Recall which radioisotope is often used in radiotherapy machines as a source of gamma rays.

Name the radioisotope that is commonly used in internal radiotherapy.

In modern radiotherapy, superconducting wire coils are used to create magnetic fields that focus particle beams in order to deliver the maximum dose of ionizing radiation to a tumor site while minimizing the destruction of healthy tissue. For which of the following types of radiation would this technique NOT be useful?Question 10 Answer Choices   A.  Alpha particles   B.  Proton beams   C.  Gamma photons   D.  Beta particles

Which of the following statements about gamma rays is incorrect?Gamma rays are used in both medical imaging and radiotherapyGamma rays are produced when there are changes to the nuclei of atomsGamma rays can penetrate the body and can damage, mutate or kill cellsWhen a gamma ray is emitted, the amount of nuclear energy stored within a nucleus increases2Which of the following statements about x-rays is incorrect?X-rays are the second shortest-wavelength type of wave on the electromagnetic spectrum (only gamma rays have shorter wavelengths than x-rays)X-rays are used in both medical imaging and medical treatmentX-rays are produced by the rapid deceleration of free electrons and by changes in the organisation of the electrons that orbit the nuclei of atomsX-rays are absorbed effectively by soft body tissue but pass easily through bone3Which of the following types of electromagnetic radiation has the lowest frequency?Radio wavesMicrowavesUltravioletVisible light4In the visible spectrum, which colour lies between blue and violet?LilacPinkUltravioletIndigo5Which of the following does NOT involve the use of infrared waves?RadiotherapyRemote controlsCookersFibre-optic communications6What a control variable?The variable which is measured in an investigationThe variable which is changed in an investigationA variable which is more important than (at least some of) the other variables in an investigationA variable that is kept constant in an investigation

Radiation occurs from three natural sources: radioactive material in the environment, such as in soil, rock, or building materials; cosmic rays; and substances in the human body, such as radioactive potassium in bone and radioactive carbon in tissues. These natural sources account for an exposure of about 100 millirems a year for the average American.The largest single source of man-made radiation is medical X rays, yet most scientists agree that hazards from this source are not as great as those from weapons test fallout, since strontium 90 and carbon 14 become incorporated into the body, hence delivering radiation for an entire lifetime. The issue is, however, by no means uncontroversial. The last two decades have witnessed intensified examination and dispute about the effects of low-level radiation, beginning with the United Nations Scientific Committee on the Effects of Atomic Radiation, which reported in 1958 that “even the smallest amounts of radiation are likely to cause deleterious genetic and perhaps also somatic effects ).”A survey conducted in Britain confirmed that an abnormally high percentage of patients suffering from arthritis of the spine who had been treated with X rays contracted cancer. Another study revealed a high incidence of childhood cancer in cases where the mother had been given prenatal pelvic X rays. These studies have pointed to the need to reexamine the assumption that exposure to low-linear energy transfer , ) presents only a minor risk.Recently, examination of the death certificates of former employees of a West Coast plant that produces plutonium for nuclear weapons revealed markedly higher rates for cancers of the pancreas, lung, bone marrow , and lymphatic system than would have been expected in a normal population.While the National Academy of Sciences committee attributes this difference to chemical or other environmental causes rather than radiation, other scientists maintain that any radiation exposure, no matter how small, leads to an increase in cancer risk. It is believed by some that a dose of one rem, if sustained over many generations, would lead to an increase of 1 percent in the number of serious genetic defects at birth, a possible increase of 1,000 disorders per million births.In the meantime, regulatory efforts have been disorganized, fragmented, inconsistent, and characterized by internecine strife and bureaucratic delays. A Senate report concluded that coordination of regulation among involved departments and agencies was not possible because of jurisdictional disputes and confusion. One federal agency has been unsuccessful in its efforts to obtain sufficient funding and manpower for the enforcement of existing radiation laws, and the chairperson of a panel especially created to develop a coordinated federal program has resigned.QUESTION 13bookmark_borderSelect the correct answerThe passage contains information that answers which of the following questions?radio_button_uncheckedHow many millirems of radiation from man-made sources is the average American exposed to each year?radio_button_uncheckedIs exposure to radiation linked to any other diseases besides cancer?radio_button_uncheckedHow many types of radiation are there?radio_button_uncheckedWhat is the maximum level of radiation to which humans can safely be exposed?radio_button_uncheckedWhy is exposure to the fallout from weapons testing considered by some to be more hazardous than exposure to X rays?

Brain tumors are often treated with radiation consisting of high energy photons, like gamma rays, that kill cancer cells through apoptosis, autophagy, DNA damage, etc.  Local drug delivery provides a high concentration of drug in the tumor while decreasing systemic toxicity.Researchers study a new drug that emits gamma rays at 50 × 1018 Hz and is injected into tumors using a vascular catheter and x-ray imaging guidance.  The x-rays have a lower frequency, 100 × 1015 Hz, compared to gamma rays.  The catheter also collects tumor samples for optical analysis using lenses, as shown in Figure 1.Figure 1  A tissue sample placed 2.5 cm from the center of a convex lens forms an image 10 cm from the lensAn x-ray tube propels high energy electrons at a tungsten target to produce x-rays but also heats the target.  To avoid overheating, tube current I is applied only to collect one x-ray image, followed by a cooling period (Figure 2).  The tungsten target is 1000 °C and 2 cm long after cooling, but it heats to 2000 °C and increases in length by 0.1 mm when generating x-rays.Figure 2  X-ray tube current over timeThe drug is injected into a blood vessel feeding the tumor with the injection syringe and catheter at the same level to eliminate gravitational effects.  In one experiment, two drug doses were compared and the higher drug dose had a greater therapeutic response.  In another experiment, the drug injection velocity was varied and the lowest injection velocity had the greatest therapeutic response. Question 41If the density of the drug is known, what additional information is required to calculate the velocity of the drug as it enters the blood vessel?  (Note: Assume ideal fluid flow.)A.Pressure in syringe, pressure in blood vessel, and mass of drugB.Pressure in syringe, velocity in syringe, and pressure in blood vesselC.Pressure in syringe, velocity in syringe, and volume of drugD.Velocity in syringe, mass of drug, and volume of drug