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Sensitivity to Radiaiton & Calculating pt dosePowerPoint Presentation

Sensitivity to Radiaiton & Calculating pt dose

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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

Most Sensitive:

Reproductive organs

Blood-forming organs

Skin

Bone and teeth

Least sensitive:

Muscle

Nervous system

- 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.

- ·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)

- 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