It is a presentation on QA Test performed in a HDR BRACHY UNIT

1. QUALITY ASSURANCE TESTS OF REMOTE AFTERLOADING
BRACHYTHERAPY UNIT
PRESENTED BY_ Champak Mudoi (PS-211-826-0015)
Taushiful Hoque (PS-211-826-0054)
MSc. 3rd semester, Radiological Physics
Dr. B. Borooah Cancer Institute, Gopinath Nagar

2. Table of Contents
 Introduction
 Types of QA test in HDR Brachytherapy & their significance
 References
 Brief overview of Brachytherapy
 Quality Assurance

3. Introduction
What is Brachytherapy ?
 Greek derivation = Short range therapy
 First conformal radiation therapy
 Sealed source placed in or in contact with the tumor providing high dose to the
tumor with small volumes of normal tissue irradiated
 Two main types :
1. Intracavitary, in which the sources are place in body cavities close to the tumor
volume. Intracavitary treatments are always temporary, of short duration
2. Interstitial, in which the sources are implanted within the tumor volume. Interstitial
treatments may be temporary or permanent.

4. What is Quality Assurance ?
Quality Assurance is planned and systematic actions necessary to provide adequate
confidence that an item or a facility will perform satisfactorily in service as per design
specifications
The purpose of a Quality Assurance Program is the objective, systematic monitoring
of the quality and appropriateness of patient care. Such a program is essential for all
activities in Radiation Oncology. The Quality Assurance Program should be related to
structure, process and outcome, all of which can be measured.

5. Lists of QA in HDR Brachytherapy
 QA Tests : Mechanical
 QA Tests : Electrical
 QA Tests : Radiation
 QA Tests: Treatment Planning System
 QA Tests: Radiation Safety

6. QA Tests : Mechanical
1. Functioning of sensors like pressure, torque, optical : Satisfactory / No
2. Coupling between guide tube and unit : Satisfactory / No
3. Coupling between guide tube and applicator : Satisfactory / No
4. Coupling between drive cable and source : Satisfactory / No
5. Time taken to drive the source to "ON" positions : --------- sec
6. Time taken to withdraw the source to "OFF" position : --------- sec
7. Source guide free of kinks? : Yes/No
8. Mechanical integrity of applicators : Acceptable / Not acceptable
& position of shield, if any

7. Significance of QA Tests : Mechanical
 The mechanical integrity of a source must be checked at regular intervals by visual
inspection, leak testing and activity measurement. Applicators, because of their
repeated clinical use, undergo severe handling, cleaning and sterilization. Visual
inspection and radiographic evaluation of all applicators should be performed at
some pre-established frequency

8. QA Tests : Electrical
 Interlocks
 Source Safe Display
 Control Console Display
 Control Console Function

9. QA Tests : Electrical
 Interlocks
1.Treatment Room Door(s)
Provided? : Yes / No
Working? : Yes / No
2.Guide Tube & Treatment Unit
Provided? : Yes / No
Working? : Yes / No
3.Applicator & Guide Tube
Provided? : Yes / No
Working? : Yes / No
4.Emergency stop button to interrupt the irradiation
Provided? : Yes / No
Working? : Yes / No
 Source Safe Display
1.Treatment "OFF" indicator
Provided? : Yes / No
Working? : Yes / No
2.Treatment "ON" indicator
Provided? : Yes / No
Working? : Yes / No

10. QA Tests : Electrical
 Control Console Display
1.Treatment "OFF" indicator :: Provided? : Yes / No
Working? : Yes / No
2.Treatment "ON" indicator :: Provided? : Yes / No
Working? : Yes / No
3.Source ON/OFF indicator :: Provided? : Yes / No
Working? : Yes / No
4.Door interlock indicator :: Provided? : Yes / No
Working? : Yes / No
5.Retrieval of the source indicator :: Provided? : Yes / No
Working? : Yes / No
6.Retrieval of the dummy indicator :: Provided? : Yes / No
Working? : Yes / No

11. QA Tests : Electrical
 Control Console Function
1.Power switch
Provided? : Yes / No Working? : Yes / No
2.Parameter reset switch
Provided? : Yes / No Working? : Yes / No
3.Treatment `ON’ switch
Provided? : Yes / No Working? : Yes / No
4.Treatment `OFF’ switch
Provided? : Yes / No Working? : Yes / No
5.Emergency `OFF’ switch
Provided? : Yes / No Working? : Yes / No
6.Treatment and elapsed time display counters
Provided? : Yes / No Working? : Yes / No
7.Multi-channel indexer function and sequence displays
Provided? : Yes / No Working? : Yes / No
8.Back-up system(s)
Provided? : Yes / No Working? : Yes / No

12. QA Tests : Electrical
 Leakage and Contamination
 Positioning Accuracy and Uniformity
 Temporal Accuracy
 Source Strength Verification

13. QA Tests : Radiation
 Leakage and Contamination ---- ( Tolerance < 200 Bq)
(Using a wet swipe measure the maximum removable activity on the surface
of the source / source holder)
1. Removable activity on Source / Source holder : Bq
2. Contamination check done on (date) :
 Positioning Accuracy and Uniformity--- (Tolerance: ± 1 mm)
(use autoradiograph / radiograph wherever required)
1.Coincidence between dummy : ------------- mm
and active source positions
2.Accuracy of source position within the : -------------- mm
applicator
3.Reproducibility of dummy source position : -------------- mm

14. QA Tests : Radiation
 Temporal Accuracy----- (Tolerance: ± 1 %)
1. Timer error : --------------
2. Timer linearity : ---------------
3. End error : --------------- sec ('or' %)
 Source Strength Verification
1.Quoted source strength (as on ……………) : ----------- µGy. h -1 at 1m ( GBq / Ci )
2.Measured source strength (as on …………) : ---------- µGy. h -1 at 1m ( GBq / Ci )
3.Deviation between specified : --------- % (Tolerance: ± 3%)
and measured source strength
4.Deviation between measured : ------------- % (Tolerance: ± 5%)
mean and individual source strength

15. Significance of QA Tests : Radiation
 Positioning Accuracy and Uniformity test is very important :
 Source strength verification test is necessary to determine the change in source
strength (activity) with time. Calculated values, often obtained by decaying a prior
calibration, should be compared with measurements.
1. High dose gradient of the source
2. It is necessary to check that the unit will position the source millimetre accuracy at
predetermined positions along treatment catheter

16. QA Tests: Treatment Planning System
 Digitizer and Localization Software: (Tolerance: 3% or 1mm)
1.Accuracy of digitization of :
Point co-ordinates
2.Accuracy of data transfer from :
orthogonal radiographs
 Calculation Algorithm:
1.Source specification required for TPS : ………….. mCi / mg.Ra.Eq./ MBq / Ref. Air. Kerma Rate
2.Initial activity quoted by the supplier :
Current activity (with date) :
3.Factor used to convert quoted source strength for TPS input :
4.Agreement of source decay correction :
5.Agreement between TPS and published/manual calculation :
for single source, at relevant points
6.Agreement for multiple source loading : (Tolerance: 3% or 1 mm)
(Specify the procedure and the result)

17. Significance of QA Tests: TPS
 QA test of Brachytherapy treatment planning system (TPS) is important because the goal of the
Brachytherapy is to achieve a dose distribution that will treat the PTV without exceeding normal
tissue tolerance limits

18. QA Tests: Radiation Safety
 Gamma Zone Monitor
 CCTV
 Unit Leakage
 Survey of the Installation

19. QA Tests: Radiation Safety
 Gamma Zone Monitor:
Provided? : Yes / No
Working? : Yes / No
 CCTV
Provided? : Yes / No
Working? : Yes / No

20. QA Tests: Radiation Safety
 Unit Leakage
Measure the dose rate on top, bottom and four sides of the container at 5 cm from the
surface and one meter from the centre of source storage for source 'OFF’ condition:
1 2 3 4 5 6
Measured dose rate (µGy.h -1 ) at 5cm
from the surface of the source storage
(Tolerance: ≤ 100 µGy.h -1 )
Measured dose rate (µGy.h -1 ) at 1m from
the centre of the source storage
(Tolerance: ≤ 10 µGy.h -1 )
Note: The above tolerance limits are applicable when the unit is loaded with the maximum capacity.

21. QA Tests: Radiation Safety
 Survey of the Installation:
In the Figure below, mark the occupancy on all sides, above and below the
installation and measure the maximum dose rates at these locations, with the
applicator loaded with maximum source activity and kept at the centre of the
treatment table.
Minimum locations recommended for radiation protection survey of the installation
are:
A , A’, B, B’ – Just outside the four walls of the installation at the level of source 'S’
C – Roof of the installation, at the level of source 'S’
D – Just outside entrance door
E &F – At the level of air conditioners
G - Entrance to control panel
(S : Source position ; CP : Control Panel )

22. QA Tests: Radiation Safety
 Survey of the Installation
1.Source Activity (GBq/Ci) during survey :
2.Instrument(s) used for survey : 6.4.3
3.Measured dose rate (µGyh -1 ) at positions marked in Fig. 1:
A A’ B B’ C D E F G
Note: The quoted dose rate should be the maximum measured in the specified
direction

23. Significance of QA Tests: Radiation Safety
 The QA test of Radiation safety is important to ensure that the radiation
level of the installation is within permissible limit

24. References
 PROFORMA FOR ACCEPTANCE / QUALITY ASSURANCE TESTS OF REMOTE AFTERLOADING
BRACHYTHERAPY UNIT (RP&AD /Remote QA/ 01)
 AERB SAFETY CODE NO. AERB/RF-MED/SC-1 (Rev. 1) RADIATION THERAPY SOURCES, EQUIPMENT AND
INSTALLATIONS (Approved by the Board on November 4, 2010)
 KHAN’S The Physics of Radiation Therapy BY Faiz M. Khan, PhD & John P. Gibbons, PhD
 AAPM REPORT NO. 46 COMPREHENSIVE QA FOR RADIATION ONCOLOGY
 Radiation Oncology Physics: A Handbook for Teachers and Students by E.B. Podgorsak (Technical Editor)
 https://www.aapm.org/education/vl/vl.asp?id=3910

25. THANK YOU