The use of prophylactic Nunchaku stents to reduce the risk of nasolacrimal duct obstruction in patients with midfacial tumours undergoing radiotherapy.

The treatment of midfacial tumours with radiotherapy, chemotherapy and radio-iodine can cause nasolacrimal duct fibrosis resulting in epiphora. Nasolacrimal patency can be maintained by stenting. We report our experience of prophylatic Nunchaku stent insertion in 5 patients prior to midfacial radiotherapy. Four out of 5 patients (80%) had patent nasolacrimal ducts without any symptoms of epiphora following removal of the stents. One patient was initially asymptomatic with patent nasolacrimal duct, but subsequently developed epiphora. Nunchaku stents may provide a simple and effective way of preventing epiphora, obviate the need for nasal retrieval that is required for other nasolacrimal stents, and reduce the risk of requiring further lacrimal surgery.

The fisherman's cards: how to address past and future radiation exposures in clinical decision making.

OBJECTIVE. The purpose of this article is to describe how to address patients' past-and future potential-radiation exposures when making an imaging decision in a given situation. CONCLUSION. The Biologic Effects of Ionizing Radiation committee has endorsed a linear no-threshold model to explain the relationship between radiation exposure and cancer risk. This model implies that past and future potential exposures should not impact current decisions. We present an analogy that deconstructs these counterintuitive conclusions and facilitates translation of key radiation risk principles to practice.

Imaging of trauma in the pregnant patient.

The pregnant trauma patient presents an important and challenging encounter for the clinical team and radiologist. In this article, we present several key aspects of the imaging workup of pregnant trauma patients, beginning with a review of the modalities that are used in this setting. Ultrasonography plays an important role in initial evaluation of the fetus but a limited role in evaluation of maternal injuries. Given that conventional radiography and computed tomography are the "workhorse" modalities for evaluation of pregnant trauma patients, radiologists must pay particular attention to radiation dose concerns. Magnetic resonance imaging can be used after the initial evaluation and for follow-up imaging, and safety concerns related to its use in pregnant patients are addressed. At imaging interpretation, radiologists must contend not only with the typical spectrum of injuries that can be seen in any trauma patient but also with pregnancy-specific injuries, such as placental abruption and uterine rupture. Particularly unusual situations, such as a ruptured ectopic pregnancy in a trauma patient, are presented. Although pregnant trauma patients are infrequently encountered, familiarity with imaging findings of injuries in these patients is essential to providing the best care for the mother and fetus.

Medical imaging radiation safety for the female patient: rationale and implementation.

For the modern practitioner of women's imaging, achieving a balance between the positive diagnostic benefits available from current medical imaging on the one hand, and the potentially deleterious effects of ionizing radiation exposure on the other, has become a central issue. Increased public and professional awareness of the side effects of radiation now require a comprehensive understanding of the facts involved, the various risks to which patients are exposed, and the measures that can be implemented to minimize these risks. The major challenges posed by pregnancy, radiosensitive breast tissue, lactation, and an inability to easily exclude ovaries from the imaging field make female patients particularly vulnerable to medical imaging radiation exposure. The nature of this vulnerability changes frequently and depends on the imaging being performed, the age of the patient, and the clinical situation. For this reason, attention to gynecologic imaging radiation exposure across the whole life span is vitally important.

Radiation exposure and pregnancy.

INTRODUCTION: The effect of radiation on the fetus has been derived primarily from animal studies and human exposures to diagnostic and therapeutic radiation as well as atomic bomb exposure. Given the variety of sources, there is controversy over the dose of radiation in addition to the other environmental conditions that surrounded these events and their relationship to exposure today. METHODS: The effects of ionizing radiation on the fetus, the prenatal period, parental exposure, the pregnant clinician, and the pregnant patient are discussed in the context of their exposure to radiation. RESULTS: The fetus is most sensitive to radiation effects between 8 and 15 weeks of pregnancy. Stepping away from the table and using movable shields help reduce the exposure by a factor of four for every doubling of the distance between the operator and the radiation source. CONCLUSION: Proposed guidelines for pregnancy during vascular residency training involving fluoroscopic procedures can help bring about awareness, clarify maximal exposure, and better delineate the role of the pregnant resident.

SCAI consensus document on occupational radiation exposure to the pregnant cardiologist and technical personnel.

Concerns regarding radiation exposure and its effects during pregnancy are often quoted as an important barrier preventing many women from pursuing a career in Interventional Cardiology. Finding the true risk of radiation exposure from performing cardiac catheterization procedures can be challenging and guidelines for pregnancy exposure have been inadequate. The Women in Innovations group of Cardiologists with endorsement of the Society for Cardiovascular Angiography and Interventions aim to provide guidance in this publication by describing the risk of radiation exposure to pregnant physicians and cardiac catheterization personnel, to educate on appropriate radiation monitoring and to encourage mechanisms to reduce radiation exposure. Current data do not suggest a significant increased risk to the fetus of pregnant women in the cardiac catheterization laboratory and thus do not justify precluding pregnant physicians from performing procedures in the cardiac catheterization laboratory. However, radiation exposure among pregnant physicians should be properly monitored and adequate radiation safety measures are still warranted.

[Radiation protectors within the radiation safety system for extended duration exploration missions].

Radiation environment in extended duration exploration missions is scrutinized in the context of the probability of the risks of deterministic and stochastic effects of radiation. Though the probability of severe radiation damage due to solar flare is very low, nonetheless it is requisite that the crew must be provided with appropriate, including pharmacological safeguards. The current nomenclature of radiation protectors composes short-term agents against acute radiation damage. Among the others, preparation B-190 is distinguished by particularly high effectiveness and universal action, and good tolerance even when organism is exposed to the extreme factors of space flight Regimen of B-290 therapy alone and with combination with aminothiol preparations have been developed to render treatment following multiple solar events. Effectiveness of radioprotectors can be increased substantially by local shielding of the abdomen and pelvis. The most promising nonspecific stimulators of total resistance of organism are riboxin (inosin) and combined preparation aminotetravit as well as vitamins tocopherol and retinol. Therapy combining B-190 with riboxin and aminotetravit is also under discussion. Cytokine neipogen is also viewed as a candidate agent for early therapy. Concern is raised about possible development of chronic oxidative stress in long-duration exploration missions. Highlighted is the significance of adequate nutrition supplemented with fresh vegetables as a source of the most valuable bioflavonoids. Antioxidants L-selenomethionine and melatonin proved their effectiveness against heavy nuclei of galactic radiation. An open issue is how to make natural antioxidants beneficial to oxidative stress control and attenuation of low-intensity galactic radiation.

Suppression of developmental anomalies by maternal macrophages in mice.

We tested whether nonspecific tumoricidal immune cells can suppress congenital malformations by killing precursor cells destined to cause such defects. Pretreatment of pregnant ICR mice with synthetic (Pyran copolymer) and biological (Bacillus Calmette-Guérin) agents significantly suppressed radiation- and chemical-induced congenital malformations (cleft palate, digit anomalies, tail anomalies, etc.). Such suppressive effects were associated with the activation of maternal macrophages by these agents, but were lost either after the disruption of activated macrophages by supersonic waves or by inhibition of their lysosomal enzyme activity with trypan blue. These results indicate that a live activated macrophage with active lysosomal enzymes can be an effector cell to suppress maldevelopment. A similar reduction by activated macrophages was observed in strain CL/Fr, which has a high spontaneous frequency of cleft lips and palates. Furthermore, Pyran-activated maternal macrophages could pass through the placenta, and enhanced urethane-induced cell killing (but not somatic mutation) in the embryo. It is likely that a maternal immunosurveillance system eliminating preteratogenic cells allows for the replacement with normal totipotent blast cells during the pregnancy to protect abnormal development.

Imaging in pregnant patients: examination appropriateness.

A recurring source of contention between clinicians and radiologists continues to be examination appropriateness when imaging pregnant patients. With the multitude of references on potential radiation risks to the fetus, radiologists tend to be cautious and hesitant about exposing the fetus to radiation. This tendency is often interpreted by referring physicians as intrusion into and delay in the care of their patients. The risk burden of radiation exposure to the fetus has to be carefully weighed against the benefits of obtaining a critical diagnosis quickly and using a single tailored imaging study. In general, there is lower than expected awareness of radiation risks to the fetus from imaging pregnant patients. Modalities that do not use ionizing radiation, such as ultrasonography and magnetic resonance imaging, should be the preferred examinations for evaluating an acute condition in a pregnant patient. However, no examination should be withheld when an important clinical diagnosis is under consideration. Exposure to ionizing radiation may be unavoidable, but there is no evidence to suggest that the risk to the fetus after a single imaging study and an interventional procedure is significant. All efforts should be made to minimize the exposure, with consideration of the risk versus benefit for a given clinical scenario.

Keratinocyte growth factor prevents radiation damage to salivary glands by expansion of the stem/progenitor pool.

Irradiation of salivary glands during radiotherapy treatment of patients with head and neck cancer evokes persistent hyposalivation. This results from depletion of stem cells, which renders the gland incapable of replenishing saliva to produce acinar cells. The aim of this study was to investigate whether it is possible to expand the salivary gland stem/progenitor cell population, thereby preventing acinar cell depletion and subsequent gland dysfunction after irradiation. To induce cell proliferation, keratinocyte growth factor (DeltaN23-KGF, palifermin) was administered to C57BL/6 mice for 4 days before and/or after local irradiation of salivary glands. Salivary gland vitality was quantified by in vivo saliva flow rates, morphological measurements, and a newly developed in vitro salisphere progenitor/stem cell assay. Irradiation of salivary glands led to a pronounced reduction in the stem cells of the tissues, resulting in severe hyposalivation and a reduced number of acinar cells. DeltaN23-KGF treatment for 4 days before irradiation indeed induced salivary gland stem/progenitor cell proliferation, increasing the stem and progenitor cell pool. This did not change the relative radiation sensitivity of the stem/progenitor cells, but, as a consequence, an absolute higher number of stem/progenitor cells and acinar cells survived after radiation. Postirradiation treatment with DeltaN23-KGF also improved gland function, and this effect was much more pronounced in DeltaN23-KGF pretreated animals. Post-treatment with DeltaN23-KGF seemed to act through accelerated expansion of the pool of progenitor/stem cells that survived the irradiation treatment. Overall, our data indicate that DeltaN23-KGF is a promising drug to enhance the number of salivary gland progenitor/stem cells and consequently prevent radiation-induced hyposalivation. Disclosure of potential conflicts of interest is found at the end of this article.

Memantine prevents acute radiation-induced toxicities at hippocampal excitatory synapses.

Background: Memantine has shown clinical utility in preventing radiation-induced cognitive impairment, but the mechanisms underlying its protective effects remain unknown. We hypothesized that abnormal glutamate signaling causes radiation-induced abnormalities in neuronal structure and that memantine prevents synaptic toxicity. Methods: Hippocampal cultures expressing enhanced green fluorescent protein were irradiated or sham-treated and their dendritic spine morphology assessed at acute (minutes) and later (days) times using high-resolution confocal microscopy. Excitatory synapses, defined by co-localization of the pre- and postsynaptic markers vesicular glutamate transporter 1 and postsynaptic density protein 95, were also analyzed. Neurons were pretreated with vehicle, the N-methyl-d-aspartate-type glutamate receptor antagonist memantine, or the glutamate scavenger glutamate pyruvate transaminase to assess glutamate signaling. For animal studies, Thy-1-YFP mice were treated with whole-brain radiotherapy or sham with or without memantine. Results: Unlike previously reported long-term losses of dendritic spines, we found that the acute response to radiation is an initial increase in spines and excitatory synapses followed by a decrease in spine/synapse density with altered spine dynamics. Memantine pre-administration prevented this radiation-induced synaptic remodeling. Conclusion: These results demonstrate that radiation causes rapid, dynamic changes in synaptic structural plasticity, implicate abnormal glutamate signaling in cognitive dysfunction following brain irradiation, and describe a protective mechanism of memantine.

Imaging the pregnant patient for nonobstetric conditions: algorithms and radiation dose considerations.

Use of diagnostic imaging studies for evaluation of pregnant patients with medical conditions not related to pregnancy poses a persistent and recurring dilemma. Although a theoretical risk of carcinogenesis exists, there are no known risks for development of congenital malformations or mental retardation in a fetus exposed to ionizing radiation at the levels typically used for diagnostic imaging. An understanding of the effects of ionizing radiation on the fetus at different gestational stages and the estimated exposure dose received by the fetus from various imaging modalities facilitates appropriate choices for diagnostic imaging of pregnant patients with nonobstetric conditions. Other aspects of imaging besides radiation (ie, contrast agents) also carry potential for fetal injury and must be taken into consideration. Imaging algorithms based on a review of the current literature have been developed for specific nonobstetric conditions: pulmonary embolism, acute appendicitis, urolithiasis, biliary disease, and trauma. Imaging modalities that do not use ionizing radiation (ie, ultrasonography and magnetic resonance imaging) are preferred for pregnant patients. If ionizing radiation is used, one must adhere to the principle of using a dose that is as low as reasonably achievable after a discussion of risks versus benefits with the patient.

[Radiotherapy during pregnancy]. / Radiothérapie et grossesse.

The diagnostic of cancer during pregnancy is a rare and delicate situation. As the developments of the embryo and the human fetus are extremely sensitive to ionizing radiations, the treatment of these tumors should be discussed. The studies - preclinical and clinical - based mostly on exposure accidents show that subdiaphragmatic treatments are possible during pregnancy. When radiotherapy is used, phantom estimations of the dose to the fetus, confirmed by in vivo measurements are required. Irradiation and imaging techniques should be arranged to decrease as much as possible the dose delivered to the fetus and hold below the threshold of 0.1Gy.

Breast cancer and pregnancy.

Breast cancer treatment during pregnancy involves a host of psychosocial, ethical, religious, and even legal considerations, as well as medical multidisciplinary decisions, since the effect of treatment on the fetus must be considered. For example, breast or chest wall radiotherapy should be avoided. The absorbed fetal dosage is at least 5 cGy early in pregnancy and increases to several hundred cGy late in pregnancy to the fetal part immediately below the diaphragm. In the second and third trimesters, chemotherapy is associated with intrauterine growth retardation and prematurity in about half of the babies; the risk of birth defects is a concern in the first several weeks. Typical anesthetic agents readily reach the fetus but are not known to be teratogenic. Although abortion will allow full and comprehensive treatment to the mother, it is not known whether the procedure itself is therapeutic. Early in pregnancy, abortion deserves strong consideration, since the effects of treatment on the fetus will not be a consideration. The poor prognosis of pregnancy-associated breast cancer in the past is probably attributable to a combination of initial delay of diagnosis and possibly to unfavorable biologic characteristics of the hormonal milieu of pregnancy. When pregnant patients are matched stage for stage with controls, survivals seem equivalent, although pregnant patients present with more advanced disease.

Accidental embryo irradiation during barium enema examinations. An estimation of absorbed dose.

RATIONALE AND OBJECTIVES: To investigate the possibility of an embryo to receive a dose of more than 10 cGy, the threshold of malformations induction in embryos reported by the International Commission on Radiological Protection, during barium enema examinations. METHODS: Thermoluminescent dosimeters were placed in a phantom to calculate the depth-to-skin conversion coefficient needed for dose estimation at the average embryo depth in patients. Barium enema examinations were performed in 20 women of childbearing age with diagnostic problems demanding longer fluoroscopy times. Doses at 6 cm, the average embryo depth, were determined by measurements at the patients' skin followed by dose calculation at the site of interest. RESULTS: The range of doses estimated at embryo depth for patients was 1.9 to 8.1 cGy. The dose always exceeded 5 cGy when fluoroscopy time was longer than 7 minutes. CONCLUSION: The dose at the embryo depth never exceeded 10 cGy. This study indicates that fluoroscopy time should not exceed 7 minutes in childbearing-age female patients undergoing barium enema examinations.

Inhibition of X-ray-induced exencephaly by protease inhibitors.

We report that protease inhibitors can reduce the incidence of radiation-induced exencephaly in mice. Previous studies from this and other laboratories have demonstrated that protease inhibitors, in particular antipain and the Bowman-Birk inhibitor, are effective anticarcinogenic agents in a variety of in vivo systems and inhibit cell transformation in vitro. Given our results, further investigation is warranted into preventive effects of protease inhibitors on the inhibition of neural tube defects.

The effects of PSK, a biological response modifier, on congenital ocular abnormalities induced by X-ray irradiation.

The antiteratogenic effects of PSK, a biological response modifier, were examined using histological and developmental analysis. The whole bodies of pregnant mice were irradiated with X-rays and injected with PSK within ten minutes after irradiation on day 7 of gestation (E7). The foetuses on E18 were examined and a high incidence of malformations were observed in X-ray irradiated embryos. Microphthalmia was the most frequent malformation. PSK administration suppressed the X-ray irradiation-induced ocular anomalies in not only the frequency, as deduced by external observation, but also in histopathological changes in the retina, lens, and cornea. In particular, the incidence of lens aplasia was significantly decreased by PSK administration. Developmental analysis using E10 and E13 embryos revealed that the decrease in the incidence of histopathological changes was first observed within 72 hours after PSK administration. In addition, X-ray irradiation-induced early foetal death (E10-13) was also suppressed by PSK administration. The possible mechanisms of the antiteratogenic effects of PSK are discussed.

WR-2721 (amifostine, ethyol) prevents motor and morphological changes induced by neonatal X-irradiation.

Neonatal X-irradiation induces permanent abnormalities in cerebellar cortex cytoarchitecture and neurochemistry, as well as impairment in motor gait. The aim of the present work was to examine the potential protective properties of WR-2721 (Amifostine, Ethyol), a free radical scavenger, against the above mentioned alterations by using a previously described neuroprotection assessment protocol. Pre-irradiation treatment with amifostine was effective in partially preventing the cerebellar morphological damage and the motor gait impairment induced by ionizing radiation. No changes in cerebellar noradrenaline (NA) levels were detected in amifostine-treated irradiated animals. These results suggest that it is possible to counteract radiation-induced damage in the cerebella and motor gait of neonatal rats through oxygen free radical scavenger administration prior to irradiation. The presence of the agent before the injury occurs, favors the efficacy of amifostine neuroprotective activity. Clinical implications of this model are related to the daily exposure of many people to different sources of radiation (accidental, diagnostical or therapeutical).

In-flight radiation exposure during pregnancy.

During high-altitude flight, the cosmic radiation dose rate in an airliner is greater than it is at ground level. For a casual traveler, the impact on pregnancy from cosmic radiation exposure during flight is trivial. Pregnant frequent flyers, pilots, and flight attendants can, however, receive exposures that exceed current recommended values if they do not appropriately modify their work schedules. In addition to the galactic cosmic-ray background that is the source of this radiation, severe disturbances on the sun may cause eruptions that significantly raise radiation levels at airliner altitudes for brief periods, possibly having an impact even on casual travelers. This article will help obstetrician-gynecologists provide advice to their pregnant patients about in-flight radiation risks. That advice should be influenced by an understanding of recommended radiation exposure limits and a perspective on how those limits relate to the potential for real harm. Resources provided by the U.S. Federal Aviation Administration and others to help pregnant women and their physicians make informed decisions about the acceptability of this type of exposure are described.