Index of physics articles (J): The index of physics articles is split into multiple pages due to its size.Certified Health Physicist: Certified Health Physicist is an official title granted by the American Board of Health Physics, the certification board for health physicists in the United States. A Certified Health Physicist is designated by the letters CHP or DABHP after his or her name.Radiation oncologist: A radiation oncologist is a specialist physician who uses ionizing radiation (such as megavoltage X-rays or radionuclides) in the treatment of cancer. Radiation oncology is one of the three primary specialties, the other two being surgical and medical oncology, involved in the treatment of cancer.Radiation protection of patients: Patients are exposed to ionizing radiations when they undergo diagnostic examinations using x-rays or radiopharmaceuticals, therapy of cancer or benign lesions using radiations emitted by radioisotopes or those by radiation generators; and in interventional procedures using fluoroscopy. There has been a tremendous increase in the use of ionizing radiation in medicine during recent decades.Irradiance: In radiometry (measurement of electromagnetic radiation), irradiance is the radiant flux (power) received by a surface per unit area, and spectral irradiance is the irradiance of a surface per unit frequency or wavelength, depending on whether the spectrum is taken as a function of frequency or of wavelength. The SI unit of irradiance is the watt per square metre (), while that of spectral irradiance is the watt per square metre per hertz (W·m−2·Hz−1) or the watt per square metre per metre (W·m−3)—commonly the watt per square metre per nanometre ().DR Systems: DR Systems, Inc. is an independent provider of enterprise imaging and information management systems for hospitals, integrated healthcare networks and diagnostic imaging centers.Automatic exposure control: Automatic Exposure Control (AEC) is an X-ray exposure termination device. A medical radiography x-ray exposure is always initiated by a human operator.