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Methods to Minimize Radiation Dose.pptx b
- 1. METHODS TO MINIMIZERADIATION DOSE Manas kumar maharana 220513006 M.Sc RIT
- 2. TABLE OF CONTENT •INTRODUCTION • RADIATION DOSE • DOSE TYPES AND DOSE LIMITS • BIOLOGICAL EFFECTS • OBJECTIVE • DOSE AFFECTING FACTORS • STRATEGY TO MINIMIZE DOSE • SUMMARY • REFERENCE • QUESTION
- 3. INTRODUCTION • Radiation isthe emission and transmission of energy in the form of waves or particle through any space or medium • TYPES a) ionizing radiation e.g. X-ray, gamma ray etc. b) non- ionizing radiation e.g. Microwave, radio wave etc. c) particulate e.g. Alpha, beta etc.
- 4. RADIATION DOSE • Whenionizing radiation penetrates the human body or an object, it deposits energy. The energy absorbed from exposure to radiation is called a dose
- 5. RADIATION DOSE TYPE ABSORBEDDOSE • it is the amount of energy deposited by ionizing radiation per unit of mass of matter •UNIT – RAD & GRAY EQUIVALENT DOSE • Equivalent dose is calculated for individual organs. It is absorbed dose to an organ, adjusted to account for the effectiveness of the type of radiation. •UNIT - SIEVERT EFFECTIVE DOSE • Sum of all the weighted equivalent doses in all tissues or organs irradiated is called effective dose •UNIT - SIEVERT
- 6. DOSE LIMITS • Doselimits are recommended by the ICRP. They are in place to ensure that individuals are not exposed to an unnecessarily high amount of ionizing radiation • Dose limits are a fundamental component of radiation protection, and breaching these limits is against radiation regulation in most countries.
- 7. DOSE LIMITS ORGAN OCCUPATIONAL DOSE PUBLICDOSE LENS 150 mSv/year 15 mSv/year SKIN 500 mSv/year 50 mSv/year HAND, FEET 500 mSv/year 50 mSv/year PREGNANT WOMAN (GESTATION PERIOD) 5 mSv/year 0.5 mSv/month 1 mSv/year EFFECTIVE DOSE OCCUPATIONAL • 20 mSv/year averaged over defined periods of 5 years • No single year exceeding 30 mSv •In pregnancy should not exceed about 1 mSv PUBLIC •1 mSv/year in special circumstances, a higher value could be allowed in a single year
- 8. BIOLOGICAL EFFECT OFRADIATON DOSE
- 9. BIOLOGICAL EFFECT OFRADIATON DOSE DETERMINISTIC EFFECT • Are the result of high dose • Occur above certain threshold • Have a severity depending on the dose STOCHASTIC EFFECT • May arise from any dose • Due to cell change and genetic mutation • Have no known threshold • Increase probability when dose is increased
- 10. OBJECTIVE OF DOSEREDUCTION • Reduce patient dose • Reduce dose to health workers • Reduce the biological effect on patient as well as for health worker
- 11. DOSE AFFECTING FACTORS •X-RAY BEAM ENERGY (KVP): higher kVp results in lower dose • ADDED FILTRATION: Higher added filtration results in lower dose • COLLIMATION: Aggressive collimation reduces the irradiated area as well as scatter radiation • GRIDS: Grids reduce scatter radiation but increase patient dose
- 12. DOSE AFFECTING FACTORS •IMAGE RECEPTOR: Faster speed image receptor reduces patient dose • TUBE CURRENT AND EXPOSURE TIME (mAs): The patient dose is proportional to mAs • PATIENT SIZE: It is beneficial to optimize the technique chart for various patient size and anatomic areas.
- 13. STRATEGIES TO MINIMIZEDOSE 1. ELIMINATE UNNECESSARY RADIATIONS • Basic principle of ‘As low as reasonably achievable’ • By eliminating unnecessary exams or using alternative modalities that don’t use radiation • No excuse for x ray examination to be carried out again and again with high dose
- 14. STRATEGIES TO MINIMIZEDOSE(CONT.) 2. X-RAY FIELD SIZE • Use of smallest practicable x ray field and its accurate positioning on patient • Beam limiting and devices such as collimators are used to give shape and size needed for the particular exam
- 15. STRATEGIES TO MINIMIZEDOSE(CONT.) 3. SID • Increase in SID results in reduce the exposure and dose by virtue of inverse square law • Receptor should be close to patient SID
- 16. STRATEGIES TO MINIMIZEDOSE(CONT.) 4. TOTAL FILTERATION • Absorbed the low energy x ray beam • Reduce the patient dose • Two types of filter : Inherent & added
- 17. STRATEGIES TO MINIMIZEDOSE(CONT.) 5. USE OF INTENSIFYING SCREEN • Contain high sensitive phosphorescent material like rare earth metals • Using intensifying screen reduces the dose required for an examination , results in shorter exposure, times and hence less movement unsharpness
- 18. STRATEGIES TO MINIMIZEDOSE(CONT.) 6. REDUCE REPEAT IRRADIATIONS • X-ray should be repeated until the new radiograph will give added information which was not available on the previous one • Use of a reference list of technical factors according to the patient shape and size
- 19. STRATEGIES TO MINIMIZEDOSE(CONT.) 7. SHIELD DOSE SENSITIVE ORGANS • There are certain organs that are more dose sensitive, use external shielding to protect the organ • This technique helps reduce dose to that organ, but doesn’t diminish image quality
- 20. STRATEGIES TO MINIMIZEDOSE FOR OCCUPATIONAL
- 21. SUMMARY • The useof medical X ray examinations needs to be ‑ minimized, and alternative tests should be used whenever possible. • If medical X ray screening and treatment are ‑ necessary, the risk benefit ratio should be weighed to ‑ determine the most effective dose, while protecting other areas from avoidable exposure. Particular attention should be paid to the increased radiation risk in children and the protection of sensitive glands
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- 23. QUESTIONS 1. What doesthe following acronym represent? A L A R A a. As Low As Reasonably Achievable b. As Long As Radiation Achievable c. As Long As Radiation Absorbed d. As Long As Radiation Allowable 2. Which of the Following is Not One of the Three Major Principles Assisting the ALARA Concept? e. Distance c. Shielding f. Maintenance d. Time
- 24. QUESTIONS 3. Following whichfactor not affect radiation dose a. kVp c. Filteration b. mAs d. Tube angle 4. Which statement is correct a. Using intensifying screen increase the dose b. Filters absorbed the high energy x ray beam c. Increase in SID results in reduce the exposure d. Grids decrease patient dose
- 25. QUESTIONS 5. Increasing themAs will produce a. More x ray photons with less penetrating power b. More x ray photon with more penetrating power c. Less x ray photon with less penetrating power d. More x ray photon with same penetrating power
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