SINCE the high incidence of iatrogenic hypothyroidism (40%/. eight years after treatment) in thyrotoxic patients treated with radioiodine was appreciated, the radiobiology of the thyroid gland has 'become a subject of great clinical importance. The method of treatment in its orthodox form and dosage is clearly unsatisfactory and efforts are being made to improve it in various centres. Unfortuna...

When I came into radiotherapy in 1950, I was puzzled that some patients were treated to 3000 rads (cGy) in 3 weeks but others received 4000 in 5 or 6000 in 6 weeks. When I asked why, there were no convincing answers given, except 'this is what we usually do'. It wasn't until I went to a course on 'Radiobiology for Radiotherapy' in Cambridge that I learnt about the basic theories of Douglas Lea ...

The radiation killing of tumor cells by ionizing radiation is best described by the linear-quadratic (LQ) model. Research into the underlying mechanisms of α- and β-inactivation has suggested that different molecular targets (DNA in different forms) and different microdosimetric energy deposits (spurs versus electron track-ends) are involved. Clinical protocols with fractionated doses of about ...

Two almost completely exclusive fields in radiobiology deal with splitting doses of radiation and comparing the effect to a similar total dose given in one exposure. In radiotherapy, dose "fractionation" is used to "spare" normal tissue and in the low dose field, the adaptive response is well documented as a phenomenon where a small "priming" dose administered before the larger "challenge" dose...

Advances in conformal radiation therapy and advancements in pre-clinical radiotherapy research have recently stimulated the development of precise micro-irradiators for small animals such as mice and rats. These devices are often kilovolt x-ray radiation sources combined with high-resolution CT imaging equipment for image guidance, as the latter allows precise and accurate beam positioning. Thi...

The use of radiochromic film (RCF) dosimetry is widely consolidated for applications in photon, electron and proton beams. It offers several advantages, in particular, two-dimensional measurements of dose distributions with high spatial resolution, no post irradiation processing required and no daylight sensitivity. In addition, it shows small LET and energy dependence. GAFCHROMIC® EBT3 films, ...

Dentists’ incorrect behavior with regards to Oral Radiology, as reported in the literature, has been related to inadequate training of undergraduates. Aim: This study assessed dental undergraduates’ knowledge of Oral Radiology. Methods: A questionnaire containing 30 questions pertaining to three domains General Principles, Radiobiology/Radioprotection and Technique/Interpretation was used as da...

A neutron generator (HIRRAC) for use in radiobiology study has been constructed at the Research Institute for Radiation Biology and Medicine, Hiroshima University (RIRBM). Monoenergetic neutrons of which energy is less than 1.3 MeV are generated by the 7Li(p,n)7 Be reaction at proton energies up to 3 MeV. The protons are accelerated by a Schenkel-type-accelerator and are bombared onto the 7Li-t...

Alpha-particle emitter labeled monoclonal antibodies are being actively developed for treatment of metastatic cancer due to the high linear energy transfer (LET) and the resulting greater biological efficacy of alpha-emitters. Our knowledge of high LET particle radiobiology derives primarily from accelerated heavy ion beam studies. In heavy ion beam therapy of loco-regional tumors, the modulati...