance has been prepared covering the content, style and presentation of letters and leaflets for patients and for medical and nursing staff. Examples are provided which describe nuclear medicine procedures and related radiation safety precautions. They also attempt to answer questions frequently put by the various groups to whom they are addressed.     

Pulmonary nuclear medicine

This article reviews the contribution made by nuclear imaging to the assessment, diagnosis and monitoring of patients with respiratory disease. It focuses on several specific areas including the diagnosis of pulmonary embolism, the investigation of intrapulmonary infection and neoplasm and the role of positron emission tomography (PET) scanning. Offprint requests to: R.F. Miller     

Nucleology, nuclear medicine, molecular nuclear medicine and subspecialties

Henry N. Wagner Jr started the presentation of the highlights of the 39th Annual Meeting of the Society of Nuclear Medicine by quoting: "The economist JM Keynes said: "the difficult lies not in new ideas but in escaping from the old ones". Many changes have taken place in the actual term describing our specialty during the last 15 years. Cardiologists have adopted an important chapter of nuclear medicine and to describe that they use the term of "nuclear cardiology". Radiologists have proposed the term "radionuclide radiology". "Nuclear endocrinology", "nuclear oncology", "nuclear nephrology" may be considered as terms describing chapters of nuclear medicine related to other specialties. Will that indicate that our specialty will be divided into smaller chapters and be offered to colleagues working in other specialties leaving to us the role of the supervisor or perhaps the radioprotection officer for in vivo studies? Of course this role is now being exercised by our colleagues in medical physics. It is suggested to use the word " nucleology", instead of "nuclear medicine" where "nuclear" is used as an adjective. Thus, we will avoid being part of another specialty and cardiologists would use the term cardiac nucleology where "cardiac" is the adjective. The proposed term "nucleology" as compared to the existing term "nuclear medicine" has the advantage of being simpler, correct from the grammar point of view and not related to combined terms that may seem to offer part of our specialty to other specialties. At present our specialty faces many problems. The term "nucleology" supports our specialty from the point of view of terminology. During the 3rd International Meeting of Nuclear Medicine of N. Greece which was held in Thessaloniki, Macedonia, Greece on 4-6 November 2005, a discussion arose among participants as to whether the name of "nucleology" could replace the existing name of "nuclear medicine". Finally, a vote (between "yes" and "no") for the new proposed term showed that the "yes" votes were 72 and the "no" votes were 49.     

Paediatric nuclear medicine

Until the 1980s no serious attempts were made to develop paediatric nuclear medicine, as for various reasons many centres were reluctant to perform radionuclide examinations on children. Then two books were published on paediatric nuclear medicine in 1984 and 1985, respectively. In 1987, a group of physicians formed an informal club of paediatricians and nuclear medicine specialists in an effort to improve the relationship and cooperation between these specialties. Carrying out nuclear medicine examinations on children requires a completely different approach than on adults. Suggestions are made and tips given, and the specific problems involved are discussed in detail.     

Cardiac nuclear medicine

In this paper, the principal applications of nuclear medicine to studies of the heart are described. First, gated cardiac blood pool imaging is discussed, then thallium-201 myocardial imaging, myocardial infarct scintigraphy with 99mTc pyrophosphate, and evaluation of intracardiac shunts. In gated cardiac blood pool imaging, the patient's red blood cells are labeled with 99mTc. Images of the cardiac blood pool are then obtained in multiple projections and displayed in an endless-loop cine display. Quantitative indices of cardiac function are readily obtained, and a variety of functional images can be generated. Blood pool imaging may also be performed with use of a first-pass technique that yields similar information. Applications of blood pool imaging are discussed. The theory and techniques of planar and tomographic thallium-201 myocardial imaging are described, together with their application in the diagnosis of coronary artery disease. The prognostic value of thallium imaging is also examined. Myocardial infarct imaging with 99mTc pyrophosphate is described, and clinical indications are reviewed. Left-to-right cardiac shunts can be evaluated by following the first transit of a bolus of radiopharmaceutical through the lungs. Right-to-left shunts may be evaluated by injection of 99mTc macroaggregated albumin.