IAEA Training Material on Radiation Protection in Radiotherapy
Radiation Protection in
Radiotherapy
Part 7
Design of Facilities and Shielding
Rationale
In radiotherapy, a potentially lethal dose
of radiation is delivered to patients. In
order to avoid misadministration and
exposure of other individuals (staff,
visitors, general public) a radiotherapy
facility must be appropriately designed.
Shielding is an essential part of this
design process.
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Contents
Lecture 1: Design of a radiotherapy facility
components of a radiotherapy department
 design criteria

Lecture 2: Shielding
general considerations
 external beam radiotherapy
 brachytherapy

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Objectives - on completion,
participants should



Understand the underlying principles for the
design of a radiotherapy facility
Be familiar with the safety requirements for
the design of radiotherapy facilities including
interlocks, maze design and warning signs.
Be able to calculate the shielding thickness
required for a particular barrier
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IAEA Training Material on Radiation Protection in Radiotherapy
Radiation Protection in
Radiotherapy
Part 7
Design of Facilities and Shielding
Lecture 1: Facility Design
Objectives of lecture 1
Be familiar with components of a
radiotherapy department
 Understand the basic layout and design
features of a radiotherapy department

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Contents of lecture 1
1. Components of a radiotherapy
department
2. Departmental planning and layout
3. Design considerations
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1. Components of a typical
radiotherapy department
Diagnostic facilities (CT, MRI, …)
 Simulator
 Mouldroom
 Treatment planning
 External beam treatment units
 Brachytherapy equipment
 Clinic rooms, beds, ...

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Components of a
Radiotherapy Department

Outpatient areas

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
Diagnostics
Clinics
Therapy
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Inpatient areas

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
Oncology ward
Brachytherapy
Non-patient areas
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Radiotherapy is typically part of a
large hospital

Use of other
services:






Diagnostics
Nuclear Medicine
Maintenance
Domestic/kitchen
In patients/nursing
Administration
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Areas not directly related to
patient care
Offices
 Workshops (physics, electronics,
mechanics)
 Storage
 Teaching
 Research

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Areas not directly related to patient care
which need to be considered from a
radiation protection point of view
Offices
 Workshops (physics, electronics,
mechanics)
 Storage (including isotopes)
 Teaching
 Research

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Workshops

Physics workshop/lab: need to consider
check sources for dosimetric equipment
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Storage areas for sources
Hotlab
 Source preparation area for interim
storage of sources
 Decay lab - decay of radioactive
material (e.g. 192-Ir) prior to disposal

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Research

Many different possibilities for radiation
protection problems:
students participating in research and
observation of practice (training?)
 after hours work (confined spaces? Should
there be more than one researcher?)
 labs including radiobiological research
 ethics - see part 9 on medical exposure

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Components of the outpatient area








Reception area
Clinic rooms - new patients and review
Waiting area
Diagnostics - e.g. CT scanner, simulator, dark
room
Treatment units - e.g. 60-Co, linacs,
superficial/orthovoltage, HDR brachytherapy
Treatment planning including mould room
Dosimetry, physics and electronics labs
Office space and storage (!)
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Flow chart
for patient
treatment...
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Flow chart for data
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Quick task
Please try to follow a patient through the
components on the previous slide. Label the
components from 1 to 7 in the order as the data of
a particular patient would be acquired and
processed
Outpatient data flow
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2. Layout of a department



Planning should include all components and
allow for growth
Easy access is required for patients and
ambulance - patient may be transported by
wheelchair or on a trolley bed
Typically a radiotherapy department is part of
a larger hospital complex - access must be
ensured, in particular to:


diagnostics (X Ray, nuclear medicine)
oncology clinic and beds
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Layout example
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Components of a brachytherapy
section

Different layout and components for

high dose-rate (HDR) brachytherapy
 similar to external beam
 usually outpatient facility

low dose-rate (LDR) or pulsed dose-rate
(PDR)
 in-patient procedure
 treatment room in a ward
Nucletron HDR unit
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Patient flow in brachytherapy
Treatment decision
Ideal plan - determines source number
and location
Implant of sources or applicators in theatre
Localization of sources or applicators
(typically using X Rays)
Treatment plan
Commence treatment
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Components of a brachytherapy
suite in the ward







Operating theatre for placement of sources or
applicators
Diagnostic facility to localize sources
Shielded room - consider manual and remote
afterloading
Dosimetry and physics area
Source preparation may be required (e.g. 192-Ir wire
cutting)
Source storage - include also case of emergency
Nurse station with patient intercom
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Transport issues
Ideally, all these components should be
close together - good departmental
planning can ensure this.
 In practice, often these components are
far apart from each other leading to the
need for patient transport (sources or
applicators can move!) or transport of
radioactive material through the hospital

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Designation of areas
Public
 Supervised



operator console
Controlled
treatment rooms
 brachytherapy source storage and
preparation

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Supervised Areas
BSS Appendix I.24. “Registrants and
licensees shall designate as a
supervised area any area not already
designated as a controlled area but
where occupational exposure conditions
need to be kept under review even
though specific protection measures and
safety provisions are not normally
needed.”
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Controlled areas

BSS appendix I.22.: “In determining the
boundaries of any controlled area, registrants
and licensees shall take account of the
magnitudes of the expected normal
exposures, the likelihood and magnitude of
potential exposures, and the nature and
extent of the required protection and safety
procedures.”
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Quick task
Please identify the areas on the handout
of the departmental plan which should be
controlled or supervised
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Controlled and supervised areas
Access restrictions
 Require warning signs
 Monitoring of staff
 Interlocks where
appropriate
 Written procedures

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Planning and lay-out





When planning a new facility assumptions
must be clearly stated
Plan for the future - consider expansions and
increase in workload
Megavoltage treatment rooms are typically in
the basement
It is usually best to place bunkers together to
use common walls
Size matters - bunkers should be generous
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Advantage of large bunker
Distance is effective shielding
 Consider special treatments such as
TBI
 Need storage space for accessories
and patient immobilisation
 Allows for future upgrades of equipment
(FAD 80 ---> 100cm) and increases in
shielding

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Treatment bunkers require lots of storage
space for patient treatment aids...
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More design criteria:
Make use of landscape features (e.g.
built bunkers into a hill) and consider
adjacent buildings
 Positioning the control room and the
equipment within so that staff have a
good view of

 the treatment room
 access corridors
 entrance to the treatment room
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…before planning and
shielding
Check and document all assumptions
 Verify them with authorities and
colleagues
 Plan size and workload of the facility be conservative, the design should be
adequate for the next 20 year including
room for expansion

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Typical assumptions for planning a
new facility
4000 new cases of cancer per year per
million population
 50% will require radiotherapy at some
stage
 400 to 500 cases per megavoltage unit
per year


...may depend on local conditions
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Design considerations: External
Beam Radiotherapy

Placement of the treatment unit
 Primary beam direction
 Operator location
 Surrounding areas - should have low
occupancy

Costs
 can be reduced if the design is good
 for extension is usually much larger than for
allowing for expansion already during the
building phase
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Typical megavoltage room layout
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Design criteria: External Beam
treatment area




clear signs are required in areas leading to
treatment units
patient and visitor waiting areas should be
positioned so that patients are unlikely to
enter treatment areas accidentally
patient change areas should be located so
that the patient is unlikely to enter a treatment
area accidentally
shielding/maze/doors discussed later
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Megavoltage Room
Is a door needed?
 Door interlocks

Protocol for closing the door and activating
radiation
 Door interlocks


Radiation warning signs are needed
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Radiation Safety in
Radiotherapy

the possibility of accidental exposure
can be minimised by measures such as

positioning the control room and the
equipment within so that staff have a good
view of
 the treatment room
 access corridors
 entrance to the treatment room
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Control area




Spacious
Patient monitor
Clear view of
surrounding
area
Control of
access to
bunker
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Radiation Safety in
Radiotherapy

the possibility of accidental exposure
can be minimised by measures such as
positioning



clear signs in areas leading to treatment units
patient and visitor waiting areas so that they are
unlikely to enter treatment areas accidentally
patient change areas so that the patient is unlikely
to enter a treatment area accidentally
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A note on ventilation
This should be reviewed for high energy
accelerators > 15 MeV
 There may be a build up of ozone and
induced radioactive Oxygen-15 and
Nitrogen-13
 10 air changes per hour or greater
should be satisfactory

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Other irradiation units for external
beam radiotherapy
Simulator and CT scanner - design of
rooms similar to the design of a
diagnostic radiology facility. This is dealt
with in the course on diagnostic
radiology
 Protons, neutrons, pions,… beyond the
scope of the present course
 Superficial/orthovoltage units

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Superficial/orthovoltage treatment room
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Some comments
The movement of the X Ray tube may
be restricted to prevent the primary
beam from hitting areas which are not
sufficiently shielded
 A lead glass window is typically
sufficient for viewing - its integrity must
be checked

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Brachytherapy

Source assembly area may be required
A secure storage area for the source safe and
source transfer procedures may be required
In room area monitor

HDR



Principles are similar
to megavoltage unit
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Design criteria: HDR treatment
rooms
The design of these rooms follow similar
guidelines to those of accelerator rooms
 Maze and door must typically be
included
 Similar interlocks to those used in
accelerator rooms are required

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HDR room design

Some centres use accelerator rooms for
HDR brachytherapy treatment. This
practice has some disadvantages:
Usually not enough space for diagnostic
equipment for source localization
 Time pressure - the next external beam
radiotherapy patient is scheduled
 Difficulties in predicting what assumptions
shall be used for shielding calculations

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HDR room design (example)
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Brachytherapy

Low Dose Rate
Usually in a ward
 Manual/Afterloading

 Safety of sources
 Staff/visitors

Remote afterloading
 Door interlocks

Shielding could also be
incorporated in the bed. This
reduces cost and increases
patient anxiety - it is
typically better to shield
the room
Shielding issues
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Design criteria: LDR
brachytherapy in the ward




Typically some shielding is required
Avoid treating more than one patient in a
single room - this leads inevitably to additional
unnecessary does to the patient(s) and most
likely to staff
Use rooms at the end of the ward, preferably
on outside walls
Consider adjacent room use (could a storage
space turn into an office?)
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An additional note on department
planning...
CT
MR
Archive
HIS / RIS Portal Imaging
LiteBox
Image
Image
Not
DICOM
All
Image
SS, Plan,
Image
SS, Plan,
Dose
Image, SS,
Plan
Image
Image, SS,
Plan
Simulator Virtual Sim.
Radiation Protection in Radiotherapy
Record
All
LiteBox
Image
Plan
LiteBox
TPS
Review St. Treatment
Part 7, lecture 1: Facility design
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Message...
A radiotherapy department is a complex
environment
 It relies heavily on data transfer patient, machine and process data
 This affects also patient and staff
safety!!!
 Planning must include allowance for
computerization and networking

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3. Design considerations

Treatment rooms
Shielding/door/maze - discussed in next
lecture
 Interlocks
 Emergency off buttons
 Warning signs
 Beam on/off indicator

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Interlocks

the possibility of accidental exposure
can be minimised by measures such as
room interlocks involving (possibly as a
combination)




door
gate
light beams
audible alarm
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Emergency off buttons: where
should they go?
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Suggested
solution
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Warning signals
There should be a visible signal when
radiation is being produced at the
entrance of the maze, control area and
in the treatment room
 There should be an audible signal in the
treatment room just prior to radiation
being produced

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Brachytherapy wards design
features



Require radiation monitor at the door to avoid patient
leaving the room with sources in place
Manual afterloading: Warning signs required
Remote afterloading: Interlocks at the entrances
should cause the sources to retract if someone
enters the room (if it is an automatic afterloading
system)
Area monitor
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Summary


Careful planning of a new radiotherapy facility
or any extensions helps to optimize protection
(and save costs)
There are many features of a radiotherapy
treatment area which must be considered
including interlocks and warning signs
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Where to Get More Information
IAEA TECDOC 1040
 parts 1, 5, and 6 of the course

Radiation Protection in Radiotherapy
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Any questions?
Question:
Consider that you would like to submit an
application for authorization of the use of
radiation for radiotherapy. What information
would a regulator need in such an application ?
Some information required

Drawings to scale - including:




direction of north
exact position of the equipment
location of doors and windows
ducts or other penetrations through a wall
relevant
 identification of rooms (number)
 cross sections (above and below?)
 exact distances where relevant

Indications of adjacent areas/buildings
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Cross sections are helpful
What is down under here???
(this MUST be stated)
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Information required (cont.)
Any features affecting radiation safety
 Indication of radiation protection
measures:

 emergency off buttons
 monitors
 safe for sources

Shielding - normal in walls and
additional (see next section…)
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Acknowledgements

John Drew, Westmead Hospital Sydney
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