Transcript Diagnostic Medical Radiation Dose in Patients after

Tamara N. Oei, M.D.
Paul B. Shyn, M.D.
Usha Govindarajulu, Ph.D.
Richard Flint, M.D.
Senior Research Presentation
February 26, 2010
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Increasing rate of obesity
◦ Epidemic
◦ Known health effects
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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%
250
Frequency of Types of Bariatric Surgery by Year
Open RYGB
Lap RYGB
Lap Band
Number
200
150
100
50
0
2004
2005
Year
2006
2007
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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
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Cohort: 100 lap RYGB and 100 lap band patients
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Retrospective
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Medical records and imaging studies reviewed
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Number of CT and fluoroscopic exams tabulated
for follow-up period of 2.5 years
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Clinically significant positive findings recorded
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Excluded: unrelated exams, plain radiographs,
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Included: outside exams when documented,
routine 24 hour post op exams
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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
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PECT: 20mSv from literature
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UGI series: 4 mSv from literature
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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.
Lap RYGB
Lap Band
• 100 patients
• 100 patients
• 83 women
• 85 women
• Mean age 41
years (20-64)
• Mean age 42
years (19-63)
• BMI: 48  7
• BMI: 45  5 (P =
0.001)
180
160
RYGB
Gastric band
Total # Exams in 100 Patients
140
120
100
80
60
40
20
0
Fluoroscopy
All CT
Exam Type
Chest CT
Abdominopelvic CT
Cum dose:
4 to 156 mSv
4 to 46 mSv
Mean dose:
20 ± 20 mSv
11 ± 11 mSv
> 50 mSv:
7 pts
0 pts
% dose from CT: 77 %
41 %
Non-linear regression analyses univariate models
Undergoing RYGB
higher BMI
were each significant predictors of increased cumulative dose
35% (24/68) of CT scans
16% (14/86) of UGI series
*None of UGI series after routine
24 post op studies were positive
24% (6/25) of CT scans
22% (35/161) of UGI series
RYGB
Band
Indications for study
Positive findings
CT
Nausea/vomiting, pain, s/p mesh for
hernia, LLQ pain, abnormal LFTs,
r/o jejunojejunostomy obstruction,
fever, post reduction, follow up fluid
collection, hypoglycemia, RUQ
pain, question leak, desaturation,
emesis, question obstruction, SBO,
renal colic, flank pain, skin
ecchymosis
Small bowel hernia (1), mild sigmoid
diverticulitis (1),
SBO (6)
(6), abdominal hernia
SBO
(3), fluid collections (8), pouchitis (1),
appendicitisinternal
(1), internalhernia
hernia (1),
(1)
gastrogastric fistula (1), LUQ hematoma (1)
Fluoroscopy
Routine 24 hours post operation,
weight gain, pain with eating,
question fistula, post endoscopy
Delayed passage through the
gastrojejunostomy, obstruction at
gastrojejunostomy, obstruction at
jejunojejunostomy, ileus
Indications for study
Positive findings
CT
Shortness of breath, question leak,
liver contusion, reflux, abdominal
pain, r/o leak, fever,
nausea/vomiting, no bowel
movement, desaturation, hematocrit
drop, LLQ pain
Liver contusion (1), atelectasis (1),
subcutaneous abscess (1), ventral hernia (1),
rectus hematoma (1), low band position (1)
Fluoro
Routine 1 day post operation, status
post revision, nausea/vomiting,
weight gain
Obstructed, reflux, slow emptying,
obstruction
paraesophageal hernia, vertical orientation
of the band, band slippage, gastric pouch
hiatal hernia
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RYGB and inc BMI a/w more studies
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Positive finding rate was 23%
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For RYGB none of the fluoro studies were
positive after POD 1
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Most of patients are female
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Avg age of 41 yrs
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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)
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Linear-no-threshhold
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10 mSv may cause cancer in 1:1000 pts
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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
Adapted from the International Commission on Radiological Protection:
Recommendations. Annals of the ICRP Publication 60. Oxford,
Pergamon Press, 1990
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7/100 RYGB pts received > 50 mSv (~2500 CXR)
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1/100 RYGB pt received > 100 mSv (~5000 CXR)
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Highest dose in band group was 46 mSv
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1 CXR = 0.02 mSv
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Background radiation = 3 mSv/yr
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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 overlooked in 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
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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?
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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
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 Surgery
Online publication date: 25-Oct-2009.
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