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Orthovoltage ("superficial") X-rays are used for treating skin cancer and superficial structures. Megavoltage X-rays are used to treat deep-seated tumors (e.g. bladder, bowel, prostate, lung, or brain), whereas megavoltage electron beams are typically used to treat superficial lesions extending to a depth of approximately 5 cm.
This is the method used in the original discovery of X-ray diffraction. Laue scattering provides much structural information with only a short exposure to the X-ray beam, and is therefore used in structural studies of very rapid events (time resolved crystallography). However, it is not as well-suited as monochromatic scattering for determining ...
Scattering angles are small and diffraction directed forward allows for simple detector setups. High energy (megavolt) X-rays are also used in cancer therapy, using beams generated by linear accelerators to suppress tumors. [1]
Medicine has used radiation therapy as a treatment for cancer for more than 100 years, with its earliest roots traced from the discovery of X-rays in 1895 by Wilhelm Röntgen. [119] Emil Grubbe of Chicago was possibly the first American physician to use X-rays to treat cancer, beginning in 1896. [120]
Due to the higher ionization density caused by soft X-ray radiation in the tissue, the relative biological effectiveness (RBE) of low-energy X-rays on tumor cells is higher when compared to high-energy X-rays or gamma rays which are delivered by linear accelerators. [15]
Orthovoltage X-rays are sometimes termed "deep" X-rays (DXR). [2] They cover the upper limit of energies used for diagnostic radiography , and are used in external beam radiotherapy to treat cancer and tumors .
An X-ray diffraction pattern of a crystallized enzyme. The pattern of spots (reflections) and the relative strength of each spot (intensities) can be used to determine the structure of the enzyme. The relative intensities of the reflections provides information to determine the arrangement of molecules within the crystal in atomic detail.
Initially, this compound was isolated for its aesthetic properties as a dye until further research demonstrated its anti-cancer properties. Shortly after the compound's discovery, the Bristol-Myers Pharmaceutical Company elucidated the structure in Japan using X-ray diffraction studies of triacetyldynemicin A; a closely related compound.