Transcript Slide 1

Fri 30th Aug 2013
Session 3 / Talk 4
14:30 – 14:50
HEAPHY 1 & 2
PLENARY
Tony COTTERILL
ABSTRACT
This presentation will be in two parts:
Under the Radiation Protection Act 1965 practitioners require a license to use irradiating apparatus and/or
radioactive materials for medical imaging. Through a license condition licensees are required to report to the
regulatory authority specified radiation incidents involving the exposure of patients.
In diagnostic radiology notified radiation incidents are generally of low dose and consequently minimal risk.
However, a significant proportion of notified incidents involve computerized tomography scans where patient doses
are more significant. Also, on rare occasions incidents have included procedures involving the injection of patients
with contrast media or radiopharmaceuticals. Causes of incidents include clerical errors, failure of staff to follow the
so-called three-point check (e.g. name, date of birth and address), and referral errors such as the mislabeling of a
request form.
This presentation will give a summary of reported incidents in diagnostic radiology between July 2009 and the end
of November 2011.
The National Radiation Laboratory (NRL) has surveyed the use of conventional plain radiography in New Zealand
since 1983. Since NRL's last supplemental survey in 1992 there have been improvements in technology, particularly
Specialist
Science
Solutions
with the widespread transition from film to
digital imaging
indicating
the need for a new survey. The most recent
survey was carried out by NRL in 2010 and involved collecting data nationally. This presentation reports the
Manaaki Tangata Taiao Hoki
findings for this latest survey and presents national
diagnostic reference levels
protecting people and their environment through science
Diagnostic Radiology:
1/ A Summary Of Reported Radiation Incidents
2/ The Results of a National Survey Of Patient
Doses In Conventional Plain Film Radiography
Tony Cotterill, Glenn Stirling
National Centre for Radiation Science
(formally the National Radiation Laboratory)
Specialist Science Solutions
Manaaki Tangata Taiao Hoki
protecting people and their environment through science
ESR - a Crown Research Institute
• Established July 1992
• Government owned
• One of eight CRIs
• Covered by CRI Act (1992)
© ESR 2012
NCRS (formally NRL) provision of
services
•
•
National training centre
- RPS course
- RPO course (non-medical)
- Regulatory Core of Knowledge
- Bespoke training courses
Radiation Protection Advisor (RPA)
- corporate RPA
- senior medical/health physicist as the
portfolio manager
- simplicity of a single contract for the provision
of all required radiation protection advice and
services
- comprehensive and flexible and cost effective
© ESR 2012
Incident reporting
• To Ministry of Health’s ORS
• A radiation incident involving the exposure of a patient to a
radiation dose much greater than intended
-
‘much greater than intended’ guideline multiplying factors
-
high dose eg, CT
medium dose eg, AP abdomen
low dose eg, chest
2
10
20
• A radiation exposure of a patient where none was intended, as
in the case of mistaken identity
• A radiation exposure of the embryo/foetus where the
exposure had not been included in the justification process
• An unexpected skin injury to a patient resulting from a
prolonged radiation exposure in an interventional procedure
© ESR 2012
Tony Cotteril 5
Reported main cause of incidents:
July 2009 to December 2011
70
60
No. of Incidents
50
171 reported
~ 6 per month
63 major centres
40
30
20
10
0
Equipment failure
© ESR 2012
Inadequate procedures
Human error
Clerial error
Referrer error
Other
Tony Cotteril 6
Analysis of causes (1)
Cause
Additional details provided on causes
Equipment
failure.
These include:
Limited possible actions as faults were

Patients administered radiopharmaceuticals just unpredictable.
prior to imaging equipment failure.

Servicing error on fluoroscopy unit.

CR cassette failure.

Image storage computer failure.

Image processor failure.
Inadequate
procedures.

Human error.
Most involved misidentification of the patient.
© ESR 2012




Corrective
and
preventive
actions taken by radiology
departments
Hand-over issues when main ordering system that Process review and staff training.
had been down was restored.
Hand-over issues between ED and Radiology.
Incorrect patient identification.
Accidental CR cassette erasure.
Inadequate training of staff on x-ray equipment.


Process review and staff training.
More consistent application of the
three-point check.
Tony Cotteril 7
Analysis of causes (2)
Referral incorrectly entered on to RIS.

CT images accidentally deleted.

NM images accidentally corrupted while 
attempting amendment.
Incorrectly booked for an x-ray when only a US
had been requested.
Misinterpreted ambiguous exam coding.
Patient
previously
administered
with
radiopharmaceutical, mistakenly turned away
when returned for scan.
Process review and staff training.
Computerised referral systems.
Computerised post-processing of
images.
Referrer error.
Most involved referral forms with inaccurately 
completed clinical details (eg, forms where the incorrect
pre-printed patient’s details label had been inadvertently 
attached), or duplicate requests.
Checking of clinical details with
patients when presenting.
Computerised referral systems.
Other.
Mostly due to patients not knowing that they were 
pregnant.

Staff training.
Consideration of the use of
pregnancy tests for the high dose
abdominal CT procedures.
Clerical error.






© ESR 2012
Tony Cotteril 8
Incidents involving: July 2009 to
December 2011
120
100
No. of Incidents
80
60
40
20
0
Pregnant patient
© ESR 2012
Skin injury
Wrong Patient
Other
Tony Cotteril 9
Modalities of incidents; July 2009
to December 2011
120
100
No. of Incidents
80
60
40
20
0
Nuclear Medicine
© ESR 2012
CT
Fluoroscopy
Plain Radiography
Tony Cotteril 10
Patient dose of incidents; July
2009 to December 2011
90
80
70
No. of Incidents
60
50
40
30
20
10
0
<1
1 to 10
>10
Effective dose (mSv)
© ESR 2012
Tony Cotteril 11
2/ Results of a National Survey Of
Patient Doses In Conventional
Plain Film Radiography
© ESR 2012
Tony Cotteril 12
Number of conventional radiography
procedures (excluding theatre mobiles)
Year
Population
(millions)
Number of x-rays
per year
Number of x-rays
per 1000 of
population
1983-84
2010
3.22
4.23
1.5 million
2.2 million
470
530
• ~ 13% increase per capita
• an average a person will be x-rayed once every
two years
• Approximately 90% digital
© ESR 2012
Tony Cotteril 13
Numbers of conventional radiography
procedures for different age groups
450
400
Patients per 1000 x-rays
350
300
250
200
150
100
50
0
0-<1
1-4
5-9
10-14
15-19
20-24
25-29
Age group (years)
30-39
40-49
50-59
>-59
1983-84 survey
2010 survey
• Marked increase in the number x-rays of older adults with
less paediatric x-rays
• Demographics (eg, ageing population) alone does
not account for this shift.
© ESR 2012
Tony Cotteril 14
Relative frequency of the main types of
conventional radiography procedures
Year
Type
Limbs & extremities
Pelvic region,
lumbo-sacral spine
Chest, heart, lungs
Ribs & sternum,
thoracic spine,
shoulder girdle
Head, neck
Abdominal soft
tissue
1983-84 (%)
31
2010 (%)
33
12
25
35
22
5
10
10
7
7
3
• The contribution of conventional plain radiography
procedures to the diagnostic radiology population
dose per capita has dropped (243 to 99 µSv per capita per annum)
This is probably because of a shift of higher dose procedures to
other modalities such as CT
© ESR 2012
Tony Cotteril 15
U.S. population exposure 2006
~ 6 mSv per person
62 million CT examinations
National Council on Radiation Protection and Measurement. Report No. 160.
© ESR 2012
Tony Cotteril 16
Diagnostic Reference Levels (DRL) in terms
of ESD (mGy) compared with other studies
Projection
(70 kg patient)
Chest PA
Chest LAT
Lumbar spine
AP
Lumbar spine
LAT
Pelvis AP
Abdomen AP
British
Institute of
Radiology
(UK) (1986)
(Current
values in
CSP5)
0.3
1.5
HPA (UK)
(2005)
AAPM (USA)
(2005)
This survey
(NZ)
(2010)
0.2
0.6
0.3
-
0.3
1.1
10
5
7
7
30
11
-
27
10
10
4
4
6
5
7
• Little change in DRL
© ESR 2012
Tony Cotteril 17
Conclusions
• There has been a small increase in the number of conventional
plain radiography procedures being performed compared
to 1983/84
• The age distribution of patients undergoing conventional plain
radiography procedures, since NRL’s survey in 1983-84, shows a
marked increase in the x-raying of older adults with
less paediatric x-rays. Demographics alone do not account for
this shift
• The contribution of conventional plain radiography procedures to
the diagnostic radiology population dose per capita has dropped.
This is because of a shift of procedures to modalities such as CT.
• Little change in the DRL
© ESR 2012
Tony Cotteril 18
© ESR 2012