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CT Radiation Management: Why and How
1. Rathachai Kaewlai, MD
Division of Emergency Radiology, Department of Radiology
Ramathibodi Hospital, Mahidol University, Bangkok
RCRT 2015 at Centara Grand @CentralPlaza Ladprao
2. ! Lack of scientific consensus
! Assumption of risk from atomic bomb survivors
! How to act? Two possible errors…
! Assume risks are real and to then discover that
they do not exist
! Assume risks are nonexistent and to
subsequently discover that they are real
Huda W. Radiation risks: what is to be done? AJR 2015 January
3. ! Lack of scientific consensus
! Assumption of risk from atomic bomb survivors
! How to act? Two possible errors…
! Assume risks are real and to then discover that
they do not exist
! Assume risks are nonexistent and to
subsequently discover that they are real
Huda W. Radiation risks: what is to be done? AJR 2015 January
4. ! Low-level radiation
(up to 100 mSv)
! 30-40X annual natural
background
! 10X a usual CT scan
! Linear no-threshold
hypothesis
! 12 cancers with significant lifetime excessive
risks: lung, liver, breast, prostate, stomach, colon,
thyroid and leukemia
Committee on the Biological Effects of Ionizing radiation of the US National Academy of Sciences (2005)
Figure from web.princeton.edu
5. ! At low doses, the risk = one
excess cancer in 100
exposed persons (100 mSv)
during their lifetime. Mortality
is about one-half.
! Higher risk in female and
children
Committee on the Biological Effects of Ionizing radiation of the US National Academy of Sciences (2005)
6. ! “Most recent data for the
survivors of the atomic
bombings are largely
consistent with linear or
linear-quadratic dose trends
over a wide range of doses”
United Nations Scientific Committee on the Effects of Atomic Radiation (2006)
7. ! “….the practical system of
radiation protection
recommended by the
Commission will continue to be
based on the assumption that, at
doses below about 100 mSv, a
given increment in dose will
produce a directly proportionate
increment in the probability of
incurring cancer.”
International Commission on Radiological Protection (2007)
8. ! Do we agree on the risk of radiation?
! Do we agree on our role in it?
Radiologists’
professional role
9. Today: IMAGING 2.0 Tomorrow: IMAGING 3.0TM
Volume-based Value-based
Transactional Consultative
Radiologist centered Patient centered
Interpretation focused Outcomes focused
Commoditized Integral
Invisible Accountable
IMAGING 3.0TM is a trademark of the American College of Radiology
10. Today: IMAGING 2.0 Tomorrow: IMAGING 3.0TM
Volume-based Value-based
Transactional Consultative
Radiologist centered Patient centered
Interpretation focused Outcomes focused
Commoditized Integral
Invisible Accountable
IMAGING 3.0TM is a trademark of the American College of Radiology
11. IMAGING 3.0TM is a trademark of the American College of Radiology
13. ! Low-level radiation is a
health hazard – LNT
hypothesis
! Radiologists have a critical
role in optimizing CT
radiation exposure (should
be a leader of the team)
14. ! Why CT?
! CT parameters and radiation units
! Ramathibodi Emergency Radiology
experience
! Case examples (acute abdomen)
! Step-by-step guide to manage CT
radiation
15. ! Medical radiation is now the majority of
radiation exposure in human
! CT accounts for most of this
! CT volume on the rise
! No dose penalty in CT
! CT radiation dose is intrinsically high
! No binding regulations on CT doses
! CT radiation errors made into headlines
16.
17.
18. ! Case volume
! Many sensitive
organs
! Patient population
who gets scanned
! It’s frequently where
the Unnecessaries
occur
Brenner DJ, Hall EJ. N Engl J Med 2007
19. ! Assuming radiation risks are real
! Doing CT is weighing this risk with benefit
! If benefit > risk means a justified examination
! Providing other diagnostic options
! Using as low radiation as possible to
obtain needed diagnostic information
(ALARA)
20. Imaging exam ordered
by referring physician
Vetting/protocoling by
radiologist
Scanning
Post-processing
Monitoring of quality
Assetprotectionlawjournal.com
Massgeneralimaging.org
Medicineworld.orgJenkinsclinic.org
Blog.vpi-corp.com
21. " Educate physicians about radiation
risks
CT order
Vetting/
protocoling
Scanning
Post-
processing
Monitoring
23. " Import exams from outside hospitals
to PACS
CT order
Vetting/
protocoling
Scanning
Post-
processing
Monitoring
! Patients transferred to trauma
center 38/137 (28%) received
duplicated scans in 24 hours
! Most common reason for
duplication = lack thin-
section data on CD (37%)
! Additional radiation 10.2 mSv
! Additional charge $409
24. Can we use radiation-free imaging
(US, MRI) instead of CT for this
clinical scenario?
CT order
Vetting/
protocoling
Scanning
Post-
processing
Monitoring
Make ultrasound
(by radiologist) available
and easily accessible 24/7
25. Can we use radiation-free imaging
(US, MRI) instead of CT for this
clinical scenario?
CT order
Vetting/
protocoling
Scanning
Post-
processing
Monitoring
26. If CT needed, design protocols
specific to answer questions
CT order
Vetting/
protocoling
Scanning
Post-
processing
Monitoring
27. “Routine” protocol with minimum scanning
phases. Nonroutine done by add-ons
CT order
Vetting/
protocoling
Scanning
Post-
processing
Monitoring
28. " Avoid Z-creep (unnecessary coverage
and scan phases)
CT order
Vetting/
protocoling
Scanning
Post-
processing
Monitoring
! Radiation dose is directly
proportional to scan volume
! Kalra et al, Radiology 2004
! 106 abdomen/pelvic CTs
! 97% had extra images
! 12 extra images/CT
29. Make standard protocols available in CT
workstations for every techs to use
CT order
Vetting/
protocoling
Scanning
Post-
processing
Monitoring
iacionline.com
31. Use automatic tube current modulationCT order
Vetting/
protocoling
Scanning
Post-
processing
Monitoring
32. " Reduce kVP
(esp for CTA,
stone protocol)
CT order
Vetting/
protocoling
Scanning
Post-
processing
Monitoring
! Effect on both
noise and
attenuation
0
10
20
30
40
50
60
0 50 100 150
Changes in CTDIw as a Function
of kVp
CTDIw Head (mGy)
CTDIw Body (mGy)
Fixed mAs
35. Incorporate patient size, age and
indication into making a protocol (work
with your physicists)
CT order
Vetting/
protocoling
Scanning
Post-
processing
Monitoring
! Image noise
increases with
less kVp but noise
is less in smaller
phantoms
Seigel MJ, et al. Radiology 2004
36. Incorporate patient
size, age and
indication into
making a protocol
(work with your
physicists)
CT order
Vetting/
protocoling
Scanning
Post-
processing
Monitoring
Partnersradiology.org
39. " Send “Dose Report” into PACSCT order
Vetting/
protocoling
Scanning
Post-
processing
Monitoring
40. " Educate radiologists and trainees
about dose parameters and standards
CT order
Vetting/
protocoling
Scanning
Post-
processing
Monitoring
41. " Regular updates of CT protocolsCT order
Vetting/
protocoling
Scanning
Post-
processing
Monitoring
libraries.psu.edu
42. o Use decision support tools
CT order
Vetting/
protocoling
Scanning
Post-
processing
Monitoring
Sanjay Saini, MD. MGH
Sistrom CL et al. Radiology 2009
43. Systemwide tackle of defensive medicine
and self referral
CT order
Vetting/
protocoling
Scanning
Post-
processing
Monitoring
Texler.deviantart.com
44. Streamlined vetting and protocoling
processes
CT order
Vetting/
protocoling
Scanning
Post-
processing
Monitoring
Claimruler.com
Managingamericans.com
45. CT order
Vetting/
protocoling
Scanning
Post-
processing
Monitoring
Color zones:
- Pink = routine, R/O situation
- Green = F/U CT with one prior
- Red = bone evaluation or
multiple priors
- Yellow = kidney stone
- Blue = subtle or small lesions
suspected or identified with other
imaging
- Gray = vascular assessment
with CTA
kVp mA Noise Index
Singh S, et al. Radiology 2009
47. Take the lead
Decide to change
Form a team
Do it!
Monitor the results
It’s radiologists’ professional role.
Our job, nobody else…
o Tell technologists to send dose
report to PACS
o Check 10-20 reports of all organ
systems
o Compare your doses with
standard DRLs
o Convince your Superior/Head
48. Take the lead
Decide to change
Form a team
Do it!
Monitor the results
It’s radiologists’ professional role.
Our job, nobody else…
o Form a team (you + other
radiologists + techs + (physicist)
o Select the target exam type (high
doses, high volume)
o Invite referring physician to join
the team
o Set your goal
49. Take the lead
Decide to change
Form a team
Do it!
Monitor the results
It’s radiologists’ professional role.
Our job, nobody else…
o Clinical guidelines
o Technical parameters
o Scan coverage, phases
o Indication-based, size-based
protocols
o Additional techniques (IR)
50. Take the lead
Decide to change
Form a team
Do it!
Monitor the results
It’s radiologists’ professional role.
Our job, nobody else…
o Team monitoring of dose
o Repeat the processes
52. ! Estimated dose x conversion
factor = SSDE
! Closer to “real” dose
! Thinner patients get more dose
compared with obese patients
of the same DLP
! Based on our own unpublished
data, SSDE is 30%+ that of
estimated dose
53. ! New techniques for further dose reduction
MGH Radiology Rounds, mghradrounds.org
54. ! New techniques for further dose reduction
MGH Radiology Rounds, mghradrounds.org
120 kVp, FBP 100 kVp, advanced IR
55. ! 1- and sub-mSv scan
MGH Radiology Rounds, mghradrounds.org
56. ! It is not a “choice” to reduce CT radiation. As
a radiologist, it is a responsibility to our
patients
! No more best-looking images. Images
should be “enough for diagnostic purpose”
! Multiphase CT should not be “routine”.
! CT dose is manageable: take a lead, make
a decision, form a team and “just do it”.
Hinweis der Redaktion
“…current scientific evidence is consistent with the hypothesis that there is a linear dose-response relationship between exposure to ionizing radiation and the development of radiation induced solid cancers”
At low doses, the risk, though increased, is small, one excess cancer in 100 exposed persons during their lifetime. Mortality, as opposed to incidence, would be about one-half.
For Radiation Protection Purposes, We Must Act on the Assumption That Radiation Risk Exists
Images good enough for diagnostic purposes
As a radiologist, it is a responsibility to our patients to reduce CT radiation
Old habits die hard – must force a change
https://farm3.staticflickr.com/2879/10926532254_039008b467.jpg
Importance of educating radiology personnel, patients and referring physicians about concerns over CT radiation
Commonly used CT parameters and radiation units
Dedicated radiology team to manage CT radiation
Specific technique to minimize radiation whie providing diagnostic examinations
In an age in which we can download movies and music from the cloud, it is inexcusable to subject patients to avoidable cost and radiation exposure when the technology exists to ensure that images are readily accessible. Zane RD. JWatch Emergency Medicine