Safety Code 35

John Aldrich PhD FCCPMRegional Leader Clinical Physics

Kevin Hammerstrom RTNMQC Coordinator

Department of RadiologyVancouver Coastal Health

University of British Columbia

Medical X-ray Safety Codes

Safety Code 20A (1976)

Recommended safety procedures for the installation, use and control of x-ray equipment. Mainly concerned with the x-ray output parameters of the equipment

Only film processor QC defined

Safety Code 35 (2008)(two drafts in 2005 and 2007)

Comprehensive safety procedures for the installation, use and control of x-ray equipment.

Includes all x-ray systems Increased emphasis on patient

dose 25% of the Code is concerned

with QC of digital imaging systems

Safety Code 35

A1. Responsibilities of owners and users (4)A2. Procedures for minimizing staff dose (2)A3. Procedures for minimizing patient dose (6)B1. Facility shielding (3)B 2-6. Equipment performance (15)C 1-3. Quality Control (17)Appendices (30)

Decoding the Code

Handout includes all slides in our presentations Attached sheets have all the tables enlarged References are to details of the tests in the Code

eg D1 is the first daily test listed, W1 – weekly, M1 - monthly, Q1 – quarterly, SY1 – semi-annually, Y1 - Annual

Normal Font – Required Test (“must do”)Italics - Recommended Test (“recommended”)Required Tests currently recommended by RPS

Overview Session 1

Requirements for all systems 20

Radiation Protection 10

Questions 10

Radiography (Film/DR/CR) 20

Radioscopy (Fluoroscopy, Angio, DF) 20

Questions 10

LUNCH

Overview Session 2 After Lunch

CT 20

Equipment Purchase/ Acceptance Testing 15

Patient dose 15

Questions 10

Personnel qualifications 20

Education and training 10

Questions 20

Daily Quality Control Tests

Quality Control Procedures Film-

based All Systems

Daily Quality Control Tests

Equipment Warm-up (D1)According to manufacturers instructions

Can include auto calibration eg CT

Meters Operation (D2) Meter, visible and audible indicators should function

Equipment Conditions (D3)Visual inspection for loose or broken components, ease of

movements

Darkroom Cleanliness (D5) (M DAP)

Film Processor Function (D6) (M DAP)

Overall Visual Assessment of Electronic Display Devices (D7)

Display SMPTE or QC pattern for general image quality of all Radiologists’ workstations

Check 5% and 95% areas visible

Normal Font – Required Test (“must do”)Italics - Recommended Test (“recommended”)Required Tests currently recommended by RPS

Weekly and Monthly Tests

Quality Control Procedures All Systems

Weekly Quality Control Tests

Viewbox condition (W2) Visual inspection for cleanliness, colour, illumination

Laser Film Printer Operation (W3)

Print pattern such as SMPTE or PQCCheck for 0/5% and 95/100% patch visibility

OD of 10% to 90% patchesNo artifacts or geometrical distortion

Monthly Quality Control Tests

Darkroom Temperature and Humidity (M2) Temp: 18-23C; Humidity 40-60%

Darkroom Light Conditions (M3) Visual check for light tightness

Film Processor Operation (M4) Temp ± 0.5C; Developer and fixer correct (M DAP)

Electronic Display Device Performance (M6) Display pattern such as SMPTE or QC on all image display devices

Laser Film Printer Operation (M7)As W3 plus measurement of optical density of the 10% to

90% grey scale

Normal Font – Required Test (“must do”)Italics - Recommended Test (“recommended”)Required Tests currently recommended by RPS

Quarterly and Annual Tests

Quality Control Procedures All Systems

Quarterly Quality Control Tests

Interlocks (Q2) These are not usually used on diagnostic doors

Annual Quality Control Tests

Safelight Test (Y1) Expose film for 2 min

Film/Screen Contact (Y2) Image mesh and check

Viewboxes (Y26) Check luminance, uniformity, homogeneity, ambient light

Electronic Display Device Performance (Y27) All clinical workstations must be calibrated for luminance, distortion, resolution and noise

Integrity of Protective Equipment (Y28) Lead aprons, glasses, integral shields

General Preventive Maintenance (Y29) As per manufacturer

Normal Font – Required Test (“must do”)Italics - Recommended Test (“recommended”)Required Tests currently recommended by RPS

Display QC

Daily (D7) – for clinical interpretation Radiologist at each login

Find suitable SMPTE test pattern Make accessible on PACS Test using various user logins/profiles Alert radiologists of requirement, frequency, and

procedure

Should see both 5% and 95% squares if calibrated properly

Problems with inconsistencyLeft Display – 5% visible / 95 % not visible Right Display – 5% not visible / 95 % visible

Display QC

Monthly (M6) All displays

TechnologistPACS administratorBiomed

SMPTE test pattern / test

pattern generator / vendor

Display QC

Annually (Y27) Clinical interpretation and interventional use

QC Coordinator PACS administrator Biomed

SMPTE test pattern / test pattern generator / vendor QC software and photometer

Viewbox QC

Weekly visual inspection (W2)

Cleanliness

Viewing area discolouration

Improper luminance

Clean, replace plastic or bulb if necessary

Technologists / Biomed / Plant services

Viewbox QC

Yearly inspection (Y26) Technologist / physicist

Maintain logsheet

Luminance > 2500 cd/m2 Should

Light output uniformity +/- 10% Should

Light output homogeneity +/- 20% Should

Ambient light control < 50 lux (50 cd/m2)5-10 lux recommended (5-10 cd/m2)

Must

Viewbox QC

Laser Film Printer QC

Weekly (W3) Use same viewbox panel

Print SMPTE from PACS workstation or from printer menu

View 5% and 95% grayscale squares

Maintain logsheet

Laser Film Printer QC

Laser Film Printer QC

Monthly (M7) Use same viewbox panel

Print SMPTE from PACS workstation or from printer menu

Measure optical density of grayscale gradient squares, geometrical distortions, artifacts

View 5% and 95% squares and compare densitometer readings

Maintain logsheet

Laser Film Printer QC

Overview Session 1

Requirements for all systems 20

Radiation Protection 10

Questions 10

Radiography DR/CR 20

Radioscopy (Fluoroscopy, Angio), DF 20

Questions 10

LUNCH

Radiation Protection

Radiation Safety Officer (1.4) Room Shielding (5.0) Lead aprons (4.1)

Radiation Safety Officer

There must be a Medical Physicist or Radiation Safety Officer to advise on all aspects of Radiation Safety Planning, registration, inspection Working conditions, procedures Classification of personnel, dosimetry Record keeping, investigations

Radiation Protection - Shielding

Design of Shielding Recommend NCRP 147

(2004) methods which are based on empirical data

(although Appendix is NCRP 49 (1976) which will tend to overshield rooms)

Surveys of rooms must be done for new or altered rooms (equipment, use or vicinity Sec A5)

Design shielding

Check lead installation

Measure radiation in surrounding areas

Lead Aprons

Lead equivalence of aprons SC 20A

<150 kVp 0.5 mm

SC 35 < 100 kVp: 0.25 mm 100< kVp <150: 0.35 mm >150 kVp: 0.5 mm

Lead apron QC

Annually (Y28) Radiographic / radioscopic Rejection if total defective area > 670 mm2

Thyroid and reproductive areas < 5 mm diameter equivalent total

Overview Session 1

Requirements for all systems 20

Radiation Protection 10

Questions 10

Radiography DR/CR 20

Radioscopy (Fluoroscopy, Angio), DF 20

Questions 10

LUNCH

Overview Session 1

Requirements for all systems 20

Radiation Protection 10

Questions 10

Radiography DR/CR 20

Radioscopy (Fluoroscopy, Angio), DF 20

Questions 10

LUNCH

Equipment Life Cycle

Baseline value determination

Device use period

Next constancy testing

Data evaluation

Within the

established criteria

Remedy

Acceptance testing

FAIL

PASS

Acceptance testing New equipment Conformance to manufacturer’s

specifications/RFP Baseline performance

Routine performance evaluations

Specific tests performed at regular intervals

Consistency checks Evaluate malfunctioning or out-

of-spec equipment

Imaging QC Principles

Proactive QC rather than Reactive QC

Test tool/phantom Standard imaging

parameters/conditions Scheduled testing (Daily/Weekly)

Defined and objective acceptance/rejection criteria

Patient replaces the phantom

Non-standard imaging parameters/conditions

Frequent testing (every patient)

Ill-defined and subjective acceptance/rejection criteria

System performance rated BEFORE clinical imaging

System performance rated AFTER clinical imaging.

Which approach would you prefer if you were a patient??

Radiographic Systems

Projection radiography Film

Digital detectors (DR)

Computed radiography (CR)

Weekly Radiographic Tests

Quality Control Procedures Film CR DR Comments

Weekly Quality Control Tests

Visual Inspection of Imaging Systems W1 W1 W1 Inspect screens/CR plates/DR housing

Viewboxes Condition W2 W2 W2 Cleanliness, luminance

Laser Film Printer Operation W3 W3 Print pattern such as SMPTE

Normal Font – Required Test (“must do”)Italics - Recommended Test (“recommended”)Required Tests currently recommended by RPS

Monthly Radiographic Tests Quality Control Procedures Film CR DR Comments

Monthly Quality Control Tests

Cassette, Screen, and Imaging Plate Cleaning

M1 M1 Clean screens/CR plates/DR housing

Darkroom Temperature and Humidity Conditions (DAP)

M2 Temp: 18-23C; Humidity 40-60%

Darkroom Light Conditions M3 Visual check for light tightness

Film Processor Operation M4 Temp ± 0.5C; Developer and fixer

correct

Retake Analysis M5 M5 M5 For film, CR and DR

Electronic Display Device Performance M6 M6 Display pattern such as SMPTE on

all image display stations

Laser Film Printer Operation M7 M7

Print pattern such as SMPTECheck for 0/5% and 95/100% patch

visibilityOD of 10% to 90% patches

No artifacts or geometrical distortion

Normal Font – Required Test (“must do”)Italics - Recommended Test (“recommended”)Required Tests currently recommended by RPS

Annual Radiographic Tests (1)

Quality Control Procedures Film CR DR Comments

Annual QC Tests

Safelight Test Y1 Expose film for 2 mins in room

Film/Screen Contact Y2 Image mesh and check

Accuracy of Loading Factors Y3 Y3 Y3 mAs Linearity

Radiation Output Reproducibility Y4 Y4 Y4 Reproducibility

Radiation Output Linearity Y5 Y5 Y5 Output with mAs

X-ray Beam Filtration Y6 Y6 Y6 HVL

Automatic Exposure Control Y7 Y7 Y7 Check AEC for all kVps and thicknesses

X-ray Field and Light Field Alignment

Y8 Y8 Y8 Congruency of x-ray beam and light field edges

X-ray Beam Collimation Y9 Y9 Y9 Congruency of x-ray beam and light field centres

Normal Font – Required Test (“must do”)Italics - Recommended Test (“recommended”)Required Tests currently recommended by RPS

Annual Radiographic Tests (2)

Quality Control Procedures Film CR DR Comments

Image Quality

Grid Performance Y10 Y10 Y10 Check uniformity and movement of grid

Exposure Index Y12 Y12 Exposure Index versus Dose 1 to 50 Gy

Noise, Uniformity and Image Artifacts

Y14 Y14 For above range of dose measure noise in center and each quadrant

Check for artifacts

Spatial Resolution Y15 Y15 Y15 Line-pair or Leeds phantom

Contrast Detectability Y16 Y16 Y16 Leeds phantom

Digital Detector Residual Images Y17 Y17 Take image at 50 Gy then zero; check for artifacts

Phantom Dose Measurements Y18 Y18 Y18 Measure dose at surface of standard phantom eg 20 cm PMMA

DAP Meter Calibrate

Normal Font – Required Test (“must do”)Italics - Recommended Test (“recommended”)Required Tests currently recommended by RPS

Digital Imaging

Any sufficiently advanced technology is indistinguishable from magic… Arthur C Clarke 1961

Digital X-ray Systems

Direct Radiography DR Formation of image without a secondary

read-out device

Computed Radiography CR Use of storage phosphor plate usually in a

cassette-based system

Digital System QC

FilmDeveloped

AndFixed

Detector ReadingViewedDisplay

DigitalProcessing

StoredPACS

QC of the digital systems is an additional requirement – in addition to the usual x-ray performance tests

- it is not performed magically

DR, CR and DF – Extra QC

Dose CalibrationDose Calibration Spatial ResolutionSpatial Resolution Low ContrastLow Contrast UniformityUniformity ArtifactsArtifacts

Dose Calibration

Each system should be calibrated according to the manufacturers protocol, as they are all slightly different

General set-up Arrange for defined dose at surface of cassette at

80 kVp Expose and read image Record Exposure Index

The image can also be used to check for uniformity, linearity and artifacts

Image Quality

All CR and some DR/DF manufacturers have custom Image Quality phantoms and automatic software to analyze image quality

Resolution and Contrast

Any high contrast resolution phantom can be used to provide comparative information

Low contrast resolution is one of the most difficult parameters to measure. There are several phantoms and measurement is subjective, so consistent technique is essential

Image Noise is usually be a good indicator of consistency

Digital Radiography QC

Many DR systems require more frequent calibration of the uniformity eg every month Flat field measurement (uniform Cu orAl plate)

Uniformity correctionNoiseArtifacts

Contrast-detail and resolution phantom

CR & DR QC

• Weekly visual inspection (W1)• Dust / dirt

• Clean if necessary

• Technologist

• Monthly inspection / cleaning (M1)• Dust / dirt / damage

• Clean each IP. Replace damaged IPs.

• Technologist

• Maintain logsheet

CR QC