Nuclear-medical irradiation during pregnancy

Aim: To estimate and evaluate the risks for the offspring due to the administration of radiopharmaceuticals to women during the first pregnancy weeks after conception (weeks p.c.). Methods: The in-utero exposition of the embryo due to diagnostic nuclear medicine procedures, for which diagnostic reference levels (DRL) are specified, as well as due to radio iodine therapy (RIT) was determined. To this end, it is assumed that the activity of the diagnostic radiopharmaceuticals administered to the mother corresponds with the DRL and amounts to 600 MBq or 4 GBq 131I for RIT of benign or malignant thyroid disease, respectively. Based on these data, the radiation risk for the offspring was assessed and compared with the spontaneous risks (R0). Results: The dose for the offspring does not exceed 7.8 mSv for the diagnostic procedures considered, resulting in an excess risk for the offspring of less than 0.12% (R0 ~ 25%) to die from cancer during life, of less than 0.07% (R0 ~ 0.2%) to develop cancer up to the age of 15 years, and of less than 0.16% (R0 ~ 2%) for hereditary effects. RIT during the first 8 weeks p.c. results in doses for the offspring of about 100–460 mSv, resulting in an excess risk for malformations of the child of 3.4%–22% (R0 ~6%). Conclusions: The risk of stochastic radiation effects for the offspring due to a diagnostic nuclear medicine procedure of the mother during the first 8 weeks p.c. is – compared with the spontaneous risks – very small; deterministic effects are unlikely. In contrast, deterministic effects for the offspring may occur following RIT. In order to decide on a possibly indicated abortion after RIT, an individual risk assessment is mandatory.

Application of radioactive substances in research in nuclear medicine: current trends and radiation exposure to the study subjects

Aim: Analysis of the application of radioactive substances in research in the field of nuclear medicine in human beings and of the resulting radiation exposure to study subjects. Methods: Assessment of applications for approval submitted in accordance with Paragraph 41 of the Radiation Protection Ordinance, evaluated by the Federal Office for Radiation Protection together with the Federal Institute for Pharmaceuticals and Medical Products, within the period from 1997 to 1999. Results: The focus of the studies on the diagnostic application of radioactive substances in medicine evaluated has, since 1998, shifted from oncological to neurological and psychological aspects, while, at the same time, the number of PET studies increased constantly. The proportion of healthy study subjects included in the diagnostic studies increased from 7 to 22%. The number of therapeutic applications of radioactive substances has, since 1997, undergone a three-fold increase, and in the process of this, the focus of attention lay within the area of radioimmuno-therapy and endovascular brachy-theropy. The effective dose was, among up to 49% of the investigated healthy study subjects higher than 5 mSv, and among up to 6% of these subjects was at levels of over 20 mSv. Up to 22% of the patients received, within the scope of diagnostic studies, an effective dose of between 20 and 50 mSv. An exceeding of the 50 mSv limit occurred among up to 3% of the patients. Conclusions: In spite of the increasing numbers of PET applications, conventional nuclear medicine has maintained its importance in the field of medical research. Further developments in the areas of radiochemistry and molecular biology led to an increase in the importance of radio-immuno therapy. The evaluation of new radiopharmaceuticals and the extension of basic biomedical research, resulted in an increase in the proportion of healthy study subjects included in the studies. The radiation exposure among subjects resulting directly from the studies showed, for the period of evaluation, an overall trend towards reduction.

Cycluridine: A novel antiviral effective against flaviviruses

This review describes the contemporary state of research for antivirals effective against flaviviruses, especially focusing on inhibitors of the pestivirus causative agent of bovine viral diarrhoea virus. We highlight cycluridine, an originally synthesized Mannich’s base [a tetrahydro-2(1H)-pyrimidinones derivative], as a highly effective antiviral possessing a strong inhibitory effect on bovine viral diarrhoea virus replication. Cycluridine was active against replication of a wide variety of bovine viral diarrhoea virus strains in cell cultures. The drug-sensitive period in the bovine viral diarrhoea virus replication cycle included the latent period and the exponential phase; a 90-min delay in the peak of viral RNA synthesis was observed. Cycluridine administered orally manifested a pronounced protective effect in calves with natural mucosal disease/viral diarrhoea and calves experimentally infected with bovine viral diarrhoea virus. Its magnitude of activity and selectivity places cycluridine in the lead among all known substances with anti- bovine viral diarrhoea virus activity. Additionally, cycluridine applied subcutaneously showed anti-tick-born encephalitis virus activity, manifesting a marked protective effect in mice infected with tick-born encephalitis virus. Cycluridine could be a prospective antiviral in veterinary and medical practice for the treatment of bovine viral diarrhoea virus and other flavivirus infections.

[Changes in the "medical research" licensing procedure under the German Radiation Protection Ordinance]

This publication outlines the "medical research" licensing procedure as specified in the amendment of the German Radiation Protection Ordinance of November 1, 2011. The general licensing requirements for the use of radiation have not been changed by the amendment. Three so-called use restrictions (i. e., dose limits of 10 mSv and 20 mSv, age limit of 50 years) have been modified. They will only apply to healthy volunteers in the future. In addition, there are considerable simplifications with respect to applications and licensing procedures of the Federal Office for Radiation Protection (Bundesamt für Strahlenschutz, BfS) regarding the use of radiation in the newly introduced "accompanying diagnostics" ("Begleitdiagnostik") case group. The newly established, independent panel of experts at the German Radiological Society (Deutsche Röntgengesellschaft, DRG) may provide essential support to principal investigators, qualified physicians and sponsors for differentiating between "medical research" and "health care", the latter not being subject to licensing. An expert statement will be issued by the DRG within four weeks of an inquiry. This consulting service is subject to confidentiality, and is free of charge for inquirers and without any commitment.

[Nuclear-medical irradiation during pregnancy. Risk assessment for the offspring]

AIM To estimate and evaluate the risks for the offspring due to the administration of radiopharmaceuticals to women during the first pregnancy weeks after conception (weeks p.c.).

METHODS

The in-utero exposition of the embryo due to diagnostic nuclear medicine procedures, for which diagnostic reference levels (DRL) are specified, as well as due to radio iodine therapy (RIT) was determined. To this end, it is assumed that the activity of the diagnostic radiopharmaceuticals administered to the mother corresponds with the DRL and amounts to 600 MBq or 4 GBq 131I for RIT of benign or malignant thyroid disease, respectively. Based on these data, the radiation risk for the offspring was assessed and compared with the spontaneous risks (R0).

RESULTS

The dose for the offspring does not exceed 7.8 mSv for the diagnostic procedures considered, resulting in an excess risk for the offspring of less than 0.12% (R0 approximately 25%) to die from cancer during life, of less than 0.07% (R0 approximately 0.2%) to develop cancer up to the age of 15 years, and of less than 0.16% (R0 approximately 2%) for hereditary effects. RIT during the first 8 weeks p.c. results in doses for the offspring of about 100-460 mSv, resulting in an excess risk for malformations of the child of 3.4%-22% (R0 approximately 6%).

CONCLUSIONS

The risk of stochastic radiation effects for the offspring due to a diagnostic nuclear medicine procedure of the mother during the first 8 weeks p.c. is--compared with the spontaneous risks--very small; deterministic effects are unlikely. In contrast, deterministic effects for the offspring may occur following RIT. In order to decide on a possibly indicated abortion after RIT, an individual risk assessment is mandatory.

[FDG-PET/CT in oncology. German Guideline]

FDG-PET/CT examinations combine metabolic and morphologic imaging within an integrated procedure. Over the past decade PET/CT imaging has gained wide clinical acceptance in the field of oncology. This FDG-PET/CT guideline focuses on indications, data acquisition and processing as well as documentation of FDG-PET/CT examinations in oncologic patients within a clinical and social context specific to Germany. Background information and definitions are followed by examples of clinical and research applications of FDG-PET/CT. Furthermore, protocols for CT scanning (low dose and contrast-enhanced CT) and PET emission imaging are discussed. Documentation and reporting of examinations are specified. Image interpretation criteria and sources of errors are discussed. Quality control for FDG and PET/CT-systems, qualification requirements of personnel as well as legal aspects are presented.

[Establishment and application of diagnostic reference levels for nuclear medicine procedures in Germany]

Diagnostic reference levels (DRL) were introduced in Germany by a publication in the Bundesanzeiger Nr. 143 from August 5, 2003. Thereby a recommendation of the International Commission on Radiological Protection (ICRP) from 1996 and a demand by the EU Guideline 97/43/EURATOM from 1997 is converted into national law. AIM of this paper is to acquaint with and to justify the determined DRL as well as to provide information on the practical use of the concept of the DRL.

MATERIAL AND METHOD

DRL were established by experts on the basis of a national survey conducted in hospitals and private practices as well as of national and international recommendations and published by the Federal Office for Radiation Protection. Besides the data basis the dosimetric principles are described for the estimation of the effective doses of the various examinations.

RESULTS

DRL were established for 10 frequent and dose-relevant examinations constituting more than 80% of all nuclear medicine examinations currently performed in Germany. For some examinations two different DRL were given to take into account clinical conditions. For paediatric examinations fractions of the activities to be administered to adults are given dependent on the body weight.

DISCUSSION

The published DRL are in agreement with the majority of national and international recommendations and with the present practice of nuclear medicine examinations in Germany. They are related to average activities for groups of patients with standard sizes and, moreover, to typical examinations with current standard equipment. It is planned to check and to reconsider the DRL about every 2-3 years.

[Application of radioactive substances in nuclear medicine research: current trends and radiation exposure of study subjects]

AIM

Analysis of the application of radioactive substances in research in the field of nuclear medicine in human beings and of the resulting radiation exposure to study subjects.

METHODS

Assessment of applications for approval submitted in accordance with Paragraph 41 of the Radiation Protection Ordinance, evaluated by the Federal Office for Radiation Protection together with the Federal Institute for Pharmaceuticals and Medical Products, within the period from 1997 to 1999.

RESULTS

The focus of the studies on the diagnostic application of radioactive substances in medicine evaluated has, since 1998, shifted from oncological to neurological and psychological aspects, while, at the same time, the number of PET studies increased constantly. The proportion of healthy study subjects included in the diagnostic studies increased from 7 to 22%. The number of therapeutic applications of radioactive substances has, since 1997, undergone a three-fold increase, and in the process of this, the focus of attention lay within the area of radioimmuno-therapy and endovascular brachytherapy. The effective dose was, among up to 49% of the investigated healthy study subjects higher than 5 mSv, and among up to 6% of these subjects was at levels of over 20 mSv. Up to 22% of the patients received, within the scope of diagnostic studies, an effective dose of between 20 and 50 mSv. An exceeding of the 50 mSv limit occurred among up to 3% of the patients.

CONCLUSIONS

In spite of the increasing numbers of PET applications, conventional nuclear medicine has maintained its importance in the field of medical research. Further developments in the areas of radiochemistry and molecular biology led to an increase in the importance of radio-immuno therapy. The evaluation of new radiopharmaceuticals and the extension of basic biomedical research, resulted in an increase in the proportion of healthy study subjects included in the studies. The radiation exposure among subjects resulting directly from the studies showed, for the period of evaluation, an overall trend towards reduction.