Decision. Conclusion. Decision. Conclusion

Maximum Permissible Dose (MPD) of Ionizing radiation for some groups of population

Category A -persons professionally contacting radiation –MPD - (5 ber/year) or 40 miliber/week.

Category B -people who are in premises adjacent to sources of radiation – MPD – 0. 5 ber/year or 500 miliber/year

Category C - all other population - MPD – 0. 1 ber/year or 100 mber/year.

Task 1. Radiologist works with a radioactive Iodin during 1 week (36 hours). The obtained dose of radiation is 0. 002 ber for hour. Give hygienic estimation, conclusion and recommendation about the condition of the work.

Decision

1) 36 hours x 0. 002 ber for hour = 0. 072 ber per 1 week = 72 mber per 1 week

Radiologist is Category A -persons professionally contacting with radiation. For this group MPD = 2 ber/year) or 40 milliber/week.

Conclusion

72 mber per 1 week more than norm (40 milliber/week). Dose of radiation should be decreased with the help of increasing time, distance or decreasing dose, or using screen.

Task 2. Find out weekly radioactive dose of doctor who works with gamma iozining source, if obtained dose of radiation is 0. 002 ber for hour. He works with radiation 5 days per 1 week, time of work - 4 hours per day. Give hygienic estimation, conclusion and recommendation about the condition of the work.

Decision

1) 0. 002 ber for hour x 5 days x 4 hours per day = 0. 04 ber per 1 week = 40 mber per 1 week

Radiologist is Category A -persons professionally contacting with radiation. Norm radiation for gr. A per 1 week =40 milliber/week.

Conclusion

40 mber per 1 week is norm (40 miliber/week).

Task 3. Patient takes roentgenoscopy of chest organs. Radiation power = 10. 000 mber/hour, irradiation time – 1 minute. What is the irradiation dose received by patient? Give hygienic estimation, conclusion and recommendation about dose of radiation after roentgenoscopy ofchest organs.

Decision

For gr. C MPD = 0. 1 ber/year or 100 milliber/ year.

1) 1 min = X hour

60 min = 1 hour

X=0. 017 hour

2) 10. 000 mber/h x 0. 017hour = 170 mber

3) For gr. C norm radiation per 1 year = 100 milliber

Conclusion

170 mber per 1 year is more than norm ( norm=100 milliber/year). Dose of radiation for roentgenoscopy of chest organs must be decreased.

Task 4. One chest organ roentgenography = 0, 4 mber. Patient takes 4 chest organs’ roentgenographies during the year. What is the ionizing dose received by patient for year? Compare this dose with the annual threshold dose of ionizing radiation for group C of population? What preventive measures are necessary in this case? What instrument is used for definition X-ray dose?

Decision

1) For gr. C MPD = 0. 1 ber/year) or 100 milliber/year

2) 0, 4 mber x 4 = 0. 16 mber

3) 0. 16 mber per 1 year less than norm (100 mber per 1 year)

Conclusion

0. 16 mber per 1 year is less than norm. Dose of radiation is safety for health.

Task 5. One chest organs’ fluorography gives 0, 1 ber. Patient takes 4 roentgenofluorography during the year. What is the ionizing dose received by patient? Compare this dose with the annual threshold dose of ionizing radiation for group C of population? What preventive measures are necessary in this case? What instrument is used for definition X-ray dose?

Decision

1) Norm radiation for gr. C MPD =0. 1 ber/year or 100 milliber/year

2) 0, 1 ber x 4 = 0. 4 ber ( for 1 year)

3) 0. 4 ber for 1 year more than norm (0. 1 ber/year)

Conclusion

Dose of radiation after 4 roentgenofluorography = 0. 4 ber. It’s more than norm ( norm=0. 1ber/year). Dose of radiation must be decreased.