In a Radiotherapy Department where cancer patients are being treated with high energy photons,gamma rays,electrons; all the radiation workers should be alert regarding radiation accidents & how to face the situation.

1. RADIATION EMERGENCIES AND
PREPAREDNESS IN RADIOTHERAPY
DEEPJYOTI SAHA
INTERN MEDICAL PHYSICIST
DEPARTMENT OF RADIATION ONCOLOGY
DR. B. BOROOAH CANCER INSTITUTE

2. Outline:
• Introduction.
• Radiation Accident & its types.
• Classification of Radiation Accidents in RT.
• Potential Accidents in RT.
• Basic safety measures & precautions to be
taken.
• Major Emergency situations in RT.
• Summary.

3. INTRODUCTION
• Radiation therapy aims to
– Destroy the cancer cells
– Using gamma rays, high-energy
x-rays, electrons, protons and
heavy ions .
– Generated from radioisotopes &
medical linear accelerators.

4. • Double-edged sword
– The cancer destroying radiation can
also be very harmful if it is not
planned & delivered properly.
It can cause-
– Deterministic effects.
– Stochastic effects .
Contd…

5. Radiation Accident & its types
• A Radiation Accident is an unintended event,
including operating errors, equipment failures or
other mishaps, the consequences of which are not
negligible from the point of view of protection or
safety.
• Radiation Accidents are classified into two types;
- External Radiation.
- Radioactive Contamination.

6. -> External radiation can results either in whole body
exposure , partial body exposure or localized skin
exposure.
-> Radioactive contamination can be External or
Internal.
External Radioactive contamination occurs from
spillage of RAM on skin or other extremities of
body.
Internal Radioactive contamination occurs most
often as a result of inhalation/ingestion of RAM in
finely divided form.
Contd…

7. Radiation Accidents in RT- Classification
Radiation Accidents in RT
Events relating to
equipments
Events relating to
individual patient.
Affects many
patients as
well as staffs.
Affects only
that patient

8. Potential Accidents in Teletherapy
1. Due to Machine malfunction :
a) Source stuck in cobalt unit.
b) Improper commissioning or acceptance testing.
c) Inadequate routine QA procedures.
d) Mishandling of Machine.
e) Use of LINAC in Service Mode.
f) Collision between Machine head & patient.
g) Failure of Interlocks.

9. Potential of Accidents
2. Possible errors in Treatment Planning :
a) Incorrect input data.
b) Multiple correction for use of wedge filters or
compensators.
c) Misunderstanding of Algorithm.
d) Incorrect manual treatment time calculation.
e) Inadequate training.
Contd…

10. 3.Possible errors in Calibration :
a) Incorrect calibration of teletherapy units.
b) Use of wrong decay chart for output
calibration in cobalt unit.
c) Not updating the output chart of cobalt unit
used in treatment time calculation.
Contd…

11. a) Improper retraction of source to OFF
position.
b) Improper measurement of source length.
c) Improper calibration of source activity.
d) Mechanical failure of treatment Unit.
e) Insufficient knowledge of TPS algorithm.
f) Failure of Interlocks.
Potential Accidents in Brachytherapy

12. Safety measures & precautions to be taken
• One should never attempt to tackle the problem
in hurry without analyzing the situation, such an
attempt will not only complicate the situation
but also will result in unnecessary radiation
exposure.

13. Operational Safety
• Area monitoring
- Gamma zone monitor for
telecobalt and brachytherapy
installations .
• Personnel Monitoring
- TLD, pocket dosimeters ,OSLD

14. Contd…
• “Last man out” switch.
• Emergency Buttons.
• Door interlocks.
• Radiation warning symbols.

15. Adequate Training & Drills
• Radiation workers should be trained to deal with
such situation.
• Regular drills & exercise should be conducted.
• All relevant actions must be trained and regularly
performed to be proficient at the time of an
accident.

16. Periodic Performance/ Status Report
• Performance tests of the unit, integrity check of the
sources, Survey of the installations to be carried out
periodically.
• TPS QA should be conducted to ensure the beam data
provided .
• Maintenance of records, to be produced during
inspection
• Submission of annual safety status report to AERB by
the end of each calendar year.
• Proper Documentation of the incident.
• Reporting incidents or accidents within 24 hrs .

17. Emergency preparedness
• Display of Emergency Procedures in Control
console of radiation unit.
• Easy Availability of the equipments required in
emergency situations.
• Ensure that all workers are familiar with the
emergency action plan.
• Communication system should be working
properly.
• Report to licensee/employer immediately and
to the competent authority within 24 hours
• Lodge written complaint with police in case of
loss or theft of radioactive sources, if not
traced within 24 hours.

18. Responsibilities of RSO
• Developing suitable emergency
response plans to deal with
accidents & maintaining
emergency preparedness.
• Investigate any situation that
could lead to potential exposures.
• Carry out routine measurements
and analysis on radiation &
radioactivity maintain records.
• Proper actions should be taken to
avoid such incident in future.

19. Contd…
• Safe storage and movement of
radiation material within radiation
facility.
• Conduct emergency drills and
make aware all the radiation
worker regarding radiation
emergency situation and safety
• Reports on all hazardous situations
along with remedial actions taken
are made available to the
employer & licensee.

20. • In consultation with RSO , prepare emergency
plans.
• Take protective actions required for the
protection of radiation workers & public, if any
emergency occurs.
• Inform the employer , the competent
authority(AERB), law enforcement agency of any
loss of source.
• Carry out physical verification of RAM periodically
& maintain inventory.
Responsibilities of Licensee

21. Major emergencies in RT
• In cobalt unit:
> Source does not, or partially go back to ‘OFF’ position.
 Responsibilities of an RSO:
i. Try to stop irradiation by pressing emergency key.
ii. Instruct the patient to come out.
iii.Close collimator to minimal field from control console.
iv. Obtain a survey meter , TLD , pocket dosimeter & T-
rod before entering the room.
v. Move the patient and other staffs away from the high
radiation level.

22. Contd…
vi. If possible try to rotate the gantry
opposite to maze wall to avoid primary
radiation.
vii. Insert the T-rod over the red indicator
and apply firm pressure to push the
source back to OFF position.
viii. Close & lock the door , hang a warning
sign on the Door.
ix. Immediately inform to the licensee ,
competent authority and service
engineer.
x. Time taken for sequence of steps should
be noted by some other RSO/medical
physicist, & division of labor should be
done.

23. Contd…
> Telecobalt Source transfer
– Replacement of Co-60 source
• Removal of old source
• Insertion of new source
– Occupational exposure during transfer
Aligned with
the machine
head, “T-rod
“used to
exchange the
source drawers

24. Contd…
 Steps for minimizing exposure:
- Plan the procedure, minimize time and limit
personnel .
- Only the certified engineer & RSO should be
present inside during the procedure.
-Wear TLD badge and pocket dosimeter
- Monitor dose level using survey meter
- Proper alignment of the source flask with the unit
head.

25. Contd…
• In Brachytherapy (HDR & LDR Unit) :
> Source stuck inside the applicator or
catheters , after treatment.
> Source stuck in guide tube
connecting the machine with the
applicators.
 Responsibilities of RSO:
i. Operate the interruption switch on
the control console .
ii. Obtain a survey meter, TLD & pocket
dosimeter then enter the room.

26. iii. Try to retract the source to ‘OFF’ position
by rotating the gold crank on the access
panel of the unit.
iv. Carefully take out the applicator from the
patient containing the source & remove
the patient in safe position.
v. Carefully keep the applicator along with
the source in it in the emergency source
container if necessary cut the source cable,
radiation symbol should be posted & seal
the room.
vi. Immediately inform to the licensee ,
competent authority and service engineer.
Contd…

27. • Calculation error of the exposure time or dose 15
• Inadequate review of the patient's chart 9
• Error in the anatomical area to be treated 8
• Error in identifying the correct patients 4
• Error involving lack of/or misuse of a wedge 4
• Error in calibration of Co-60 source 3
• Transcription error of the prescribed dose 3
• Decommissioning of teletherapy source error 2
• Human error during simulation 2
• Error in commissioning of TPS 2
• Technologist misread the treatment time or MU 2
• Malfunction of accelerator 1
• Treatment unit mechanical failure 1
• Accelerator control software error 1
• Wrong repair followed by human error 1
EXAMPLES OF RADIATION ACCIDENTS
IN EXTERNAL BEAM RADIOTHERAPY

28. • Wrong activities of brachytherapy sources were used 13
• Inadequate procedures for placement of sources in applicator 9
• Error in calculating the treatment dose 8
• Error entered into the computer data 5
• Lack of training of involved personnel 3
• Brachytherapy source mishandling 3
• Error in defining the treatment area 3
• Failure to perform surveys and/or a week radiation safety 3
• Lost of brachytherapy source 3
• Equipment malfunction 2
• Inadequate review of patient's chart 2
• Unintended removal of sources by patient 2
• Leaking 1-125 source used in patient 1
• Broken brachytherapy cable left source in patient 1
• Incorrect number of brachytherapy source 1
• Miscommunication among the licensee and staff 1
• Wrong isotope entered into treatment planning system 1
EXAMPLES OF RADIATION ACCIDENTS
IN BRACHYTHERAPY

29. Discussion
History shows that accidents rarely occur due to a single
equipment failure or a single human error. In most accident
cases there was a combination of elements such as:
a) No prior safety assessment.
b) Poor education and lack of training, especially when faced
with an unusual situation.
c) Management pressure (real or perceived) to continue work
even when safety systems were inoperable or deficient.
d) Poor maintenance programmed or none at all, leading to a
reduction in layers of safety.

30. Recommendations
 Each radiation professional in RT must cooperate
with the Radiation Safety Officer to ensure-
• Effective organization of all radiotherapy practice .
• Education, training and awareness .
• Communication .
• Follow-up of equipment faults.
• Frequent Quality assurance.
• General radiation safety measures (Area and
personnel monitoring, routine survey, audio-visual
system, safety interlocks and warning symbols).

31. Contd…
• AERB guidelines must be followed for installation,
commissioning and decommissioning of
radiotherapy equipment.
• AERB approved procedure for procurement,
replacement and disposal of sources.
This will enable each radiation worker to handle
radiation in a safe environment and limit the
occupational exposure to “As Low as Reasonably
Achievable - ALARA” .

32. Reference
• Chapter 11, Textbook of Radiological safety, K
Thaylan.
• Presentation on ‘EMERGENCY RESPONSE &
PREPAREDNESS in a Radiation Department’- Libin
Sacaria, TMH, Mumbai.
• Presentation on ‘Radiation Hazard Evaluation and
Control’ - Dr. P K Dash Sharma, AERB.
• www.google/images

33. Acknowledgement
• Shashi Bhushan Sharma; Medical Physicist
• Bhabesh kumar Yadav; Medical physicist
• Shayori Bhattacharjee; Intern Medical Physicist
• Dimpal saikia; Intern Medical Physicist