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Harold E. Johns
Harold Elford Johns (4 July 1915 – 23 August 1998) was a Canadian medical physicist, noted for his extensive contributions to the use of ionizing radiation to treat cancer. Early life and education Johns was born to missionary parents in Szechuan, China. He lived in China until 1926, when political unrest there prompted his parents to return to North America. After spending time in Tacoma, Washington, and in Brandon, Manitoba, his family settled in Hamilton, Ontario. In Hamilton, Johns pursued a degree in mathematics and physics at McMaster University, and he completed his Bachelor of Science degree (BSc) in 1936. He then moved to the University of Toronto, where he earned his Master of Arts and Doctor of Philosophy (PhD) degrees in physics in 1939. Early career Johns' graduation coincided with the start of World War II. For the duration of the war, he taught physics, mathematics, radar systems, and radio navigation to newly recruited airplane pilots as part of the Br ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canadians
Canadians (french: Canadiens) are people identified with the country of Canada. This connection may be residential, legal, historical or cultural. For most Canadians, many (or all) of these connections exist and are collectively the source of their being ''Canadian''. Canada is a multilingual and Multiculturalism, multicultural society home to people of groups of many different ethnic, religious, and national origins, with the majority of the population made up of Old World Immigration to Canada, immigrants and their descendants. Following the initial period of New France, French and then the much larger British colonization of the Americas, British colonization, different waves (or peaks) of immigration and settlement of non-indigenous peoples took place over the course of nearly two centuries and continue today. Elements of Indigenous, French, British, and more recent immigrant customs, languages, and religions have combined to form the culture of Canada, and thus a Canadian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radar
Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. A radar system consists of a transmitter producing electromagnetic waves in the radio or microwaves domain, a transmitting antenna, a receiving antenna (often the same antenna is used for transmitting and receiving) and a receiver and processor to determine properties of the objects. Radio waves (pulsed or continuous) from the transmitter reflect off the objects and return to the receiver, giving information about the objects' locations and speeds. Radar was developed secretly for military use by several countries in the period before and during World War II. A key development was the cavity magnetron in the United Kingdom, which allowed the creation of relatively small systems with sub-meter resolution. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
External Beam Radiotherapy
External beam radiotherapy (EBRT) is the most common form of radiotherapy (radiation therapy). The patient sits or lies on a couch and an external source of ionizing radiation is pointed at a particular part of the body. In contrast to brachytherapy (sealed source radiotherapy) and unsealed source radiotherapy, in which the radiation source is inside the body, external beam radiotherapy directs the radiation at the tumour from outside the body. Orthovoltage ("superficial") X-rays are used for treating skin cancer and superficial structures. Megavoltage X-rays are used to treat deep-seated tumours (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 (increasing beam energy corresponds to greater penetration). X-rays and electron beams are by far the most widely used sources for external beam radiotherapy. A small number of centers operate experimental and pi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
London, Ontario
London (pronounced ) is a city in southwestern Ontario, Canada, along the Quebec City–Windsor Corridor. The city had a population of 422,324 according to the 2021 Canadian census. London is at the confluence of the Thames River, approximately from both Toronto and Detroit; and about from Buffalo, New York. The city of London is politically separate from Middlesex County, though it remains the county seat. London and the Thames were named in 1793 by John Graves Simcoe, who proposed the site for the capital city of Upper Canada. The first European settlement was between 1801 and 1804 by Peter Hagerman. The village was founded in 1826 and incorporated in 1855. Since then, London has grown to be the largest southwestern Ontario municipality and Canada's 11th largest metropolitan area, having annexed many of the smaller communities that surround it. London is a regional centre of healthcare and education, being home to the University of Western Ontario (which brands it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chalk River Laboratories
Chalk River Laboratories (french: Laboratoires de Chalk River; also known as CRL, Chalk River Labs and formerly Chalk River Nuclear Laboratories, CRNL) is a Canadian nuclear research facility in Deep River, about north-west of Ottawa. CRL is a site of major research and development to support and advance nuclear technology, particularly CANDU reactor technology. CRL has expertise in physics, metallurgy, chemistry, biology, and engineering, and hosts unique research facilities. For example, Bertram Brockhouse, a professor at McMaster University, received the 1994 Nobel Prize in Physics for his pioneering work in neutron spectroscopy while at CRL from 1950 to 1962. Sir John Cockcroft was an early director of CRL and also a Nobel laureate. Until the shutdown of its nuclear reactor in 2018, CRL produced a large share of the world's supply of medical radioisotopes. It is owned by the Canadian Nuclear Laboratories subsidiary of Atomic Energy of Canada Limited and operated under con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiation Therapy
Radiation therapy or radiotherapy, often abbreviated RT, RTx, or XRT, is a therapy using ionizing radiation, generally provided as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Radiation therapy may be curative in a number of types of cancer if they are localized to one area of the body. It may also be used as part of adjuvant therapy, to prevent tumor recurrence after surgery to remove a primary malignant tumor (for example, early stages of breast cancer). Radiation therapy is synergistic with chemotherapy, and has been used before, during, and after chemotherapy in susceptible cancers. The subspecialty of oncology concerned with radiotherapy is called radiation oncology. A physician who practices in this subspecialty is a radiation oncologist. Radiation therapy is commonly applied to the cancerous tumor because of its ability to control cell growth. Ionizing radiation works by damaging the DNA of cancerous tissue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gamma Ray
A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves, typically shorter than those of X-rays. With frequencies above 30 exahertz (), it imparts the highest photon energy. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium. In 1903, Ernest Rutherford named this radiation ''gamma rays'' based on their relatively strong penetration of matter; in 1900 he had already named two less penetrating types of decay radiation (discovered by Henri Becquerel) alpha rays and beta rays in ascending order of penetrating power. Gamma rays from radioactive decay are in the energy range from a few kiloelectronvolts (keV) to approximately 8 megaelectronvolts (MeV), corresponding to the typical energy levels in nuclei with reasonably long lif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cobalt-60
Cobalt-60 (60Co) is a synthetic radioactive isotope of cobalt with a half-life of 5.2713 years. It is produced artificially in nuclear reactors. Deliberate industrial production depends on neutron activation of bulk samples of the monoisotopic and mononuclidic cobalt isotope . (PDF also located aCanadian Nuclear FAQ Measurable quantities are also produced as a by-product of typical nuclear power plant operation and may be detected externally when leaks occur. In the latter case (in the absence of added cobalt) the incidentally produced is largely the result of multiple stages of neutron activation of iron isotopes in the reactor's steel structures via the creation of its precursor. The simplest case of the latter would result from the activation of . undergoes beta decay to the stable isotope nickel-60 (). The activated nickel nucleus emits two gamma rays with energies of 1.17 and 1.33 MeV, hence the overall equation of the nuclear reaction (activation and decay) is: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Saskatchewan
A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities typically offer both undergraduate and postgraduate programs. In the United States, the designation is reserved for colleges that have a graduate school. The word ''university'' is derived from the Latin ''universitas magistrorum et scholarium'', which roughly means "community of teachers and scholars". The first universities were created in Europe by Catholic Church monks. The University of Bologna (''Università di Bologna''), founded in 1088, is the first university in the sense of: *Being a high degree-awarding institute. *Having independence from the ecclesiastic schools, although conducted by both clergy and non-clergy. *Using the word ''universitas'' (which was coined at its foundation). *Issuing secular and non-secular degrees: grammar, rhetoric, logic, theology, canon law, notarial law.Hunt Janin: "The university ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chalk River, Ontario
Chalk River (2016 population: 1029) is a small rural village, part of the Laurentian Hills municipality in Renfrew County, Ontario, Canada. It is located in the Upper Ottawa Valley along Highway 17 (Trans-Canada Highway), inland (west) from the Ottawa River, approximately northwest of Petawawa, and northwest of Ottawa. Chalk River was a separate municipality until January 1, 2000, when the United Townships of Rolph, Buchanan, Wylie and McKay and the Village of Chalk River were merged. Chalk River's area is environmentally pristine with extensive forests, hills and numerous small lakes, all of which support a variety of wildlife typical to the southern edge of the Canadian Shield. St. Anthony's Elementary School is the only educational institution in the community, instructing grades Junior Kindergarten to Grade 8. It provides Catholic education to the children in the neighbourhood, with a church next door. Students in higher grades are bussed to nearby Deep River. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Valentine Mayneord
William Valentine Mayneord, CBE FRS (14 February 1902 – 10 August 1988) was a British physicist and pioneer in the field of medical physics. Early life and education He was born in Redditch, Worcestershire to Walter and Elizabeth Mayneord but after the early death of his mother was adopted by an aunt in Evesham. He was educated at Prince Henry's School, Evesham and gained a Bachelor of Science at the University of Birmingham Career He entered the field of medical physics in 1924 at St Bart's Hospital in London. In 1927 he moved to the Cancer Hospital, now the Royal Marsden Hospital. There he was involved in pioneering work with Izrael Hieger. During World War II he was seconded by the government to work in Canada on the radiological aspects of atomic energy development. It has been said that such was his renown, especially for bringing in the use of the radiological unit the rad, that the SI unit may well have been called the mayneord instead of the gray (2). It was dur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-ray
An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz ( to ) and energies in the range 145 eV to 124 keV. X-ray wavelengths are shorter than those of UV rays and typically longer than those of gamma rays. In many languages, X-radiation is referred to as Röntgen radiation, after the German scientist Wilhelm Conrad Röntgen, who discovered it on November 8, 1895. He named it ''X-radiation'' to signify an unknown type of radiation.Novelline, Robert (1997). ''Squire's Fundamentals of Radiology''. Harvard University Press. 5th edition. . Spellings of ''X-ray(s)'' in English include the variants ''x-ray(s)'', ''xray(s)'', and ''X ray(s)''. The most familiar use of X-rays is checking for fractures (broken bones), but X-rays are also used in other ways. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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