Ionizing radiation affects the metabolism of the nucleic acids (1). The synthesis of deoxyribonucleic acid (DNA), measured by the incorporation of a tracer, is consistently depressed (2) while the response of ribonucleic acid (RNA) is quite variable (3). Since most studies of radiation effects on metabolism have been done with extremely high doses of whole-body x-radiation, the results may be c...

The dose distributional properties of a p(50) Be neutron beam using a continuously variable multi-leaf collimator are presented and compared with a 6 MV photon beam. The differences in physical dose delivery between these two radiation modalities are generally insignificant for radiation therapy, and stringent comparisons of neutron and photon treatments should therefore be possible. The flexib...

Radiotherapy is an effective cancer treatment, but, there are individualized variable responses and also even with highly conformal treatment planning, associated radiation toxicities in neighboring normal tissues remain the major limiting factor for delivering tumoricidal doses. Clear differences exist between patients regarding their individual tissue responses after radiotherapy. Even after ...

Synchrotrons and storage rings deliver radiation across the electromagnetic spectrum at high repetition rates, and free electron lasers produce radiation pulses with high peak brightness. However, at present few light sources can generate both high repetition rates and high brightness outside the optical range. We propose to create steady-state microbunching (SSMB) in a storage ring to produce ...

Chronic obstructive pulmonary disease (COPD) and lung cancer coexist in many smokers. In those with more advanced COPD in whom surgical resection is contraindicated, palliative or curative radiotherapy may be considered. The effects of radiation treatment on respiratory physiology and functional status in patients with background COPD are highly variable and difficult to predict [1]. Radiation-...

Internal solitary waves commonly observed in the coastal ocean are oftenmodeled by a nonlinear evolution equation of the Korteweg–de Vries type. Because these waves often propagate for long distances over several inertial periods, the effect of Earth’s background rotation is potentially significant. The relevant extension of the Kortweg–de Vries is then the Ostrovsky equation, which for interna...

Curative radiation therapy of pelvic malignancies, frequently results in dose limiting toxicities such as serous, mucoid, or more rarely, bloody diarrhea. Several studies have evaluated the cytoprotective effects of amifostine in preventing rectal mucositis associated with radiation treatment. We searched Medline for published comparative studies that evaluated the use of amifostine to reduce r...

BACKGROUND Intensity-modulated radiation therapy (IMRT) uses solid compensators or multileaf collimators to modulate the intensity of radiation in each field, delivering highly conformal dose distributions. This technique allows treating volumes with concave shapes when the target is close to a critical structure. The movement of multileaf collimator under computer control can modulate the dose...

In the framework of a two-moment photo-hydrodynamic modelling of radiation transport, we introduce a concept for the determination of effective radiation transport coefficients based on the minimization of the local entropy production rate of radiation and matter. The method provides the nonequilibrium photon distribution from which the effective absorption coefficients and the variable Eddingt...

By means of a recently-proposed metric or structural derivative, called scale − q−derivative approach, we formulate differential equation that models the cell death by a radiation exposure in tumor treatments. The considered independent variable here is the absorbed radiation dose D instead of usual time. The survival factor, FS, for radiation damaged cell obtained here is in agreement with the...