Design Flashcards
(102 cards)
1
Q
Application: Smoke detectors (Americium-241)
A
Alpha rays
2
Q
Application: Static eliminator
A
Alpha rays
3
Q
Application: Research in nuclear physics
A
Alpha rays
4
Q
Alpha rays ionizing power and penetrating ability
A
IP: Very high
PA: Very low
5
Q
Alpha rays can be stopped by:
A
- Thin sheet of paper (0.05mm)
- Clothing
- Outer layer of human skin
6
Q
Application: Thickness gauging (e.g., paper, plastic gilms)
A
Beta rays
7
Q
Application: Tracers in medical diagnostics
A
Beta rays
8
Q
Application: Cancer treatment (eg. Strontium-90)
A
Beta rays
9
Q
Beta rays IP and PA
A
IP: Moderate
PA: Low
10
Q
Beta rays can be stopped by:
A
- Metal sheets (aluminum <3mm)
- Plexiglass
- Plastic (5mm)
11
Q
Application: Cancer radiotherapy (e.g. Cobalt-60)
A
Gamma rays
12
Q
Application: Sterilization of medical equipment
A
Gamma rays
13
Q
Application: Sterilization of medical equipment
A
Gamma rays
14
Q
Application: Industrial radiography
A
Gamma rays
15
Q
Application Food irradiation
A
Gamma rays
16
Q
Gamma rays can be stopped by:
A
- Thick layers of lead (1 cm per HVL)
- Concrete (10 cm per HVL)
- Several meters of water
17
Q
Gamma rays IP anf PA
A
IP: Low
PA: Very high
18
Q
Application: Medical imaging (XRs, CT)
A
X-rays
19
Q
Application: Airport security scanners
A
X-rays
20
Q
Application: Crystallography and material analysis
A
X-rays
21
Q
X-rays can be stopped by:
A
- Lead sheets (0.5-2mm)
- Heavy concrete (10-30cm)
22
Q
X-rays IP and PA
A
IP: Low
PA: High
23
Q
Application: Nuclear reactors and power generation
A
Neutron
24
Q
Application: CA treatment (boron neutron capture therapy)
A
Neutron
25
Application: Scientific research (neutron activation analysis)
Neutron
26
Neutron radiation is best shielded by --- substances
Hydrogen-rich
27
Hydrogen-rich substances like these best shields neutron radiation
1. Water (25-50 cm)
2. Plastic (polyethylene) (10-30 cm)
3. Concrete (30-100 cm)
28
Neutron IP anf PA
IP: Low
PA: Very high
29
Neutron
- Often combined with (1)
- (2) is not effective
1. boron/ cadmium
2. Lead
30
Designed to block direct radiation from the source.
Primary barrier
31
Positioned perpendicular to the central x-ray beam
Primary barrier
32
Factors determining the thickness
* Energy of radiation
* Workload
* Occupancy factor
* Distance from sourc
33
Diagnostic primary barrier/s based on NCRP
Diagnostic:
1. Lead (1/16”-5/64”)
2. Concrete (6”-8”)
3. Leaded gympsum (1/16” Pb equivalent)
34
Therapeutic primary barrier/s based on NCRP
Therapeutic:
1. High density Concrete
a. 1.2m-1.5m (6MV)
b. 2.0m-2.5m (15-18MV)
2. Lead (rarely used)
3. Steel/ Barite concrete
35
Diagnostic secondary barrier/s based on NCRP
1. Lead (1/32”-1/16”)
2. Concrete (4”-6
36
Control room secondary barriers based on NRCP
Control rooms:
1. 1.5m-2mm Pd glass windows
2. 0.25-1.00 mm Pb-lined drywall or lead curtains for
portable X-ray shielding.
37
Therapeutic secoondary barrier/s based on NCRP
1. High density Concrete
a. 0.8m-1.2m (6MV)
b. 1.5m-2.0m (15-18MV)
2. Lead (rarely used)
38
To prevent radiation leakage, lead barriers should overlap by at least 1 cm at joints.
Seamless Overlaps
39
Shielded with lead-lined wood or lead glass panels
Doors and Windows
40
Concrete or lead barriers must be continuous without gaps to ensure complete shielding
Structural Integration
41
The thickness of a material that reduces the radiation intensity by 50%
Half-Value Layer (HVL)
42
The thickness required
to reduce radiation intensity by 90% (or one-tenth of its original value).
Tenth-Value Barrier (TVL(
43
HVL and TVL quivalent
1 TVL = 3.3 HVL
44
Shielding thickness for X-ray rooms is calculated using --- (Medical Imaging)
HVL values
45
Used to design treatment room barriers (RadThera)
TVL values
46
Guides the placement of lead or concrete shielding (Nuclear Facilities)
HVL/TVL values
47
Space where radiation exposure levels are higher than in the surrounding environment
Controlled Areas
48
Shielding design in focuses on minimizing radiation exposure to workers.
Controlled Areas
49
Use of dense materials like lead or concrete to absorb and scatter radiation effectively.
Controlled Areas
50
Barrier is required to reduce the exposure to a worker in the area to less than 1 mSv/wk (100 mrem per week).
Controlled Areas
51
Spaces where radiation levels are not sufficiently high.
Uncontrolled Areas
52
Shielding is generally designed to limit radiation levels to very low, background levels
Uncontrolled Areas
53
Shielding materials are typically less thick or dense
Uncontrolled Areas
54
Maximum exposure rate allowed is based on the recommended dose limit for the public of 1 mSv/ yr (100
mrem/yr) or 20μSv/wk (2 mrem/wk)
Uncontrolled Areas
55
The percentage of time during which the x-ray beam is on and directed toward a particular protective barrier is called the use factor for that barrier.
Use Factor (U)
56
U: The NCRP recommends that walls be assigned a use factor of (1) and the floor a use factor of (2).
* The use factor for secondary radiation is always (3)
1.1/4
2. 1
3. 1
57
A measure of how much radiation a facility produces, expressed in milliampere-minutes per week (mAmin/week) for diagnostic X-ray rooms or Gy/week for therapy facilities
Workload (W)
58
The greater the number of examinations performed each week, the thicker the shielding that is required.
Workload (W)
59
A busy, general purpose x-ray room may have a workload of (1). Rooms in private offices have workloads of (2)
1. 500 mAmin/wk
2. less than 100 mAmin/wk
60
Accounts for how often an area is occupied
Occupancy Factor (T)
61
Shielding is increased for areas with higher occupancy to reduce exposure to workers and the public.
Occupancy Factor (T)
62
A wall along which an x-ray imaging system is positioned probably requires more shielding than the other walls of the room.
Distance (D)
63
Distance (D) is the distance bn --- and the ---
source of rad and the barrier
64
It may be desirable to position the x-ray imaging system in the middle of the room because then no single wall is subjected to especially intense radiation exposure.
Distance (D)
65
Makes use adjustable lead shutters to shape the X-ray beam.
Collimators
66
Modern collimators include --- to assist with proper patient positioning
light fields
67
Fixed lead openings that restrict the size of the beam
Aperture Diaphragms
68
Commonly used in dental radphy
Aperture Diaphragms
69
Extend from the X-ray tube to further narrow the beam
Cones and cylinders
70
Used in mammography and dental imaging.
Cones and cylinders
71
Detects patient thickness and adjusts exposure accordingly.
AEC
72
Prevents overexposure due to incorrect manual settings.
AEC
73
Commonly used in chest X-rays and fluoroscopy
AEC
74
Allow operators to set exposure parameters manually
Manual Exposure Controls
75
Require precise calibration to prevent unnecessary dose increases
Manual Exposure Controls
76
Limits total exposure time to prevent prolonged radiation delivery
Timer-Based Controls
77
Timer-Based Controls are found in ---
fluoroscopy and radthera
78
Many systems require a preparation phase (activating the X-ray tube) before exposure.
Two-Step Exposure Activation
79
In high-dose environments (e.g., fluoroscopy), controls are placed outside the radiation area for operator safety.
Remote Control Operation
80
If the machine is left idle or malfunctions, an automatic
shutdown prevents unnecessary exposure.
Automatic Shutoff
81
The machine cannot be activated if the door is open.
Room Interlocks (Radiation Therapy, CT, & Nuclear Medicine)
82
Used in linear accelerator (LINAC) rooms and PET scan areas
Room Interlocks (Radiation Therapy, CT, & Nuclear Medicine)
83
Prevent operation if safety parameters are exceeded (e.g., overexposure limits in fluoroscopy).
Equipment Interlocks
84
Prevent scanning if the patient is not correctly positioned.
Motion Interlocks (CT and MRI Systems)
85
Enable immediate shutdown if an unexpected radiation hazard occurs
Emergency Interlocks
86
Allow operators to observe the patient from a safe distance.
Closed-Circuit Television (CCTV) Cameras
87
Used in fluoroscopy, CT, and interventional radiology
Closed-Circuit Television (CCTV) Cameras
88
Audible alarms alert operators when exposure exceeds a threshold.
Radiation Exposure Alarms
89
Used in nuclear medicine, industrial radiography, and high-dose therapy rooms
Radiation Exposure Alarms
90
Two-way intercoms allow communication between the patient and radiologic technologist.
Patient Communication Systems
91
Essential in MRI, CT, and radiation therapy suites
Patient Communication Systems
92
Displays the real-time radiation dose delivered to the patient.
Fluoroscopy Dose Monitoring
93
Required by modern fluoroscopic units to prevent excessive exposure.
Fluoroscopy Dose Monitoring
94
Instantly shuts down all radiation-producing equipment.
Emergency Stop Buttons ("Kill Switches")
95
Found in radiotherapy rooms, fluoroscopy labs, and nuclear reactors
Emergency Stop Buttons ("Kill Switches")
96
If a machine overheats or exceeds radiation limits, power is automatically disconnected
Automatic Power Cutoff Systems:
97
If radioactive materials are accidentally released (e.g., in nuclear medicine), containment systems seal off affected areas to prevent exposure.
Radiation Containment Systems
98
Worn by radiation workers to alert them if their exposure level exceeds safety thresholds
Personal Radiation Dosimeters with Alarm
99
Ensures that radiation output matches expected dose levels
Calibration
100
Require daily, weekly, and annual calibration to maintain image quality and dose accuracy.
X-ray and CT Scanners (Diagnostic Imaging)
101
Must be calibrated using dosimeters to verify treatment dose.
Linear accelerators (LINACs) (RadThera)
102
Require frequent recalibration due to transport-related variability
Portable X-ray Units
