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Diagnostic Medical Radiation Dose in Patients after Laparoscopic Bariatric Surgery

Diagnostic Medical Radiation Dose in Patients after Laparoscopic Bariatric Surgery. Tamara N. Oei, M.D. Paul B. Shyn, M.D. Usha Govindarajulu, Ph.D. Richard Flint, M.D. Senior Research Presentation February 26, 2010. BACKGROUND. BARIATRIC SURGERY. Increasing rate of obesity Epidemic

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Diagnostic Medical Radiation Dose in Patients after Laparoscopic Bariatric Surgery

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  1. Diagnostic Medical Radiation Dose in Patients after Laparoscopic Bariatric Surgery Tamara N. Oei, M.D. Paul B. Shyn, M.D. Usha Govindarajulu, Ph.D. Richard Flint, M.D. Senior Research Presentation February 26, 2010

  2. BACKGROUND

  3. BARIATRIC SURGERY • Increasing rate of obesity • Epidemic • Known health effects • Bariatric surgery has proven to be one of the most effective and definitive solutions • Known complications and risks with bariatric surgery 9-23 %, mortality 0.1-0.3%

  4. Bariatric Surgery techinques

  5. DIAGNOSTIC MEDICAL RADIATION • Post bariatric surgery imaging plays important role in evaluating complications, especially since clinical exams are often inconclusive • WHAT IS THE RADIATION DOSE ACQUIRED IN THIS POPULATION? • Mostly female • Young population

  6. MATERIALS AND METHODS

  7. Who, What, When • Cohort: 100 lap RYGB and 100 lap band patients • Retrospective • Medical records and imaging studies reviewed • Number of CT and fluoroscopic exams tabulated for follow-up period of 2.5 years • Clinically significant positive findings recorded • Excluded: unrelated exams, plain radiographs, • Included: outside exams when documented, routine 24 hour post op exams

  8. Radiation dose estimation • Abdominopelvic CT: • mean DLP determined from 19 studies where this info available from protocol display. • Effective dose = mean DLP x 0.017 mSv/mGy-cm • PECT: 20mSv from literature • UGI series: 4 mSv from literature

  9. Statistical Analysis • Student t test for unpaired data • Non-linear regression model was employed with cumulative dose as the outcome adjusted by gender, age, type of surgery, and BMI in separate univariate models • Multivariate analysis was not performed because of the high correlation of BMI with type of surgery.

  10. RESULTS

  11. Patient demographics of the two bariatric surgery groups.

  12. Radiological exams by type for each surgical cohort over a 2.5 year post-operative interval

  13. RYGB Band Cum dose: 4 to 156 mSv Mean dose: 20 ± 20 mSv > 50 mSv: 7 pts % dose from CT: 77 % 4 to 46 mSv 11 ± 11 mSv 0 pts 41 % Non-linear regression analyses univariate models Undergoing RYGB higher BMI were each significant predictors of increased cumulative dose

  14. Cumulative radiation dose over the 2.5 year interval following bariatric surgery

  15. Frequency of Positive Findings 35% (24/68) of CT scans 16% (14/86) of UGI series 24% (6/25) of CT scans 22% (35/161) of UGI series *None of UGI series after routine 24 post op studies were positive

  16. Complications RYGBBand SBO (6) internal hernia (1) obstruction

  17. Key findings • RYGB and inc BMI a/w more studies • Positive finding rate was 23% • For RYGB none of the fluoro studies were positive after POD 1 • Most of patients are female • Avg age of 41 yrs

  18. What now?

  19. Radiation induced carcinogenesis • BEIR VII: 1:100 persons could be expected to develop a cancer in their lifetime from a single dose of 100 mSv (42:100 from other causes unrelated to radiation) • Linear-no-threshhold • 10 mSv may cause cancer in 1:1000 pts

  20. Bariatric population • Younger patients: TEEN-LABS, 200 patients younger than 19 years old undergoing RYGB • Mostly female (84%), women are subject to a slightly increased risk relative to men of developing solid tumors secondary to radiation exposure

  21. Adapted from the International Commission on Radiological Protection: Recommendations. Annals of the ICRP Publication 60. Oxford, Pergamon Press, 1990

  22. So what? • 7/100 RYGB pts received > 50 mSv (~2500 CXR) • 1/100 RYGB pt received > 100 mSv (~5000 CXR) • Highest dose in band group was 46 mSv • 1 CXR = 0.02 mSv • Background radiation = 3 mSv/yr

  23. Food for thought • In addition to known complications, potential risks a/w DMR in the post-operative period should also be considered • Possible that pts who do not undergo bariatric surgery will later develop complications from obesity that could prompt similar or even greater numbers of radiological exams • Radiation risks are easily overlookedin the clinical setting since the carcinogenic effects of ionizing radiation take many years to manifest and causation is generally not provable on an individual basis

  24. More food for thought • How would be radiation dose change with patient size? • How does patient size limit image quality and diagnostic interpretation? • How often are other complications discovered at surgery or endoscopy that were not evident by radiology?

  25. Furthermore • While the risks-to-benefit ratio may be justified, strategies to minimize radiation dose in this patient population should be pursued. • Judicious use of radiologic tests should be emphasized. • Appropriate technique factors should be applied for all radiologic exams according to ALARA

  26. Many Thanks! Research Mentor: Paul Shyn, MD Richard Nawfel, PhD (physicist) Richard Flint, MD (surgeon) Usha Govindarajulu (statistician) Tamara N. Oei, Paul B. Shyn, Usha Govindarajulu, Richard Flint. (2009) Diagnostic Medical Radiation Dose in Patients After Laparoscopic Bariatric Surgery. Obesity SurgeryOnline publication date: 25-Oct-2009.

  27. References • Brenner D, Hall E. Computed tomography—an increasing source of radiation exposure. N Engl J Med 2007; 357: 2277-2284. • Health risks from exposure to low levels of ionizing radiation—BIER VII. Washington, DC: National Academies Press, 2005. • Brenner D, Doll R, Goodhead, D, et al. Cancer risks attributable to low doses of ionizing radiation: assessing what we really know. Proc Natl Acad Sci 2003; 100: 13761-13766. • Overweight and obesity. Centers for Disease Control and Prevention, Department of Health and Human Services, 2009. (Accessed January 26, 2009, at http://www.cdc.gov/nccdphp/dnpa/obesity/). • Ogden C, Carroll M, Curtin L, et al. Prevalence of overweight and obesity in the United States, 1999-2004. JAMA 2006; 295: 1549-1555. • Elder K, Wolfe B. Bariatric surgery: a review of procedures and outcomes. Gastroenterology 2007; 132: 2253-2271. • Parikh MS, Laker S, Weiner M, et al. Objective comparison of complications resulting from laparoscopic bariatric procedures. J Am Coll Surg 2006; 202: 252-261. • Tice JA, Karliner L, Walsh J, et al. Gastric banding or bypass? A systematic review comparing the two most popular bariatric procedures. Am J Med 2008; 121: 885-893. • Livingston, EH. Procedure incidence and in-hospital complication rates of bariatric surgery in the United States. Am J Surg 2004; 188: 105-110. • Sovik TT, Erlend TA, Kristinsson J, et al. Establishing laparoscopic roux-en-y gastric bypass: perioperative outcome and characteristics of the learning curve. Obesity Surgery 2009; 19: 158-165. • Santry HP, Gillen DL, Lauderdale DS. Trends in bariatric surgical procedures. JAMA 2005; 294: 1909-1917. • Rosenthal RJ, Szomstein S, Kennedy C, et al. Laparoscopic surgery for morbid obesity: 1,001 consecutive bariatric operations performed at the bariatric institute, Cleveland Clinic Florida. Obesity Surgery 2006; 16: 119-124. • Campos GM, Ciovica RC, Rogers SJ, et al. Spectrum and risk factors of complications after gastric bypass. Arch Surg 2007; 142: 969-975. • Filip JE, Mattar SG, Bowers SP, et al. Internal hernia formation after laparoscopic roux-en-y gastric bypass for morbid obesity. Am Surg 2002; 68: 640-643. • Merkle EM, Hallowell PT, Crouse C, et al. Roux-en-y gastric bypass for clinically severe obesity: normal appearance and spectrum of complications at imaging. Radiology 2005; 234: 674-683. • European Guidelines on Quality Criteria for Computed Tomography, EUR 16262 EN, May 1999 (Accessed June 9, 2008, at http://www.drs.dk/guidelines/ct/quality/index.htm). • Hurwitz LM, Reiman RE, Yoshizumi TT, et al. Radiation dose from contemporary cardiothoracic multidetector CT protocols with an anthropomorphic female phantom: implications for cancer induction. Radiology 2007; 245: 742-750. • Huda, W and Slone, R. Review of Radiologic Physics. 2nd ed. 2003: p 80 • ICRP Publication 60: 1990 Recommendations of the International Commission on Radiologic Protection. International Commission on Radiological Protection. Oxford, Pergamon Press, 1990. • Inge TH, Zeller M, Harmon C, et al. Teen-longitudinal assessment of bariatric surgery: methodological features of the first prospective multicenter study of adolescent bariatric surgery. J Pediatr Surg 2007; 42: 1969-1971. • Preston D, Shimizu Y, Pierce D, et al. Studies of mortality of atomic bomb survivors. Report 13: solid cancer and noncancer disease mortality: 1950-1997. Radiat Res 2003; 160: 381-407. • Amis E, Butler P, Applegate K, et al. American college of radiology white paper on radiation dose in medicine. J Am Coll Radiology 2007; 4: 272-84. • Lee CL, Haims AH, Monico EP, et al. Diagnostic CT scans. Radiology 2004; 231: 393-98. • Martin D, Semelka R. Health effects of ionizing radiation from diagnostic CT. Lancet 2006; 367: 1712-1713.

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