Time-resolved mirrorless scintillation detector @ KSMPRS2018

Development of a time-resolved mirrorless
scintillation dosimetry system
for accurate measurement from small to large segment
Wonjoong Cheon1), Hyunuk Jung2), Moonhee Lee1), Jinhyeop Lee1),
Sung Jin Kim3), Sungkoo Cho3), Youngyih Han4)*
1) Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, Seoul, 06351, Korea.
2) Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75235, USA
3) Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, 06351, Korea.
2018 16th 대한방사선 수술물리 연구회 @ 고려대학교 의과대학 문숙의학관1

Introduction
2 2018 16th 대한방사선 수술물리 연구회 @ 고려대학교 의과대학 문숙의학관

1. History of dosimetry using 2D scintillator
# Title Year Author Structure of detector
1 A fast 2D phantom dosimetry system for scanning proton beams 1998 S.N Boon and P. van Luijk 2D Scintillation sheet + Mirror + CCD camera
2 Performance of a fluorescent screen and CCD camera as a two-dimensional dosimetry system for dynamic treatment techniques 2000 S.N Boon and P. van Luijk 2D Scintillation sheet + Mirror + CCD camera
3 Development and characterization of a tissue equivalent plastic scintillator based dosimetry system. 2006 Petric 2D Scintillation sheet + Mirror + CCD camera
4 A new scintillating fiber dosimetry using a single optical fiber and a CCD camera 2006 Ferelin 1D Scintilation fiber + Mirror + CCD camera
5 The DosiMap, a new 2D scintillating dosimeter for IMRT quality assurance: characterization of two Cerenkov discrimination methods. 2008 Ferelin 2D Scintillation sheet + Mirror + CCD camera
6 The DOSIMAP, a high spatial resolution tissue equivalent 2D dosimeter for LINAC QA and IMRT verification 2009 Collomb-Patton 2D Scintillation sheet + Mirror + CCD camera
7 2D dosimetry in a proton beam with a scintillating GEM detector 2009 E seravalli 2D Scintillation sheet + Mirror + CCD camera
8 A new water-equivalent 2D plastic scintillation detectors array for dosimetry of megavoltage energy photon beams in radiation therapy 2011 Guillot 2D Scintillation fiber + Mirror + CCD camera
9 Performance assessment of a 2D array of plastic scintillation detector 2013 Guillot 2D Scintillation fiber + Mirror + CCD camera
10 https://www.iba-dosimetry.com/solutions/radiation-therapy/particle-therapy-qa/lynx-pt/ 2015 IBA_Dosimetry 2D Scintillation sheet + Mirror + CCD camera
11 Development and characterization of a 2D scintillation detecotr for quality assuracne in scanned carbon ion beam 2016 A. Tamborini 2D Scintillation sheet + Mirror + CCD camera
12 Characterization of a GEM-based scintillation detector with He-CF4 gas mixture in clinical proton beams. 2016 Nichiporov D, 2D Scintillation sheet + Mirror + CCD camera
13 Characterization of a commercial scintillation detector for 2-D dosimetry in scanned proton and carbon ion beams 2017 S. Susso 2D Scintillation sheet + Mirror + CCD camera
Table 1. Researches of 2D scintillation dosimetry since 1998.
3

To measure two-dimensional dose distribution
by using “Time-resolved” “Mirror-less” scintillation detector
H/W
Time-resolved mirrorless scintillation detector
S/W
Visible
light
Dose
distribution
Dose
profile
4

Conventional
Scintillation detector system
(in-house)
Too much Heavy
Too much Bulky
Specification
Conventional
Size (L x W x H) 60.7 x 37.0 x 33.5 cm3
Weight 18.26 kg
Effective field of view 20.0 x 20.0 cm2
Specification
Mirror-less Compact
Size (L x W x H) 40.5 × 32.5 × 15.5 cm3
Weight 1.74 kg
Effective field of view 17.0 x 17.0 cm2
Time-resolved mirrorless
5Radiation Protection Dosimetry, Vol. 131(1), 2008
Compact: Without Mirror and Optical fibers
5

10 X 10 cm2 open field measured by GoPro Hero5 Black camera without the mirror
3. Geometric distortion
• Lens distortion
• Perspective distortion
2. Noise (hot-pixel)
4. Dependency of luminance
• Output factor of field size
• Dependency with distance
5. Penumbra
1. Optimization of camera parameters
• ISO value
• Shutter speed
6

Materials and Methods

1. Selecting GoPro Hero5 Black camera parameters
Optimization of
camera parameters
Noise reduction
based on frames
Geometric correction Penumbra region correction
 CCD camera specification
• Model: GoPro Hero5 Black
Weight : 118 g
• Parameters:
- Resolution: 4K/1440/1080
- Frame Rates: 24
- Field Of View: Wide/Narrow/Medium/Linear
- ProTune: On/Off
- Shutter speed: Auto/FPS-1
- Exposure value compensation: -2.0 to 2.0
- ISO limit: 6400/3200/1600/1200/800/400
But, to use GoPro5 as for radiation dosimetry, selecting camera parameters is necessary.
8
Light dependency
correction
8

 Shutter speed
: The time the shutter was opened and closed
 ISO Limit
: Level of sensitivity of a camera to available light.
ISO LIMIT: 800 ISO LIMIT: 1600 ISO LIMIT: 3200ISO LIMIT 9
Trial #
Parameters
1 2 3 4 5 6 7 8 9 10
Resolution
Frame rates
Field of view
Protune OFF
Shutter -
Exposure -
ISO value - 800 1600 3200 800 1600 3200 800 1600 3200
-2 2-
4K
24
Wide Angle
ON
24 AUTO
1 Selecting GoPro Hero5 Black camera parameters
Optimization of
camera parameters
Frame-based noise
reduction technique
Light dependency
correction
9

𝐢𝐟
𝒗𝒇𝒏 = 𝒏
𝒏+𝒌
𝑷 𝒗𝒇𝒏, 𝒊, 𝒋 ≤ 𝒕𝒉𝒓𝒆𝒔𝒉𝒐𝒍𝒅 𝒗𝒂𝒍𝒖𝒆? ? , 𝐭𝐡𝐞𝐧 𝑷 𝒗𝒇𝒏, 𝒊, 𝒋 = 𝟎
𝐟𝐨𝐫 𝐚𝐥𝐥 𝒊 , 𝒋 𝐢𝐧 𝐩𝐢𝐱𝐞𝐥 𝐜𝐨𝐨𝐫𝐝𝐢𝐧𝐚𝐭𝐞𝐬
Frame number= n Frame number= n+1 Frame number= n+2 Frame number= n+k
Radiation directly interact with sensor
 “Noise” (Hot-pixel)
10
• n : selected frame for applying noise reduction technique
• k : The frame receive a scan for detecting hot-pixel
• vfn : video frame number
• i, j : pixel(image) coordinates
To eliminate noise, the above procedure was applied to over all frames
2. Frame-based noise reduction technique
Optimization of
camera parameters
Frame-based noise
reduction technique
Light dependency
correction
10

Original image
captured by GoPro5
Correction of
Lens distortion
Correction of
perspective effect
(Problems caused by the angle of the camera)(Problems caused by fish eye lens)
11
3. Geometry correction: Lens correction and Perspective correction
Optimization of
camera parameters
Frame-based noise
reduction technique
Light dependency
correction
11

Horizontal and vertical profile
Field size: 20.0 X 20.0
Correction map (2D)
Distance dependency correction map
Inverse 1/r square law !
12
4. Distance dependency correction
Optimization of
camera parameters
Frame-based noise
reduction technique
Light dependency
correction
12

5. Penumbra region correction using combination of kernels
Optimization of
camera parameters
Frame-based noise
reduction technique
Light dependency
correction
13
[cm]
Absorbeddose(norm.)
Deconvolution with Fourier theory
Laub, Wolfram U., and Tony Wong. "The volume effect of detectors in the dosimetry of small fields
used in IMRT." Medical physics 30.3 (2003): 341-347.

5. Penumbra region correction using combination of kernels
Optimization of
camera parameters
Frame-based noise
reduction technique
Light dependency
correction
13
[cm]
Absorbeddose(norm.)
Deconvolution with deep-learning approach

Results

1. Linearity and Repeatability (TRMLSD vs EBT3)
Figure 1. (a) Linearity: Plot for scintillation intensity corresponding to absorbed dose; red line is linear fit to measured date.
(b) Repeatability: Measured absorbed dose of TRMLSD (red star) and Gafchromic EBT3 (blue square) are plotted.
2
0
c
G
y
15
2
0
0
c
G
y

2. Percent depth dose (PDD): TRMLSD vs EBT3 vs Ion chamber
Figure. 2. Percent depth dose measured by TRMLSD (red star), EBT3 film (blue square), and ionization chamber
(blue dash) for 6MV photon beam. TRMLSD and EBT3 data were normalized at depth 5.0 cm
16

3. Lateral Profile (TG-142):
TRMLSD vs EBT3 vs Ion chamber
Measurement
tool
Flatness (%) Symmetry (%) Penumbra (cm)
Ion Chamber 1.78 0.83
L: 0.85
R: 0.85
EBT3 film 1.62 0.85
L: 0.42
R: 0.46
TRMLSD 1.88 0.86
L: 0.49
R: 0.49
Table 1. Beam profile verification of Novalis Tx accelerator: 6MV photon beam,
reference depth 5.0 cm.
17
Figure 3. two-dimensional dose
distribution of 10 x 10 cm2 field
measured by TRMLSD

4. Simple IMRT plan (time-resolved dosimetry):
TRMLSD vs EBT3 film
Field type 1 [%]
Accumulation time (sec)
Criterion 81.6 110.4 127.2
2% / 2mm 91.59 93.47 92.93
3% / 3mm 94.72 97.84 96.89
4% / 4mm 99.93 99.99 99.86
Figure 4. Signal of scintillation over time for simple intensity
modulated plan (field type-1). The accumulated two-dimensional (2D)
dose distribution of TRMLSD at (a) 81.6, (b) 110.4, and (c) 127.2 sec.
2D dose distribution of EBT3 film (d)
Table 2. Gamma analysis between TRMLSD
and EBT3 film for different gamma criterion.
18
Image analysis over measurement time
Time [sec]
Scintillationsignal

5. Clinical IMRT plan (Prostate: 7 beam with 50 segments):
TRMLSD vs TPS (Pinnacle)
2% / 2 mm 3 % / 3 mm 4 % / 4 mm
TRMLSD 93.62 96.89 99.43
EBT3 film 94.76 97.34 99.63
1 2 3 4 5 6 7 Avg.
2% / 2mm 92.51 92.75 92.95 92.29 92.42 93.29 93.28 92.78
3% / 3mm 97.38 97.42 97.28 96.44 96.31 97.02 95.81 96.81
4% / 4mm 99.38 99.42 98.44 99.03 99.48 99.17 99.37 99.18
Table 3. Gamma passing rate with diverse gamma criterion for
comparing two-dimensional dose distribution of
TRMLSD and EBT3 film with RTP
Table 4. Gamma passing rate with diverse gamma criterion between two-dimensional dose distribution of
TRMLSD and RTP.
19

Summary
We developed Times-resolved mirrorless compact scintillation detector.
The weight is just 10% of a conventional scintillation detector (compact)
It could analyze the two-dimensional dose distribution of plan per segment and/or beam.
(time-resolved)
The effective field size is 17.0 x 17.0 cm2 in 2000 x 2000 pixel resolution
(high-resolution)
The gamma passing rate for Clinical IMRT plan is about 96 percent (3% / 3mm) which is
capable to used for clinical dosimetry.
Feasibility study on Applying the TRMLSD to VMAT and IMPT are under way.

Thank you for your
attention
wonjoongcheon@gmail.com
https://www.cakeresume.com/wonjoong-cheon
https://github.com/wjcheon
2018 16th 대한방사선 수술물리 연구회 @ 고려대학교 의과대학 문숙의학관

𝐢𝐟
𝒗𝒇𝒏 = 𝒏
𝒏+𝒌
𝑷 𝒗𝒇𝒏, 𝒊, 𝒋 ≥ 𝒕𝒉𝒓𝒆𝒔𝒉𝒐𝒍𝒅 𝒗𝒂𝒍𝒖𝒆 , 𝐭𝐡𝐞𝐧 𝑷 𝒗𝒇𝒏, 𝒊, 𝒋 = 𝟎
𝐟𝐨𝐫 𝐚𝐥𝐥 𝒊 , 𝒋 𝐢𝐧 𝐩𝐢𝐱𝐞𝐥 𝐜𝐨𝐨𝐫𝐝𝐢𝐧𝐚𝐭𝐞𝐬
Frame number= n Frame number= n+1 Frame number= n+2 Frame number= n+k
Radiation directly interact with sensor
 “Noise” (Hot-pixel)
24
• n : selected frame for applying noise reduction technique
• k : The frame receive a scan for detecting hot-pixel
• vfn : video frame number
• i, j : pixel(image) coordinates
To eliminate noise, the above procedure was applied to over all frames
2. Frame-based noise reduction technique
Optimization of
camera parameters
Frame-based noise
reduction technique
Light dependency
correction

IF, Scanning this frame with k = 5. the maximum threshold value is 5
5
3
signal
Noise(hot-pixel)

Time-resolved mirrorless scintillation detector @ KSMPRS2018

More Related Content

What's hot (19)

Similar to Time-resolved mirrorless scintillation detector @ KSMPRS2018 (20)

Recently uploaded (20)

Time-resolved mirrorless scintillation detector @ KSMPRS2018