Xray History
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A History of X-Rays For more than 100 years, the use of X-rays has developed along two separate paths. In diagnostic medicine their use has been restricted to the imaging of transmitted X-rays. In contrast X-ray diffraction, based on the scattering of X-rays, is the method of choice for studying atomic and molecular structure. Indeed, medical imaging employs techniques to eliminate the scattered radiation that diffraction physicists try to detect! In order to explain why there is still enormous scope for improving the diagnostic quality of Xrays more than 100 years after their discovery it is informative to take a look at the history.
Wilhelm Conrad Röntgen discovered X-Rays in 1895. He was awarded the Nobel prize for physics in 1901, a mere 6 years after his discovery "in recognition of the extraordinary services he has rendered by the discovery of the remarkable rays subsequently named after him". Röntgen's discovery unleashed an enormous amount of work on the new mystery rays. Wilhelm Conrad Röntgen (1845-1923)
On the right are two radiographs of a hand. These images are separated in time and technology by 100 years. The most remarkable thing about these images is that they are not so very different. The modern one is sharper and displays some rather poor soft tissue contrast. Nevertheless the improvement is rather poor for 100 years development. Remember that it was only 66 years from the first powered flight in 1903 to landing a man on the moon in 1969!
http://cxpi.spme.monash.edu.au/xray_history.htm
2007/02/24
Page 2 of 5
Bertha Röntgen’s Hand 8 Nov, 1895
A modern radiograph of a hand
Plane Radiography Radiographs like the ones above are simply shadowgrams. They are formed simply because the X-rays either pass straight through or are stopped by the object. The diagram on the left illustrates the principle and shows a perfect shadow.
In reality, things are not like this. A large fraction of the Xrays are not simply absorbed or transmitted by the object but are scattered. The diagram on the right illustrates this effect and illustrates the fuzzy edge of the object that is
http://cxpi.spme.monash.edu.au/xray_history.htm
2007/02/24
Page 3 of 5
produced in the image by the scattered X-rays. The scatter is due to a number of effects.
X-Ray Diffraction The first kind of scatter process to be recognised was discovered by Max von Laue who was awarded the Nobel prize for physics in 1914 "for his discovery of the diffraction of X-rays by crystals". His collaborators Walter Friedrich and Paul Knipping took the picture on the right in 1912. It shows how a beam of X-rays is scattered into a characteristic pattern by a crystal. In this case it is copper sulphate. Max von Laue (1897-1960)
Bragg's Law
The very next year 1915, the father and son team of Sir William Henry and William Lawrence Bragg were awarded the Nobel prize for physics "for their services in the analysis of crystal structure by means of Xrays". These gentlemen were responsible for the famous Bragg Law which describes the mechanism by which X-ray diffraction occurs and is illustrated in the following diagram.
http://cxpi.spme.monash.edu.au/xray_history.htm
2007/02/24
Page 4 of 5
Sir William Henry Bragg (18621942)
William Lawrence Bragg (1890-1971)
Bragg's law was an extremely important discovery and formed the basis for the whole of what is now known as crystallography. This technique is one of the most widely used structural analysis techniques and plays a major role in fields as diverse as structural biology and materials science. Nevertheless the effect has been ignored in the application of X-rays to medical imaging.
The Photoelectric Effect
Albert Einstein (1879 - 1955)
The most important effect in medical radiography, the photoelectric effect, was not understood until somewhat after the understanding of X-ray diffraction. Albert Einstein was awarded the Noble prize for physics in 1921 "for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect". It is photoelectric absorption that is responsible for most of the absorption in a mammogram that creates the contrast in the image.
The Compton Effect
http://cxpi.spme.monash.edu.au/xray_history.htm
2007/02/24
Page 5 of 5
Another important effect was discovered by Arthur Holly Compton who was awarded the Nobel prize for physics in 1927 "for his discovery of the effect named after him". The Compton effect is considered to be responsible for the bulk of scattering effects in radiography. Arthur Holly Compton (1892 - 1962)
The importance of these various processes and how they are helping us improve the use of X-rays for medical research is discussed in X-ray Processes.
Copyright © 2003 Monash University ABN 12 377 614 012 - Caution - Privacy - CRICOS Provider Number: 00008C Last updated: - Maintained by [email protected] - Accessibility information
http://cxpi.spme.monash.edu.au/xray_history.htm
2007/02/24
A History of X-Rays For more than 100 years, the use of X-rays has developed along two separate paths. In diagnostic medicine their use has been restricted to the imaging of transmitted X-rays. In contrast X-ray diffraction, based on the scattering of X-rays, is the method of choice for studying atomic and molecular structure. Indeed, medical imaging employs techniques to eliminate the scattered radiation that diffraction physicists try to detect! In order to explain why there is still enormous scope for improving the diagnostic quality of Xrays more than 100 years after their discovery it is informative to take a look at the history.
Wilhelm Conrad Röntgen discovered X-Rays in 1895. He was awarded the Nobel prize for physics in 1901, a mere 6 years after his discovery "in recognition of the extraordinary services he has rendered by the discovery of the remarkable rays subsequently named after him". Röntgen's discovery unleashed an enormous amount of work on the new mystery rays. Wilhelm Conrad Röntgen (1845-1923)
On the right are two radiographs of a hand. These images are separated in time and technology by 100 years. The most remarkable thing about these images is that they are not so very different. The modern one is sharper and displays some rather poor soft tissue contrast. Nevertheless the improvement is rather poor for 100 years development. Remember that it was only 66 years from the first powered flight in 1903 to landing a man on the moon in 1969!
http://cxpi.spme.monash.edu.au/xray_history.htm
2007/02/24
Page 2 of 5
Bertha Röntgen’s Hand 8 Nov, 1895
A modern radiograph of a hand
Plane Radiography Radiographs like the ones above are simply shadowgrams. They are formed simply because the X-rays either pass straight through or are stopped by the object. The diagram on the left illustrates the principle and shows a perfect shadow.
In reality, things are not like this. A large fraction of the Xrays are not simply absorbed or transmitted by the object but are scattered. The diagram on the right illustrates this effect and illustrates the fuzzy edge of the object that is
http://cxpi.spme.monash.edu.au/xray_history.htm
2007/02/24
Page 3 of 5
produced in the image by the scattered X-rays. The scatter is due to a number of effects.
X-Ray Diffraction The first kind of scatter process to be recognised was discovered by Max von Laue who was awarded the Nobel prize for physics in 1914 "for his discovery of the diffraction of X-rays by crystals". His collaborators Walter Friedrich and Paul Knipping took the picture on the right in 1912. It shows how a beam of X-rays is scattered into a characteristic pattern by a crystal. In this case it is copper sulphate. Max von Laue (1897-1960)
Bragg's Law
The very next year 1915, the father and son team of Sir William Henry and William Lawrence Bragg were awarded the Nobel prize for physics "for their services in the analysis of crystal structure by means of Xrays". These gentlemen were responsible for the famous Bragg Law which describes the mechanism by which X-ray diffraction occurs and is illustrated in the following diagram.
http://cxpi.spme.monash.edu.au/xray_history.htm
2007/02/24
Page 4 of 5
Sir William Henry Bragg (18621942)
William Lawrence Bragg (1890-1971)
Bragg's law was an extremely important discovery and formed the basis for the whole of what is now known as crystallography. This technique is one of the most widely used structural analysis techniques and plays a major role in fields as diverse as structural biology and materials science. Nevertheless the effect has been ignored in the application of X-rays to medical imaging.
The Photoelectric Effect
Albert Einstein (1879 - 1955)
The most important effect in medical radiography, the photoelectric effect, was not understood until somewhat after the understanding of X-ray diffraction. Albert Einstein was awarded the Noble prize for physics in 1921 "for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect". It is photoelectric absorption that is responsible for most of the absorption in a mammogram that creates the contrast in the image.
The Compton Effect
http://cxpi.spme.monash.edu.au/xray_history.htm
2007/02/24
Page 5 of 5
Another important effect was discovered by Arthur Holly Compton who was awarded the Nobel prize for physics in 1927 "for his discovery of the effect named after him". The Compton effect is considered to be responsible for the bulk of scattering effects in radiography. Arthur Holly Compton (1892 - 1962)
The importance of these various processes and how they are helping us improve the use of X-rays for medical research is discussed in X-ray Processes.
Copyright © 2003 Monash University ABN 12 377 614 012 - Caution - Privacy - CRICOS Provider Number: 00008C Last updated: - Maintained by [email protected] - Accessibility information
http://cxpi.spme.monash.edu.au/xray_history.htm
2007/02/24
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