Staff and Patient Radiation Protection In The Cath Lab Andrés Sinisterra Assistant Radiation Safety Officer for Medicine
Radiation vs. Radioactivity Radiation Energy in transit in the form of high speed particles and electromagnetic waves. Ionizing Radiation Radiation with enough energy so that during an interaction with an atom, it can remove tightly bound electrons from their orbits, causing the atom to become charged or ionized. Radioactivity Spontaneous transformation of an unstable atom and often results in the emission of radiation. This process is referred to as a transformation, a decay or a disintegration of an atom.
External vs. Internal Radiation Exposure External Exposure – X-rays, Diagnostic Procedures. Internal Deposition – Contamination from nuclear medicine patient undergoing a diagnostic or therapeutic procedure resulting in an ingestion of radioactive materials by the staff. + = T E D E
Units of Radiation Exposure Roentgen Measure of electrical charge produced in air 1,000 mr = 1R Fluoro @ SSD ~3-10 R/min Measure of energy absorbed, usually in tissue or bone. 200 rad = transient erythema 1 Gray = 100 Rad Rad (Gray)
Units of Radiation Exposure Rem (Sievert) Measure of occupational risk (cancer) from radiation exposure 1,000 mrem = 1 Rem 1 Sievert = 100 Rem 1 R = 1 Rad = 1 Rem
INCIDENT X-RAY PHOTOELECTRON Photoelectric effect occurs when an incident x-ray is totally absorbed during the ionization of the inner-shell electron. The incident photon disappears and the k-shell electron, now called a photoelectron, is ejected from the atom.
Head and shoulders knees and toes !!!!! Be aware of critically exposed areas
30-cm FOV Image intensifier 70-cm SSD 1Medium conventional fluoroscopy 2Setting C for fluorography 3Floor kVp is 110 Dose = 50 rad Pail of water 28-cm deep 55-cm SSD 1Medium conventional fluoroscopy 2Setting C for fluorography 3Floor kVp is 80 Dose = 140 rad 15-cm air gap Pail of water 28-cm deep 23-cm FOV Image intensifier The effects of an air gap are significant, even if the image is properly collimated
Know Where Your Head Is At……!!! The greater the distance the greater the scatter
The following Table illustrates the effect of changing Field- Of-View, or magnification modes, for a typical fluoroscopy system Mag Mode (Field-Of-View) ESE (R/min)Increase Factor Normal (9 inch) 1.21.0 Mag 1 (6 inch) 2.92.4 Mag 2 (4.5 inch) 5.24.3
Inverse Square Law (X-Rays & Gamma Rays) For a point source, the intensity varies inversely as the square of the distance from the source. 1 cm 10,000 2 cm 2,500 5 cm 400 10 cm 100 20 cm 25 Leakage Radiation X-Ray Tube Scattered X-rays
Basic Radiation Safety Principles T ime D istance C ontamination Control S hielding
Whole Body Radiation Badge Worn Underneath Pb Apron Collar Radiation Badge Worn Outside Pb Apron At Neck Level BLACK ICON RED ICON Extremity Radiation Badge Worn on Primary Hand Closest to Radiation Source Radiation Exposure and Monitoring
Whole Body Radiation Badge WornUnderneath Pb Apron Collar Radiation Badge WornOutside Pb Apron At Neck Level
At Breast ~30 cm At Thyroid ~45 cm So whats the big deal where I put my @% badges ? DOH !
Get The Lead Out but Watch Your Back !! PROTECTIVE EQUIPMENT
A s L ow A s R easonably A chievable ALARA Level I > 10% of the maximum quarterly exposure limit (125 mrem) ALARA Level II > 30% of the maximum quarterly exposure limit (375 mrem)
Reducing Patient Dose During Fluoroscopy (And Yours) Get off the pedal!! – Fluoro intermittently Get off the pedal!! – Fluoro intermittently Collimate and only expose clinical area Collimate and only expose clinical area Use larger fields when possible Use larger fields when possible (Magnification increases patient dose) Use distance of at least 30 cm for mobile units and 38 cm for fixed installations Use distance of at least 30 cm for mobile units and 38 cm for fixed installations Use appropriate mA and KVp Use appropriate mA and KVp
Reducing Patient Dose During Fluoroscopy (And Yours) Remember the egg timer!!! Remember the egg timer!!! Be aware of the 5 minute timer (especially in high level mode) Have sufficient beam filtration Have sufficient beam filtration > 90 KVp requires 2.5 mm Al to 3.5 mm Al @ 130 KVp Fluoro only when necessary Fluoro only when necessary Schedule annual QA of equipment Schedule annual QA of equipment
Radiation Dose The amount of energy deposited in any substance by ionizing radiation per unit mass of the substance. It is expressed numerically in rads (traditional units) or grays (SI units). Absorbed Dose Dose Equivalent Deep Dose Equivalent Eye Dose Equivalent Shallow Dose Equivalent Effective Dose Equivalent Committed Dose Equivalent Total Effective Dose Equivalent
Absorbed Dose - The amount of energy deposited in any substance by ionizing radiation per unit mass of the substance. It is expressed numerically in rads (traditional units) or grays (SI units). Dose Equivalent - The dose equivalent (H) is the product of the absorbed dose in tissue, the quality factor and all other modifying factors at the location of interest. The unit is the rem (R) or the sievert (Sv). Radiation Dose
Deep Dose Equivalent (Hd) - Applies to external whole body exposure, means the dose equivalent at a tissue depth of 1 cm or greater. Eye Dose Equivalent - The external dose equivalent to the lens of the eye at a tissue depth of 0.3 cm. Shallow Dose Equivalent (Hg) - Applies to the external exposure of the skin or extremity. The dose equivalent at a tissue depth of 0.007 cm averaged over an area of 1 cm2. Radiation Dose
Committed Dose Equivalent (HE.50) - The dose equivalent (H) is a given organ or tissue that will be accumulated over 50 years following a single intake of radioactive material. Effective Dose Equivalent (HE) - The sum of the products of the dose equivalent (HT) to each organ or tissue and the weighting factor (WT) applicable to each of the body organs or tissues that are irradiated (HE = WTHT). Total Effective Dose Equivalent - The sum of the deep dose equivalent for external exposures and the committed effective dose equivalent for internal exposures. Radiation Dose
Radiation Exposure Limits Whole body; head and trunk; active blood-forming organs; lens of eyes, or gonads. Hands and forearms; feet and ankles. Skin of whole body. 1.25 18.75 7.5 ( ( 1,250 mrem) (5.0 rem/yr) (18,750 mrem) (75 rem/yr) (7,500 mrem) (30 rem/yr) Rem Per Calendar Quarter Type of Exposure (State of Connecticut Administrative Regulations Sect. 19-24-5) Fetus 500 mrem Total Gestation (0.5 rem)
Radiation Exposure Limits The total effective dose equivalent.5.0(0.05 Sv) Rem Per Calendar Year Type of Exposure (USNRC 10CFR20 - § 20.1201 ) (USNRC 10CFR20 - § 20.1201 ) The sum of the deep-dose equivalent and the committed dose equivalent to any individual organ or tissue other than the lens of the eye 50(0.5 Sv)
Radiation Exposure Limits Rem Per Calendar Year Type of Exposure (USNRC 10CFR20 - § 20.1201 ) (USNRC 10CFR20 - § 20.1201 ) In Utero exposure to the Fetus 0.5 rem Total Gestation (500 mrem & <50/mo) An eye dose equivalent and A shallow dose equivalent to the skin or to any extremity. 15 rem ( 0.15 Sv ) 50 rem ( 0.50 Sv )
Conditions For Exceeding Quarterly Doses To Whole Body < 3.0 rem Total Whole Body Dose <= 5 (N-18) rem All Previous Whole Body Doses Plus N = Your Age In Years N = Your Age In Years Prior Dose Must Be On a Clear Record ! ! ! ! ALARA PROGRAM EXISTS ! ! ! ! Total Dose For Any Quarter
Confidential Declaration of Pregnancy NRC requires a signed declaration of pregnancy for occupational workers to limit exposures to 500 mrem/9months or 50 mrem in any one month.
Radiation Exposures From ? Smoking a pack and a half of cigarettes a day will add about 1,300 mrem/year to one's effective dose Flying from New York to London results in the absorption of an extra 2-3 mrem of cosmic radiation 6-8 mrem from NY to Japan
Risks which Increase Chance of Death by 1 in 1 million a a B.L. Cohen and I.S. Lee, Catalog of Risks Extended and Updated, Health Physics, Vol. 61, Sept. 1991.
Estimated Loss of Life Expectancy from Health Risks Health RiskAverage Days of Life Expectancy Lost Smoking 20 cigarettes/day2370 (6.5 years) Overweight (by 20%)985 (2.7 years) All accidents combined435 (1.2 years) Auto accidents200 Alcohol consumption130 Home accidents95 Drowning41 Natural background radiation8 Medical diagnostic x-rays6 All catastrophes (fire, flood, etc.)3.5 1,000 mrem (1 rem) occupational radiation dose1 1,000 mrem (1 rem)/yr for 30 years30 Note: Average U.S. occupational radiation dose is estimated at 0.34 - 0.65 rem/year.
PROGRAM FOR IMPLEMENTING PATIENT INFORMED CONSENT AND FOLLOW UP REGARDING HIGH DOSE SPECIAL X-RAY PROCEDURES
There are certain x-ray guided procedures that could result in the delivery of a radiation dose to an area of a patients skin of sufficient magnitude to produce clinical symptoms. This program was developed to inform patients of this potential risk prior to such procedures, determine if a procedure may lead to a large skin dose and to follow up with the patient if there is a possibility of a skin reaction. Purpose:
This program is applicable to following x-ray guided procedures: Policy: Percutaneous Transluminal Angioplasty Percutaneous Transluminal Angioplasty Radiofrequency Cardiac Catheter Ablation Radiofrequency Cardiac Catheter Ablation Vascular Embolization Vascular Embolization Stent and Filter Placement Stent and Filter Placement Thrombolytic & Fibrinolytic Procedures Thrombolytic & Fibrinolytic Procedures Percutaneous Transhepatic Cholangiography and/or Biliary Drainage Percutaneous Transhepatic Cholangiography and/or Biliary Drainage
Any other x-ray guided procedure that could expose the area of the skin for more expose the same area of the skin for more than 30 minutes Policy (continued): Endoscopic Retrograde Cholangiopancreatography Endoscopic Retrograde Cholangiopancreatography Transjugular Intrahepatic Portosystemic Shunt Transjugular Intrahepatic Portosystemic Shunt Percutaneous Nephrostomy Percutaneous Nephrostomy Urinary/Biliary Stone Removal Urinary/Biliary Stone Removal Or
For such cases, the patient must be informed in writing prior to the procedure of the risks associated with large x-ray skin doses. Appropriate follow up must be made, if after completion of a procedure, a large skin dose is possible. Policy (continued):
Connective tissue diseases (e.g. scleroderma, lupus erythematosus, mixed connective tissue disease), diabetes mellitus, hyperthyroidism and the homozygous form of ataxia telangiectasia have been associated with an increased sensitivity to radiation. Some chemotherapy agents are also known to increase radiation effects. To avoid injuries when using an oblique or lateral beam projection, the patient's arm must be secured away from the primary beam. Direct exposure of the female breast, especially entrance-beam exposure, must also be avoided. Policy (continued):
Radiosensitivity of Cells 1 As cells mature they become less sensitive to radiation As metabolic rate increases cells become more sensitive to radiation As reproductive rate increases cells become more sensitive to radiation Cell types that are most sensitive to radiation include lymphocytes and stem cells Cell types that are least sensitive to radiation include muscle and ganglion cells 1 Adapted from The 1906 Law of Bergonie and Tribondeau
Various degrees of sensitivity to radiation exist due to the type of tissue which receives the exposure RadiosensitiveRadioresistant Breast tissueHeart tissue Bone marrow cellsLarge arteries Mucosa lining of small intestinesLarge veins Sebaceous (fat) glands of skinMature blood cells Immune response cellsNeurons All stem cell populationsMuscle cells Lymphocytes
Radiation Induced Skin Injuries SKIN EFFECTSingle-Dose Threshold rad (Gy)Time to Onset Early transient erythema200 (2)Hours Main Erythema600 (6)~10 d Temporary epilation300 (3)~3 wk Permanent epilation700 (7)~3 wk Dry desquamation1400 (14)~4 wk Moist desquamation1800 (18)~4 wk Secondary ulceration2400 (24)>6 wk Late erythema1500 (15)~6 – 10 wk Ischemic dermal necrosis1800 (18)>10 wk Dermal atrophy (1 st phase)1000 (10)>14 wk Dermal atrophy (2 nd phase)1000 (10)>1 yr Induration (Invasive Fibrosis)1000 (10)>1 yr Telangiectasia1000 (10)>1 yr d: day(s); wk: week(s); yr: year(s)
Stochastic Effects (by chance) Health effects that occur randomly. Effects that occur by chance, generally occurring without a threshold level of dose, whose probability is proportional to the dose and whose severity is independent of the dose.. (examples: cancer incidence and genetic effects)
1,000,000 persons buy a lottery ticket for $1,00 each. 999,999 persons will not get the large prize. Only one will win the BIG ONE. Return on scratch tickets is not certain. Stochastic Effects (by chance)
Nonstochastic (Deterministic) Effects Health effects that can be induced upon reaching an apparent threshold, and their severity varies with the radiation dose. examples: cataract in the lens of the eye, non-malignant damage to the skin
100 persons invest $1,000 at 5% interest Each person will receive $1,050.00 Return is certain Nonstochastic (Deterministic) Effects
So....., how really dangerous is this so called RADIATION??
An example of a skin injury attributable to x-rays from fluoroscopy is shown in Figure 2. This case, patient A in Table 2, is that of a 40-year-old male who underwent coronary angiography, coronary angioplasty and a second angiography procedure due to complications, followed by a coronary artery by- pass graft, all on March 29, 1990. Source: Thomas B. Shope, Ph.D. (HFZ-140) FDA/Center for Devices and Radiological Health
Figure 2(a). Condition of patient's back six to eight weeks following multiple coronary angiography and angioplasty procedures Source: Thomas B. Shope, Ph.D. (HFZ-140) FDA/Center for Devices and Radiological Health
Figure 2(b). Appearance of skin injury approximately 16 to 21 weeks following the procedures with small ulcerated area present. Source: Thomas B. Shope, Ph.D. (HFZ-140) FDA/Center for Devices and Radiological Health
Figure 2(c). Appearance of skin injury approximately 18 to 21 months following procedures, evidencing tissue necrosis. Source: Thomas B. Shope, Ph.D. (HFZ-140) FDA/Center for Devices and Radiological Health
Figure 2(d). Close-up view of lesion shown in 2(c). Source: Thomas B. Shope, Ph.D. (HFZ-140) FDA/Center for Devices and Radiological Health
Figure 2(e). Appearance of patient's back following skin grafting procedure. Source: Thomas B. Shope, Ph.D. (HFZ-140) FDA/Center for Devices and Radiological Health
Transjugular Intrahepatic Portosystemic Shunt Source: Koening, Wagner, et al., University of Texas Health Science Center 6 month 7.5 month 10 month 22 month 23 month This patient received 3 TIPS procedures within a week
Radiofrequency Cardiac Catheter Ablation Source: Koening, Wagner, et al., University of Texas Health Science Center Tissue necrosis 5 months after procedure, and deep ulceration with exposure of the humerus at 6.5 months
Both patients with Discoid Lupus Erythematosis received skin doses believed insufficient to cause such effects in normal skin. Reproduced with permission from Gironet et al, 1998, Ann Dermatol Venerol, 125, 598 - 600 Reproduced with permission from Wagner et al, 1999, Radiology, 213, 773 - 776 Radiation-sensitive patients In right photo, G = graft, R = rib Courtesy of IAEA
Lessons from injured patients Case #1:Electrophysiological and ablation procedure Three attempts in 4 months, each with more than 100 minutes of fluoroscopy. After first attempt erythema observed by patient, but not recognized as due to procedure. Erythemas on back healed. Arm lesion required grafting. Material used here previously copyrighted by Louis K Wagner 2004 or Partners in Radiation Management LTD Company 2004 and used here by permission. Courtesy of IAEA
Lessons from injured patients If cause of initial erythemas was correctly identified, injury would likely have been avoided because failures of initial ablations would not have been blamed on faulty equipment. Erythemas on back healed. Arm lesion required grafting. Material used here previously copyrighted by Louis K Wagner 2004 or Partners in Radiation Management LTD Company 2004 and used here by permission. Courtesy of IAEA
Lessons from injured patients Case #2: PTCA and stent placement of RCA. Involved 63 minutes of fluoroscopy and nearly 5000 frames of cine in LAO orientation with cranial tilt. Lesion required grafting. Material used here previously copyrighted by Louis K Wagner 2004 or Partners in Radiation Management LTD Company 2004 and used here by permission. Courtesy of IAEA
Lessons from injured patients Case #2: Dose buildup due to long fluoroscopy and fluorography with steep angle through thick chested patient not recognized Lesion required grafting. Material used here previously copyrighted by Louis K Wagner 2004 or Partners in Radiation Management LTD Company 2004 and used here by permission. Courtesy of IAEA
Lessons from injured patients Case #2: Cause of injury initially misidentified as pressure wound due to defibrillator pad. Lesion required grafting. Material used here previously copyrighted by Louis K Wagner 2004 or Partners in Radiation Management LTD Company 2004 and used here by permission.
Lessons from injured patients Case #3: PTCA : 51 minutes high- dose fluoroscopy, 74 seconds cine in 141 kg man. Dose estimated retrospectively at 22 Gy. Lesion required grafting. Courtesy of IAEA
Lessons from injured patients Case #3: Cumulative buildup of dose for steeply angled high-dose beam through large patient not recognized Lesion required grafting. Courtesy of IAEA
If you use too much radiation … you will get your ass in trouble RULE 1 Courtesy of IAEA
RULE 2 Excess radiation can sneak up on you and catch you unaware A fluoroscope can be a dangerous beast Courtesy of IAEA
Rule 3 Use all protective measures at your disposal to minimize risk