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Sensitivity to Radiaiton & Calculating pt dose

Sensitivity to Radiaiton & Calculating pt dose. Stat ch 8 Bush ch 40. Tissue and Cell Sensitivity to Radiation. Most Sensitive: Reproductive organs Blood-forming organs Skin Bone and teeth. Least sensitive : Muscle Nervous system. Tissue Radiation Sensitivity.

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Sensitivity to Radiaiton & Calculating pt dose

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  1. Sensitivity to Radiaiton&Calculating pt dose Stat ch 8 Bush ch 40

  2. Tissue and Cell Sensitivity to Radiation

  3. Most Sensitive: Reproductive organs Blood-forming organs Skin Bone and teeth Least sensitive: Muscle Nervous system Tissue Radiation Sensitivity

  4. Effects of Overdose to Humans

  5. Effects of Acute Radiation Exposures in Humans

  6. Why cancer risks at low doses are uncertain • It has been difficult to estimate cancer induction risks, because most of the radiation exposures that humans receive are very close to background levels. • At low dose levels of millirems to tens of rems, the risk of radiation-induced cancers is so low, • that if the risk exists, it is not readily distinguishable from normal levels of cancer occurrence. • In addition, leukemia or solid tumors induced by radiation are indistinguishable from those that result from other causes. 

  7. Relative Risk of a 1 in a million chance of death from activities common to our society: • ·Smoking 1.4 cigarettes in a lifetime (lung cancer) • Eating 40 tablespoons of peanut butter (aflatoxin) • Spending two 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 a dose of 10 mrem of radiation (cancer)

  8. PATIENT DOSE • RAD • MR/MAS PER EXPOSURE - At each kVp level – there is a determined output for each radiographic room • EX 70 kvp = 2.5 mr/mas • ABD done 70 kVp, 20 mas • 2.5 x 20 = 50 mR for that one exposure. • LOOK AT formula: mr/mas Ch 8 Stat • CH 40 BUSHONG

  9. LOOK AT CHART: mr/mas PG 210 Stat • “AVE” CHEST EXPOSURE - 2 IMAGES • (Ave – Pt meas 23cm pa 40cm lat) • PA 110 KVP 5 MAS 16:1 GRID 400RS 72” • LAT 110 KVP 20 MAS 16:1 GRID 400 RS 72” • WHAT IS THE PATIENT’S DOSE??

  10. LOOK AT CHART: mr/mas PG 210 Stat • “AVE” CHEST EXPOSURE - 2 IMAGES • WHAT IS THE PATIENT’S DOSE?? • OUTPUT OF TUBE NEEDED: • PA Chest = mr/mas = 9.5 • LAT 110 KVP 20 MAS 16:1 GRID 400 RS 72”

  11. Which of the following technical factors will create the highest skin entrance dose to the patient? • A. 80 kvp 300 ma .5s no filter B. 80 kvp 300ma 1/10s no filter • C. 80 kvp 1000ma 1/20s 2.5mm al eq. filter • D. 80 kvp 800ma 1/60 sec .05mm al eq filter

  12. The exposure rate to a tech at 4 feet from the source is 240 m R/hr. What distance would be necessary to reduced the rate below 60 mR/hr? • A. 1 foot • B. 6 feet • C. 2 feet • D. 9 feet

  13. If the exposure at 2 inches = 9 R/min, what is the exposure at 6 inches from the source? • A. 1 R B. 5 R C. 3 R • D. 81 R E. 60R

  14. If 85 kvp, 400ma 0.12s = 150mR - what is the mr/mas? • A. 0.32 • B. 3.1 • C. 33.1 • D. 17.6

  15. Primary radiation barriers must be at LEAST how high (in feet)? • A. 5 • B. 6 • C. 7 • D. 8

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