X-ray and γ-ray photons have been widely used for studying radiobiological effects of ionizing radiations. Photons are indirectly ionizing radiations so they need to set in motion electrons (which are a directly ionizing radiation) to perform the ionizations. When the photon dose decreases to below a certain limit, the number of electrons set in motion will become so small that not all cells in...

M. H. SEEGENSCHMIEDT, MD Professor, Dept. of Radiation Oncology and Therapeutic Radiology, Alfried Krupp Hospital, Alfried Krupp Strafle 21, 45117 Essen, Germany 9.5.3 Radiotherapeutic Management 174 9.5.3.1 Radiobiological Rationale 175 9.5.3.2 Radiotherapy Technique 176 9.5.3.3 Results of Radiotherapy in Morbus Dupuytren I77 9.5.3.4 Possible Risks of Radiotherapy 178 9.5.3.5 Own Clinical Resu...

Radiobiological limitations for dose escalation in external radiotherapy are presented. Biological and clinical concept of brachytherapy boost to increase treatment efficacy is discussed, and different methods are compared. Oncentra Prostate 3D conformal real-time ultrasound-guided brachytherapy is presented as a solution for boost or sole therapy.

BACKGROUND Although two-dimensional (2-D) monolayer cell cultures provide important information on basic tumor biology and radiobiology, they are not representative of the complexity of three-dimensional (3-D) solid tumors. In particular, new models reproducing clinical conditions as closely as possible are needed for radiobiological studies to provide information that can be translated from be...

Nuclear emulsions of the Ilford K series, exposed to X-rays from 15 to 150 kVp and systematically underdeveloped, exhibit supralinear blackness--exposure curves ranging from 1- to 4-hit in character, and whose shape is the same at all excitation voltages. Processing can be so adjusted that the curve shape is well represented by the alpha--beta model, and matches an experimental dose--response c...

Targeted radionuclide therapy holds promise as a new treatment for cancer. Advances in imaging are making it possible for researchers to evaluate the spatial distribution of radioactivity in tumors and normal organs over time. Matched anatomical imaging, such as combined single-photon emission computed tomography/computed tomography and positron emission tomography/computed tomography, has also...

Two methods were proposed for determining alpha-particle fluence for radiobiological experiments. The first involved calculating the probabilities of hitting the target for alpha particles emitted from a source through Monte Carlo simulations, which when multiplied by the activity of the source gave the fluence at the target. The second relied on the number of chemically etched alpha-particle t...

Glioblastoma is the most frequent and malignant brain tumour. For many years, the conventional treatment has been maximal surgical resection followed by radiotherapy (RT), with a median survival time of less than 10 months. Previously, the use of adjuvant chemotherapy (given after RT) has failed to demonstrate a statistically significant survival advantage. Recently, a randomized phase III tria...

PURPOSE We present a framework, in which we compare a conventional standard dose of 50 Gy in 25 fractions with accelerated partial breast irradiation (APBI) using electronic brachytherapy (eBT). We discuss how radiobiological modelling enables us to establish a framework, within which we can compare external beam radiotherapy (EBRT). This leads to a determination of the shell of isoeffect in br...

There is strong evidence that ionizing radiation increases cancer risks at high doses (e.g., >or=1 Gy), and persuasive, if controversial, epidemiological evidence that cancer risks are increased at low doses ( approximately 10 mGy). Discussed here are the issues related to extrapolating radiation risks from low radiation doses to very low doses (<or=1 mGy) - for which purpose we are forced to r...