Radiation exposure during fluoroscopy: should we be protecting our thyroids?

BACKGROUND: Recent reports on thyroid cancer among Australian orthopaedic surgeons prompted the present study which sought to evaluate the effectiveness of lead shielding in reducing radiation exposure (RE) to the thyroid region during endo-urological procedures. METHODS: Radiation exposure to the thyroid region of the surgeon and scrubbed nurse was monitored for 20 consecutive operations over a 6-week period by thermoluminescent dosimeters (TLD). A TLD was placed over and underneath a thyroid shield of 0.5 min lead equivalent thickness to monitor the effect of shielding. RESULTS: Eight percutaneous nephrolithotomies, seven retrograde pyelograms and ureteric stentings and five ureteroscopies for calculous disease were monitored. Total exposure time was 63.1 min. For the surgeon, the total cumulative RE over and under the lead shield was 0.46 and 0.02 mSv, respectively, equating to a 23-times reduction in RE if shielding was used. This effectively reduced RE to almost background levels, which was represented by the control TLD exposure (0.01 mSv). CONCLUSION: Although RE without thyroid shields did not exceed current standards set by radiation safety authorities, no threshold level has been set below which thyroid carcinogenesis is unlikely to occur. Because lead shields are easy to wear and can effectively reduce RE to the thyroid region to near-background levels, they should be made easily available and used by all surgeons to avoid the harmful effects of radiation on the thyroid.

Altered neutrophil permeability following shock wave exposure in vitro.

Human neutrophils were exposed to varying numbers of shock waves using the Dornier XL-1 experimental lithotripter. Cellular changes were observed with as few as 60 shock waves generated with 20 KV at a frequency of one per second. A graded reduction in cell numbers and cell viability was observed up to 300 SW. With exposure to 140 SW or above a decrease in mean cell size occurred. When cells were shocked in the presence of adriamycin or after loading with fluorescein, flow cytometry revealed that influx of extracellular components and efflux of cytoplasmic components had occurred. An ultrastructural and functional analysis of cells exposed to 60 SW, where cellular disruption and loss of viability were minimal, revealed several types of cellular changes which may precede SW-induced cell death. Electron microscopic examination revealed in some cells a loss of staining intensity. Plasma membrane rupture and leakage of cytoplasmic components were occasionally evident. The adherence of shocked cells to glass, and the spreading of cells that had adhered, were also reduced. From these studies, it is concluded that cellular permeability and other vital cellular functions in neutrophils are perturbed by SW exposure.

The combined effects of shock waves and cisplatin therapy on rat prostate tumors.

The effects of focused high energy shock waves (SW) generated by the Dornier experimental XL-1 lithotripter alone or in combination with cisplatin (CDDP) on the AT-2 prostate tumor were examined. They were assessed by measuring 1) clonogenic cell survival 24 hours after treatment, 2) tumor growth delay, and 3) the number of lung metastases. The survival of clonogenic cells was reduced 38% by exposure to 2000 SW and tumor growth was delayed by 1.5 days. The limb bearing the tumor was excised in all animals when the tumor reached seven cm.3 The subsequent occurrence of lung metastases in three out of 13 unshocked animals and two out of 14 shocked animals indicated that SW did not promote the dissemination of tumor cells. At doses of one to four mg. CDDP/kg. body weight, SW exposure increased the effectiveness of the chemotherapy measured by a clonogenic assay. The fractional survival was 0.62 after 2000 SW alone, 0.23 with four mg. cisplatin/kg. alone and 0.10 after the combination treatment. At higher doses of CDDP, there was no added effect of SW over that of CDDP therapy alone. Tumor growth to one cm.3 was delayed by seven days after treatment with four mg. CDDP/kg., in comparison to untreated controls. SW exposure combined with CDDP treatment delayed the time taken for the tumor to reach one cm.3 by 13 days in comparison with untreated controls. However, the combination treatment increased animal mortality from 9% with CDDP alone to 29%. These results indicate that SW could be used focally to enhance the cell killing effects of CDDP.

Neoadjuvant treatment of stages T2 to T4 bladder cancer with cis-platinum, cyclophosphamide and doxorubicin.

In an ongoing phase II study 17 patients with potentially operable transitional cell carcinoma of the bladder (stages T2 to T4, Nx, Mo) have been treated with intravenous cis-platinum (50 mg.per m.2), cyclophosphamide (400 mg.per m.2) and doxorubicin (40 mg.per m.2). They were to receive 3 treatments at 3-week intervals before cystectomy and 2 treatments at 3-week intervals commencing 5 weeks after cystectomy. Of 17 patients 14 (82 per cent) completed all 3 preoperative treatments but only 7 (41 per cent) continued on to complete the entire 5 treatments. In most cases incomplete therapy was due to patient refusal. Toxicity was low as measured by World Health Organization standards. Of the 17 patients 9 (53 per cent) exhibited objective tumor response (pathological downstaging or greater than 50 per cent reduction of tumor volume determined by either computerized tomography scan and/or endoscopic examination. When the determination was made by endoscopy the changes were dramatic and not borderline.) No patient demonstrated a pathological complete response. All 9 of the responders (100 per cent) remain clinically free of disease at a median follow-up of 19 months (range 4 to 30 months). The 8 nonresponders have done poorly with 5 dead of disease, 1 alive with pelvic recurrence and 2 free of disease at 4 and 12 months. These tumor response rates compare favorably with other cis-platinum-based combination regimens. The response to the chemotherapy appears to be an important prognostic indicator. Phase III trials must be conducted to determine whether this neoadjuvant chemotherapy regimen has a significant effect on long-term patient survival.

Effects of shock waves on the rat ovary.

The studies reported in this paper were undertaken to investigate the effect of shock waves on ovarian function. In an initial study, five female Wistar rats underwent general anesthesia. One ovary was then exposed to 1500 shock waves at 20 kV using the Dornier XL-1 experimental lithotripter. One week following this treatment, the animals were sacrificed and both ovaries were step sectioned. We counted all follicles that contained both an oocyte and antrum. These follicles in turn were classified further as being healthy or atretic. No statistical difference in these counts was observed between shocked and unshocked ovaries taken from the same animal. In the definitive study, thirty-one adult female Wistar rats underwent unilateral oophorectomy. These rats were then divided into treated, sham-treated and control groups. The eleven treated animals were given general anesthesia and received 1500 shocks at 15 kV directed at their remaining ovary using the Dornier XL-1 lithotripter. The ten sham treated animals received identical anesthesia and duration of waterbath immersion as the treated group. In contrast, however, sham treated animals were positioned outside the path of the focused shock wave. The control group received no treatment. Normal estrus cycle was maintained in all groups following shock wave exposure. Two weeks after this exposure, all three groups of animals were allowed to mate. All animals in each of the three groups became pregnant. There was no statistical difference in litter size or fetal weights at three weeks gestation. No gross teratogenic effects were observed. The rat ovary appears to be structurally and functionally resistant to the shock wave energy levels used in this experiment.

Effects of shock waves on the structure and growth of the immature rat epiphysis.

The left proximal tibia of eighteen five week old male Sprague-Dawley rats was exposed to 1500 shock waves at 20 kV in a Dornier XL-1 experimental lithotripter. Six of these rats, and six age-matched controls, were sacrificed two, four and ten weeks later. Eight of 18 (44%) of treated animals had lesions of focal growth plate dysplasia attributable to treatment. In the absence of extensive lesions, no significant difference was identified in the growth plate thickness of shocked versus unshocked limbs. In the group sacrificed at ten weeks, two of six (33%) treated animals had extensive dysplastic lesions which were associated with marked shortening of the shocked limb. In the absence of extensive lesions, there was no significant shortening of shocked limbs. Shock wave exposure of the rat epiphysis can affect subsequent bone growth.