ACR Phantom Phantom Images. Overview Session 2 CT20 Patient dose15 Equipment Purchase/ Acceptance...
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Transcript of ACR Phantom Phantom Images. Overview Session 2 CT20 Patient dose15 Equipment Purchase/ Acceptance...
ACR Phantom Phantom Images
Overview Session 2
CT 20
Patient dose 15
Equipment Purchase/ Acceptance Testing 15
Questions 10
Personnel qualifications 20
Education and training 10
Questions 20
Patient Dose (A 3.0)
It is recommended that Diagnostic Reference Levels (DRLs) be used as guidance in the optimization of patient dose
DRLs are values related to patient dose using Dose Indicators which can be easily measured
dose-linear product (DLP) for CT or dose-are product (DAP) for radiography/radioscopy.
Conversion factors are available to convert from Dose Indicator values to Effective Dose (E)
Diagnostic Reference Levels
It is very difficult to ‘optimize’ patient dose However, it is relatively easy to decide those doses
which are clearly too high and unacceptable DRLs are derived from large surveys of
examinations in a region or country; usually the DRL is set at the 75% level of the distribution
BC CT Dose Survey 2004
Hospitals around BC were asked to provide data on routine head, chest, abdomen, pelvis CT
Data collected from 18 hospitals
BC Patient Dose - Head
0
500
1000
1500
2000
2500
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
Hospital #
DL
P (
mG
y.c
m) DRL
BC Patient Dose - Chest
0
200
400
600
800
1000
1200
1400
1600
1800
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
Hospital #
DL
P (
mG
y.c
m)
BC Patient Dose – Abdomen
0
200
400
600
800
1000
1200
1400
1600
1800
2000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
Hospital #
DL
P (
mG
y.c
m)
Reference Doses BC
* 75 percentile
Exam ReferenceDLP
Reference Dose mSv
mGy.cm
Head 1300 3
Chest 600 10.2
Abdomen 900 13.8
Pelvis 650 12.3
Abdomen-Pelvis 1100 18.7
Reference Doses
For other imaging systems the dose-area product (DAP) is the most convenient to use to evaluate patient dose
Should be a requirement on all new radiographic and radioscopic systems
Dose Area Product Meter
Dose Area Product detector Dose Area Product detector after collimator intercepts after collimator intercepts all radiation used both for all radiation used both for radiography and radioscopyradiography and radioscopy
X-ray X-ray TubeTube
CollimatorCollimator
X-ray X-ray fieldfield
5.2 Gy.cm2
DAP meterPACS
Patient Dose MonitoringIt is now technically possible to estimate patient dose
from most x-ray systems
Equipment Dose Indicator Status
CT Dose-length product DLP
Available on all CTs
Radiographic/
Fluoroscopic/
Angiographic
Dose-area product DAP
Available on all new units- can be retrofitted
CR Exposure Index (EI) of detector
All CR
Both DLP and DAP values are directly related to patient dose
CT Patient Dose Monitoring
Patient ID: Exam No:
Exam Description: CABD2PCT Date:
Dose Report
Series Type Scan Range
(mm)
CTDIvol
(mGy)
DLP
(mGy.cm)
Phantom
cm
1 Scout - - - -
2 Helical S111-I319 12.77 577.08 Body 32
1/1
Diagnostic Reference Levels
Radiographic Exam View DRL
Generalized Conversion Coefficients DAP to Effective Dose
Gy.cm2 mSv per Gy.cm2
Skull PA 2 0.03
Lat 1.3 0.03
Chest PA 0.15 0.12
Lat 0.6 0.1
T Spine Lat 7 0.1
AP 4 0.2
L Spine Lat 11 0.1
AP 5 0.2
Abdomen PA 4 0.1
AP 4 0.2
Pelvis AP 4 0.3
Diagnostic Reference LevelsComplete Exams DRL DAP to E
FluoroscopyTime
Gy.cm2 mSv per Gy.cm2 minutes
Barium Swallow 9 0.26 2.3
Barium Meal 14 0.26 2.7
Ba follow thru 12 0.26 2.2
Barium enema 24 0.26 2.8
IVP 14 0.2
MCU 12 0.2 1.9
Nephrostography 12 0.2 4.8
Retro Pyelogram 13 0.2 3
T tube cholangiogram 8 0.26 1.9
Sinography 9 2.1
Small bowel enema 40 9.2
Venography leg 7 2.2
Coronary angiography 29 0.2 4.5
Diagnostic Reference Levels
Complete Exam DRL DAP to EFluoroscopy
Time
Gy.cm2 mSv per Gy.cm2 minutes
Biliary Drainage 50 0.26 15
Facet joint injection 5 0.2 1.8
Hickman line 3 0.1 1.4
Nephrostomy 14 0.16 5.1
Esophageal stent 25 0.1 5.9
Esophageal dilation 11 0.1 2.8
Pacemaker 11 0.1 8.2
PTCA single stent 50 0.2 26
Diagnostic Reference Levels
Exam
EU DRL
Dose Area Product
Gy cm2
VGH DR
Ave Dose Area Product
Gy cm2
DAP to E Conversion
Factor
mSv/Gy cm2
Skull AP 4 0.2 0.03
Chest PA 0.2 0.15 0.12
Abdomen AP 7 2.3 0.2
Pelvis AP 5 1.4 0.2
Barium enema 30 0.2
IVP 14 0.1
Coronary Angiography
35-75 120* 0.15
*diagnostic + angioplasty
Overview Session 2
CT 20
Patient dose 15
Equipment Purchase/ Acceptance Testing 15
Questions 10
Personnel qualifications 20
Education and training 10
Questions 20
Acceptance Testing (C 1.0)
“The following steps must be included for the establishment of QC procedures Clear performance specifications Baseline performance Reference images QC Action Levels”
Quality Control
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
Acceptance testing
Items for Acceptance Testing Film CR DR Radioscopic CT
1.0 Identification
1.1 Initial Inspection and Inventory X X X X X
1.2 Inspection of Documentation X X X X X
2.0 Visual and Functional Tests
2.1 Mechanical Properties X X X X X
2.2 Safety Systems X X X X X
Acceptance testing
Items for Acceptance Testing Film CR DR Radioscopic CT
3.0 Performance Evaluation (X-ray Generator)
3.1 X-ray Tube Voltage X X X X X
3.2 Current Time Product X X X
3.3 Loading Time X X X
3.4 Radioscopic Timer and Chronometer X
3.5 Beam Limitation and Indication X X X X X
3.6 X-ray Beam Filtration X X X X
3.7 Automatic Exposure Control X X X
3.8 Automatic Intensity Control X X
3.9 Radiation Output X X X X X
3.10 Maximum Air Kerma Rate X
3.11 Phantom (Entrance) Dose (Rate) X X X X X
Acceptance testing
Items for Acceptance Testing Film CR DR Radioscopic CT
4.0 Performance Evaluation (Image Receptor)
4.1 Exposure Index X X
4.2 Dynamic Range X X X
4.3 Spatial Resolution X X X X X
4.4 Contrast Detectability X X X X X
4.5 Uniformity X X X
4.6 Artifacts X X X X X
4.7 Digital Detector Residual Image X X
4.8 Noise X X X
4.9 Modulation Transfer Function X X
4.10 Mean CT Numbers (calibration and linearity) X
4.11 Tomographic Section Thickness X
4.12 Axial Patient Positioning Accuracy X
4.13 Positioning of Patient Support X
Equipment Purchase
This new Code has implications for new equipment
Code 20A was usually a condition for RFPs With Code 35 much more is involved
Performance of the x-ray system At acceptance In routine operation
Performance of the image receptor At acceptance In routine operation
Ability to determine patient dose indicators At control For transfer to PACS
Equipment Purchase
Will service contracts cover the increased testing? For new units For existing equipment
At the moment radiation doses such as CTDI are not measured by any of the companies as part of QC
What about equipment not on service contract?
Overview Session 2
CT 20
Patient dose 15
Equipment Purchase/ Acceptance Testing 15
Questions 20
Personnel qualifications 20
Education and training 10
Questions 20
Personnel Qualifications
Responsible User
X-ray equipment Operator
RSO
Responsible User
Possess qualifications required by applicable province or statute eg RCPSC, CAMRT
Acquire refresher training according to similar standard
Ensure equipment functions correctly Ensure equipment is used correctly Establish safe operating procedures Promulgate radiation safety for staff Ensure radiation levels are within regulatory limits
X-ray Equipment Operator
Possess qualifications required by applicable province or statute eg RCPSC, CAMRT
Acquire refresher training according to similar standard
Have documented training Ensure equipment is used correctly Establish safe operating procedures Promulgate radiation safety for staff Ensure radiation levels are within regulatory limits
Overview Session 2
CT 20
Equipment Purchase/ Acceptance Testing 15
Patient dose 15
Questions 20
Personnel qualifications 20
Education and training 10
Questions 20
Education and Training - Standards
Collation of Standards/Action Levels Although frequency of tests is well covered
in SC 35 not all Action Levels are defined.
Education and Training - QC
PACS and image display systems QC Visual Measurements
Image receptor quality tests and calibration CR DR DF CT
Education and Training - Dose
Patient dose measurement Dose- area product (DAP) in radiography
and radioscopy. Calibration of meters. CTDI in computed tomography
The Future
The only perfect science is hindsight