Computed tomography for pulmonary embolism: assessment of a 1-year cohort and estimated cancer risk associated with diagnostic irradiation.

BACKGROUND: The principal concern of any radiation exposure in computed tomography (CT) is the induction of stochastic risks of developing a radiation-induced cancer. The results given in this manuscript will allow to (re-)calculate yield of chest CT. PURPOSE: To demonstrate a method to evaluate the lifetime attributable risk (LAR) of cancer incidence/mortality due to a single diagnostic investigation in a 1-year cohort of consecutive chest CT for suspected pulmonary embolism (PE). MATERIAL AND METHODS: A 1-year cohort of consecutive chest CT for suspected PE using a standard scan protocol was analyzed retrospectively (691 patients, 352 men, 339 women). Normalized patient-specific estimations of the radiation doses received by individual organs were correlated with age- and sex-specific mean predicted cancer incidence and age- and sex-specific predicted cancer mortality based on the BEIR VII results. Additional correlation was provided for natural occurring risks. RESULTS: LAR of cancer incidence/mortality following one chest CT was calculated for cancer of the stomach, colon, liver, lung, breast, uterus, ovaries, bladder, thyroid, and for leukemia. LAR remains very low for all age and sex categories, being highest for cancer of the lungs and breasts in 20-year-old women (0.61% and 0.4%, respectively). Summation of all cancer sites analyzed raised the cumulative relative LAR up to 2.76% in 20-year-old women. CONCLUSION: Using the method presented in this work, LAR of cancer incidence and cancer mortality for a single chest CT for PE seems very low for all age groups and both sexes, but being highest for young patients. Hence the risk for radiation-induced organ cancers must be outweighed with the potential benefit or a treatment and the potential risks of a missed and therefore untreated PE.

Radionuclide-labeled somatostatin analogues for diagnostic and therapeutic purposes in nonmedullary thyroid cancer.

Despite the fact that several recent studies report an expression of somatostatin receptors in nonmedullary thyroid cancer (non-MTC), there is still no consensus concerning the diagnostic and therapeutic usefulness of radionuclide-labeled somatostatin analogues in non-MTC. We present the results of 50 scintigraphic studies with (111)In-Pentetreotide ((111)In-P) in 48 patients with metastasizing non-MTC (n = 9 papillary, n = 9 follicular, n = 29 Hurthle cell, n = 1 insular carcinoma). The findings were compared with histology and with other imaging modalities. (111)In-P provided unequivocally positive results in 37 of 50 (74%) of the patients (27% in the 11 patients with current thyroglobulin levels <10 ng/mL and 85% in the patients with thyroglobulin >10 ng/mL). Histopathology demonstrated that maximal uptake was observed in Hurthle cell carcinoma (95% positive examinations if thyroglobulin exceeds 10 ng/mL). We also describe for the first time dosimetric and clinical data from the courses of 90Y-DOTATOC therapy in three patients with progressive, somatostatin-receptor-positive non-MTC (up to 9.3 GBq per 4 cycles). Tumor progression could not be stopped in any of the patients treated with 90Y-DOTATOC. We conclude that (111)In-P is a promising tool for whole-body diagnosis in nonradioiodine-accumulating non-MTC, especially in Hürthle cell cancer, and if 2-[18F]fluorodeoxyglucose-positron emission tomography (FDG-PET) is not available. Although the number of patients treated with 90Y-DOTATOC is still limited, our applied treatment protocol appears to be ineffective in metastasizing non-MTC.

[Radiation exposure of the patient by intraoperative imaging of intramedullary osteosyntheses]. / Strahlenexposition des Patienten durch intraoperative Bildgebung bei Marknagelosteosynthesen.

MATERIAL AND METHOD: 39 patients with pertrochanteric femur fracture (n = 32) or lower leg fracture (n = 7) were treated with closed intramedullary nailing. The related radiation exposure of the patients was calculated. RESULTS: Osteosynthesis of pertrochanteric fractures took less fluoroscopic time than osteosynthesis of lower leg fractures. The effective dose was 14 mSv for nailing osteosynthesis of proximal pertrochanteric fractures and less than 0.1 mSv for osteosynthesis of distal lower leg fractures. CONCLUSION: Radiation exposure of the patient due to intraoperative fluoroscopic imaging during osteosynthesis can be estimated based on the data given above. Intraoperative observations imply, consequent application of radiation protection by the orthopaedic surgeons may reduce intraoperative radiation exposure even more.

Quality assurance of physical parameters in radiation oncology at the University Hospital of Basel--a retrospect.

BACKGROUND AND PURPOSE: The necessity for and the benefit of a quality assurance program in radiation oncology are not questioned. Nevertheless, a retrospective analysis of the accumulated results of several years of quality assurance offers the possibility for further optimization. MATERIALS AND METHODS: The results of the physical quality control in radiation treatment planning and on radiation treatment units in the Institute for Radiation Oncology at the University Hospital of Basel for the years 1985, 1991 and 1994 are analyzed and compared mutually. The frequencies of the deviations from the nominal values for the different tests are stated. RESULTS: The relevance of the deviations for the different parameters is rated and the manifested influence of the type and age of the equipment on the results of the quality assurance is discussed. CONCLUSIONS: A condition for the maximum benefit gained from the quality assurance is the oncologist's understanding of the necessity for regular checks and the urgency for eliminating the established deficiencies. In that way the accuracy for the treatment planning, simulation and set-up process and for the realization of the radiation treatment can be increased and the methods can be improved.

Plasma potassium in patients with terminal renal failure during and after haemodialysis; relationship with dialytic potassium removal and total body potassium.

BACKGROUND: Chronic haemodialysis (HD) patients may present with severe predialysis hyperkalaemia which is improved by dialytic treatment. However, factors influencing the behaviour of postdialysis plasma potassium (plasma K) are not well known. METHODS: In this prospective study 14 patients (7 female, 7 male) on chronic HD were investigated during a standardized 4-h HD with a 2 m2 high-flux dialyser and up to 6 h postdialysis. Dialytic potassium removal was measured by dialysate collection. Total body potassium (TBK) was measured by whole-body counting of 40K. RESULTS: Plasma K declined from 5.65 to 3.62 mmol/l on HD. In spite of a total dialytic removal of 107 mmol of potassium plasma K rose to 5.01 mmol/16 h postdialysis. TBK, as adjusted for age, was 38.2 and 49.0 mmol/kg BW in female and male patients respectively, i.e. in the normal range. Of a total potassium removal of 107 mmol on HD only 42% originated from the extracellular space. Dialytic potassium removal was best correlated with removal of intracellular potassium but also with extracellular potassium content and with the product of plasma K x TBK. The 6-h postdialysis plasma K was correlated with the predialysis value but not with TBK or dialytic potassium removal. CONCLUSION: A rather high dialytic removal of potassium (which is correlated with plasma K x TBK) does not necessarily prevent a rapid postdialysis rebound of plasma K. Therefore patients with marked hyperkalaemia should be monitored closely postdialysis. TBK can be normal in haemodialysis patients who are well nourished.

DOTATOC: a powerful new tool for receptor-mediated radionuclide therapy.

This study presents the first successful use of a peptidic vector, DOTATOC, labelled with the beta-emitting radioisotope yttrium-90, for the treatment of a patient with somatostatin receptor-positive abdominal metastases of a neuroendocrine carcinoma of unknown localization. Tumour response and symptomatic relief were achieved. In addition, the new substance DOTATOC was labelled with the diagnostic chemical analogue indium-111 and studied in three patients with histopathologically verified neuroendocrine abdominal tumours for its diagnostic sensitivity and compared with the commercially available OctreoScan. In all patients the kidney-to-tumour uptake ratio (in counts per pixel) was on average 1. 9-fold lower with 111In-DOTATOC than with OctreoScan. DOTATOC could be a potential new diagnostic and therapeutic agent in the management of neuroendocrine tumours.

HIV-enteropathy and bile acid malabsorption: response to cholestyramine.

Chronic diarrhea and weight loss are common in patients with AIDS. We report on an AIDS patient with chronic diarrhea, steatorrhea, and marked weight loss. A 75SeHCAT test demonstrated that the diarrhea was mainly due to bile acid malabsorption. Therapy with cholestyramine dramatically reduced bowel movements and led to significant reversal of weight loss.