IBHRE国际心律失常考官委员会英文资料：IX.Safety

1、Safety (5%) 2 Safety (A-E = 4%= 8 Questions, F-G = 1%= 2 Questions) A. Infection Control B. Sterile Technique C. Radiation Physics / Safety D. Electrical Safety E. Drug Interaction F. Device Interaction G. Recalls and Advisories 3 Infection Control & Sterile Technique 1. Chain of infection - Infecti

2、ous agent eg: Bateria, Fungi - Susceptible host eg: Elderly - Means of transmission eg: Contact, Airborne 2. Methods of interruption of chain of infections - Destruction of infectious agent Heat sterilization (steam, hot air) Ethylene oxide gas sterilization Chemical sterilization (Glutaraldehyde/ f

3、ormaldehyde) - Reduction of host susceptibility - Interruption of transmission Strict sterile technique intraprocedure Isolation of incision site from environment 3. Maintenance of Sterility Intraprocedure - Sterile drape integrity - Traffic control within room - Sterile occlusive dressing 4 Infecti

4、on Control & Sterile Technique Radiation Safety Exposure to X-rays is a cumulative effect Types of radiation - Non-ionizing Radiation Electromagnetic waves given off by the sun Various electronic devices Example UV light, Infrared radiation, RF radiation Microwaves Does not have enough energy to cau

5、se ionization of atoms 5 Radiation Safety Ionizing Radiation - By the sun - By radioactive materials - By high energy electronic devices ( X-ray machines) - Has enough energy to cause atoms to lose electrons and become ions or charged atoms. - Example / particles Gamma rays X-rays 6 Radiation Safety

6、 Characteristics of Ionizing Radiation Inversely proportional to the distance from the energy source The further you move away from the source of radiation, exposure is decreased by the square of the distance Since X-rays have no charge, they cannot be bent Travel in a linear path Damage at the cell

7、ular level is irreparable and irreversible If male of female germ cells or gametes (egg or sperm) have been affected, the damage could be inherited in the next generation. 7 Radiation Safety EXPOSURE If exposure time is doubled, the doses will be doubled. Exposure = Exposure rate x Time. Exposure is

8、 a measure of source intensity x time. Exposure rate is measured in milliroentgens(mR). Example- A radiation source has an exposure rate of 225 mR/hr at a position occupied by a radiation worker. If the worker remains at that position for 36 minutes, what will be the total occupational exposure? Ans

9、wer: Occupational exposure = (225mR/hr) * (36min/60min/hr) = 135mR 8 Radiation Safety DISTANCE As distance between the source of radiation and a person increases, the exposure decreases rapidly. This can be calculated by the inverse square law. - Inverse square law: ( I1/ I2 ) = (d2 /d1) Example Wit

10、h an exposure rate of 0.5mR/hr at 5 ft. = 0.125 mR/hr at distance of 10ft. 2 Formula: 0.5mR(5/10) = 0.5mR(0.25) = 0.125mR 9 Radiation Safety Rad (Radiation absorbed dose) - A unit of absorbed dose. - One rad is 0.01 Joule absorbed per kilogram of any material - Being replaced by the gray (Gy) - One

11、rad equals one hundredth of a gray REM - Roentgen Equivalent Man - The unit of dose equivalent or occupational exposure - Express radiation quantity received by radiation workers ( 1 rem equals to 1.07185 rntgen). 10 Radiation Safety Scatter Radiation Formula - no exact formula to calculate scatter

12、- “rule of thumb” does exist in that the scatter at 1 meter from patient center field is approximately 0.1% of primary beam dose rate at 1 meter from center beam Example If the exposure rate in the center of a primary beam were 1 R/min, the scattered exposure rate would be 0.1 R/min. at 1 meter from

13、 that point. The inverse square law does apply here. 11 Review Questions 1.The output intensity of a radiographic unit is 4.2 mR/mAs. What is the total output following a 200ms exposure at 300mA? Ans: 4.2mR/1mAs = x/60mAs x=252mR 2.What is the approximate patient skin dose following a 3.2-minute flu

14、oroscopic examination of 1.5 mA? Ans: Exposure= (ExposureRate)(time) (1.5mA)(3.2min)= xmAs (1.5mA)(192s)=288mAs 3.At 60 cm from the side of a fluoroscopic table (assume 90 cm from a point source) the exposure rate is 50mR/hr. What is the exposure rate at 180 cm from the source? Ans: I1/I2=(d2/d1) 2

15、50mr/hr/x=(180/190) 2 50mr/hr = x(2) x=12.5 mr/hr. 12 4.If an individual remained 30 cm from the table (60 from the source) for a total of 150 minutes of beam-on time during a week, what would be the expected personnel exposure? Ans: I1/I2 = (d2/d1) 50mr/hr /x = (60/90) 50mr/hr = x (.444) x = 112.5

16、mr/hr (112.5 mR/hr) (150min) (1hr/60min) = 112.5mR/hr (2.5hr) = 281.25mR 13 5.What exposure will an individual receive when exposed for ten minutes at 4m to a source with intensity of 100mR/hr at 1m while wearing a protective apron equivalent to 2 HVLs? Ans: 100mR/x= (4/1) = 6.25 mR/hr 2 (6.25mR/hr)

17、(10min) (1hr/60min) /2 2 = 1.0416662/2 = .2604 6.The exposure from an X-ray tube operated at 70kVp, 200 mAs is 400 mR at 36 in. What will be the exposure rate at 72 in? Ans: I1/I2 = (d2/d1) 2 I1 = I2(d2/d1) 2 I1 = 400mR (36in/72in) I1 = 400 mR(1/4) I1 = 100 mR 14 7.A radiographic unit shows patient

18、skin dose to be 5.4mR/mAs at 70Kvp. What will be the appropriate rate at 72 in? Ans: I1/I2 = mAs1/mAs2(Kvp1/Kvp2) 2 x/5.4 mR/mAs= 120mAs/1(84/70) 2 x/5.4 mR/mAs= 120 mAs (1.2) x = (5.4mR/mAs) (120 mAs) (1.44) x = 933.12 mR/mAs 15 Radiation Safety 1. Equipment safety a)Inspected at intervals recommen

19、ded by state/federal guidelines b)Maintain ongoing preventive maintenance as per institutional/ governmental requirements c)Complete repairs promptly d)Use appropriate cords, cables, and grounding e)Complete calibration/inspection/certification on new equipment prior to use f)Post appropriate signag

20、e in areas where X-ray is used. 2. Exposure levels for non-occupationally exposed workers = workers with the potential to receive greater doses must wear a radiation badge. 1) 500mrem/year 2) 125mrem/year 16 Radiation Safety cont 3. Radiation field a) Minimize time and dose b) Decrease time in and a

21、round radiation field c) Increase distance from radiation field double the distance to decrease dose by a factor of 4 d) Increase shielding between personnel and the radiation source soft tissue as well as lead attenuates ionizing radiation. 4. Lower room lights during procedure less fluoroscopy tim

22、e needed 17 Radiation Safety cont 5. Tube placement a) Place image intensifier close to patient to reduce irradiated field size and “scatter” b) Raising image intensifier from patient reduces radiation dose to patient 6. Collimate system to area of interest only reduces field size and scatter 7. Mov

23、e monitor close to viewing personnel reduces time required for study 8. Always record fluoroscopy time and exam- allows for more accurate dosimetry 18 Always Evaluate device after the end of procedure Electro- cautory MRIRFLithotri- psy DF shock Radiation Therapy Possible effects -Reprogramming -Noi

24、se reversion -Transient inappropriate inhibition or triggering -Transient alternation in capture or sensing thresholds - do - - do - - do - - do - do - do Transient malfunction - do - do - - do - - do - Precau- tions -Low energy setting -Bipolar cautery -Ground placement -minimize current path Avoid procedure Inactivate if ppm not dependant Distance 8- 10cm Distance the paddle placement Distance shielding Relocation of Device 19 Device Interaction Other Devices Interaction Arc welders Diathermy Tr