Ionizing irradiation and the induction of clinically significant disease in the human thyroid gland

Radiation-Related Thyroid Cancer

Radiation is an environmental factor that elevates the risk of developing thyroid cancer. Actual and possible scenarios of exposures to external and internal radiation are multiple and diverse. This article reviews radiation doses to the thyroid and corresponding cancer risks due to planned, existing, and emergency exposure situations, and medical, public, and occupational categories of exposures. Any exposure scenario may deliver a range of doses to the thyroid, and the risk for cancer is addressed along with modifying factors. The consequences of the Chornobyl and Fukushima nuclear power plant accidents are described, summarizing the information on thyroid cancer epidemiology, treatment, and prognosis, clinicopathological characteristics, and genetic alterations. The Chornobyl thyroid cancers have evolved in time: becoming less aggressive and driver shifting from fusions to point mutations. A comparison of thyroid cancers from the 2 areas reveals numerous differences that cumulatively suggest the low probability of the radiogenic nature of thyroid cancers in Fukushima. In view of continuing usage of different sources of radiation in various settings, the possible ways of reducing thyroid cancer risk from exposures are considered. For external exposures, reasonable measures are generally in line with the As Low As Reasonably Achievable principle, while for internal irradiation from radioactive iodine, thyroid blocking with stable iodine may be recommended in addition to other measures in case of anticipated exposures from a nuclear reactor accident. Finally, the perspectives of studies of radiation effects on the thyroid are discussed from the epidemiological, basic science, and clinical points of view.

Spatial geochemical differentiation of the iodine-induced health risk and distribution of thyroid cancer among urban and rural population of the Central Russian plain affected by the Chernobyl NPP accident

The main goal was to study the spatial distribution of thyroid cancer (THYC) among the population of urban and rural settlements of four regions of Russia, which were characterized by different contents of stable iodine in soils and exposed to radioactive fallout of ¹³¹I from the Chernobyl NPP. Using GIS technologies, zoning of territories for the deficiency of ¹²⁷I and pollution with ¹³¹I was performed. The resulting risk maps were compared with the THYC distribution. The association between the spatial distribution of the total (natural and man-made) risk assessment and the incidence of THYC at the district level tended to have a higher positive correlation (r = 0.505, p < 0.001, n = 94) compared with the correlation of the latter parameter with a fallout density of ¹³¹I (r = 0.468, p < 0.001). After latent period, the incidence of THYC among residents of urban settlements of the Bryansk region was considerably higher than in rural, the difference increasing with time. The correlation between the assessed total risk and THYC distribution in risk zones was significant and higher in the rural areas than in the urban ones. A tendency for a negative significant correlation (r = - 0.55, p = 0.01) between daily iodine intake (based on the main components of the diet) and THYC cases among the rural population was found. A definite difference in the influence of geochemical environmental factors on the distribution of THYC among urban and rural populations deserves more detailed study to prevent this disease.

Iodine-131 and Iodine-131-Meta-iodobenzylguanidine Dosimetry in Cancer Therapy

Radioactive iodine was first used for the treatment of benign thyroid disease and thyroid cancer 80 years ago. I-131 mIBG was later developed for the treatment of adult and pediatric neuroendocrine tumors. Physicists were closely involved from the outset to measure retention, to quantify uptake and to calculate radiation dosimetry. As the treatment became widespread, contrasting treatment regimes were followed, either given with empirically derived fixed levels of activity or guided according to the radiation doses delivered. As for external beam radiotherapy, individualized treatments for both thyroid cancer and neuroendocrine tumors were developed based on the aim of maximizing the radiation doses delivered to target volumes while restricting the radiation doses delivered to organs-at-risk, particularly the bone marrow. The challenge of marrow dosimetry has been met by using surrogate measures, often the blood dose for thyroid treatments and the whole-body dose in the case of treatment of neuroblastoma with I-131 mIBG. A number of studies have sought to establish threshold absorbed doses to ensure therapeutic efficacy. Although different values have been postulated, it has nevertheless been conclusively demonstrated that a fixed activity approach leads to a wide range of absorbed doses delivered to target volumes and to normal organs. Personalized treatment planning is now technically feasible with ongoing multicenter clinical trials and investigations into image quantification, biokinetic modelling and radiobiology.

Severe radiation thyroiditis after radioactive iodine for treatment of Graves' disease

Radiation thyroiditis resulting from radioactive iodine-131 treatment for Graves' disease is an uncommon complication. Although a majority of patients are asymptomatic or manifest mild symptoms that can be managed conservatively, published literature describing severe radiation thyroiditis resulting in significant morbidity is lacking. We herein report on six patients with severe radiation thyroiditis that resulted in hospitalisation, including an unusual complication of myopericarditis.

Thyroid Sequelae of Pediatric Cancer Therapy

The hypothalamic-pituitary-thyroid axis is a common site of unintended, acquired disease either during or after the treatment of cancer. Children treated with external radiation therapy are at the highest risk for developing a thyroid-related late effect, but thyroid dysfunction and second primary thyroid neoplasms can also occur after treatment with radiopharmaceutical agents such as 131I-metaiodobenzylguanidine. Increasingly recognized is the development of early thyroid dysfunction as an off-target consequence of the more novel cancer therapeutics such as the tyrosine kinase inhibitors and immune checkpoint inhibitors. Thyroid sequelae resulting from irradiation may manifest only after years to decades of follow-up, and their resultant clinical symptoms may be indolent and non-specific. Therefore, lifelong monitoring of the childhood cancer survivor at risk for thyroid disease is paramount. In this comprehensive review, the myriad thyroid adverse effects resulting from pediatric cancer treatment are discussed and an overview of screening and treatment of these thyroid sequelae provided.

The ocular surface status in individuals having long-term exposure to ionizing X-radiations

PURPOSE

The present investigation was done to assess the status of tear film and corneal topography in individuals with long-term exposure to X-ray.

METHOD

This historical cohort study was carried out to compare the lacrimal and corneal findings between radiographers (n = 126) and non-radiographers (n = 172). Radiographers included individuals with at least 5 years of experience in radiography while subjects in the control group had no history of exposure to X-ray. The Ocular Surface Disease Index (OSDI) was filled out by all individuals. Besides, the Pentacam imaging of both eyes was done. Finally, the lacrimal tests including tear break-up time and Schirmer (with anesthesia) were performed for both eyes of the participants.

RESULTS

The mean values of the Schirmer and Tear breakup time (TBUT) in the radiographer group (Schirmer: 11.1 ± 3.2 mm, TBUT: 11.3 ± 4.1 s) were significantly lower than the values in control group (14.6 ± 8.1 mm, TBUT: 12.8 ± 4.8 s) (P < 0.0001). The mean OSDI score of the radiographers was significantly higher compared to the control group (24.1 ± 17.6, and 12.3 ± 12.4 respectively (P < 0.0001)). The corneal thickness in the center, inferior, superior, temporal and nasal parts was significantly higher in radiographers versus the control group. In addition, the maximum thickness difference was observed in temporal part (34.00 μm thicker) (P < 0.0001). On the other hand, the corneal eccentricity factor was lower in radiographers compared to the control group (P < 0.0001).

CONCLUSION

Based on the findings of this study, it is concluded that the radiographers have thicker and flatter corneas are than the corneas of the subjects in the control group. However, their corneas had no irregularities. Regarding the tear point, a higher prevalence of dry eye symptoms was observed in the radiographers compared to the control group.

Developing an objective assessment of surgical performance from operating room video and surgical imagery

An unbiased, repeatable process for assessing operating room performance is an important step toward quantifying the relationship between surgical training and performance. Hip fracture surgeries offer a promising first target in orthopedic trauma because they are common and they offer quantitative performance metrics that can be assessed from video recordings and intraoperative fluoroscopic images. Hip fracture repair surgeries were recorded using a head-mounted point-of-view camera. Intraoperative fluoroscopic images were also saved. The following performance metrics were analyzed: duration of wire navigation, number of fluoroscopic images collected, degree of intervention by the surgeon's supervisor, and the tip-apex distance (TAD). Two orthopedic traumatologists graded surgical performance in each video independently using an Objective Structured Assessment of Technical Skill (OSATS). Wire navigation duration correlated with weeks into residency and prior cases logged. TAD correlated with cases logged. There was no significant correlation between the OSATS total score and experience metrics. Total OSATS score correlated with duration and number of fluoroscopic images. Our results indicate that two metrics of hip fracture wire navigation performance, duration and TAD, significantly differentiate surgical experience. The methods presented have the potential to provide truly objective assessment of resident technical performance in the OR.

The effect of surgical experience on the amount of radiation exposure from fluoroscopy during dynamic hip screw fixation

INTRODUCTION Dynamic hip screw (DHS) fixation for proximal femur fractures is one of the most common procedures in trauma that requires the use of fluoroscopy. Emphasis is often placed on producing the 'perfect picture', which may lead to excessive use of fluoroscopy, without added patient benefit. This study, the largest of its kind, aimed to determine the effect of surgical experience on the amount of radiation exposure from fluoroscopy during DHS fixation. METHODS All hospital admissions for extracapsular proximal femur fractures to our institution between 2007 and 2012 were analysed. Patient demographics, fracture configuration, grade of surgeon and the total radiation dose after fixation were recorded. Analysis of variance was performed to assess differences in radiation levels between different grades of surgeon. RESULTS A total of 1,203 patients with a mean age of 81.3 years (range: 21-105 years) were included in the study. The majority of the fractures were three-part (33.3%), followed by two-part (32.2%), four-part (25.7%) and basicervical (8.9%). Registrars (ST3-ST8) used a significantly higher radiation dose than consultants for all fracture types (p=0.009). When analysed separately by trainee group, the most junior registrars (ST3-ST4) and the most senior registrars (ST7-ST8) were found to use significantly higher radiation levels than consultants (p=0.037 and p<0.001 respectively). CONCLUSIONS The level of surgical experience does influence the amount of radiation exposure from fluoroscopy during DHS fixation. Surgical trainees should not ignore the potential harmful effects of radiation and should be equipped with the knowledge of how to keep the radiation exposure as low as possible.

ICRP Publication 131: Stem Cell Biology with Respect to Carcinogenesis Aspects of Radiological Protection

This report provides a review of stem cells/progenitor cells and their responses to ionising radiation in relation to issues relevant to stochastic effects of radiation that form a major part of the International Commission on Radiological Protection's system of radiological protection. Current information on stem cell characteristics, maintenance and renewal, evolution with age, location in stem cell 'niches', and radiosensitivity to acute and protracted exposures is presented in a series of substantial reviews as annexes concerning haematopoietic tissue, mammary gland, thyroid, digestive tract, lung, skin, and bone. This foundation of knowledge of stem cells is used in the main text of the report to provide a biological insight into issues such as the linear-no-threshold (LNT) model, cancer risk among tissues, dose-rate effects, and changes in the risk of radiation carcinogenesis by age at exposure and attained age. Knowledge of the biology and associated radiation biology of stem cells and progenitor cells is more developed in tissues that renew fairly rapidly, such as haematopoietic tissue, intestinal mucosa, and epidermis, although all the tissues considered here possess stem cell populations. Important features of stem cell maintenance, renewal, and response are the microenvironmental signals operating in the niche residence, for which a well-defined spatial location has been identified in some tissues. The identity of the target cell for carcinogenesis continues to point to the more primitive stem cell population that is mostly quiescent, and hence able to accumulate the protracted sequence of mutations necessary to result in malignancy. In addition, there is some potential for daughter progenitor cells to be target cells in particular cases, such as in haematopoietic tissue and in skin. Several biological processes could contribute to protecting stem cells from mutation accumulation: (a) accurate DNA repair; (b) rapidly induced death of injured stem cells; (c) retention of the DNA parental template strand during divisions in some tissue systems, so that mutations are passed to the daughter differentiating cells and not retained in the parental cell; and (d) stem cell competition, whereby undamaged stem cells outcompete damaged stem cells for residence in the niche. DNA repair mainly occurs within a few days of irradiation, while stem cell competition requires weeks or many months depending on the tissue type. The aforementioned processes may contribute to the differences in carcinogenic radiation risk values between tissues, and may help to explain why a rapidly replicating tissue such as small intestine is less prone to such risk. The processes also provide a mechanistic insight relevant to the LNT model, and the relative and absolute risk models. The radiobiological knowledge also provides a scientific insight into discussions of the dose and dose-rate effectiveness factor currently used in radiological protection guidelines. In addition, the biological information contributes potential reasons for the age-dependent sensitivity to radiation carcinogenesis, including the effects of in-utero exposure.

Painful Radiation Thyroiditis after 131I Therapy for Graves' Hyperthyroidism: Clinical Features and Ultrasonographic Findings in Five Cases

BACKGROUND

Radiation thyroiditis caused by ¹³¹I therapy for Graves' hyperthyroidism is asymptomatic in most patients and is rarely associated with pain or fever. Currently, there are few reports on the ultrasonographic findings of radiation thyroiditis after ¹³¹I therapy for Graves' hyperthyroidism.

CASE REPORT

We herein report 5 cases with painful radiation thyroiditis (including 2 febrile cases) after ¹³¹I therapy for Graves' hyperthyroidism. The cases included 4 women, aged 49, 50, 76, and 81 years, and 1 man, aged 60 years. Anterior neck pain developed 0-10 days after ¹³¹I administration (fixed dose of 481 MBq). Each patient visited our clinic 0-4 days after the development of anterior neck pain. The thyroid glands were noticeably enlarged (increasing from 18 g at ¹³¹I administration to 35 g after the development of anterior neck pain in 1 patient, and from 20 to 33 g, 21 to 39 g, 21 to 51 g, and 40 to 51 g in the other patients) and tender. The echogenicity of the thyroid parenchyma was increased, and the parenchyma was more heterogeneous. Granular hyperechoic lesions were scattered throughout the thyroid gland in the most severe case. The border between the thyroid gland and the surrounding tissue was blurred, and the surrounding tissue was hyperechoic.

CONCLUSION

Painful radiation thyroiditis should be reacknowledged as one of the complications of ¹³¹I therapy for Graves' hyperthyroidism. Ultrasonography demonstrated the characteristic changes caused by ¹³¹I-induced radiation thyroiditis.

Assessing Wire Navigation Performance in the Operating Room

OBJECTIVE

There are no widely accepted, objective, and reliable tools for measuring surgical skill in the operating room (OR). Ubiquitous video and imaging technology provide opportunities to develop metrics that meet this need. Hip fracture surgery is a promising area in which to develop these measures because hip fractures are common, the surgery is used as a milestone for residents, and it demands technical skill. The study objective is to develop meaningful, objective measures of wire navigation performance in the OR.

DESIGN

Resident surgeons wore a head-mounted video camera while performing surgical open reduction and internal fixation using a dynamic hip screw. Data collected from video included: duration of wire navigation, number of fluoroscopic images, and the degree of intervention by the surgeon׳s supervisor. To determine reliability of these measurements, 4 independent raters performed them for 2 cases. Raters independently measured the tip-apex distance (TAD), which reflects the accuracy of the surgical placement of the wire, on all the 7 cases.

SETTING

University of Iowa Hospitals and Clinics in Iowa City, IA-a public tertiary academic center.

PARTICIPANTS

In total 7 surgeries were performed by 7 different orthopedic residents. All 10 raters were biomedical engineering graduate students.

RESULTS

The standard deviations for anteroposterior, lateral, and combined TAD measurements of the 10 raters were 2.7, 1.9, and 3.7mm, respectively, and interrater reliability produced a Cronbach α of 0.97. The interrater reliability analysis for all 9 video-based measures produced a Cronbach α of 0.99.

CONCLUSIONS

Several video-based metrics were consistent across the 4 video reviewers and are likely to be useful for performance assessment. The TAD measurement was less reliable than previous reports have suggested, but remains a valuable metric of performance. Nonexperts can reliably measure these values and they offer an objective assessment of OR performance.

Intraoperative radiation use by trainees during ankle fracture fixation

Orthopedic trainees are assessed during training regarding their use of radiological screening during operative procedures. The authors investigated whether orthopedic trainees' use of fluoroscopic screening during ankle fixation operations varied with the 2 variables of consultant supervision and trainee experience. Data from operative fixation of isolated Weber B ankle fractures were reviewed. The intraoperative radiation dose was retrieved from radiographers' data. Operations performed by consultants were used as a control group (n=25 patients). Trainee supervision was assessed as "trainer in operating room (OR)" and "trainer out of OR." Regarding experience, the patients were divided into those operated on primarily by trainees in their first (n=36 patients) and in their last (n=34 patients) 3 years of formal specialist training. All trainee groups used more radiation than consultants. Supervision did not affect the radiation use of senior trainees (P<.05). Senior trainees used less radiation than their junior peers (P<.02). Junior trainees supervised by a trainer in the OR used less radiation than junior trainees supervised by a trainer outside of the OR (P<.05). During open reduction and internal fixation of ankle fractures, junior orthopedic trainees use less intraoperative radiation when they are supervised by a trainer in the OR. The more experience a surgeon has, the less fluoroscopic screening is used during operative ankle fixation.

Radiation exposure during the lateral lumbar interbody fusion procedure and techniques to reduce radiation dosage

BACKGROUND

Fluoroscopy is widely used in spine surgery to assist with graft and hardware placement. Previous studies have not measured radiation exposure to a surgeon during minimally invasive lateral lumbar spine surgery for single-level discectomy and interbody cage insertion. This study was performed to model and measure radiation exposure to a surgeon during spine surgery using the direct lateral lumbar procedure.

METHODS

The study was performed using a mannequin substituting for the surgeon and a cadaver substituting for the patient. Radiation was measured with dosimeters attached to 6 locations on the mannequin using a OEC Medical Systems 9800 C-arm fluoroscope (OEC Medical Systems, Salt Lake City, Utah). Three different fluoroscopy setups were tested: a standard imaging setup, a standard setup using pulsed-mode fluoroscopy, and a reversed setup. The experiment was tested 5 times per setup, and the dosimeters' values were recorded.

RESULTS

The highest amount of radiation exposure occurred when obtaining an anteroposterior view of the spine in the standard setup. Compared with the standard setup, the pulsed-mode setting decreased the radiation exposure to the mannequin by a factor of 6 times (P < .001). Compared with the standard setup, the reversed setup also decreased the radiation exposure to the mannequin by a factor of 6 times (P < .001) and it had the lowest amount of radiation exposure to the eye level (P < .001).

CONCLUSIONS

Care should be taken when one is obtaining an anteroposterior view of the lumbar spine during lateral lumbar procedures to limit radiation exposure. Radiation exposure to the surgeon can be greatly minimized by using either a pulsed imaging mode or the reversed setup. The reversed setup has the lowest amount of radiation exposure to the eye level.

Radiation exposure to the surgeon during open lumbar microdiscectomy and minimally invasive microdiscectomy: a prospective, controlled trial

STUDY DESIGN

This is a prospective in vivo study comparing radiation exposure to the surgeon during 10 minimally invasive lumbar microdiscectomy cases with 10 traditional open discectomy cases as a control.

OBJECTIVE

Radiation exposure to the eye, chest, and hand of the operating surgeon during minimally invasive surgery (MIS) and open lumbar microdiscectomy were measured. The Occupational Exposure Guidelines were used to calculate the allowable number of cases per year from the mean values at each of the 3 sites.

SUMMARY OF BACKGROUND DATA

Fluoroscopy is a source of ionizing radiation and as such, is a potential health hazard with continued exposure during surgery. Presently, radiation exposure to the surgeon during MIS lumbar microdiscectomy is unknown.

METHODS

Radiation exposure to the surgeon (millirads [mR]) per case was measured by digital dosimeters placed at the level of the thyroid/eye, chest, and dominant forearm. Other data collected included operative side and level, side of the surgeon, side of the x-ray source, total fluoroscopy time, and energy output.

RESULTS

The average radiation exposure to the surgeon during open cases was thyroid/eye 0.16 ± 0.22 mR, chest 0.21 ± 0.23 mR, and hand 0.20 ± 0.14 mR. During minimally invasive cases exposure to the thyroid/eye was 1.72 ± 1.52 mR, the chest was 3.08 ± 2.93 mR, and the hand was 4.45 ± 3.75 mR. The difference between thyroid/ eye, chest, and hand exposure during open and minimally invasive cases was statistically significant (P = 0.010, P = 0.013, and P = 0.006, respectively). Surgeons standing in an adjacent substerile room during open cases were exposed to 0.2 mR per case.

CONCLUSION

MIS lumbar microdiscectomy cases expose the surgeon to significantly more radiation than open microdiscectomy. One would need to perform 1623 MIS microdiscectomies to exceed the exposure limit for whole-body radiation, 8720 cases for the lens of the eye, and 11,235 cases for the hand. Standing in a substerile room during x-ray localization in open cases is not fully protective.

Factors that modify radiation-induced carcinogenesis

It is known that numerous factors can influence radiation carcinogenesis in animals; these factors include the specific characteristics of the radiation (radiation type and dose, dose-rate, dose-fractionation, dose distribution, etc.) as well as many other contributing elements that are not specific to the radiation exposure, such as animal genetic characteristics and age, the environment of the animal, dietary factors and whether specific modifying agents for radiation carcinogenesis have been utilized in the studies. This overview focuses on the modifying factors for radiation carcinogenesis, in both in vivo and in vitro systems, and includes a discussion of agents that enhance (e.g., promoting agents) or suppress (e.g., cancer preventive agents) radiation-induced carcinogenesis. The agents that enhance or suppress radiation carcinogenesis in experimental model systems have been shown to lead to effects equally as large as other known modifying factors for radiation-induced carcinogenesis (e.g., dose-rate, dose-fractionation, linear energy transfer). It is known that dietary factors play an important role in determining the yields of radiation-induced cancers in animal model systems, and it is likely that they also influence radiation-induced cancer risks in human populations.

Transcriptional Profile of Ki-Ras-Induced Transformation of Thyroid Cells

In the last years, an increasing number of experiments has provided compelling evidence for a casual role of Ras protein mutations, resulting in their constitutive activation, in thyroid carcinogenesis. However, despite the clear involvement of Ras proteins in thyroid carcinogenesis, the nature of most of the target genes, whose expression is modulated by the Ras-induced signaling pathways and that are ultimately responsible for Ras-induced cellular transformation, remains largely unknown. To analyze Ras-dependent modulation of gene expression in thyroid cells we took advantage of a differentiated rat thyroid cell line, FRTL-5. As a model for Ras-dependent thyroid transformation, we used FRTL-5 cells infected with the Kirsten murine sarcoma virus, carrying the v-Ki-Ras oncogene. The infected cells (FRTL-5 v-Ki-Ras) have lost expression of the thyroid differentiation markers and also are completely transformed. We hybridized two different Affimetrix chips containing probe sets interrogating both known rat genes and ESTs for a total of more than 17,000 sequences using mRNA extracted from FRTL-5 and FRTL-5 v-Ki-Ras cell lines. We identified about 50 genes whose expression was induced and about 40 genes whose expression was downregulated more than 10-fold by Ras. We confirmed the differential expression of many of these genes in FRTL-5 v-Ki-Ras as compared to parental cells by using alternative techniques. Remarkably, we investigated the expression of some of the Ras-regulated genes in human thyroid carcinoma cell lines and tumor samples, our results, therefore, providing a new molecular profile of the genes involved in thyroid neoplastic transformation.

X-ray-based machine vision system for distal locking of intramedullary nails

In surgical procedures for femoral shaft fracture treatment, current techniques for locking the distal end of intramedullary nails, using two screws, rely heavily on the use of two-dimensional X-ray images to guide three-dimensional bone drilling processes. Therefore, a large number of X-ray images are required, as the surgeon uses his/her skills and experience to locate the distal hole axes on the intramedullary nail. The long-term effects of X-ray radiation and their relation to different types of cancer still remain uncertain. Therefore, there is a need to develop a surgical technique that can limit the use of X-rays during the distal locking procedure. A robotic-assisted orthopaedic surgery system has been developed at Loughborough University to assist orthopaedic surgeons by reducing the irradiation involved in such operations. The system simplifies the current approach as it uses only two near-orthogonal X-ray images to determine the drilling trajectory of the distal locking holes, thereby considerably reducing irradiation to both the surgeon and patient. Furthermore, the system uses robust machine vision features to reduce the surgeon's interaction with the system, thus reducing the overall operating time. Laboratory test results have shown that the proposed system is very robust in the presence of variable noise and contrast in the X-ray images.

Evaluation of the thyroid nodule

BACKGROUND

Thyroid nodules are common, yet treatment modalities range from observation to surgical resection. Because thyroid nodules are frequently found incidentally during routine physical examination or imaging performed for another reason, physicians from a diverse range of specialties encounter thyroid nodules. Clinical decision making depends on proper evaluation of the thyroid nodule.

METHODS

The current literature was reviewed and synthesized.

RESULTS

Current evidence allows the formulation of recommendations and a general algorithm for evaluating the incidental thyroid nodule.

CONCLUSIONS

Only a small percentage of thyroid nodules require surgical management. Diagnosis and treatment selection require a risk stratification by history, physical examination, and ancillary tests. Nodules causing airway compression or those at high risk for carcinoma should prompt evaluation for surgical treatment. In nodules larger than 1 cm, fine-needle aspiration biopsy is central to the evaluation as it is accurate, low risk, and cost effective. Subcentimeter nodules, often found incidentally on imaging obtained for another purpose, can usually be evaluated by ultrasonography. Other laboratory and imaging evaluations have specific and more limited roles. An algorithm for the evaluation of the thyroid nodule is presented.

Radiation exposure to the surgeon during fluoroscopically assisted percutaneous vertebroplasty: a prospective study

STUDY DESIGN

A prospective case control study design was conducted.

OBJECTIVES

The purpose of the current study was to determine the intraoperative radiation hazard to spine surgeons by occupational radiation exposure during percutaneous vertebroplasty and possible consequences with respect to radiation protection.

SUMMARY OF BACKGROUND DATA

The development of minimally invasive surgery techniques has led to an increasing number of fluoroscopically guided procedures being done percutaneously such as vertebroplasty, which is the percutaneous cement augmentation of vertebral bodies.

METHODS

Three months of occupational dose data for two spine surgeons was evaluated measuring the radiation doses to the thyroid gland, the upper extremities, and the eyes during vertebroplasty.

RESULTS

The annual risk of developing a fatal cancer of the thyroid is 0.0025%, which means a very small to small risk. The annual morbidity (the risk of developing a cancer including nonfatal ones) is 0.025%, which already means a small to medium risk. The dose for the eye lens was about 8% of the threshold dose to develop a radiation induced cataract (150 mSv); therefore, the risk is very low but not negligible. The doses measured for the skin are 10% of the annual effective dose limit (500 mSv) recommended by the ICRP (International Commission on Radiologic Protection); therefore, the annual risk for developing a fatal skin cancer is very low.

CONCLUSION

While performing percutaneous vertebroplasty, the surgeon is exposed to a significant amount of radiation. Proper surgical technique and shielding devices to decrease potentially high morbidity are mandatory. Training in radiation protection should be an integral part of the education for all surgeons using minimally invasive radiologic-guided interventional techniques.

Skill dependence of radiation exposure for the orthopaedic surgeon during interlocking nailing of long-bone shaft fractures: a clinical study

INTRODUCTION

The objective of this clinical trial was to determine whether there is a skill dependence for the total amount of radiation exposure to orthopaedic surgeons caused by fluoroscopy during intramedullary fracture fixation.

MATERIALS AND METHODS

Surgical teams were assigned to either the 'Senior group' or the 'Junior group' according to their professional qualification and clinical appointment. Twenty-two long-bone shaft fractures were stabilized with intramedullary nails. The radiation exposure was measured at different body locations including fingers, trunk and head by means of thermoluminescent LiF:Mg,Cu,P detectors. The total time of fluoroscopy was registered for each operation.

RESULTS

Mean time of fluoroscopy per operation was 4.43 min for the 'Senior group' and 6.95 min for the 'Junior group'. The surgeons' hands were exposed to markedly higher doses (range 0-2.88 mSv 'Senior group'; 0-11.94 mSv 'Junior group') than their trunk and head (range 0-0.27 mSv 'Senior group'; 0-0.38 mSv 'Junior group'). After analysis of variance, differences between both groups proved to be statistically significant for all fingers measured (p</=0.02) and for the total time of fluoroscopy (p=0.019).

CONCLUSIONS

Generally, the hands are at higher risk than are the trunk and the head, and this finding is independent of surgical skills. However, an additional hazard is created for the less experienced surgeon by a highly varying and poorly predictable exposure of the hands and time needed for fluoroscopy. Thus, the use of radiation is more consistent and standardized with a skilled surgeon.

A prospective study of thyroid nodular disease in children and adolescents in western Poland from 1996 to 2000 and the incidence of thyroid carcinoma relative to iodine deficiency and the Chernobyl disaster

BACKGROUND

In Poland, where soil is deficient in iodine, supplementation of iodine was introduced in 1935, discontinued in 1980, and then re-introduced in 1997. One of the effects of inadequate iodine intake, prior to 1997, was an increase in the prevalence of thyroid nodular disease (TND) in children. Chernobyl, located in the neighbouring country of Ukraine, suffered a catastrophic nuclear explosion in April 1986.

PROCEDURE

A total of 411 children with TND (an incidence of 7.53/100,000) were diagnosed and registered in western Poland between 1996 and 2000 and further evaluated as a population-based study.

RESULTS

Based on the patient's clinical status, ultrasound examination, scintiscan, laboratory tests, cytology and the family history, many of the patients qualified for surgery and, as a result, histopathologic data were obtained from 155 of the 411 patients operated on to date (37.7% of all TND). Thyroid carcinoma was detected in 37 of the operated children, i.e. 23.9% or 9.0% of all children with TND with a median incidence of 0.68/100,000. Papillary carcinoma was the predominant histologic type (26-70.3%) compared to follicular carcinoma (10-27.0%) and medullary carcinoma (1-2.7%). Retrospective analysis of the figures for the 23 years (1972-1995) showed that in that period a total of 23 thyroid carcinomas were registered. However, only 12 of these were detected in the 20-year period between 1972 and 1991, none in the years 1992-1993 and, significantly, 11 from 1994 to 1995.

CONCLUSIONS

Thyroid carcinoma appears to be an ongoing and increasing problem in the children and adolescents of our region, and it is developing more intensively when compared, both to other parts of Poland and to previous statistics (2000 vs. 1985; P<0.002). Iodine deficiency and radiation resulting from the Chernobyl disaster might be important risk factors in the development of thyroid carcinoma in the young population analysed in our region in the period since 1994. The high percentage of follicular carcinoma and follicular adenoma with an undetermined prognosis (19 out of 46) indicates that the long-term iodine deficiency in our region may be more significant in the pathogenesis of malignant transformation than has previously been postulated.

Second primary cancers in patients with laryngeal cancer: a population-based study

BACKGROUND

Literature regarding incidence of site-specific second cancers after laryngeal cancer is limited. Risk factors associated with second primaries are unknown.

METHODS

Second primaries after laryngeal cancer in the SEER database (1973-1996) were analyzed for incidence, relative risk compared with the general population, and potential risk factors, including radiotherapy. Information on chemotherapy and tobacco smoking was not available in the SEER database.

RESULTS

Of 20,074 laryngeal cancer patients surviving at least 3 months, 3533 (17.6%) developed second cancers. The cumulative risk of developing a second cancer was 26% at 10 years and 47% at 20 years. Compared with age-adjusted, gender, and tumor-specific rates in the general population, laryngeal cancer patients had higher risks of second cancers overall (observed-to-expected ratio [O/E] = 1.68, 95% confidence interval [CI] = 1.58-1.79), head-and-neck (4.81 [4.31-5.58]), esophageal (3.99 [3.29-4.83]), and lung (3.56 [3.34-3.79]) cancer. Advanced age at initial diagnosis was associated with increased risks of second cancers (p = 0.0001). Radiotherapy was associated with increased risk of second cancers overall (relative risk [RR] = 1.10 [1.02-1.18], p = 0.012), especially second cancers of the lung (RR = 1.18, [1.05-1.33], p = 0.006) and possibly second cancers of the head and neck (RR = 1.26, [0.99-1.60], p = 0.061). Radiotherapy was associated with a 68% excess risk (RR = 1.68, [1.16-2.43], p = 0.007) of developing a second head-and-neck cancer in patients who survived more than 5 years. Second primary was associated with a poor survival (p = 0.0001).

CONCLUSIONS

Second cancers after laryngeal cancer are common, especially for long-term survivors. Radiotherapy was associated with a small increased risk of developing second cancers overall and long-term risk of head-and-neck cancers. This data should be interpreted with caution in light of the lack of information on chemotherapy and tobacco smoking in the SEER database. Prevention and early detection are indicated.

Thyroid neoplasms after therapeutic radiation for malignancies during childhood or adolescence

BACKGROUND

Recent data indicate that the risk of developing a thyroid neoplasm clearly is increased after high-dose, therapeutic radiation therapy during childhood. To better understand the time course, natural history, and histopathology of thyroid lesions that develop after high-dose irradiation, the authors undertook a retrospective study of all survivors of childhood and adolescent malignancies who were treated at Memorial Sloan-Kettering Cancer Center and who developed a clinically apparent thyroid neoplasm.

METHODS

The authors searched the data base of the Department of Pediatrics, the hospital-based tumor registry, and the hospital medical records database for patients with thyroid neoplasms.

RESULTS

Thirty-three patients were identified who developed a thyroid neoplasm after therapeutic radiation. Primary diagnoses were Hodgkin disease (n = 18 patients), non-Hodgkin lymphoma (n = 10 patients), acute lymphoblastic leukemia (n = 2 patients), acute myeloid leukemia (n = 1 patient), Wilms tumor (n = 1 patient), and neuroblastoma (n = 1 patient). The median age at the time of diagnosis of the primary malignancy was 12.0 years (range, 3.7-18.3 years), the median radiation dose to the thyroid gland was 2400 centigrays (cGy; range, 1000-4200 cGy), and the median interval from the time of radiation therapy until the recognition of thyroid disease was 13.0 years (range, 6.2-30.1 years). Thirteen of 33 thyroid lesions (39%) were malignant (11 papillary carcinomas and 2 follicular carcinomas). Age at diagnosis, gender ratio, and time elapsed since initial treatment did not differ between patients with malignant and benign lesions, but the median radiation dose to the thyroid was lower in patients who had malignant disease compared with patients who had benign disease (2000 cGy vs. 2950 cGy; P = 0.03). Disease was confined to the neck in all patients who had malignant thyroid lesions; after a median follow-up of 6.5 years (range, 0.9-12 years), none of the patients developed progressive or recurrent disease.

CONCLUSIONS

Data from this study suggest that a high proportion of clinically apparent thyroid neoplasms that develop after therapeutic radiation for a childhood malignancy are malignant. However, most of these thyroid malignancies do not appear to behave in an aggressive fashion. Because thyroid neoplasms may not become evident for decades after radiation therapy, all individuals who are at risk require life-long follow-up.

[Results of treatment with calculated doses of radioiodine depending on gland size and morphology in graves' disease. Analysis of variables]

OBJECTIVE

To assess the efficacy of the administered doses of Radioiodine (RAI) in the treatment of patients with hyperthyroidism in Graves' disease, calculated on the basis of gland size and morphology (assessment by palpation and scintigraphy), analyzing which variables influence the final result of our sample, and on the early development of hypothyroidism.

METHODS

99 patients treated with RAI between april 1996 and november 2000 were evaluated retrospectively, 77 women and 22 men, mean age 44 years (range: 18-76). 67 patients received treatment with oral antithyroid drugs. The administered dose range was: 185-629 MBq. Mean follow-up time was 13.4 months. Success was defined as elimination of hyperthyroidism; and early hypothyroidism which appeared in the six months after therapy.

RESULTS

30 patients remained with euthyroidism, 53 patients had hypothyroidism and 16 had recurrent hyperthyroidism. A total of 84% of the patients were controlled with one dose of RAI. Only the time of evolution influenced the final results. The rest of the variables (gender, age, doses and antithyroid drugs) did not influence them. No relationship was found between the appearance of early/late hypothyroidism and the administered doses. A certain tendency was found for early hypothyroidism to appear in the youngest patients (p = 0.111).

CONCLUSIONS

The administered doses in our department have been shown to be effective in controlling thyrotoxicosis. In our sample, only time of evolution influenced on the final results of the patients. Only the age factor showed a certain tendency in the evolution to early/late hypothyroidism.

Hyperparathyroidism and subsequent cancer risk in Denmark

BACKGROUND

There is increasing evidence that hyperparathyroidism (HPT), a condition that leads to elevated serum calcium levels, is associated with endocrine and other malignancies, suggesting a possible causal link between HPT and carcinoma.

METHODS

To investigate the relation of HPT to subsequent cancer risk, the authors conducted a record-linkage study among 2425 patients who were diagnosed with HPT in Danish hospitals. Patients were identified in hospital discharge records, and records were then linked with the Danish National Cancer Registry for the years 1977-1993 to identify cancer incidence. To estimate cancer risk, standardized incidence ratios (SIRs) were computed.

RESULTS

After excluding patients who were diagnosed in the first year of follow-up, a total of 219 malignancies were observed, resulting in an SIR of 1.25 (95% confidence interval [95%CI], 1.1-1.4). Cancer risk among women was higher than among men. Among those with primary (idiopathic) HPT, hematopoetic malignancies were elevated significantly (SIR, 1.88; 95%CI, 1.0-3.2; based on 13 patients), with the excess derived primarily from 4 observed patients with multiple myeloma. Patients with secondary HPT had an insignificantly increased risk of overall cancers. Patients who were diagnosed with other or unspecified types of HPT had significant increases in carcinoma of the urinary tract (SIR, 2.71; 95%CI, 1.2-5.3; based on 8 patients) and carcinoma of the thyroid gland (SIR, 21.19; 95%CI, 4.3-61.9; based on 3 patients).

CONCLUSIONS

Future studies should monitor whether specific endocrine alterations associated with HPT may affect the long-term risk of hematopoetic, thyroid, and urinary tract carcinomas.

Radiation exposure to surgeon and patient in intramedullary nailing of the lower limb

Intramedullary nailing is probably the best method of treating long bone fractures in the lower limb. The operation is guided by fluoroscopy, for guide-wire insertion, fracture reduction and distal locking. No study so far has measured the scatter radiation to the patient's gonads during intramedullary, particularly femoral, nailing. The purpose here was to estimate the radiation hazard to the patients' gonads and surgeons' hands during intramedullary nailing for lower limb fractures. From April 1994 to June 1998, 184 consecutive patients had 224 nailings for lower limb fractures. Twenty-eight patients had Marchetti-Vincenzi nails and the rest had Russell-Taylor nails. There were 45 males and 40 females who had femoral nailing and 71 males and 28 females who had tibial nailing. The mean (range) age for femoral nailing was 56 (17-95.5) years and the mean age for tibia nailing was 44 (16.5-87.5) years. The average time of radiation when done by consultants was half that of middle-grade surgeons. The mean tibial nailing radiation time for the consultant was 0.56 min and for the middle-grade 1.28 min. The mean femoral nailing radiation time for the consultant was 0.52 min and for the middle-grade 1.61 min (P<0.05). The mean tibial and femoral nailing time were less for Marchetti nailing (P<0.05). Regular protection of the gonads of these patients is mandatory. This study shows that the radiation exposure for Marchetti-Vincenzi nailing is significantly less than for Russell-Taylor nailing. The overall radiation to patient gonads and surgeon hands was within acceptable limits.

Thyroid dosimetry in Europe following the Chernobyl accident

Thyroid dose estimates for European populations following the Chernobyl accident in 1986 have been presented in the literature. These dose estimates used standard values for parameters such as thyroid mass, iodine uptake and biological half-life. Previous work has shown that these values are not representative of European populations and that local values should be utilized. Using published data on revised thyroid dose estimates, thyroid dosimetry data arising as a result of the Chernobyl accident are presented for 22 European countries. When these are compared with previously published estimates it is found that in all cases the previous results underestimate the thyroid dose by up to a factor of 4. Risk estimates on the incidence of fatal and non-fatal thyroid cancers are also determined from this new data and, again, the results are underestimated. The results show an increase in the number of fatal cancers, rising from 149 as predicted by the NEA to 310 under the new estimates, and from 180 as predicted by UNSCEAR to the new estimate of 380.

Controversies in the management of thyroid nodule

Few subjects in surgery have generated as much controversy as the management of thyroid nodule. The controversial issues include classification and histology, diagnostic evaluation including needle biopsy, indications for surgery, management of incidentalomas of the thyroid, the role of frozen section, extent of thyroidectomy, management of neck nodes, the role of suppressive therapy, the use of radioactive iodine, and appropriate follow-up. The two major issues in relation to the controversies are diagnostic workup and extent of thyroidectomy. Whenever the issue related to extent of thyroidectomy is discussed, there are two strong groups believing in total thyroidectomy or less than total thyroidectomy. This has generated considerable debate and panel discussions, and this article reviews this on-going debate.

[Late effects of ionizing radiations on the thyroid gland]

The thyroid is the purest endocrine gland in the body and is likely to produce clinically significant abnormalities after external radiotherapy. Functional clinical modifications after direct irradiation exceeding 30 Gy are essentially related to hypothyroidism which may be clinically overt or subclinical with normal serum free thyroxine levels and high thyrotropin concentrations; the risk of hyperthyroidism, silent thyroiditis and Hashimoto's disease is also increased. Secondary hypothyroidism related to irradiation of the hypothalamus and the pituitary gland may arise with doses over 40-50 Gy following treatment for brain and nasopharyngeal tumors--Morphological glandular modifications induced by radiotherapy are responsible for the appearance of benign adenomas, more rarely cystic degenerations and specially well differentiated papillary or follicular carcinomas among children and adults. After irradiation during childhood for benign or malignant tumors, thyroid cancers are more frequent, higher for younger children, and the relative excess risk is increased from 15.6-to 53-fold; tumors can belatedly occur, more than 35 years after initial therapy. Thereby, in order to limit excess morbidity, it is evident that long term supervision with careful clinical and biological evaluations is necessary for patients who previously received neck, upper mediastinum and pituitary radiation therapy.

Thyroid dysfunction after mantle irradiation of Hodgkin's disease patients

Thyroid dysfunction can develop in patients with Hodgkin's disease who are treated with mantle irradiation. During the period 1970-89, the records of 320 patients who received mantle irradiation and who had thyroid function tests (TFT) were retrospectively reviewed. The median age was 30 years (range, 7-69 years). The median mantle and thyroid dose was 36 Gy (range, 30-40 Gy) and 39.8 Gy (range, 32-65 Gy), respectively. Overall thyroid dysfunction was present in 39% of the patients. Clinical hypothyroidism was seen in 10% and biochemical hypothyroidism was noted in 25%. Hyperthyroidism was found in 4% of patients. Thyroid nodules had developed in six patients (2%), of which those in four patients were malignant. Age, sex, histological subtype, stage of disease, dose, lymphangiogram and treatment with chemotherapy were not significant factors in the development of thyroid dysfunction. The narrow dose range prevented adequate analysis of dose effect. The results indicate that the incidence of thyroid abnormalities is high enough to warrant regular TFT assessment with pre-irradiation levels and follow-up testing for life because the development of abnormalities can occur many years later. Thyroid examination should form part of the routine follow-up examination and any abnormality should be promptly investigated.

The epidemiology of thyroid disease and implications for screening

The burden of thyroid disease in the general population is enormous. As many as 50% of people in the community have microscopic nodules, 3.5% have occult papillary carcinoma, 15% have palpable goiters, 10% demonstrate an abnormal thyroid-stimulating hormone level, and 5% of women have overt hypothyroidism or hyperthyroidism. Despite this high prevalence of thyroid disease, screening for these disorders is not recommended by any major health agency. This article explores the epidemiologic issues surrounding this complex problem by analyzing prevalence, incidence, and mortality data from a worldwide variety of sources.

Ultrasonography for thyroid screening after head and neck irradiation in childhood cancer survivors

We prospectively used ultrasonography to detect thyroid abnormalities in 96 long-term survivors of childhood cancer, who received head and neck radiation therapy at a median age of 8.9 years. The median time interval since irradiation was 10.8 years (range 5.6-22.8 years). Most survivors of leukemia received 24 Gy cranial irradiation for central nervous system prophylaxis; patients with solid tumors received between 20 and 66 Gy (median 37.5 Gy). The total evaluation included clinical history, physical examination, thyroid function tests, and thyroid ultrasonography; radionuclide scans were performed in patients whose abnormalities persisted on subsequent ultrasound exams. Clinical history and physical examination revealed thyroid abnormalities in 14 patients (15%), but ultrasound detected abnormalities in 42 patients (44%). These findings included inhomogeneity (n = 29), cysts (n = 15), and nodules (n = 22) and occurred in nearly half of patients treated with 15 Gy or more directly to the thyroid gland. Radionuclide scans confirmed the presence of thyroid nodules in 13 of 15 patients with ultrasonographic evidence of nodules. Six patients had thyroid neoplasia, including one case of papillary carcinoma. All patients with neoplasia had nodules demonstrated on ultrasonography. Our experience suggests that in childhood cancer survivors, ultrasonography is a sensitive, affordable, and noninvasive means of detecting subtle parenchymal abnormalities. We recommend thyroid ultrasonography for childhood cancer survivors who received head and neck irradiation. A baseline study should be obtained within 1 year of completion of therapy. The frequency of subsequent examinations should be based on the radiation dose and the patient's age at the time of irradiation.

Sonographic abnormalities of the thyroid gland following radiotherapy in survivors of childhood Hodgkin's disease

The aims of this study were as follows. (1) To demonstrate the spectrum, frequency and changes on follow-up of sonographic abnormalities in the thyroid gland of survivors of Hodgkin's disease who had received radiotherapy to the neck in childhood. (2) To compare the sonographic findings with clinical examination and radionuclide imaging. (3) To investigate the association between the presence or absence of focal sonographic abnormalities with age at radiotherapy, the interval from radiotherapy, the presence of a raised thyroid stimulating hormone (TSH) and the length of time the TSH had been raised. 46 patients were scanned prospectively and rescanned at 6-18 months. The mean age at first sonography was 22.7 years, the median age at radiotherapy was 12.5 years, and the median interval post-radiation was 10.3 years. Sonographic abnormalities were seen in all 46 patients. 45 had diffuse atrophy and 30 had focal sonographic abnormalities. 18 patients developed new focal sonographic abnormalities on follow-up. Focal sonographic abnormalities were more commonly associated with longer duration of a raised TSH. Two patients had thyroid carcinoma. Sonographic abnormalities of the thyroid are common in patients following neck radiotherapy in childhood. Focal abnormalities are usually associated with a longer duration of raised TSH.

Manipulation under anaesthetic of children's fractures: use of the image intensifier reduces radiation exposure to patients and theatre personnel

During simulated manipulation of children's forearm fractures, levels of scattered radiation from both plain radiographs and an image intensifier in different modes were measured at various sites on the surgeon, anaesthetist, radiographer, and patient both with and without recommended shielding. By using fluoroscopy in the pulsed screening mode but allowing only single pulses to occur, radiation levels could be substantially reduced to the eye, thyroid, and gonads of all those exposed. The radiographer and the anaesthetist were so far from the source and guarded by various pieces of equipment that levels were almost unrecordable. Effective dose equivalent for the surgeon using pulsed mode, based on circa six pulses per manipulation, during 100 manipulations per year, would equate to 1 microSv even in the unshielded state (< 0.1 microSv shielded), which is approximately 1/1,000 of background radiation at sea level. Because the current dose limit is 50 mSv (50,000 microSv) per year for employees, we are many orders of magnitude in the safety zone.

Large cystic/solid thyroid nodules: a potential false-negative fine-needle aspiration

BACKGROUND

False-negative fine-needle aspiration (FNA) biopsy results of thyroid nodules are of particular concern because they imply missed malignant lesions. The purpose of this study was to identify characteristics of thyroid nodules that may lead to false-negative cytologic interpretation after FNA.

METHODS

We reviewed 90 consecutive patients who underwent preoperative FNA of thyroid nodules followed by thyroid surgery during a period of 27 months, including their clinical data, type and size of thyroid nodule, FNA cytology results, and final pathology report of the surgical specimen.

RESULTS

Thyroid nodules that had the highest probability of malignancy were those that were large (3 cm or larger), cystic/solid, or large and cystic/solid. The overall false-negative rate for preoperative FNA was 11%. Large, cystic/solid, and thyroid nodules with both characteristics had false-negative rates of 17%, 25%, and 30%, respectively, compared with 0%, 9%, and 17% for small (less than 3 cm), solid, and solid nodules 3 cm or larger, respectively.

CONCLUSIONS

Because of the high prevalence of malignancy in thyroid nodules that are large (3 cm or larger), cystic/solid, or large and cystic/solid and the high false-negative rate of FNA in diagnosing these lesions, thyroid lobectomy for diagnosis should be strongly considered in these patients even when FNA cytologic finding is interpreted as benign.

Thyroid dysfunction following combined therapy for laryngeal carcinoma

The thyroid function of 27 patients who previously had carcinoma of the larynx treated by total laryngectomy with thyroid lobectomy was studied by measuring levels of thyroxine (T4) and thyroid stimulating hormone (TSH). Twenty-two of these patients also received external beam radiotherapy. Abnormal results were found in 45% (10 patients) of those who received combined therapy. Clinical hypothyroidism developed in two patients (9%) and subclinical hypothyroidism (elevated TSH) was seen in eight patients (36%). Eighty-eight per cent of those patients with subclinical hypothyroidism had low or low normal T4 levels. All the patients treated with surgery only had normal thyroid function. To prevent hypothyroidism and identify those at risk of developing hypothyroidism, post-operative testing of thyroid function should be carried out on a routine basis in patients receiving combined therapy for laryngeal cancer. In addition we recommend that patients with subclinical hypothyroidism who have had combined treatment should be treated with thyroxine to prevent the complications of this condition.

Thyroid abnormalities among children in the contaminated area related to the Chernobyl accident

Gradual increases of various radiation-related diseases including thyroid cancer following the Chernobyl accident have been recently reported. We have carried out systematic thyroid surveys in school children aged 10-15 years in the highly contaminated area and compared the results with a similar survey in a nonaffected neighboring area as a control. Systematic examinations of the thyroid gland were performed in 888 schoolchildren (408 males and 480 females) in the districts of Chechelsk city with 5 to over 40 Ci/km2 of radiation level for 137Cs. In the control area (Bobruisk city), 521 children with the same age range (229 males and 292 females) were examined. Thyroid surveys were carried out as follows: palpation, ultrasonography, blood examinations of thyroid function, and measurements of daily urinary excretion of iodine. Certain thyroid abnormalities were observed in the high radioactive fallout area more frequently than in the control region. In particular, the prevalence of multiple micronodular lesions in diffuse goiter in the contaminated area was significantly higher than in the control area. However, endemic goiter due to iodine deficiency was present in both districts. The environment factor of iodine deficiency might have resulted in the early occurrence of ultrasonographic thyroid abnormalities attributed to radioactive contamination.

Standardized radioiodine therapy in Graves' disease: the persistent effect of thyroid weight and radioiodine uptake on outcome

OBJECTIVE

To assess the incidence of hypothyroidism, euthyroidism, and recurrent hyperthyroidism following a standard dose of Na131I (3.7 MBq or 100 microCi) per g thyroid tissue, adjusted for radioiodine tracer uptake.

DESIGN

A single-centre prospective follow-up study from January 1990 to December 1992.

SETTING

Academic Hospital in Utrecht, the Netherlands.

SUBJECTS

Newly diagnosed patients with Graves' disease (n = 148).

INTERVENTIONS

Radioiodine treatment at a standard dose of 3.7 MBq or 100 microCi per g thyroid tissue.

MAIN OUTCOME MEASURES

Confidence interval testing of resulting thyroid status, defined by biochemical criteria.

RESULTS

The overall cure rate was 70% (103 of 148 subjects), confidence interval (CI) 62-77%. A 90% incidence of hypothyroidism was found in patients with a small thyroid (less than 20 g). Recurrent hyperthyroidism was found significantly more often in subjects with a thyroid weight exceeding 60 g compared to those who had a thyroid of 9-59 g. More recurrences were found in subjects in the highest tertile of a 24-h radioiodine uptake test (> 80% uptake) compared to those in the lowest tertile (< 60% uptake).

CONCLUSIONS

No uniform treatment results expressed per thyroid weight category were obtained, in spite of standardizing the treatment Na131I dose (3.7 MBq per g thyroid). Graves' patients with a thyroid smaller than 20 g and those with less than 60% 24-h radioiodine uptake have a 50-90% chance of hypothyroidism at the 12-month follow-up.

Modern Imaging of Paranasal Sinuses and the Role of Limited Sinus Computerized Tomography; Considerations of Time, Cost and Radiation

The modern diagnostic radiology department is equipped with a variety of medical imaging systems that can be used for evaluation of diseases of the sinonasal cavities. Each has advantages and disadvantages. The imaging examinations of the paranasal sinuses may include conventional films, complex motion tomography, computed tomography (CT) and magnetic resonance imaging (MRI). The indications for these imaging methods are reviewed, along with a discussion on the role of imaging for endoscopic sinus surgery. A summary of CT anatomy relating to the ethmoidal sinuses and ostiomeatal complex is given, as is a review of the risk of radiation for radiologic sinus imaging.

Radioiodine-associated thyroid cancers

Numerous investigations document that exposure to low dose external therapeutic radiation leads to the development of benign and malignant thyroid neoplasms. There is considerable controversy, however, concerning whether radioactive iodine (131I) causes thyroid cancer. The aim of this investigation was to examine our experience and that in the literature related to this problem. From 1982 to March 1993 seven of 373 patients (1.9%) with thyroid cancer who were treated by one surgeon had a history of treatment with radioactive iodine for Graves' disease and toxic nodular goiter. Sixty-five patients have previously been reported in the literature from 1957 to present. Our patients (five women, two men) ranged in age from 26 to 80 years (mean 57 years). The interval between the exposure to the internal radiation and development of cancer ranged from 3 to 29 years (mean 11.4 years), and the mean age at the time of 131I treatment was 45 years (18-76 years). The therapeutic dose of 131I was 5 to 100 mCi (mean 25.3 mCi) in our patients. Two of our patients received 131I twice. The age of patients reported in the literature at the time of 131I treatment ranged from 7 to 74 years (mean 48 years). The mean therapeutic dose of 131I was 20.6 mCi (1.25-180.0 mCi) and the latent period was documented for a mean 8.7 years (0.25-28.0 years) in these patients. Three of 29 patients in the literature received 131I twice. Fine-needle aspiration cytology of thyroid nodules was positive for cancer in six of our patients (86%).(ABSTRACT TRUNCATED AT 250 WORDS)