External beam

External-beam PDCE refers to measurements with the specimen removed from a vacuum environment. This mode permits the analysis of large or volatile specimens and consists of allowing the panicle beam to exit, through a thin window, the vacuum of the beam line and impinge on the specimen held at atmospheric pressure of air or other gases (e.g., helium). 

Local therapy of early-stage breast cancer consists of modified radical mastectomy or lumpectomy plus external-beam radiation therapy. The surgical approach to the ipsilateral axilla may consist of a full level I/II axillary lymph node dissection or a lymph node mapping procedure with sentinel lymph node biopsy. 

In most instances, external-beam radiation therapy used in conjunction with breast-conserving procedures involves 4 to 6 weeks of radiation therapy directed to the breast tissue to eradicate residual disease. Complications associated with radiation therapy to the breast are minor and include reddening and erythema of the breast tissue and subsequent shrinkage of total breast mass beyond that predicted on the basis of breast tissue removal. Some clinical situations also require postmastectomy radiation therapy as well (see section on locally advanced breast cancer). 

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. 

External beam radiotherapy Treatment by radiation emitted from a source located at a distance from the body also called beam therapy and external beam therapy. 

Applications The main application fields of PIXE are earth science, air pollution studies (aerosol analysis), mineralogical studies, forensic science, arts and archaeology. In the external-beam PIXE technique, the proton beam is taken out to ambient air. This mode finds application in the analysis of art objects (paintings, books, etc.). 

If thick samples are placed in the specimen chamber for analysis, the particles are slowed down and eventually stopped in the sample, so the calculation of the X-ray yield and their absorption is more complicated. Some objects may be too large to be placed in the specimen chamber, in which case the external beam technique is employed. The particle beam passes through a window at the end of the beam-line into the air where an object of any size (e.g. an archaeological artefact) may be analyzed. 

The diode laser is scanned up and down in frequency by a triangle wave, so that the scan should be linear in time and have the same rate in both directions. In the thermal accommodation coefficient experiments, the external beam heats the microsphere to a few K above room temperature and is then turned off. The diode laser is kept at fairly low power ( 7 pW) so that it does not appreciably heat the microsphere. Displacement of a WGM s throughput dip from one scan trace to the next is analyzed to find the relaxation time constant as the microsphere returns to room temperature. Results from the two scan directions are averaged to reduce error due to residual scan nonlinearity. This is done over a wide range of pressures (about four orders of magnitude). The time constant provides the measured thermal conductivity of the surrounding air, and fitting the thermal conductivity vs. pressure curve determines the thermal accommodation coefficient, as described in Sect. 5.5.2. 

Abraham, M. H., Grime, G. W., Marsh, M. A., and Northover, J. P. (2001). The study of thick corrosion layers on archaeological metals using controlled laser ablation in conjunction with an external beam microprobe. Nuclear Instruments and Methods in Physics Research B 181 688-692. 

Calligaro, T., Colinart, S., Poirot, J. P., and Sudres, C. (2002). Combined external-beam PIXE and mu-Raman characterisation of garnets used in Merovingian jewelry. Nuclear Instruments and Methods in Physics Research B 189 320-327. 

Mando, P. A. (1994). Advantages and limitations of external beams in applications to arts and archaeology, geology and environmental-problems. Nuclear Instruments and Methods in Physics Research B 85 815-823. 

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]... 

Radiotherapy is a local treatment aiming to achieve local control or cure of locally confined tumours. It cannot treat metastases. Radiotherapy may be administered as external beam radiotherapy with X-rays or gamma rays, in sealed radioactive sources (e.g. prostate brachytherapy), or unsealed sources (e.g. orally administered radioiodine for thyroid cancer, intravenous strontium-89 for bone metastases). In external beam radiotherapy, the X-ray or gamma ray beams are targeted at the tumour to damage and kill the tumour cells. Inevitably, surrounding normal tissues are also affected resulting in the early and late side effects of radiotherapy. 

Warde P, O Sullivan B, Bristow R, et al. T1/T2 glottic cancer managed by external beam radiotherapy the influence of pretreatment hemoglobin on local control. Int J Rad One Biol Phys 1998 41(2) 347-353. 

Langer CJ, Paulus R, Ruffer J, Movsas B, Murray K, Rhodes H, Curran WJ. Pro Am Soc Clin Oncol. Phase IIRTOG Trial of Weekly Paclitaxel (TAX) and Conventional External Beam Radiation Therapy for Supratentorial Glioblastoma Mutiforme (abstract 534) 1999. 18. 

S af ar AM, Altamiro PS, Recht A, et al. Phase I trial of gemcitabine, cisplatin and external beam radiation therapy for pancreatic cancer. Proc Am Soc Clin Oncol 1999 18 227a. 

Langer CJ, Ruffer J, Rhodes H, et al. Phase II Radiation Therapy Oncology Group trial of weekly paclitaxel and conventional external beam radiation therapy for supratentorial glioblastoma multiforme. Int J Radiat Oncol Biol Phys 2001 51 113-119. 

No distinct advantage has been noted when other forms of external beam irradiation, other than photons, or brachytherapy have been used. Neutron irradiation has not proven to be better than photons for stage III inoperable NSCLC (14,15). The use of brachytherapy has been limited to endobronchial treatment for palliation or as a boost after external beam. There have been institutional reports of interstitial brachytherapy, also usually done as aboost. Neither of these two approaches has been shown to be superiorto external beam (16,17). 

Aygun C, Weiner S, Scariato A, et al. Treatment of non-small cell lung cancer with external beam radiotherapy and high dose rate brachytherapy. Int J Radiat Oncol Biol Phys 1992 23 127-132. 

Intensified Radiation (External Beam) as a Component of Chemoradiation... 

Gaspar LE, Winter K, Kocha WI, Coia LR, Herskovic A, Graham M. A phase I/II study of external beam radiation, brachytherapy, and concurrent chemotherapy for patients with localized carcinoma of the esophagus (Radiation Therapy Oncology Group Study 9207) final report. Cancer 2000 88(5) 988-995. 

Pollack A, Zagars GK, Swanson DA. Muscle-invasive bladder cancer treated with external beam radiotherapy prognostic factors, ltd J Rad Oncol Biol Phys 1994 2 267-277. 

Androgen deprivation therapy (ADT) is being used increasingly as neo-adjuvant and adjuvant therapy. Neo-adjuvant ADT for 4-6 months before external beam radiation can enhance survival and reduce the prostate volume to be irradiated. Similar benefits have not been seen prior to radical prostatectomy. The benefits of neo-adjuvant therapy are most evident for high risk localized prostate cancer. Adjuvant ADT for up to 2 years following external beam radiation increases disease-free survival and overall survival for locally advanced (T3) tumors. 

High-Energy Electrons, X-Rays, and -y-Rays External Beam Therapy... 

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