Sensitivity to radiaiton calculating pt dose
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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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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


Effects of Overdose to Humans


Effects of Acute Radiation Exposures in Humans


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. 


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)


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


  • 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??


  • 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”


  • 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


  • 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


  • 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


  • If 85 kvp, 400ma 0.12s = 150mR - what is the mr/mas?

  • A. 0.32

  • B. 3.1

  • C. 33.1

  • D. 17.6


  • Primary radiation barriers must be at LEAST how high (in feet)?

  • A. 5

  • B. 6

  • C. 7

  • D. 8


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