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Yoon, Park, Kim, Kim, and Lee: Acceptance Testing and Commissioning of Robotic Intensity-Modulated Radiation Therapy M6 System Equipped with InCiseTM2 Multileaf Collimator
Original Article

Progress in Medical Physics 2018;29(1):8-15.

Published online: 20 March 2018

DOI: https://doi.org/10.14316/pmp.2018.29.1.8

Acceptance Testing and Commissioning of Robotic Intensity-Modulated Radiation Therapy M6 System Equipped with InCiseTM2 Multileaf Collimator

Jeongmin Yoon∗, Kwangwoo Park†, Jin Sung Kim†, Yong Bae Kim†, Ho Lee†

∗Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea

†Department of Radiation Oncology, Yonsei University College of Medicine, Seoul, Korea

Corresponding author Ho Lee (holee@yuhs.ac) Tel: 82-2-2228-4363 Fax: 82-2-2227-7823

Copyright © 2018 Korean Society of Medical Physics

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This work reports the acceptance testing and commissioning experience of the Robotic Intensity-Modulated Radiation Therapy (IMRT) M6 system with a newly released InCiseTM2 Multileaf Collimator (MLC) installed at the Yonsei Cancer Center. Acceptance testing included a mechanical interdigitation test, leaf positional accuracy, leakage check, and End-to-End (E2E) tests. Beam data measurements included tissue-phantom ratios (TPRs), off-center ratios (OCRs), output factors collected at 11 field sizes (the smallest field size was 7.6 mm×7.7 mm and largest field size was 115.0 mm×100.1 mm at 800 mm source-to-axis distance), and open beam profiles. The beam model was verified by checking patient-specific quality assurance (QA) in four fiducial-inserted phantoms, using 10 intracranial and extracranial patient plans. All measurements for acceptance testing satisfied manufacturing specifications. Mean leaf position offsets using the Garden Fence test were found to be 0.01±0.06 mm and 0.07±0.05 mm for X1 and X2 leaf banks, respectively. Maximum and average leaf leakages were 0.20% and 0.18%, respectively. E2E tests for five tracking modes showed 0.26 mm (6D Skull), 0.3 mm (Fiducial), 0.26 mm (Xsight Spine), 0.62 mm (Xsight Lung), and 0.6 mm (Synchrony). TPRs, OCRs, output factors, and open beams measured under various conditions agreed with composite data provided from the manufacturer to within 2%. Patient-specific QA results were evaluated in two ways. Point dose measurements with an ion chamber were all within the 5% absolute-dose agreement, and relative-dose measurements using an array ion chamber detector all satisfied the 3%/3 mm gamma criterion for more than 90% of the measurement points. The Robotic IMRT M6 system equipped with the InCiseTM2 MLC was proven to be accurate and reliable.

Keywords: Robotic IMRT, InCiseTM2 MLC, Commissioning

References

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Fig. 1.
Analysis of leaf positioning accuracy using RIT software.
pmp-29-8f1.tif
Fig. 2.
Results of leakage test: (a) EBT3 film and image analysis of X1 closed leakage and (b) EBT3 film and image analysis of X2 closed leakage.
pmp-29-8f2.tif
Fig. 3.
Visual comparisons of OCRs between measurement and composite data at a depth of 15 mm. OCRs with (a) X field size of 7.6 mm, 15.4 mm, and 23 mm and (b) Y field size of 7.7 mm, 15.4 mm, and 23.1 mm. OCRs with (c) X field size of 30.8 mm, 46.2 mm, 69.2 mm, and 100 mm and (d) Y field size of 30.8 mm, 46.2 mm, 69.3 mm, and 100.1 mm. OCRs with (e) X field size of 38.4 mm, 53.8 mm, 84.6 mm, and 115 mm and (f) Y field size of 38.5 mm, 53.9 mm, 84.7 mm, and 100.1 mm.
pmp-29-8f3.tif
Fig. 4.
Point dose errors of patient-specific QA: (a) stereotactic dose verification phantom, (b) pelvis phantom, and (c) thorax phantom.
pmp-29-8f4.tif
Table 1.
Percent differences of TPRs between measurement and composite data.
Depth (mm) 7.6× 7.7 (%) 15.4× 15.4 (%) 23.0× 23.1 (%) 30.8× 30.8 (%) 38.4× 38.5 (%) 46.2× 46.2 (%) 53.8× 53.9 (%) 69.2× 69.3 (%) 84.6× 84.7 (%) 100× 100.1 (%) 115× 100.1 (%)
0 −4.05 1.08 0.33 −6.30 −6.16 2.52 −3.46 −5.32 −5.35 −5.27 −5.46
5 −4.81 −7.26 −6.23 −5.44 −5.29 −3.26 −3.84 −3.52 −3.81 −3.07 −3.14
10 −0.80 −1.94 −1.59 −1.87 −1.77 −1.14 −1.27 −1.16 −1.23 −1.16 −1.05
13 −0.08 −0.45 −0.45 −0.65 −0.58 −0.21 −0.33 −0.04 −0.15 −0.09 −0.15
15 0 0 0 0 0 0 0 0 0 0 0
20 0.33 0.37 0.27 −0.11 0.13 0.29 0.21 0.18 0.33 0.33 0.13
30 0.23 0.37 0.33 0.05 −0.02 0.23 0.18 0.23 0.20 0.29 0.25
50 0.83 0.91 0.94 0.81 0.56 0.59 0.46 0.60 0.57 0.64 0.60
100 0.87 1.18 0.81 0.76 0.62 0.86 0.70 0.72 0.87 0.71 0.75
150 1.06 1.07 1.14 0.76 0.78 0.89 1.03 0.77 0.81 0.74 0.77
200 0.81 1.59 1.49 1.31 0.94 0.92 0.98 0.95 0.98 0.91 1.03
250 1.02 1.26 1.45 0.98 0.80 1.30 1.19 1.02 0.99 1.01 1.11
300 0.91 1.41 1.60 1.36 1.04 1.27 1.26 1.31 1.48 1.22 1.32
Table 2.
Percent differences of OFs between measurement and composite data.
X (mm) Y (mm) Composite data PTW 60018 diode SRS (%) PTW 60019 microDiamond (%)
7.6 7.7 0.818 −0.32 −1.53
15.4 15.4 0.950 −0.24 0.14
23.0 23.1 0.977 −0.22 0.14
30.8 30.8 0.987 −0.24 −0.03
38.4 38.5 0.993 −0.19 0.13
46.2 46.2 0.999 −0.17 0.05
53.8 53.9 1.003 −0.13 −0.35
69.2 69.3 1.011 −0.16 −0.21
84.6 84.7 1.017 −0.05 −0.35
100.0 100.1 1.022 −0.04 −0.29
115.0 100.1 1.023 0.08 −0.35
Table 3.
Patient-specific QA results using Octavius 1000 SRS detector.
ID Point dose error (%) Gamma passing ratio (%)
p7514820 2.04 95.0
p2317947 3.87 92.7
p7863469 3.26 90.0
p8028173 0.62 97.6
p3863606 1.26 100.0
p7594455 −0.84 100.0
p8006687 0.46 97.7
Table 4.
Patient-specific QA results using MC fixed cone for thorax phantom.
ID Calculated dose (cGy) Measured dose (cGy) Difference (%)
p8028173 602.53 600.26 0.38
p8006687 511.57 512.12 −0.11
p7714291 598.43 587.62 1.84
p7594455 627.74 638.90 −1.75
p2317947 803.57 786.38 2.19
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