© s. balter 2008 sb0802 ihe - 1 radiation dose data management ihe presentation – february 2008...

© S. Balter 2008SB0802 IHE - 1

Radiation Dose Data Management

IHE Presentation – February 2008Stephen Balter, Ph.D.

Columbia University Medical Center, New York, New York


Measurements and documentation When you can measure what

you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind.

Lord Kelvin (1824-1907)

1902 Skiameter of Benoist


Purposes and costs

• The purpose of any diagnostic procedure is to reduce uncertainty about the patient’s health status.

• The purpose of most therapeutic procedures is to stabilize or improve the patient’s health.

• There are always associated costs– Money and time– Procedural risks– Often radiation risks


Real World Case Range

• Patient brought into the emergency room by ambulance after an auto crash with evidence of multi-organ trauma.

• PCI in place of coronary bypass surgery.• Screening mammogram.• Employee of a high-tech company visiting a

‘wellness clinic’ for an annual check-up. Offered add-on CT scans ‘as long as you are already on the table’.

• Whole body security CT scan (before visiting a prisoner or boarding an aircraft).


Past radiation history

• Rarely has any influence on the decision to order a diagnostic procedure.

• May provide additional help in interpreting the results of a diagnostic procedure.

• Can be important in planning therapeutic procedures.

• Imaging history is another matter.


Historical dose recording

• Non regulatory recommendations for dose recording – In some form since early 20th century– FDA Radiation “Passport” (circa 1970)– SIR Standard of practice (2004)

• Interventional– FDA Recommendation (1994):Record skin dose and location – IEC 60601-2-43 (2001): KAP and Dose at Reference Point– FDA Regulations (2005): Dose at Reference Point

(new fluoroscopic equipment)• DICOM MPPS Report (1996)

– Assumes RIS and linkages• EURATOM Directive (1997)

– National Dose Recording Regulations– Primarily KAP (Stochastic Risk Concerns)– No formal scheme for recording– Space available in DICOM Headers


FDA X-RAY Record Card c 1970X-RAY RECORD CARD

Name:

Health Ins.Co.:

Policy No.:

For additional cards, write to FDA, HFZ-220, 1350 Piccard Dr.,Rockville, MD 20850

HELP REDUCEX-RAY RISKS & COSTS

Feel free to ask your doctor how an x-ray will help with thediagnosis and treatment.

Don't refuse an x-ray if there's a clear need for it. Remember,the risk is small.

Ask if a gonad shield can be used for yourself and for yourchildren during x-rays of the abdomen.

Tell the doctor or x-ray personnel if you are, or might bepregnant, before having an x-ray of the abdomen.

Don't insist on an x-ray if the doctor explains there is no needfor it.

DATETYPE OF

EXAMREFERRINGPHYSICIAN

ADDRESS WHEREX-RAYS ARE KEPT


NCRP 2008? US Population Dose

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Radon Medical Internal Cosmic Terrestrial Other

Source

mS

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ear

1987 - 3.62003 - 6.3

CT 1.45Nuclear 0.70Rad. & Fluoro 0.60 Interventional 0.40Other 0.02

07 NCRP PRELIMINARY


FDA Poster Child

© S. Balter 2008SB0802 IHE - 10

Why capture dose data?

• Patient Risk Supervision– Deterministic– Stochastic (not really applicable to an individual

patient)• Quality Assurance

– Departmental vs. Guidance Levels– Local deviations

• Equipment• Operators

– CQI process

• Regulatory Mandate

© S. Balter 2008SB0802 IHE - 11

How much to capture?

• Stochastic risk to the population– Collect everything?– Sampling

• Deterministic injury potential– Collect data on every procedure

where injury is possible

• Quality Assurance– Collect everything (for local use)

© S. Balter 2008SB0802 IHE - 12

Data elements

• Direct dose measurements

• Technical settings of equipment

• Irradiation geometry

• Patient and procedure data

© S. Balter 2008SB0802 IHE - 13

Modalities

• Radiography, Mammography, and Fluoroscopy– Closed system with digital image capture– Independent image receptor with CR or DR– Film/screen image receptor

• Dental Radiography– DR image receptor– Film image receptor

• Computed Tomography

© S. Balter 2008SB0802 IHE - 14

Fluoroscopy - 2008

• All images via common digital video channel

• Feedback loop for Automatic Dose Rate Control (ADRC)

• Copper spectral shaping filters

• (Flat detector)• IEC 60601-2-43

© S. Balter 2008SB0802 IHE - 15

Issues 2008

• DICOM header data usually only exists when digital images are saved.

• MPPS report is often an exact mirror of the headers of saved images.

• No info usually available– Procedures without any saved images– Procedures partially saved images– Repeated exposures

© S. Balter 2008SB0802 IHE - 16

Available dose metrics

• Reference Point Air Kerma (Ka,r )– IEC 60601-2-43 (2000)– FDA (2005)

• Kerma Area Product (PKA)

– IEC 60601-2-43 (2000)– Common in Europe

• Fluoroscopy Time ± Number of Images

• Skin Dose Maps

© S. Balter 2008SB0802 IHE - 17

Analysis using DICOM header or MPPS

-50

-40

-30

-20

-10

0

10

20

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0:00 0:15 0:30 0:45 1:00 1:15 1:30 1:45 2:00 2:15

Time from start of procedure

Be

am

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LA-RA

CR-CA

LAO CRA

RAO CAU

© S. Balter 2008SB0802 IHE - 18

DICOM-DOSE Project

• DICOM Limitations– Data is bound to DICOM digital images.– Little or no data about non-stored images.– DICOM MPPS process needs tight coupling to an

informatics system

• Project– The need for complete documentation of interventional

procedures was presented to the IEC (62b MT38) by DIMOND

– Co-developed with DICOM committee– Initial version covers all projection radiography and

fluoroscopy (except mammography).– Mammo and CT extensions are foreseen.

© S. Balter 2008SB0802 IHE - 19

-50

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DD simulation using service log

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Time from start of procedure

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© S. Balter 2008SB0802 IHE - 20

RDSR Outputs• Near Real Time

Updated RDSR transmitted over network after each irradiation

• Post ProcedureComplete RDSR transmitted over network once

procedure is marked as complete.

• Sneaker NetRDSRs stored in imaging system extracted on storage

media and physically carried to AGENTIEC PAS specifies storage of at least

500 RDSRs with or without network connections.

• AGENT LOCATIONSPACS, RIS, Independent

© S. Balter 2008SB0802 IHE - 21

IEC PAS Overview

• Claimed compliance with an IEC standard assures minimum requirements

• IEC Compliance LevelsBased on maximum expected cumulative Air

Kerma at the IEC interventional reference point for any normal use of the equipment

1: Stochastic Risk Only (< 2 Gy expected)2: Deterministic Injury Conceivable (> 2 Gy)3: Deterministic Injury Possible (> 7 Gy)

Presently a place-holder in the standardImplementation planned when adequate dose-mapping software is available

© S. Balter 2008SB0802 IHE - 22

IEC Level 1

Equipment where the estimated maximum cumulative Air Kerma for any examination (study) is expected to be less than two (2) gray (Gy) for all normal uses

The defining dose is the cumulative dose for a complete examination at the interventional reference point defined in IEC 60601-2-43 (for equipment capable of measuring Air Kerma at this point or

The equipment manufactures estimate of the cumulative dose for a complete examination at the closest point to the X-ray source where the patient’s skin might be placed

© S. Balter 2008SB0802 IHE - 23

Not only stored digital images

• The RDSR is a DICOM object that is independent of any stored images

• Valid RDSRs can be generated by equipment used to produce stored or not-stored analog or digital images

• IEC specifies that RDSRs be stored by the imaging equipment (downloaded locally or via a network)

© S. Balter 2008SB0802 IHE - 24

Verification of displayed “dose”

• Accuracy of display– IEC ± 50% (RPDose &KAP)– FDA ± 35% (RPDose)– Stability usually better

• Usually validated at factory• Seldom validated by installers• When verified as part of QA

Should be able to maintain ± 20%

© S. Balter 2008SB0802 IHE - 25

Generic Cases

• Forget-about-it• Regulatory Requirement

– All Procedures– Reportable Procedures

• Institutional Quality Program– All procedures with subgroups for trending– Out of bounds procedures

• Stochastic Risk Estimates– Data from population (complete or sampled)– Individual patient (significant difficulties in validly using data)

• Potential Tissue Reaction– All patients at risk

• Standards of care– Establish reference (guidance) levels– Monitor radiation load on population and its sources

© S. Balter 2008SB0802 IHE - 26

Sources of Data

• X-ray producing equipment

• Manual data entry

• Robotic translation (straw man)

© S. Balter 2008SB0802 IHE - 27

Consumers of Data

• Quality management

• Research community– Generate reference levels– Estimate population risks

• Policy makers

• Individual providers (potential tissue reactions)

• Individual patients ???

© S. Balter 2008SB0802 IHE - 28

IHE and data collection issues

• Procedure Lexicon

• Accuracy of reported procedure names and description

• Accuracy of demographic data

• Accuracy of dosimetric data

• Missing data

© s. balter 2008 sb0802 ihe - 1 radiation dose data management ihe presentation – february 2008...

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