FLUOROSCOPIC PATIENT & OPERATOR RISK REDUCTION

Transcription

1 FLUOROSCOPIC PATIENT & OPERATOR RISK REDUCTION Ray Dielman RSO ST ANTHONY S HOSPITAL James Menge CHP ARSO ST ANTHONY S HOSPITAL BAYCARE HEALTH SYSTEM 1

2 FLUROSCOPY EDUCATIONAL OBJECTIVES I. Understand the requirements the Joint Commission (TJC) FLUOROSCOPY STANDARDS 01/01/2019 and FDA Advisory letter. II. III. IV. Identify the Biological Risks to humans from X-Ray radiation. Relate the Radiation Units and Doses used in Fluoroscopy with associated Risks. Describe the Operation of Fluoroscopy X-Ray equipment. V. Describe the Techniques used with Fluoroscopy equipment Operability to minimize Risks to Patients, Operators and personnel. VI. Understand and apply Dose Limits and threshold trigger levels for Patients, Operator and Personnel. 2

3 PURPOSE A credentialing CME for Cardiologists, Gastroenterologist, Orthopedists, Surgeons, Radiologists, Urologists, Pain Management and any physician who uses Fluoroscopy. The principal objective of this training is to provide information and methodologies for reduction in radiation dose to patients and staff during Interventional Fluoroscopy procedures. 3.0 Credits of Category 1 AMA Credits. This material was developed to comply with The Joint Commission Education Requirement Specified in the Fluoroscopy Standards effective January 1, 2019 and FDA Advisory 3

4 BACKGROUND Interventional radiologic procedures differs from diagnostic imaging in that interventional radiologic procedures are generally therapeutic, thus shifting the risk benefit ratio for radiation exposure. Radiation dose for interventional procedures >> than radiographic studies. A major intervention, such as transcatheter embolization, can deliver an effective dose to the patient of 100 msv, whereas a typical chest radiograph delivers 0.1 msv. Deterministic injuries occur only after the radiation dose to the tissue exceeds a given threshold dose. In interventional fluoroscopy procedures, the tissue of concern is the skin although the lens of the eye is another consideration for staff. Appearance of radiation-induced skin injury approximately 18 to 21 months following multiple coronary angiography and angioplasty procedures - evidence of progressive tissue necrosis (Source: The skin at the site where radiation enters the body receives the highest radiation dose of any body tissue. Once the threshold dose is exceeded, the injury becomes progressively more severe with increasing dose, although the true severity of major injuries will only become apparent weeks to months after the procedure 4

5 Understanding Radiation Quantities and Units Ref Wagner & Archer- Minimizing Risks from Fluoroscopic X Rays 5

6 THE BIOLOGICAL EFFECTS OF RADIATION Deterministic effects are due to injury in populations of cells, characterized by a threshold dose and an increase in the incidence and severity of the reaction as the dose is increased further. Deterministic effects are also termed tissue reactions (i.e. skin necrosis, lens opacities). Stochastic effects are malignant disease and heritable effects for which the probability of an effect occurring, but not its severity, is regarded as a function of dose without threshold (i.e. cancer). Radiation-induced skin injuries may not become fully manifest until months after the radiation dose was administered. The diagnosis of a radiation induced skin injury is often delayed. The lens of the eye is a radiosensitive tissue. In the lens of the eye, ionizing radiation typically causes posterior subcapsular cataract formation Surveys of interventionists and support staff have found a high percentage of lens opacities attributable to occupational radiation exposure when radiological protection tools have not been used properly. 6

7 BACKGROUND RADIATION In Florida the average background dose is 360 mr/year. 7

8 Policy for Interventional Fluoroscopy Patient Radiation Safety is based on NCRP REPORT #168 At 30 minutes of FLUORO or 3000mGy, SAH begins tracking the dose and time At 60 minutes of FLUORO or 5000mGy, A PRISM report is required. 8

9 Effects in Skin from FLUOROSCOPY X-Rays of sufficient intensity to cause effects do not typically cause any sensation during or immediately after procedure. Unlike a thermal burn, X-Ray injuries develop slowly and over time. Typically induced erythema does not occur until days or weeks later. If dose exceeds threshold levels, tissue degeneration occurs over months into ulceration and dermal necrosis. 9

10 Hospital Accreditation SENTINEL Events expanded to include Radiation Overdosing Prolonged fluoroscopy with cumulative dose >1500 rads(15gy) to a single field or any delivery of radiotherapy to wring region or 25% above planned dose. Entrance Skin Dose Exposure can be tracked, measureable, recordable, reportable and able to be limited. Skin Dose (cumulative) can be determined if Beam is stationary Fluro technique factors Fluro exposure time (including image recording) The Medical need for life-saving or not, if dose to be delivered >15Gy, then involvement of Medical Physicist is required to review dose exposure 10

11 Preprocedural Planning Patient Consent Radiation risks should also be discussed when the following patient criteria are met, especially when one of the above procedures is planned: weight less than 10 kg (22 lbs) or greater than 135 kg (300 lbs) intervention in pediatric and young adult patients involving substantial absorbed dose to radiosensitive organs (eg, lens of eye, breasts, gonads, thyroid pregnancy procedure anticipated to be technically difficult, unusually prolonged, or that could, within a reasonable likelihood, result in a skin dose metric that will require follow-up 11

12 DETERMINISTIC EFFECTS of RADIATION DOSE to SKIN 12

13 FLUROSCOPIC IMAGING COMPENTS IDENTIFY THE FOLLOWING COMPONENTS IMAGE INTENSIFIER Note proximity of Image intensifier to patient. Locate the X-Ray tube in picture. Note distance between tube and patient Review use of shields to minimize dose to Operator Note use of Landaurer Radiation badge being used to monitor dose. 13

14 MAJOR PARAMETERS THAT INFLUENCE PATIENT & STAFF DOSE Number of Images Fluoroscopy Time, field size, and overlap of fields Tube Filtration, Generator Voltage & Current Pulsed vs Continuous Geometry concerns patient to tube and patient to image receptor Patient Body Habitus 14

15 Patient Specific Factors that affect Dose Most fluoroscopy machines automatically adjust radiation exposure, through automatic exposure control (AEC). The AEC is an electronic system which detects the signal being produced at the image receptor and adjusts the x-ray generator to increase or decrease exposure factors (typically kv, ma 750 and pulse time) so that the image is of consistent quality. The result is a similar quality image, but also an increase in the radiation dose to the patient. Increased patient dose will result in increased scatter and increased radiation dose to staff. 15

16 DISTANCE Between X-RAY TUBE & IMAGE RECEPTOR The distance between the x-ray source (the x-ray tube focus) and the patient s skin is called the source-to-skin distance (SSD). As SSD increases, the radiation dose to the patient s skin decreases due to the increased distance and the effect of the inverse square law. Maximize SSD The image receptor (image intensifier or flat panel detector) should be placed as close to the patient as practical. In simplest terms, to minimize patient entrance dose, maximize SSD and minimize SID. This is an important tool for prevention of deterministic effects 16

17 Keep unnecessary body parts out of the x-ray beam 17

18 GANTRY ANGULATIONS vs DOSE Gantry angulations (oblique and lateral positions) increase the length of the radiation path through the body as compared to a posteroanterior (frontal) projection. A greater thickness of tissue must be penetrated, and requires higher radiation dose rates. When Gantry positions are required, - Recognize that the radiation dose is relatively high. Avoid steep gantry angulations when possible 18

19 Patient Exposure reduction by factors other than time Patient dose management is a complex topic and practitioners should know the operational capabilities of their X ray systems. There are several parameters that have an effect on the exposure rate (mgy/min). The basic exposure rate is set by the AEC, Reduction of unnecessary cine series or number of frames per series, the proper use of collimation, the influence of C-arm angulations and position of the table and image detector (geometry), to avoid the use of high quality of cine modes, will have a substantial influence on patient (and staff) doses. Collimation of the X ray beam to the smallest practical size and keeping the distance between the patient and image receptor as short as possible contribute to good exposure management. 19

20 Key Points for Minimizing Risks from Fluoroscopy X rays Dose rates are greater and Dose accumulates faster as patient size and tissue penetration thickness increases. Review Dose and Dose rate controls for best compromise in image quality and radiation dose accumulation. Keep Image Receptor as close to patient as practicable. Keep Patient at maximum practicable distance from x-ray tube. Don t overuse Geometric or Electronic Magnification Collimate to Area of Interest Keep Beam-On time and Dose Accumulation in a single area of skin to the lowest level practicable. 20

21 10 PEARLS: Radiation Protection of PATIENTS in FLUORO Procedures 21

22 Relative Radiation Intensity Near and Around the Patient Table The primary source of radiation is the x-ray tube, but only the patient should be exposed to the primary x-ray beam. Radiation scattered from the patient, - secondary radiation or scatter radiation, is the main source of radiation exposure of the Operator and Personnel. 22

23 DOSE EXPOSURE TO EYES Ionizing radiation is generally (but not exclusively) associated with posterior sub-capsular and sometimes cortical opacities. A number of studies in the last decade indicate that there is risk of lens opacities at doses below 1 Gy and the threshold may range from none to 0.8 Gy. However, the International Commission on Radiological Protection (ICRP) has recently accepted the threshold of 0.5 Gy. Many years or decades could pass before radiation-induced eye lens injuries become apparent. At relatively high exposures of few Gy, lens opacities may occur within a few years; however, at lower doses and dose rates (< 1 Gy), lens opacities may occur after many years. The duration of the latency period is inversely dependent on dose 23

24 Operator Dose Isometrics as Patient Geometry Increases 24

25 LEAD APRON DOSE ATTENUATION The foremost and most essential component of personal shielding in a Fluoro room is the lead apron which shall be worn by all those present in the fluoroscopy room. 2 piece leads with skirt type lead apron is recommended Thyroid Protection collar Lead Glass Eyewear with side protection 25

26 10 PEARLS: RADIATION PROTECTION of STAFF DURING FLUORO PROCEDURES 26

27 Strategies to Mange Radiation Dose to Patients and Staff IMMEDIATE USE Proper Radiologic techniques: Maximize distance between x-ray tube and patient Minimize distance between patient and image receptor Limit use of electronic magnification Control Fluoroscopy time: Limit use to necessary evaluation of moving structures Employ last-image hold to review findings Control images: Limit acquisition to essential diagnostic and documentation purposes Reduce Dose Reduce field size (collimate) and minimize field overlap Use pulsed fluoroscopy and low frame rate OPTIMIZE DOSE TO PATIENT LONG-TERM Include Medical Physicists in decisions Use Dose reduction technologies and dose measurement devices in equipment Establish a facility quality improvement program that includes an appropriate x-ray equipment quality assurance program, overseen by a Radiation Physicist which includes equipment evaluation/inspection at appropriate intervals. 27

28 Strategies to Mange Radiation Dose to Patients and Staff IMMEDIATE LONG-TERM MINIMIZE DOSE TO OPERATORS AND STAFF Keep hands out of beam Use moveable shields Maintain awareness of body position relative to the x-ray beam: Horizontal x-ray beam operator and staff should stand on the side of the image receptor Vertical x-ray beam the image receptor should be above the table Wear adequate protection Wear proper fitted lead aprons Leaded glasses with side protection Improve ergonomics of Operators and Staff Train operators and staff in ergonomically good positioning when using fluoroscopy equipment periodically assess their practice Identify and provide the ergonomically best personal protective gear for operators and staff 28

29 RADIATION MANAGEMENT FACTORS 29

30 SUMMARY Interventional fluoroscopy is an increasing important and valuable tool for treating disease, but it is not without risks. Physicians must continuously think about optimizing radiation dose to the patient. Understanding that dose to the skin can and will cause skin erythema and potentially skin necrosis. (Mettler 2002) Radiation dose is optimized when imaging is performed with the least amount of radiation required to provide adequate image quality and imaging guidance. Optimizing patient radiation dose provides direct correlation to physician and staff since scattered radiation is proportional to the patient dose. Follow-up after the procedure is important and patients should be counseled on radiation-related injury risks with a visit 30 days after procedure with a physician with a dose of 2 Gy or more. 30

31 REFERENCES 1) ICRP Draft Report Patient and Staff Radiological Protection in Cardiology ICRP ref May 20, ) Guidelines for Patient Radiation Dose Management J Vasc Interv Radiol 2009; 20:S263 S273 3) Journal of Vascular and Interventional Radiology , DOI: ( /j.jvir ) 4) ST Anthony s Hospital: INTERVENTIONAL FLUOROSCOPY PATIENT RADIATION SAFETY Procedure 5) FDA Advisory letter for The Joint Commission Educational Requirements for Fluoroscopy Standards effective Jan, 1, ) Wagner, Archer; Minimizing Risks from Fluoroscopic X Rays, (4 ed.) 31

32 QUESTIONS?? 32

33 EXAM DIAGNOSTIC PROCEDURES SHOULD BE DONE UNDER MAXIMUM POWER SINCE THIS WILL PRODUCE THE BEST IMAGES AND SHORTEN THE PROCEDURE. True False IT IS NECESSARY TO ROTATE THE BODY PART THAT A BADGE IS WORN ON DAILY, THAT WAY A PERSON IS ASSURED THAT HIS OR HER TOTAL BODY IS BEING MONITORED. True False THE DOORS TO THE INTERVENTIONAL LAB SHOULD BE CLOSED BEFORE OPERATING FLUOROSCOPY. True False THE MAIN SOURCE OF RADIATION EXPOSURE TO OPERATOR AND PERSONNEL IS FROM: Primary radiation Scatter radiation 33

34 EXAM Leaded glasses with side shields do not provide any reduction in dose to the eyes. True False Placement of your personal dosimetry badge is not critical to obtain dose record True False Use of Shields have decreased exposure dose to staff members True False Relationship between skin entrance dose and development of post-radiation ulceration is not a concern during Preprocedural Planning for patient having multiple procedures in past 12 months. True False PRISM reports are generated at 60 minutes of Fluoro time True False 34

35 EXAM Use of Shields is not necessary during a heart catheterization patient since only the heart and chest cavity are being visualized to minimize staff dose. True False Which is incorrect: The best defense against x-ray exposure is to: Minimize the total fluoroscopy time Keep the Image Intensifier close to the patient Maximize the field size Maximize the operator's distance from the patient Radiation exposure to patient and personnel in the interventional lab are among the highest found with any commonly performed diagnostic x-ray study. True False A cine run and a fluoro run produce the same amount of x-radiation. True False 35

36 EXAM THE IMAGE INTENSIFIER SHOULD BE POSITIONED AS FAR FROM THE PATIENT AS POSSIBLE SINCE THIS WILL GIVE THE BEST IMAGE AVAILABLE AND CUT DOWN ON EXPOSURES. True False APRONS AND THYROID SHIELDS ARE REQUIRED DURING ANY FLUORO PROCEDURE FOR ALL PERSONNEL IN ROOM True False IMAGE INTENSIFIER IS THE TERM THAT IS GIVEN TO THE X-RAY TUBE IN AN INTERVENTIONAL LAB. True False THE CONVENTIONAL RADIATION SAFETY TRIAD OF PRINCIPLES ARE: primary; background; reflection distance; time; shielding maximize; minimize; catheterize 36

37 EXAM ANGULATION OF THE X-RAY TUBE AND IMAGE INTENSIFIER GEOMETRY HAS NO EFFECT ON STAFF RADIATION RISK True False RADIATION EXPOSURE CAN BE LESSENED BY JUST MOVING FATHER AWAY FROM THE TABLE. True False THE INVERSE SQUARE LAWS STATES THAT DOUBLING THE DISTANCE FROM A POINT OF RADIATION: Increases the intensity by a factor of two Decreases the intensity by a factor of two Increases the intensity by a factor of four Decreases the intensity by a factor of four. Which of the following is not an operator factor: tissue type field size Location mode of operation 37