Estimated risk of radiation-induced cancer from paediatric chest CT: two-year cohort study

BACKGROUND

The increasing absolute number of paediatric CT scans raises concern about the safety and efficacy and the effects of consecutive diagnostic ionising radiation.

OBJECTIVE

To demonstrate a method to evaluate the lifetime attributable risk of cancer incidence/mortality due to a single low-dose helical chest CT in a two-year patient cohort.

MATERIALS AND METHODS

A two-year cohort of 522 paediatric helical chest CT scans acquired using a dedicated low-dose protocol were analysed retrospectively. Patient-specific estimations of radiation doses were modelled using three different mathematical phantoms. Per-organ attributable cancer risk was then estimated using epidemiological models. Additional comparison was provided for naturally occurring risks.

RESULTS

Total lifetime attributable risk of cancer incidence remains low for all age and sex categories, being highest in female neonates (0.34%). Summation of all cancer sites analysed raised the relative lifetime attributable risk of organ cancer incidence up to 3.6% in female neonates and 2.1% in male neonates.

CONCLUSION

Using dedicated scan protocols, total lifetime attributable risk of cancer incidence and mortality for chest CT is estimated low for paediatric chest CT, being highest for female neonates.

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.

Imaging for suspected pulmonary embolism in pregnancy-what about the fetal dose? A comprehensive review of the literature

OBJECTIVE: To give a comprehensive overview of fetal doses reported in the literature when imaging the pregnant woman with suspected pulmonary embolism (PE). METHODS: A comprehensive literature search in the PubMed, MEDLINE and EMBASE databases yielded a total of 1,687 papers that were included in the analysis and have been analysed with regard to fetal dose in suspected PE radiological imaging strategies. RESULTS: Fetal dose in chest computed tomography (CT) ranges between 0.013 and 0.026 mGy in early and 0.06-0.1 mGy in late pregnancy compared with 99mTc-MAA perfusion scintigraphy with a fetal dose of 0.1-0.6 mGy in early and 0.6-0.8 mGy in late pregnancy. (99m)Tc-aerosol ventilation scintigraphy results in 0.1-0.3 mGy. However, there is concern about female breast irradiation in CT, which is higher than in scintigraphy. CT radiation risks for breast tissue remain unclear. CONCLUSION: Knowledge of dosimetry and radiation risks is crucial in the radiological work-up of suspected PE in pregnancy. It is reasonable to reserve scintigraphy for pregnant patients with normal chest radiography findings and no history of asthma or chronic lung disease. Performing CT applying dose reduction instead of scintigraphy will minimise fetal radiation dose and maximise the diagnostic value.

Long-term outcomes after intracoronary Beta-irradiation for in-stent restenosis in bare-metal stents

OBJECTIVE

We sought to characterize the long-term outcomes of patients undergoing intracoronary brachytherapy using Beta- irradiation (Beta-BT).

BACKGROUND

Beta-BT is effective in reducing angiographic restenosis as well as target vessel revascularization (TVR) in patients with in-stent restenosis (ISR) after bare-metal stenting (BMS).

METHODS

81 consecutive patients undergoing Beta-BT for ISR (irradiated length 32 [32-54] mm) after BMS in native vessels (n = 79) or saphenous vein grafts (n = 2) between 2001 and 2003 were followed. Major cardiac events (MACE), including cardiac death, nonfatal myocardial infarction (MI), and TVR occurring > 1 year or > 1 year were assessed 5.2 (4.4-5.6) years after the index procedure.

RESULTS

During the entire follow-up period, the total MACE rate was 49.4%. Within the first year and at > 1 year, MACE rates were 25.9% and 23.5%, cardiac death occurred in 2.4% and 6.2%, and nonfatal MI in 6.2% and 12.3% for annual cardiac death/MI rates of 8.7% at < 1 year and 4.1% thereafter. TVR was required in 19% at < 1 year and in 16% of patients later on. The only independent predictor of MACE occurring < 1 year was an irradiated vessel length > 32 mm (odds ratio [OR] 2.73, 95% confidence interval [CI] 1.10-6.78; p = 0.03). The best, albeit not statistically significant, predictor of MACE occurring at > 1 year was the presence of diabetes mellitus (OR 2.49, 95% CI 0.94-6.57; p = 0.07).

CONCLUSIONS

Patients undergoing Beta-BT for ISR after BMS carry a substantial risk of MACE also beyond the first year, with annual cardiac death and nonfatal MI rates of 1.5% and 2.9% up to 5 years postprocedure.

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]

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.