Background: High-energy linear accelerator (linac) is a valuable tool and the most commonly device for external beam radiation treatments in cancer patients. In the linac head, high-energy photons with energies above the threshold of interaction produce photoneutrons. These photoneutrons deliver the extra dose to the patients in the planning treatment and increase the risk of secondary cancer.O...

The possible effect of contrails in modifying the weather is reconsidered in the light of information obtained from ground-level contrails in Alaska. It appears likely that inadvertent cloud seeding b y jet aircraft may be of the same order of magnitude as that attained in commercial cloud seeding operations. Further investigation is needed; but in the meantime, the possibility of contrail cont...

9 The cross section for photoneutron production in Be at energies of 1. 692, 1. 720, and 1. 78 Mev has been investigated using radioisotope gamma-ray sources. Neutron counting was by manganous sulfate bath and a long counter. Gamma-ray counting was by a scintillation spectrometer consisting of a Nal(Tl) scintillation crystal and a 256-channel pulse^height analyzer. The following results were ob...

A new experiment configuration was designed, developed, and implemented to measure photoneutron yields using the Rensselaer Polytechnic Institute (RPI) electron linear accelerator (LINAC) at RPI Gaerttner LINAC Center. The includes a target assembly that converts beam into high energy bremsstrahlung photon flux incident upon sample material of interest. photons excite nuclei in interest, which ...

Introduction: GRID therapy is a treatment modality in which a high dose of radiation in a single fraction is given to the tumor. This technique previously was used to treat bulky tumors with orthovoltage beams. Recently, studies have been conducted to suggest that GRID therapy with megavoltage photons can be useful in palliative treatments. On the other hand, there has always ...

objective: using megavoltage photons generated by medical linear accelerator is a common modality for the treatment of malignant. the crucial problem for using photon beams >8mv is the photoneutron yields that increase the risk of secondary cancer that treated with high-energy photon beams. the contaminated neutrons produced in different components of the accelerator head and rely on many param...