CT Radiation Management: Why and How

Rathachai Kaewlai, MD Division of Emergency Radiology, Department of Radiology Ramathibodi Hospital, Mahidol University, Bangkok RCRT 2015 at Centara Grand @CentralPlaza Ladprao

!  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

!  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

!  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

!  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)

!  “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)

!  “….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)

!  Do we agree on the risk of radiation? !  Do we agree on our role in it?

Radiologists’ professional role

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

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

IMAGING 3.0TM is a trademark of the American College of Radiology

Image © Alex Saurel on flickr

!  Examination vetting !  Selecting appropriate protocol !  Optimize scanning protocols !  Mindset “lowest dose possible to achieve

diagnostic purposes” !  No more “good-looking images”

!  Monitoring doses at level of patients, divisions, groups, departments

!  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)

!  Why CT? !  CT parameters and radiation units !  Ramathibodi Emergency Radiology

experience !  Case examples (acute abdomen) !  Step-by-step guide to manage CT

radiation

!  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

!  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

!  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)

Imaging exam ordered by referring physician

Vetting/protocoling by radiologist

Scanning

Post-processing

Monitoring of quality

Assetprotectionlawjournal.com

Massgeneralimaging.org

Medicineworld.org Jenkinsclinic.org

Blog.vpi-corp.com

" Educate physicians about radiation risks

CT order

Vetting/protocoling

Scanning

Post-processing

Monitoring

"  Implement clinical prediction rules, expert recommendation guidelines

CT order

Vetting/protocoling

Scanning

Post-processing

Monitoring

"  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

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

Can we use radiation-free imaging (US, MRI) instead of CT for this

clinical scenario?

CT order

Vetting/protocoling

Scanning

Post-processing

Monitoring

If CT needed, design protocols specific to answer questions

CT order

Vetting/protocoling

Scanning

Post-processing

Monitoring

“Routine” protocol with minimum scanning phases. Nonroutine done by add-ons

CT order

Vetting/protocoling

Scanning

Post-processing

Monitoring

" 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

Make standard protocols available in CT workstations for every techs to use

CT order

Vetting/protocoling

Scanning

Post-processing

Monitoring

iacionline.com

" Reduce mAs CT order

Vetting/protocoling

Scanning

Post-processing

Monitoring

!  mA: effects noise only

0

10

20

30

40

50

60

0 200 400 600

Changes in Dose (CTDIw) as a Function of mAs

CTDIw Head (mGy) CTDIw Body (mGy)

Fixed kVp

Dos

e (m

Gy)

mAs

Use automatic tube current modulation CT order

Vetting/protocoling

Scanning

Post-processing

Monitoring

" 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

Reduce kVP CT order

Vetting/protocoling

Scanning

Post-processing

Monitoring

Reduce kVP CT order

Vetting/protocoling

Scanning

Post-processing

Monitoring

120 kV, 300 mAs, 100 mL contrast Aorta = 237 HU, noise = 13.1 HU

90 kV, 300 mAs, 80 mL contrast Aorta = 334 HU, noise = 19.4 HU

Dose reduction of up to 57%

120 kV 90 kV

Nakayama Y, et al. Radiology 2005

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

Incorporate patient size, age and indication into

making a protocol (work with your

physicists)

CT order

Vetting/protocoling

Scanning

Post-processing

Monitoring

Partnersradiology.org

CT order

Vetting/protocoling

Scanning

Post-processing

Monitoring

Use smooth kernels (algorithms)

CT order

Vetting/protocoling

Scanning

Post-processing

Monitoring

5 mm 3 mm

View thicker slices

" Send “Dose Report” into PACS CT order

Vetting/protocoling

Scanning

Post-processing

Monitoring

" Educate radiologists and trainees about dose parameters and standards

CT order

Vetting/protocoling

Scanning

Post-processing

Monitoring

" Regular updates of CT protocols CT order

Vetting/protocoling

Scanning

Post-processing

Monitoring

libraries.psu.edu

o  Use decision support tools

CT order

Vetting/protocoling

Scanning

Post-processing

Monitoring

Sanjay Saini, MD. MGH Sistrom CL et al. Radiology 2009

Systemwide tackle of defensive medicine and self referral

CT order

Vetting/protocoling

Scanning

Post-processing

Monitoring

Texler.deviantart.com

Streamlined vetting and protocoling processes

CT order

Vetting/protocoling

Scanning

Post-processing

Monitoring

Claimruler.com

Managingamericans.com

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

Use iterative reconstruction

(IR)

CT order

Vetting/protocoling

Scanning

Post-processing

Monitoring

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

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

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)

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

Exams CTDI vol per phase (mGy)

DLP (mGycm)

Brain CT 75 1050 Chest CT 21 650 Upper abdomen CT 25 900 Lower abdomen CT 25 570 Whole abdomen CT 25 780

ACR/AAPM 2014 European Commission 2004

!  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

!  New techniques for further dose reduction

MGH Radiology Rounds, mghradrounds.org

!  New techniques for further dose reduction

MGH Radiology Rounds, mghradrounds.org

120 kVp, FBP 100 kVp, advanced IR

!  1- and sub-mSv scan

MGH Radiology Rounds, mghradrounds.org

!  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”.