work process in checking patient plans

1. Improvement of the
Independent MU
Hand-calculations in
Physicist Work
Process in Oncology
Department

2. Members
• Zamzarinah Kamarul Zaman
• Nurul Hidayah Moksem
• Zulaikha Jamalludin
• Munira Mohd Rejab
• Moktar Mat Nudin

3. Introduction –
Medical
Physicist in
Oncology
Department
Medical physics unit started the service when the
Oncology Department officially opened in 1997.
Medical physicist is part of radiotherapy team to
deliver accurate radiotherapy treatment to cancer
patients.
Routine duties including:
- Treatment planning
- Treatment plan checking
- Quality Assurance

4. Definition of
Terms
Linac- Treatment
machine that
uses high photon
energy.
TPS- Treatment
Planning System. A
computer to
generate patient’s
treatment plan
CT- Computed
Tomography
MU- Monitor Unit,
is a measure of
radiation output to
deliver certain dose
to specific depth
within a patient.
Independent MU
calculation-
calculations based
on water phantom
data gathered at
time of machine
commissioning.

5. Contouring
Process (MO)
Contouring
Review
(Oncologist)
Contouring
Breakdown
(Physicist)
Beam
Arrangement
(Physicist)
Optimization
Queue
(Physicist)
Optimization
Process
(Physicist)
Planning review
& approval
(Oncologist &
Physicists)
Patient
specific QA
(Physicist)
Plan
check
(Physicis
t & RTT)
Treatment
verification
(Physicist &
RTT)
Treatment
delivery (RTT)
Treatment Planning
- Workflow

6. Independent Plan Checking - Workflow
User origin checking &
isocentre checking
Prescribed dose
Beam parameter checking
on TPS
•Fields Naming/ID
•Beam Arrangement
•Setup Fields
Beam parameter
transfer to Tx sheet
Manual MU calculation
(for each tx field)
•Beam output
interpolation
•Correction factors
•Determine MU
deviation (≤ 5%)
Pass over for
2nd level plan
check (RTT)

7. Results &
Analysis
No of fields
Amount of time spent
on manual checking.
Amount of time (Minutes)
1
3 to 4
5 and above
45 minutes
and above
10
minutes
30 minutes

8. Results &
Analysis
475
628
853
49
84 105
10 18 27
0
100
200
300
400
500
600
700
800
900
2017 2018 2019
no of plans
no of plans with
human error
no of plans due to
misinterpretation

9. Problem Statement
• Problems with manual calculation:
• Longer time (10 min per field)
• Prone to human error (wrong data interpolation)
• Consumed more paper
• Bad handwriting (data misinterpretation)
• Consequences:
• Redundant plan checking (due to error rectification)
• Treatment delay

10. Problem Analysis
MU calculated from TPS
Manual data transfer from TPS
Manual beam output interpolation
Correction factors are determined manually
MU TPS vs Manual hand calculation is compared
Deviation ≤5%
2nd layer check
Error
Yes No
Treatment Delivery
Deviation ≥5%
Recheck
Recheck

11. Root cause analysis using Ishikawa diagram
(Fishbone)
MANUAL MU
Calculation
SYSTEM / PROCEDURES
PEOPLE
POLICIES
EQUIPMENTS / FACILITIES
Melepas aku
nak claim
Misinterpolation
Wrong beam
data referred
Wrong calculation formalism referred
Wrong dose prescription
Limited TPS availability
Lengthy process
Limited to 3DCRT plan only
2 LINACs – 2 beam data
Following updated international
recommendation
Paperless environment
Paper storage
Too many checklist

12. Objectives
• To shortened total plan checking
time
• To minimize and eliminate
human error
• To reduce paper usage
• To eliminate data
misinterpretation

13. Strategy for
improvement
No. Problem Remedial
Intervention
1. Plan checking time
The use of a
comprehensive
treatment
planning
calculation
tools/software
with systematic
data storage.
2. Number of plan with human
error
3. Amount of papers
4. Number of plan due to data
misinterpretation

14. Indicator
No. Indicator Standard
1. Plan checking time 5 min/plan
2. Number of plan with near
missed due to wrong MU
calculation
2 plans/month
3. Amount of papers 0 paper
4. Number of plan due to
data misinterpretation
1 plan/month

15. Process of
gathering
information
• Data treatment plan from
2017 – 2019:
• Study of total plan checking time
• Number of plan with human error
• Amount of paper usage
• Number of plan error due to data
misinterpretation

16. Thank you