A cobalt-60 source with activity 2.60×10-4 Ci is embedded in a tumor that has mas 0.20 kg. The source emits gamma photons with average energy 1.25 MeV. Half the photons are absorbed in the tumor, and half escape. i. What energy is delivered to the tumor per second? ii. What absorbed dose, in rad, is delivered per second? iii. What equivalent dose, in rem, is delivered per second if the RBE for these gamma rays is 0.70? iv. What exposure time is required for an equivalent dose of 200 rem? B. A laser with power output of 2.0 mW at a wavelength of 400 nm is projected onto a Calcium metal. The binding energy is 2.31 eV. i. How many electrons per second are ejected? ii. What power is carried away by the electrons? C. A hypodermic needle of diameter 1.19 mm and length 50 mm is used to withdraw blood from a patient? How long would it take for 500 ml of blood to be taken? Assume a blood viscosity of 0.0027 Pa.s and a pressure in the vein of 1,900 Pa. D. A person with lymphoma receives a dose of 35 gray in the form of gamma radiation during a course of radiotherapy. Most of this dose is absorbed in 18 grams of cancerous lymphatic tissue. i. How much energy is absorbed by the cancerous tissue? ii. If this treatment consists of five 15-minute sessions per week over the course of 5 weeks and just one percent of the gamma photons in the gamma ray beam are absorbed, what is the power of the gamma ray beam? iii. If the gamma ray beam consists of just 0.5 percent of the photons emitted by the gamma source, each of which has an energy of 0.03 MeV, what is the activity, in Curies, of the gamma ray source? E. A water heater that is connected across the terminals of a 15.0 V power supply is able to heat 250 ml of water from room temperature of 25°C to boiling point in 45.0 secs. What is the resistance of the heater? The density of water is 1,000 kg/m2 and the specific heat capacity of water is 4,200 J/kg/°C.
A cobalt-60 source with activity 2.60×10-4 Ci is embedded in a tumor that has mas 0.20 kg. The source emits gamma photons with average energy 1.25 MeV. Half the photons are absorbed in the tumor, and half escape. i. What energy is delivered to the tumor per second? ii. What absorbed dose, in rad, is delivered per second? iii. What equivalent dose, in rem, is delivered per second if the RBE for these gamma rays is 0.70? iv. What exposure time is required for an equivalent dose of 200 rem? B. A laser with power output of 2.0 mW at a wavelength of 400 nm is projected onto a Calcium metal. The binding energy is 2.31 eV. i. How many electrons per second are ejected? ii. What power is carried away by the electrons? C. A hypodermic needle of diameter 1.19 mm and length 50 mm is used to withdraw blood from a patient? How long would it take for 500 ml of blood to be taken? Assume a blood viscosity of 0.0027 Pa.s and a pressure in the vein of 1,900 Pa. D. A person with lymphoma receives a dose of 35 gray in the form of gamma radiation during a course of radiotherapy. Most of this dose is absorbed in 18 grams of cancerous lymphatic tissue. i. How much energy is absorbed by the cancerous tissue? ii. If this treatment consists of five 15-minute sessions per week over the course of 5 weeks and just one percent of the gamma photons in the gamma ray beam are absorbed, what is the power of the gamma ray beam? iii. If the gamma ray beam consists of just 0.5 percent of the photons emitted by the gamma source, each of which has an energy of 0.03 MeV, what is the activity, in Curies, of the gamma ray source? E. A water heater that is connected across the terminals of a 15.0 V power supply is able to heat 250 ml of water from room temperature of 25°C to boiling point in 45.0 secs. What is the resistance of the heater? The density of water is 1,000 kg/m2 and the specific heat capacity of water is 4,200 J/kg/°C.
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