IMAGE GENTLY HOW CAN YOU HELP? Keith J. Strauss, MSc, FAAPM, FACR Director, Radiology Physics & Engineering Children s s Hospital Boston Harvard Medical School
Acknowledgment Marilyn J. Goske,, MD Robert Pizzutiello
INTRODUCTION A. Introduction to Image Gently B. Image Gently Focus C. Pediatric Considerations D. Your Involvement 1. Training 2. CT Patient Dose Index? 3. Pediatric CT Scan Parameters
The Alliance. A. Coalition of health care organizations dedicated to providing safe, high quality pediatric imaging worldwide. B. Primary objective is to raise awareness of the need to adjust pediatric radiation dose. C. The ultimate goal of the Alliance is to accelerate the change of local practice. 1. Scientific observation to local practice change ~ 17 years! 1 1 Greenberg SB. Trans Clin Climatol Assoc 119:2450261, 2008
What is Image Gently? A Campaign Of education and awareness To improve radiation protection for children
How much do we really understand? Under estimation by 75% of MDs! Lee et al. Radiology. 2004; 231:393-398
PARTNERSHIPS A. 42 Affiliates; 13 International; > 700,000 individuals Academy of Radiology Research American Academy of Pediatrics American Institute of Ultrasound in Medicine American Osteopathic College of Radiology American Registry of Radiologic Technologists American Roentgen Ray Society American Society of Emergency Radiology American Society of Head and Neck Radiology American Society of Pediatric Neuroradiology Asian-Oceanic Society for Paediatric Radiology Association of University Radiologists Australian & New Zealand Society for Paediatric Radiology Canadian Association of Medical Radiation Technologists Canadian Association of Radiologists Canadian Interventional Radiology Association Canadian Organization of Medical Physicists Coalition for Imaging and Bioengineering Research College of Radiology, Academy of Medicine of Malaysia Conference of Radiation Control Program Directors European Society of Paediatric Radiology National Council on Radiation Protection and Measurements North American Society for Cardiovascular Imaging Radiological Society of North America The Royal Australian and New Zealand College of Radiologists Society of Interventional Radiology Sociedad Latino Americana de Radiología Pediátrica Society for Pediatric Interventional Radiology Society of Computed Body Tomography and Magnetic Resonance Society of Gastrointestinal Radiologists The Society of Nuclear Medicine The Society of Nuclear Medicine - Technologist Section Sociedad Mexicana De Radiologia E Imagen Society of Radiologists in Ultrasound Society of Uroradiology
IMAGE GENTLY S S FOCUS A. Positive, unified message 1. Vetted through Alliance member committees 2. Adds depth, clarity, and credibility. B. Consistent tone 1. Respectful to all a. Medical professionals and b. Families 2. Seeking information about patient radiation doses.
IMAGE GENTLY S S FOCUS Managing Patient Dose in CT Holistically Configuration of CT Scanner Radiation Dose / Image Radiation Output Calibration Operation of CT Tissue Volume Irradiated Should CT be Performed? Image Quality Verification Automatic Exposure Control Exam Specific Acquisitions Scan Length? Contrast Media Management Total Patient Dose from CT
IMAGE GENTLY S S FOCUS C. Advocacy issues include: 1. Improved education regarding radiation risk 2. Promotion of standardized a. Nomenclature of technique parameters b. Radiation dose utilization (technique factors) c. Radiation dose display 3. Improving medical literacy for parents and patients. a. Medical Image Record Card b. Educational brochures for parents - Multiple translations
IMAGE GENTLY S S FOCUS Working together to change practice Medical Physicist Radiologists Radiologic Technologist Imager vendor
GROWTH OF MEDICALRADIATION DOSE A. Early 1980s Snapshot 1. 15% of Annual Radiation Dose due to medical imaging 2. 0.53 msv per year a. X-rays: X 0.39 b. Nuc Med: 0.14 Nuclear Medicine 4% Medical X-rays 11% Internal 11% Consumer Products 3% Other 1% Radon 54% Terrestiral 8% Cosmic 8% Adapted from Mahesh
Procedures vs Effective dose contributions Interventiona 2% CT 12% Nuclear Medicin e Radiography & Fluoroscopy* 19% Interventiona l CT 46% Radiography & Fluoroscopy* 83% Percent Procedures Nuclear Medicin e Effective Dose Contributions Adapted from Mahesh 17% of All Exams Deliver 81% of Total Effective dose 91% of Pediatric Dose in the ED comes from CT
Preliminary estimate of changes in Medical radiation exposure to US population US 1980* US 2006 Medical 0.54 Other 0.06 Radiography 0.6 msv Interventional 0.4 msv Nuclear Medicine Natural?? (3.0 msv) Natural 3.0 msv CT 1.5 msv Medical 0.54 msv per capita Total 3.6 msv per capita Medical 3.2 msv per capita Total?? msv per capita * NCRP 93 Adapted from Mahesh
IMAGE GENTLY S S FOCUS E. Newest Development 1. Image Gently in Pediatric Interventional Radiology F. Currently Under Development 1. Pediatric Nuclear Medicine 2. Pediatric CR/DR 3. Pediatric Fluoroscopy
PEDIATRIC CONSIDERATIONS A. Radiation Induced Cancer Lifetime Risk From 1 Sv Dose 1. Average a. 5% Males b. 6% Females 2. First Decade 15% 3. Middle Age 2-3 % 4. Children 3 5 times more sensitive Adapted from Hall
PEDIATRIC CONSIDERATIONS Radiation Risk based on Effective Dose? A. Almen and S. Mattsson, J. Radiol. Prot. 16 (2), 81-89 (1996). Somatic risk %/Sv Hereditary risk %/Sv Total risk %/Sv Children Aged 0-9 14.5 2.5 17 Children Aged 10-19 8.5 2.5 11 Whole population 5 1 6
PEDIATRIC CONSIDERATIONS B. Pediatric Patient Size Variation is Large Abdomen 1. 5 yr old: 10 17 cm 2. 15 yr old: 14 24 cm
RADIATION PROTECTION FOR CHILDREN ONE SIZE DOES NOT FIT ALL
PEDIATRIC CONSIDERATIONS
PEDIATRIC ANATOMICAL CONSIDERATIONS Large Adult Adult 5 year 1 year 5 cm Neonate 1 HVL @ 120 KVP 1 HVL @ 70 KVP
ASSUME 5 CM TISSUE HVL Abdominal Girth (kg) Mass PA (cm) # HVL LAT (cm) # HVL Neonate 2 6 1.2 6 1.2 Newborn 3 9 1.8 10 2 1 yr 10 12 2.4 14 2.8 5 yr 19 16 3.2 22 4.4 12 yr 31 18 3.6 27 5.4 Adult 68 22 4.4 33 6.6 Adult 100+ 35 7 48 9.6
PEDIATRIC CONSIDERATIONS Clinical dynamic range of mas per image to maintain a fixed kvp PA projection 6 HVL Range of 64 LAT projection 9 HVL Range of 512
PEDIATRIC CONSIDERATIONS CTDI vol Tube Tube Current Changed by Weight or Mass
PEDIATRIC CONSIDERATIONS CLINICAL EDUCATIONAL MATERIALS Table II: mas Reduction Factors for the Pediatric Head Room #: CT Unit: Date: kvp ma Time (sec) Pitch Filter Head Baseline: fill in fill in fill in fill in fill in PA Thickness Head (cm) Approx Age mas Reduction Factor (RF) Estimated mas = BL x RF 12 newborn 0.74 #VALUE! 16 2 yr 0.86 #VALUE! 17 6 yr 0.93 #VALUE! 19 med adult 1 fill in 1. Type in baseline head techniques and mas in yellow cells 2. Spreadsheet will calculate mas estimated for pediatric patients of varying sizes IMAGE GENTLY HEAD Table II: mas Reduction Factors for the Pediatric Head Room #: CT Unit: Date: kvp ma Time (sec) Pitch Filter Head Baseline: 120 150 2 1 fill in PA Thickness Head (cm) Approx Age mas Reduction Factor (RF) Estimated mas = BL x RF 12 newborn 0.74 222 16 2 yr 0.86 258 17 6 yr 0.93 279 19 med adult 1 300 1. Type in baseline head techniques and mas in yellow cells 2. Spreadsheet will calculate mas estimated for pediatric patients of varying sizes
PEDIATRIC CONSIDERATIONS CLINICAL EDUCATIONAL MATERIALS Abdomen kvp ma Time (sec) Pitch Abdomen Pitch Thorax Baseline: fill in fill in fill in fill in fill in Abdomen Thorax PA Thickness (cm) Approx Age mas Reduction Factor (RF) Estimated mas = BL x RF mas Reduction Factor (RF) Estimated mas = BL x RF 9 newborn 0.43 #VALUE! 0.42 #VALUE! 12 1 yr 0.51 #VALUE! 0.49 #VALUE! 14 5 yr 0.59 #VALUE! 0.57 #VALUE! 16 10 yr 0.66 #VALUE! 0.64 #VALUE! 19 15 yr 0.76 #VALUE! 0.73 #VALUE! 22 small adult 0.90 #VALUE! 0.82 #VALUE! 25 med adult 1.0 fill in 0.91 #VALUE! 31 large adult 1.27 #VALUE! 1.16 #VALUE! IMAGE GENTLY BODY Abdomen kvp ma Time (sec) Pitch Abdomen Pitch Thorax Baseline: 120 400 1 1.25 1.5 Abdomen Thorax PA Thickness (cm) Approx Age mas Reduction Factor (RF) Estimated mas = BL x RF mas Reduction Factor (RF) Estimated mas = BL x RF 9 newborn 0.43 172 0.42 202 12 1 yr 0.51 204 0.49 235 14 5 yr 0.59 236 0.57 274 16 10 yr 0.66 264 0.64 307 19 15 yr 0.76 304 0.73 350 22 small adult 0.90 360 0.82 394 25 med adult 1.0 400 0.91 437 31 large adult 1.27 508 1.16 557
IMAGE GENTLY NEEDS YOU TRAINING Complete training fosters Full use of equipment design Improved image quality Reduced radiation dose
IMAGE GENTLY NEEDS YOU TRAINING Training is only as effective as the trainer s understanding of their trainees Each trainee may have a bit different perspective! YOUR HOUSE as seen by... Yourself
Your Lender Your Buyer Your Appraiser Your Tax Assessor
IMAGE GENTLY NEEDS YOU CT Patient Dose Index? A. Limitations of CTDI 1. CTDI 100 measured with 100 mm pencil chamber a. Two Standard Phantoms b. Scanner Dose Index c. Allows compari- son of radiation output of different CT scanner models & manufaturers
IMAGE GENTLY NEEDS YOU CT Patient Dose Index? A. Limitations of CTDI 2. CTDI vol (mgy) responds to changes in: a. Scanner Design i. Bow Tie Filter Composition & Shape ii. Focal Spot to Detector Distance b. Scan Parameters i. kvp ii. Pitch iii. mas c. Patient Size? NO
CT RADIATION DOSE BODY, 32 cm. HEAD, 16 cm. 100 100 100 90 100 100 50 100 Adapted from Frey 100 CTDI vol = 97 100 CTDI vol = 84
IMAGE GENTLY NEEDS YOU CT Patient Dose Index? A. Limitations of CTDI 3. CTDI vol (mgy) does not respond to changes in Patient Size!! a. IG recommendations deliver similar patient dose independent of patient size IMAGE GENTLY BODY Abdomen kvp ma Time (sec) Pitch Abdomen Pitch Thorax Baseline: 120 400 1 1.25 1.5 Abdomen Thorax PA Thickness (cm) Approx Age mas Reduction Factor (RF) Estimated mas = BL x RF mas Reduction Factor (RF) Estimated mas = BL x RF 9 newborn 0.43 172 0.42 202 12 1 yr 0.51 204 0.49 235 14 5 yr 0.59 236 0.57 274 16 10 yr 0.66 264 0.64 307 19 15 yr 0.76 304 0.73 350 22 small adult 0.90 360 0.82 394 25 med adult 1.0 400 0.91 437 31 large adult 1.27 508 1.16 557
IMAGE GENTLY NEEDS YOU CT Patient Dose Index? A. Limitations of CTDI 4. CTDI doses UNDERESTIMATE pediatric doses: creates false sense of security a. New Born vs Adult dose display error i. Head: ~ 35% ii. Thorax: ~ 175% iii. Abdomen:~200%
IMAGE GENTLY NEEDS YOU CT Patient Dose Index? A. Limitations of CTDI 4. CTDI doses UNDERESTIMATE pediatric doses: b. Solution: Pediatric CT Physics Work Group i. Group within Medical Imaging & Technology Alliance (MITA) Developing Correction Factors to estimate a Patient Dose Index from CTDI vol as a function of patient size ii. AAPM Task Group Developing standardized recommendation that can be universally adapted.
IMAGE GENTLY NEEDS YOU CT Patient Dose Index? A. Limitations of CTDI 5. No uniformity of display currently exists among CT Scanner manufacturers a. Incomplete information b. Confusion among Users
IMAGE GENTLY NEEDS YOU 6. Actual Displays a. CTDI vol in mgy CT Patient Dose Index?
IMAGE GENTLY NEEDS YOU CT Patient Dose Index? 6. Actual Displays c. CTDI: Which one? d. DLP with units
CURRENT DOSE DISPLAYS 6. Actual Displays e. CTDI vol Units? f. How does Eff. DLP differ from DLP?
CURRENT DOSE DISPLAYS 6. Actual Displays g. CTDI vol & DLP with units h. Phantom size identified! i. Is only DLP additive for multiple series? 4. Does the vendor bother to to teach this information?
IMAGE GENTLY NEEDS YOU CT Patient Dose Index? A. Limitations of CTDI 7. Dixon s s challenge to 100 mm pencil chamber a. A New Look at CT Dose Measurement: Beyond CTDI Med Phys 30(6) 2003. b. Restructuring CT Dosimetry A A Realistic Strategy for the Future Requiem for the Pencil Chamber Med Phys 33(10) 2006.
IMAGE GENTLY NEEDS YOU CT Patient Dose Index? A. Limitations of CTDI 8. Boone s s response to 100 mm chamber dilemma The Trouble with CTDI 100 Med Phys 34(4) 2007. a. 100 mm chamber underestimates the dose for all scans, 40 mm vs a 10 mm fan beam.
IMAGE GENTLY NEEDS YOU CT Patient Dose Index? B. Solutions to Limitations of CTDI 1. Point Chamber Measurement of Dose 2. Develop agreed upon correction factors to estimate and display Patient Dose Index 3. Simplify and standardize dose displays on CT Scanners
IMAGE GENTLY NEEDS YOU CT Pediatric Scan Parameters A. AAPM CT Dose Summit 1. Atlanta at end of April 2. All 11 hours of presentations will be in AAPM Virtual Library 3. Clinical Users Need Help Setting Up Scan Parameters a. Not a simple endeavor. b. ACR CT Accreditation
A. Conclusions IMAGE GENTLY NEEDS YOU 1. Image Gently is an Awareness Campaign 2. Vast majority of Pediatric Imaging Occurs in Adult facilities 3. Children are not small Adults... 4. CT Patient Dose Index Function of Size 5. Help Clinicians with CT Scan Techniques Now 6. Children are not small Adults, but...... Most Adults are BIG Babies!
Working together to improve radiation protection for children worldwide! Don t forget to Image Gently and Step Lightly. www.imagegently.org