Patient Occupational radiation dose management Chapter 37 38

Patient & Occupational radiation dose management Chapter 37 & 38 RTMR 284 – Radiation Protection & Biology WINTER 2014 Medical Radiography Program

3 ways patient dose from diagnostic x-rays is reported: Entrance Skin Exposure (ESE) or Entrance Skin Dose (ESD) • Most often reported & referred to as pt. dose , easy to measure • Ave Fluoro ESE can be est. at 40 m. Gy/min (hard to estimate) Gonadal Dose-GSD Genetically Sig. Dose • Important due to genetic responses, easy to measure Bone Marrow Dose • Mean Marrow Dose is the ave radiation dose to the entire active bone marrow • Important due to rad-induced leukemia, est. from ESE and cannot be directly measured. Medical Radiography Program

TLD’s » Thermoluminescence Dosimters are used most often to measure ESE. § Response is proportional to exposure dose § Very accurate to within 5% § Can be used to measure all levels experienced, even low doses § Not used in most occupational monitoring due to no permanent record or re-readability is provided an immediate, on the job readout is not possible. Medical Radiography Program

Pt. Dose in Special Exams » Mammography: • ESE ~ 800 m. R/view • Glandular does Dg ~ 15% of ESE • Adverse biological response is small • Screening should be kept to two views for lower doses to pt. » CT Imaging: • Slices in CT produce much higher skin doses • Est. 10% of x-ray exams are CT w/ 70% of dose! • Dose ~ 50% of the ESE for body CT • Narrow, well collimated beams reduces dose • The higher the multislice value, the lower the dose Medical Radiography Program

A 64 slice CT scanner will result in lower pt. dose than fewer slices because a lower contribution is made from the pnenumbra for the same volume tissue. Medical Radiography Program

Additional pt. dose savings occur when the same beam width is imaged with combined pixel rows because the m. A can be reduces without compromising resolution. Medical Radiography Program

Patient Dose Reduction » Unnecessary Examinations • Mass screening for TB • Hospital Admission • Pre-Employment physicals • Periodic Health Examinations • ER CT » Repeat Exams *** ? ? ? » Technique (k. Vp) » Positioning » Shielding-contact/shaped, shadow Medical Radiography Program

Medical Radiography Program

Pregnant Patient » Physical and Emotional land minds ~ Time Frame 2 to 10 ~ Talk to patients & work w/ dr. ~ Always ask… » Pt. Information » Elective booking » Questionnaire » Posting Medical Radiography Program

Pt dose trends NCRPNational Council on Radiation Protection Medical Radiography Program

Occupational Dose Recommended dose limit for radiologic personal is 0. 5 Sv/yr (5000 mrem/yr) NORMAL exposure in diagnostic radiology for personal should not exceed 1 m. Sv/yr (100 mrem/year) Effective Dose (E) = Radiation Weighting Factor (Wr) { = 1 for xray} x Tissue Weighting Factor (Wt) x Absorbed Dose • Fluoroscopy • Interventional Radiology • Mammography • CT • Surgery • Mobile Medical Radiography Program

Radiologic SI (customary) Units Quantity Radio. Activity Absorbed dose Dose Equivalent Exposure Name Becquerel (curie) Gray (rad) Sievert (rem) Coulumb/kg (roentgen) See conversion factors on inside cover! 1 R/rad/rem = 100 Si units ex. 100 mrem = 1 m. Sv Medical Radiography Program Symbol Bq (Ci) Gy (rad) Sv (rem) C/kg (R)

Dose Limits » DL imply that if received annually, the risk of death would be less than 1 in 10, 000 • Based on Linear, non-threshold dose response ~ Basic annual = 50 m. Sv or 5000 mrem ~ Lens of eye = 150 m. Sv/yr or 15 rem/yr ~ Organs/Skin/Extremities = 500 m. Sv/yr or 50 rem/yr » Cumulative whole-body DL is 10 m. Sv times age in years » During Pregnancy DL = 5 m. Sv or 500 mrem (table 38 -4) » After declared DL/month < 0. 5 m. Sv or 50 mrem » Public /Students <18 yo DL = 1 m. Sv/yr or 100 mrem/year • DL established for non-occupationally exposed persons is 1/10 of that established for the radiation worker Medical Radiography Program

Reduction of Occupations Exp » In Diag Radiology 95% of Technologists occupational dose comes from Fluoro and mobile exams. » How to reduce your exposure? (x 3 pg. 588) Portable apron, 2 m cord, beam direction » Monitoring-Film Badges / TLD / OSL » During fluoro exp to collar region is 20 times greater than truck of body! » Protective Apparel (0. 25 -0. 5 mm Pb eq. 66 -90% attenuation at 75 k. Vp) » Position , Holding, Pregnant Tech rules, Management Principles, Education Medical Radiography Program

Final Next Week » 75 Questions Total worth 150 points » MC Questions » Covers: Chapter 33 -38 » BOOK BASED QUESTIONS !!! » Chapter 33 Deterministic Effects…………. 19% » Chapter 34 Stochastic Effects …………. . . 13% » Chapter 35 Health Physics ………………. 13% » Chapter 36 Rad Protection Design ……… 21% » Chapter 37 Pt Rad Dose ………………… 15 % » Chapter 38 Occup Rad Dose…………. . 19% Medical Radiography Program