Physical dose distribution due to multi-sliced kV X-ray beam in labeled tissue-like media: an experimental approach.

Radiotherapy remains a major modality of cancer therapy. Thanks to high flux and high brilliance of synchrotron-generated X-ray, laboratory research with planar microscopically thin X-ray beam promise exciting new opportunities for treatment of cancer. High tolerance of normal tissues at doses up to several hundred Gy in a single dose fraction and preferential damage of tumors at very high doses have been uniquely observed in animal models exposed to microbeams. The fact that beams as thick as 0.68 mm could retain a part of these effects, opens the possibility that the required beam can be produced by high power X-ray tubes besides a dedicated synchrotron. Fortunately, dose distribution due to kilovolt X-rays could be enhanced by the introduction of high-Z contrast agents to tissue-like media. In this work, dose deposition in a phantom--partially loaded with Au and I as contrast agents--irradiated by multi-sliced kV X-ray beam was experimentally investigated in the peak and valley regions both on the surface and in the depth of phantom. The results of experimental dosimetry using Gaf-chromic films were compared with corresponding Monte-Carlo simulation. Relative reduction in the deposited dose in the peak regions downstream the area containing contrast agents in comparison with the adjacent areas was experimentally observed.

Comparison of one-side and bilateral intracavernosal papaverine injection on a Doppler study of the penis.

Intracavernosal injection of a vasodilating agent, followed by color Doppler ultrasonography of the penis, is used to diagnose vascular impotence. The vasodilating agent is usually injected into one of the corpora cavernosa and the peak systolic velocity (PSV) of the cavernosal arteries is measured on both sides, presuming that the connection between the two cavernosal bodies will distribute the drug uniformly on both sides and will consequently affect the cavernosal arteries and sinusoids equally. According to our experience, the PSV of the injection side is higher than that of the contralateral side. This difference could affect the results of the evaluation. In this study, our objective was to compare the results of both-side injections with those of one-side injection. A total number of 60 patients with a normal Doppler study of the penis were enrolled in the study and were randomly divided into three groups. In the first and second group, 60 mg papaverine was injected into the right and left corpus cavernosa each. In the third group, half of the dose was injected into each side. The mean maximum PSV was measured and compared in each group. The mean maximum PSV in the group with the right-side injection was 47.7+/-10.8 and 40.3+/-9.2 on the right and left side, respectively. The mean maximum PSV in the group with the left side injection was 44.4+/-7.1 and 51.4+/-7.1 on the right and the left side, respectively. The mean maximum PSV in the group with bilateral injection was 47+/-9.9 on the right side and 46.7+/-10.7 on the left side. In the first two groups, there was significant difference between the mean maximum PSV of the right and left cavernosal arteries, but in the third group, there was no significant difference between the mean maximum PSV of both side cavernosal arteries. Injecting papaverine in only one corpus cavernosum, despite a perfect postinjection manipulation of the penis, will affect the sinusoids and cavernosal artery at the same side of the injection more than the contralateral side. This results in a higher increase in the blood flow and PSV on that side and results in an artifactual difference between the velocity of the right and left side, which could ultimately exaggerate or mask the actual difference between the two sides. Dividing the total dose of the vasodilating agent and injecting half of the dose into each corpus cavernosum separately prevents artifactual difference between blood flow and velocity on the right and left side.

Teratogenic effects of sinusoidal extremely low frequency electromagnetic fields on morphology of 24 hr chick embryos.

To examine the potential teratogenicity of electromagnetic fields (EMF; sinusoidal and rectangular) on development of chick embryos (white leghorn), 221 freshly fertilized chicken eggs (55-65 g) were exposed during first 24 hr of postlaying incubation (38 degrees +/- 0.5 degree C) to 24 different EMFs, with 50Hz repetition rate and 8.007-10.143 mT flux density. Following exposure, the exposed fertilized chicken eggs (n = 8-10) and sham-exposed fertilized chicken eggs (n = 15) were incubated simultaneously for 8 more days and unexposed control fertilized chicken eggs (n = 20) for 9 days in absence of EMFs. The embryos were removed from egg shells and studied blind. All 24 EMF exposed-groups (inside the coil with exposure) showed an increase in the percentage of developmental anomalies compared to sham-exposed (inside the coil with no exposure) and control groups (outside the coil). Further, egg's weight was evaluated on day 9. This variable did not show significant difference between control and exposed-groups. The investigation also covered the measurement of body weight, length of crown to rump, length of tip of the beak to occipital bone, heart and liver weight. Statistical comparison between sham-exposed and control values did not show significant differences, but comparison between 8.007, 8.453 and 8.713 mT exposed-groups and control groups showed significant differences; in other exposed-groups, the changes were not significant. These results revealed that 50 Hz electromagnetic fields can induce irreversible developmental alterations in 24 hr chick embryos and confirm that its strength could be a determinant factor for the embryonic response to extremely low frequency electromagnetic fields (window effects).