Impact of range straggling and multiple scattering on proton therapy of brain, using a slab head phantom

The advantages of proton beam in radiation therapy- like small lateral scattering as well as absence of exit dose tail in the organs which are after the tumor- make it capable of delivering more treatment doses to the target and much lesser to the critical tissues near it. In this study, the Monte Carlo MCNPX code has been used to simulate a slab head phantom irradiated by proton pencil beams. The simplified slab has tissue compositions of the ICRU 46, and the necessary data have been taken from adult male phantom of MIRD-ORNL family series. Suitable energy range of incident proton beams has been estimated in order to have the Bragg peaks inside the brain tissue. Energy straggling or, rather, range straggling, and multiple scattering which affect the lateral broadening of incident beams, have been investigated. The results show that the FWHM [Full Wide in Half Maximum] increases more than six times from 1.73 mm to 10.78 mm for the energy range of 50 - 135 MeV. The FWHM values of lateral dose profiles change from 1 mm in 50 MeV to 7.5 mm in 135 MeV, and it has been shown that when a pencil beam is used to irradiate a tissue, the absorbed dose in depth along the central axis does not show a Bragg peak pattern

Diagnosis of pendred syndrome: MRI versus other traditional criteria

Background and purpose: Pendred syndrome, defined traditionally as the constellation of goiter, sensori-neural hearing loss and positive perchlorate discharge test. Since the relatively newer approaches to the diagnosis of this syndrome, as MRI and genetic and/or molecular analysis are much more expensive and complicated than the traditional approaches, we planned to study the value and reliability of MRI as the sole, or adjunctive diagnostic approach to the syndrome

Materials and methods: We presumed the classic triad is still the most widely accepted gold standard, and compared MRI findings in six such defined patients with six seemingly incomplete forms with goiter and hearing loss, but with negative Perchlorate discharge test

Results: There were a sensitivity and specificity of 83.3% and 66.7%, respectively for MRI in patients fulfilling all three criteria and 66.7% and 100% for sensitivity and specificity in the group lacking perchlorate test positivity

Conclusion: Although MRI can not replace the holistic approach, In [partial] cases with equivocal findings, and in the evaluation of relatives of the patients MRI may be considered as a valuable diagnostic adjunct

Regression of metastatic neuroblastoma to ganglioneuroma

The spontaneous regression of neuroblastoma to ganglioneuroma is a rare occurrence. Reviewing the literature, we found no more than 12 cases reported-"2'9'10'14'15 We report a case of metastatic neuroblastoma of multifocal skeletal and soft tissue areas with gross deformities which regressed to ganglioneuroma, with good prognosis