6 1 X 1895 Born 27 March 1845

6 -1. 서 언 X 선은 1895년 독일의 물리학자 뢴트겐에 의해 음극선관 근처 에 있던 형광체가 빛을 내는 것을 발견하여 미지의 방사선이란 의미로 명명되었다. Born 27 March 1845 Lennep, Prussia Died 10 February 1923 (aged 77) Munich, Germany Nationality Germany Fields Physics Wilhelm Conrad Röntgen

Hand mit Ringen: print of Wilhelm Röntgen's first "medical" x-ray, of his wife's hand, taken on 22 December 1895 and presented to Professor Ludwig Zehnder of the Physik Institut, University of Freiburg, on 1 January 1896 An X-ray picture (radiograph) taken by Röntgen of Albert von Kölliker's hand

The X-ray Tube

Possible Interaction Between Electron Beam and the Target

Interaction of Electron Beam with Target Outer Electrons • Kinetic energy loss by emission of infra -red photons (heat) • Very high probability of occurring (9599% energy produced at the target)

Interaction of Electron Beam with Target Nuclei • Elastic collision with nuclei (deflection, occurs very often increases with the target atomic number) • Inelastic collision - production of Bremsstrahlung radiation – Occurs only a sudden change of energy – Small probability (1 -5%) – Intensity is proportional to the atomic number of target and the energy of electron beam I ZE 2 – The direction of the emitted radiation depends on the energy of the electron beam (isotropic for low energy, right angle for medium energy and same direction for high energy from accelerator).

Elastic Deflection

Inelastic Bremsstrahlung X-ray Production

Excitation or Ionisation

Production of Characteristic Radiation

n=3 n=5 n=4 Paschen Series n=3 n=1 Balmer Series n=2 Lyman Series n=2 n=1 Difference in energy between two levels: Absorption Emission

How much Ionising Radiation is Dangerous? • 10 Sv: Immediate illness and subsequent death within a few weeks. • 1 Sv: Temporary illness such as nausea and decreased white blood cell count, but not death. Probable fatal cancer some years later. • 0. 05 Sv/yr: Lowest dose rate where there is any evidence of cancer being caused. • 0. 001 - 0. 005 Sv/yr: Average background radiation from natural sources - dependant on location, altitude, etc. • Dose from a Dental X-Ray (0. 00001 - 0. 00008 Sv)

Relative risk of 1 in a Million Chance of Dying: • • Smoking 1. 4 cigarettes (lung cancer) Eating 40 tablespoons of peanut butter Spending 2 days in New York City (air pollution) Driving 40 miles in a car (accident) Flying 2500 miles in a jet (accident) Canoeing for 6 minutes (drowning) Receiving 0. 1 m. Sv of radiation (cancer)