Radiotherapy implantation

The two commonly used methods for radiation therapy are external-beam radiotherapy and brachytherapy.26 In external-beam radiotherapy, doses of 70 to 75 Gy are delivered in 35 to 41 fractions in patient with low-grade prostate cancer and 75 to 80 Gy for those with intermediate- or high-grade prostate cancer. Brachytherapy involves the permanent implantation of radioactive beads of 145 Gy of 125I or 124 Gy of 103Pd and generally is reserved for individuals with low-risk cancers. 

Radiation therapy The use of high-energy radiation from x-rays, gamma rays, neutrons, and other sources to kill cancer cells and shrink tumors. Radiation may come from a machine outside the body (external-beam radiation therapy), or it may come from radioactive material placed in the body in the area near cancer cells (internal radiation therapy, implant radiation, or brachytherapy). Systemic radiation therapy uses a radioactive substance, such as a radiolabeled monodonal antibody, that circulates throughout the body. Also called radiotherapy, [nih]... 

Figure 5. Radiotherapy afterloading cell for interstitial implantation (ALC-X)...

Figure 7. Radiotherapy applicator tube for intracavitary implantation (AT-X)...

Figure 8. Radiotherapy seed assemblies for interstitial implantation (Seeds)...

The treatment of infiltrating brain tumors, particularly oligodendrogliomas, requires radiotherapy, which provides a median survival of 3.5-11 years [205]. Since IdUrd is a powerful radio sensitizer [206], the intracranial implantation of... 

It is possible to predict the effect of treatment in cancer in a noninvasive manner by apoptosis imaging in vivo after radiotherapy by using I-Annexin V. Brain tumors were implanted in susceptible (nude) mice. By 6 h after receiving levels of x-irradiation as low as 2 Gy both autoradiography and immunohistochemical staining showed more apoptosis in the tumors of irradiated groups than in the control group (Watanabe et al, 2006). 

Iodine-125 sources. Iodine-125 is widely used for permanent implants in radiotherapy. The encapsulation consists of a 0.05 mm thick titanium tube welded at both ends to form a cylindrical capsule of dimensions 4.5 x 0.8 mm. Iodine-125 decays exclusively by electron capture to an excited state of Technetium-125, which then emits a 35.5 keV photon. Characteristic x-rays in the range of 27 to 35 keV also are produced due to the electron capture and internal conversion processes. 

Hedyotis corymbosa. H. diffusa Anti- neoplastic, anti-toxic and immuno-properties. Geniposide Antitumoral Decreases the growth of tile implanted tumor by ascitic cells. Increase die tumor growth inhibition when is combined with the X-irradiation. Inhibit the hematological and blastogenic damage by radiotherapy. 1731... 

Several radionuclides of copper are suitable for labeling mAbs, their fragments, or peptides for PET (e.g., Cu, Cu, or " Cu Table 6.7-2) [216]. " Cu decays with a half-life of 12.7 hours by three different pathways (1) electron capture (41%) emitting Auger and conversion electrons, (2) positron (P+) emission (19%), and (3) P emission (40%). The P emissions make the radionuclide useful not only for PET but also for radiotherapy of tumors. Indeed, in one study, " Cu-labeled octreotide inhibited the growth of CA20948 rat pancreatic tumors in Lewis rats [217]. In another study, Cu-labeled 1A3 mAbs were used to treat hamsters implanted s.c. 

External beam radiotherapy (including three-dimensional radiotherapy, intensity modulated radiotherapy, and extracranial stereotactic radiotherapy) is the most common way radiation is used to eradicate solid tumors, often with combined chemotherapy. The key limitation of external beam radiotherapy is the tolerance of normal liver parenchyma to radiation, which is much less than the dose required to control the liver tumors. Direct implantation of radionuclides into the tumor (brachytherapy) using interstitial seeds... 

Sheldon PW et al. (1974) The incidence of lung metastases in C3H mice after treatment of implanted solid tumors with X-rays or surgery. Br J Cancer 30(4) 342 348 SRC Trial Group (1997) Improved survival with preoperative radiotherapy in resectable rectal cancer. Swedish Rectal Cancer Trial. N Engl J Med 336(14) 980-987 Stausbol-Gron B, Overgaard J (1999) Relationship between tumor cell in vitro radiosensitivity and clinical outcome after curative radiotherapy for sqiuimous cell carcinoma of the head and neck. Radiother Oncol 50(l) 47-55 Stuschke M, Thames HD (1999) Fractionation sensitivities and dose-control relations of head and neck carcinomas analysis of the randomized hyperfractionation trials. Radiother Oncol 51(2) 113-121... 

Gerard et al. 1998 Anal canal carcinoma Tl-4 NO 3 External beam radiotherapy plus implant and chemotherapy 5-Year colostomy-free survival 72% 5-Year disease-specific survival 90%... 

Sathya et al. 2005 T2-3 NO prostate cancer External beam radiotherapy plus implant 8-Year failure-free survival 65% 8-Year overall survival 82%... 

MeUenbeig DE Jr. A pohey for radiotherapy in patients with implanted pacemakers. Med Dosira 1991 16 221-223. 

Finally, changes in the brain that occur during the course of therapy are not properly considered in this model. Irradiation can be safely administered when a BCNU-loaded polymer has been implanted in monkey brains, suggesting the feasibility of adjuvant radiotherapy. Flowever, irradiation also causes necrosis in the brain. The necrotic region has a lower perfusion rate and interstitial pressure than tumor tissue thus, the convective interstitial flow due to fluid leakage is expected to be smaller. Interstitial... 

An important modality in cancer treatment is that of radiotherapy, either alone or in combination with chemotherapy. Indeed, the first treatment of cancer by X-rays followed within a year of their discovery by Rontgen [1] and it is estimated that today approximately half of all cancer patients receive radiation in some form. Conventional sources such as X-rays and Co-y rays are now supplemented with particles such as protons, neutrons and mesons [2] and also by internal delivery (brachytherapy) using various implanted isotopes [3]. 

Kawashita M, Miyaji F, Kokubo T, Takaoka GH, Yamada I, Suzuki Y, Inoue M. (1999) Surface structure and chemical durability of PH—implanted Y2O3—AI2O3—Si02 glass for radiotherapy of csincei. JNon-Crys Solids 255 140-148. 

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