Volumetric-modulated arc radiotherapy for pancreatic malignancies: Dosimetric
comparison with helical TomoTherapy
By
Sanja Ognjenovic
A PROJECT
submitted to
Oregon State University
University Honors College
in partial fulfillment of
the requirements for the
degree of
Honors Baccalaureate of Science in Microbiology
(Honors Scholar)
Presented May 13, 2015
Commencement June 2015
AN ABSTRACT OF THE THESIS OF
Sanja Ognjenovic for the degree of Honors Baccalaureate of Science in Microbiology
presented on May 13 2015. Title: Volumetric-modulated arc radiotherapy for pancreatic
malignancies: Dosimetric comparison with helical TomoTherapy.
Abstract approved: ______________________________________________________
Krystina Tack
Purpose: To compare target dose conformality and OAR sparing afforded by VMAT and
HT for pancreatic cancer.
Materials and Methods: A retrospective planning study was performed in 18 patients.
Total treatment dose was 59.4Gy. OAR and PTV mean doses, conformity indices,
isodose volumes, and integral doses were compared. The relationship between tumor
volume, patient circumference, and these variables was also evaluated.
Results: Mean doses to the left kidney (p<.001), right kidney (p<.001), and liver (p<.001)
were smaller with VMAT. The mean dose to the PTV was smaller with HT (p=.002). The
large field VMAT resulted in a smaller CI percent deviation from 1.0 (p=.025). There
was no significant difference for the boost plan (p=.092). Integral dose was significantly
lower with VMAT (p<.001). Integral dose was lower for smaller tumor volumes and
patent circumferences with both techniques.
Conclusion: There appears to be an advantage in using VMAT over HT in reducing
radiation doses to the liver and kidneys, in obtaining tighter isodose volumes, and in
obtaining a lower integral dose. VMAT may provide superior conformity indices for
larger doses, but the techniques are comparable for low doses. Smaller tumor volume and
patient circumference result in lower integral doses with both techniques.
Key Words: pancreatic malignancy, VMAT, HT, integral dose
Corresponding e-mail address: ognjenos@onid.orst.edu
©Copyright by Sanja Ognjenovic
May 13 2015
All Rights Reserved
Volumetric-modulated arc radiotherapy for pancreatic malignancies: Dosimetric
comparison with helical TomoTherapy
by
Sanja Ognjenovic
A PROJECT
submitted to
Oregon State University
University Honors College
in partial fulfillment of
the requirements for the
degree of
Honors Baccalaureate of Science in Microbiology
(Honors Scholar)
Presented May 13, 2015
Commencement June 2015
Honors Baccalaureate of Science in Microbiology project of Sanja Ognjenovic presented
on May 13, 2015.
APPROVED:
Krystina Tack, Mentor, representing OSU Nuclear Engineering and Radiation Health
Physics
James Tanyi, Committee Member, representing OHSU Department of Radiation
Medicine
Alena Paulenova, Committee Member, representing OSU Nuclear Engineering and
Radiation Health Physics
Toni Doolen, Dean, University Honors College
I understand that my project will become part of the permanent collection of Oregon
State University, University Honors College. My signature below authorizes release of
my project to any reader upon request.
Sanja Ognjenovic, Author
Table of Contents
Introduction ..................................................................................................................................... 1
Materials and Methods .................................................................................................................... 1
Patients......................................................................................................................................... 1
Treatment Planning...................................................................................................................... 2
Comparison of Techniques .......................................................................................................... 2
Results ............................................................................................................................................. 3
Discussion ....................................................................................................................................... 3
Conclusions ..................................................................................................................................... 4
Limitations ...................................................................................................................................... 4
References ....................................................................................................................................... 5
Appendix ......................................................................................................................................... 7
Table 1 ......................................................................................................................................... 7
Table 2 ......................................................................................................................................... 8
Table 3 ......................................................................................................................................... 9
Table 4 ....................................................................................................................................... 10
Introduction
Pancreatic cancer treatment is commonly a tri-modality approach of chemotherapy,
radiation therapy, and surgical resection. As the tumor is close to normal tissue and critical
organs toxicity is a primary concern. Treatment with traditional radiotherapy techniques such as
3D-CRT can result in toxicity to critical organs such as the liver, stomach, small bowel, and
kidneys.1 Intensity-modulated radiotherapy (IMRT) has been shown to improve target dose
conformality and reduce toxicity when compared to 3D-CRT.2-5 The availability of even more
refined radiation therapy techniques such as RapidArc (RA) and Helical TomoTherapy (HT)
presents new opportunities to study dose conformality and sparing of these critical structures.
RapidArc is a form of volumetric-modulated arc therapy (VMAT) in which the radiation
dose is delivered through one or more dynamically modulated arcs. During treatment planning,
the dose optimization algorithm simultaneously modulates the rotation speed of the gantry, the
shape of the multi-leaf collimator (MLC) aperture, and the delivery dose rate allowing for shorter
treatment times, improved conformality, and the delivery of fewer monitor units.6-8 Helical
TomoTherapy (HT) is an arc-based approach to IMRT in which the radiation dose is delivered
slice by slice as opposed to the entire volume being irradiated at once. During HT the gantry
rotates at a constant speed while the shape of the binary MLC aperture changes and the patient
table moves in and out of the beam aperture. When compared with traditional IMRT techniques
HT has been shown to reduce radiation doses to organs at risk thereby reducing gastrointestinal
toxicity.9-10
There are currently only a few analyses comparing these two techniques. Cao et al. and
Fogliata et al. both compared VMAT and HT for the treatment of intracranial tumors. Cao et al.
concluded that the techniques are generally comparable, but HT can provide superior results for
more complex cases.11 Fogliata et al. also concluded that the techniques are comparable in terms
of conformality and organ sparing, but reported that more complex studies need to be done. Our
goal was to dosimetrically compare target dose conformality and organ-at-risk sparing afforded
by VMAT and HT in the treatment of pancreatic tumors.12 We also sought to evaluate if tumor
volume or patient circumference affects treatment quality for either technique.
Materials and Methods
Patients
A retrospective planning study was performed on eighteen patients with advanced
pancreatic cancer with and without previous resection. Data collection and analysis was
approved by the Institutional Review Board of the Knight Cancer Institute at the Oregon Health
and Science University. During treatment patients were immobilized using the BodyFix wholebody double vacuum immobilization system (Medical Intelligence, Schwabmuenchen, Germany)
without diaphragmatic control and with abdominal compression.13 All patients underwent a freebreathing computed tomography (CT) scan as well as a free-breathing respiratory-correlated,
four-dimensional CT (4DCT) on a 16-slice helical big-bore simulator (Philips Medical Systems,
Cleveland, OH) in the supine position.
1
Treatment Planning
The 4DCT scans were reconstructed in 10 equally spaced time bins of 3mm slice
thickness using respiratory phase binning. The 4D maximum intensity projection data set (MIP),
the free breathing CT, and the average intensity projection CT were all exported to Eclipse
v8.9.08 (Varian Medical Systems, Palo Alto, CA) for target and OAR segmentation. Using the
MIP, free breathing CT, and the 10 respiratory phases of the 4DCT an internal target volume
(ITV) was created. The ITV was expanded by a 5mm margin to create the planning target
volume (PTV). Organs at risk such as the spinal cord, kidneys, liver, stomach, and bowel were
contoured on the average intensity projection CT. The average-intensity projection CT was also
used for dose calculation. Individual isodose constraints were placed to ensure that the maximal
tolerated doses to the OARs per published Quantitative Analysis of Normal Tissue Effects in the
Clinic guidelines were not exceeded14.Plans were created so that the prescribed dose of 45Gy
encompassed at least 95% of the PTV (tissue heterogeneity was accounted for). A boost plan was
created on a new planning CT resulting in a cumulative dose of 59.4 Gy.
All VMAT plans were created using 10MV photons and delivered on a Varian Clinac
that is equipped with a 120-leaf Millennium multileaf collimator system, with forty 5-mm central
leaf-pairs and twenty 10-mm peripheral leaf-pairs. VMAT plans were generated with two
simultaneously optimized coplanar volumetric arcs with the same isocenter and with 360˚
rotation. HT plans were generated using the Hi-Art Helical Tomotherapy inverse planning
software. Tomotherapy plans were designed to match the isodose constraints used on VMAT
planning.
Comparison of Techniques
The CT data sets with contours and isodose lines were transferred to VelocityAl
(Velocity Medical Solutions, Atlanta, Georgia) to generate the cumulative dose from the original
plan and the boost plan. This was done through deformable registration, an optimization process
that correlates anatomical features observed in two different images of the same patient and ROI.
Once an optimal match is found between the input images (original and boost plan CTs) the
system is able to provide a cumulative dose.13.
Cumulative dose volume histograms (cDVH) were obtained for the PTV and OARs for
all patients. The following parameters were calculated for all patients and compared: Dmean
(mean dose) and D95% (the dose received by 95% of the PTV) for the PTV, Dmean and V30 (the
volume receiving more than 30Gy) for the liver, Dmean, V15 and V20 (volume receiving more than
15Gy and 20Gy, respectively) for the kidneys, and Dmax (maximum dose) for the spinal cord. No
cDVHs were obtained for the stomach or the small bowel. Expanding the GTV to the PTV
incorporates the dose to the small bowel so it is unnecessary to report this as a separate result.
The conformity indices of the plans, as well as the volumes of the 25%, 50%, 90%, and 100%
isodose lines, were also calculated. The conformity index of the plans was defined as the ratio
between the volume of the 100% isodose line and the PTV volume. Conformity indices were
compared by calculating their percent deviation from 1.0, as a value of 1.0 is ideal. The volumes
encompassed by the isodose lines were obtained using the VelocityAl system. We also calculated
the overall integral dose delivered to the patient. The integral dose was defined as the mean dose
delivered to the total body minus the PTV12,15,16. Additionally, all 18 patients were sorted into
three groups based on tumor volume. The first group averaged a tumor volume of 438.0cm3, the
second group 717.6 cm3, and the third group 1075.1 cm3. Dmean for the left kidney, right kidney,
and liver as well as Dmax for the spine, integral dose, and CI deviation from 1.0 for both original
2
and boost plans were compared between tumor volume groups. Lastly, we compared the effect
patient circumference had on these variables by sorting the patients into two groups based on
their circumference. Circumference was estimated by calculating the circumferential length
around the body at isocenter. The first group averaged a circumference of 295cm and the second
group averaged 541cm. All statistical analyses were performed using a paired, two-sided
Student’s t-test with a significance level of p < 0.05.
Results
Table 1 summarizes and compares the mean doses to the defined organs at risk for the
two treatment techniques. Mean doses were lower with VMAT plans than HT plans for the left
kidney (15.6 vs. 28.5, p<.001), the right kidney (15.0 vs. 27.4, p<.001), and the liver (13.0 vs.
28.8, p<.001). Maximum doses to the spinal cord were statistically insignificant (VMAT=35.1,
HT=39.4, p=.053). The mean dose to the PTV was lower with the HT plans (55.6 vs. 60.9,
p=.002). D95% was statistically insignificant (VMAT=56.6, HT=51.1, p= .826). Table 2
summarizes and compares the conformity indices as well as the volumes of the 25%, 50%, 90%,
and 100% isodose lines. For the large field plan VMAT produced a smaller CI percent deviation
from 1.0 (4.5% vs. 7.5%, p=.025). However, for the boost plan there was no significant
difference in CI deviation (VMAT=4.2%, HT=10.4%, p=.092). For the 25%, 50%, 90%, and
100% large field isodose lines the HT plans had significantly larger volumes than the VMAT
plans (p<.001 for 25%, 90%, 100%, p=.021 for 50%). The same trend was observed for the boost
plan 25%, 50%, and 90% isodose volumes (p<.001 for 25%, 50%, p=.001 for 90%). There was
no significant difference in the 100% boost plan isodose volumes (p=.145). Integral dose was
significantly lower with the VMAT plans than with the HT plans (p<.001). Table 3 compares
tumor volume and Dmean for the left kidney, right kidney, and liver, Dmax for the spine, integral
dose, and CI deviation from 1.0 for both original and boost plans. There were no significant
trends between tumor volume and any of these variables, except integral dose. Smaller tumor
volumes resulted in significantly lower integral doses with both VMAT (G1-G2 P=.001, G1-G3
P<.001, G2-G3, P=.005) and HT (G1-G2 P=.002, G1-G3 P<.001, G2-G3, P=.012). Table 4
compares the same variables, but with patient circumference. Similarly, there was only a
significant trend between patient circumference and integral dose. Patients with a smaller
circumference had significantly lower integral dose delivery with both VMAT (P=.002) and HT
(P=.009).
Discussion
In this study we dosimetrically compared target dose conformality and organ-at-risk
sparing afforded by VMAT and HT for the treatment of pancreatic cancer. Our results indicate
that double-arc 10MV VMAT plans may provide superior sparing of the kidneys and liver when
compared with HT plans. Our results also indicate that VMAT may provide tighter isodose
volumes for 25%, 50%, 90% and 100% isodose lines. To make a conclusion about conformity
indices more research needs to be done. Our results suggest that VMAT may provide superior
conformity indices for larger doses, but that for lower doses the treatment techniques may
provide comparable results. Our results also indicate that VMAT provides significantly lower
integral doses than HT. There appears to be no relationship between tumor volume or patient
circumference and dose conformality or sparing of organs at risk for either of these two
3
techniques. Only integral dose is affected. Smaller tumor volumes and patient circumferences
appear to result in lower integral dose delivery for both VMAT and HT.
Cai et al. conducted a similar pancreatic study and found that single-arc 6MV and 15MV
VMAT plans provide statistically comparable conformity indices when compared to HT plans
for radiation doses of 50Gy.17 The study by Cai et al. also found that there were small but
significant decreases in the mean dose to the bowel, duodenum, kidneys, and liver with the
VMAT plans. Pasquier et al. studied the treatment of prostate cancer with whole pelvic radiation
therapy (WPRT) using VMAT and HT for radiation doses of 46Gy and 76Gy.18 That study found
that at high doses VMAT better spared the rectal wall, but HT better spared the bladder wall. No
significant differences in mean dose to the rectal wall, bladder wall, or small bowel were found
between the two techniques at the lower dose. Pasquier et al. also found that the integral dose
was significantly lower with VMAT, as did Oliver et al19. There are no published works
evaluating the effects of either tumor volume or patient circumference on the effectiveness of
these techniques.
Conclusions
Both VMAT and HT can deliver conformal dose distributions while limiting the dose to
normal tissues regardless of tumor volume or patient circumference. There may be an advantage
in using VMAT over HT in the reduction of radiation doses to certain organs at risk such as the
kidneys and liver and in obtaining tighter isodose volumes. More research needs to be done to
develop a conclusion about which technique, if either, provides superior conformity indices.
Overall, VMAT provides a lower integral dose. However, both smaller tumor volume and
smaller patient circumference result in lower integral doses for both treatment techniques.
Limitations
The dose constraints used by our institution are unique and there is no guarantee that
another institution, using different dose constraints, will obtain the same results. Furthermore
there is variability in amongst patients and because of our small sample size (n=18) we cannot
confidently make a conclusion about the entire population of pancreatic cancer patients.
4
References
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
[13]
Regine WF, Winter KA, Abrams RA, et al. Fluorouracil vs gemcitabine chemotherapy
before and after fluorouracil-based chemoradiation following resection of pancreatic
adenocarcinoma: A randomized controlled trial. JAMA : the journal of the American
Medical Association 2008;299:1019-1026.
Landry JC, Yang GY, Ting JY, Staley CA, Torres W, Esiashvili N, Davis LW. Treatment
of pancreatic cancer tumors with intensity-modulated radiation therapy (IMRT) using the
volume at risk approach (VARA): employing dose-volume histogram (DVH) and normal
tissue complication probability (NTCP) to evaluate small bowel toxicity.Med Dosim.
2002 Summer;27(2):121-9.
Poppe MM, Narra V, Yue NJ, Zhou J, Nelson C, Jabbour SK. A comparison of helical
intensity-modulated radiotherapy, intensity-modulated radiotherapy, and 3D-conformal
radiation therapy for pancreatic cancer. Med Dosim. 2011 Winter;36(4):351-7.
Brown MW, Ning H, Arora B, et al. A dosimetric analysis of dose escalation using two
intensity-modulated radiation therapy techniques in locally advanced pancreatic
carcinoma. Int J Radiat Oncol Biol Phys 2006;65:274-283.
Yovino S, Poppe M, Jabbour S, et al. Intensity-modulated radiation therapy significantly
improves acute gastrointestinal toxicity in pancreatic and ampullary cancers. Int J Radiat
Oncol Biol Phys 2011;79:158-162.
Otto K. Volumetric modulated arc therapy: Imrt in a single gantry arc. Medical physics
2008;35:310-317.
Palma D, Vollans E, James K, et al. Volumetric modulated arc therapy for delivery of
prostate radiotherapy: Comparison with intensity-modulated radiotherapy and threedimensional conformal radiotherapy. Int J Radiat Oncol Biol Phys 2008;72:996-1001.
White P, Chan KC, Cheng KW, Chan KY, Chau MC. Volumetric intensity-modulated
arc therapy vs conventional intensity-modulated radiation therapy in nasopharyngeal
carcinoma: a dosimetric study. J Radiat Res. 2013 May;54(3):532-45.
Taylor R, Opfermann K, Jones BD, Terwilliger LE, McDonald DG, Ashenafi MS,
Garrett-Meyer E, Marshall DT. Comparison of radiation treatment delivery for pancreatic
cancer: Linac intensity-modulated radiotherapy versushelical TomoTherapy. J Med
Imaging Radiat Oncol. 2012 Jun;56(3):332-7.
Chargari C, Campana F, Beuzeboc P, Zefkili S, Kirova YM. Preliminary experience of
helical TomoTherapy for locally advanced pancreatic cancer. World J Gastroenterol.
2009 Sep 21;15(35):4444-5.
Cao D, Holmes TW, Afghan MK, Shepard DM. Comparison of plan quality provided by
intensity-modulated arc therapy and helical TomoTherapy. Int J Radiat Oncol Biol Phys.
2007 Sep 1;69(1):240-50.
Fogliata A, Clivio A, Nicolini G, Vanetti E, Cozzi L. Intensity modulation with photons
for benign intracranial tumours: a planning comparison of volumetric single arc, helical
arc and fixed gantry techniques. Radiother Oncol. 2008 Dec;89(3):254-62.
Fuss M, Salter BJ, Rassiah P, et al. Repositioning accuracy of a commercially available
double-vacuum whole body immobilization system for stereotactic body radiation
therapy. Technology in cancer research & treatment 2004;3:59-67.
5
[14]
[15]
[16]
[17]
[18]
[19]
Marks, L.B.; Yorke, E.D.; Jackson, A.; et al. Use of normal tissue complication
probability models in the clinic. Int. J. Radiat. Oncol. Biol. Phys. 76:S10–9,
http//dx.doi.org/10.1016/j.ijrobp.2009.07.1754
D’Souza W, Isaac R. Nontumor integral dose variation in conventional radiotherapy
treatment planning. Med. Phys. 2003 Aug; 30(8):2065-71.
Yang R, Xu S, Jiang W, Wang J, Xie C. Dosimetric comparison of postoperative whole
pelvic radiotherapy for endometrial cancer using three-dimensional conformal
radiotherapy, intensity-modulated radiotherapy, and helical Tomotherapy. Acta Oncol.
2010;49(2):230-6.
Cai J, Yue J, McLawhorn R, et al. Dosimetric comparison of 6 MV and 15 MV single arc
rapidarc to helical TomoTherapy for the treatment of pancreatic cancer. Med Dosim.
2011 Autumn; 36(3):317-20.
Pasquier D, Cavillon F, Lacornerie T, Touzeau C, Tresch E, Lartigau E. A dosimetric
comparison of TomoTherapy and volumetric modulated arc therapy in the treatment of
high-risk prostate cancer with pelvic nodal radiation therapy. Int J Radiat Oncol Biol
Phys. 2013 Feb 1;85(2):549-54.
Oliver M, Ansbacher W, Beckham WA. Comparing planning time, delivery time and
plan quality for IMRT, RapidArc and Tomotherapy [abstract] J appl Med
Phys. 2009;10:3068.
6
Appendix
Table 1
OAR
t-test
VMAT vs.
HT
VMAT
HT
15.6±3.5
28.5±3.5
14.7
45.2±14.4
56.0
23.6±10.2
41.0
12.1
114.9±56.6
183.3
58.0±35.5
160.5
Dmean (Gy)
15.0±3.9
27.4±4.6
Range
V15 (cc)
Range
V20 (cc)
Range
15.0
44.9±17.3
67.4
24.6±14.1
19.1
101.2±36.3
133.5
50.8±20.5
59.0
78.2
Dmean (Gy)
13.0±5.3
Range
V30 (cc)
Range
16.2
10.4±7.8
28.8±5.0
22.1
247.1±161.2
28.0
602.2
35.1±6.1
39.4±5.2
27.5
19.8
55.6±6.8
28.6
0.002
Range
60.9±1.5
7.0
56.1±10.4
45.3
0.826
Range
56.6±8.0
26.7
169624±63089.6
205649.4±72791.7
277276.7
<.001
Left kidney
Dmean (Gy)
Range
V15 (cc)
Range
V20 (cc)
Range
<.001
<.001
<.001
Right kidney
<.001
<.001
<.001
Liver
<.001
<.001
Spinal cord
Dmax (Gy)
Range
0.053
PTV
Dmean (Gy)
D95% (Gy)
Integral Dose
Range
226271.9
7
Table 2
VMAT
HT
t-test
4.5±2.9
14.2
4.2±5.2
23.5
5437.1±1947.2
7767.5
2412.6±966.9
4120.3
7.5±4.3
16.8
10.4±13.1
59.4
8142.2±3046.2
12632.7
2821.8±1216.3
5451.6
0.025
884.7±360.0
1586.6
717.0±298.9
1294.0
2837.7±1555.2
6331.4
1057.9±736.1
3019.5
1098.8±449.2
1956.1
800.8±345.1
1487.8
4378.0±2444.8
10085.9
1327.7±843.9
3522.6
<.001
342.8±235.4
939.9
290.6±200.0
830.5
461.5±301.7
1266.5
310.3±213.7
895.8
0.001
CI Deviation (%)
Large field
Range
Boost
Range
Iso 25% (cc)
Range
Iso 50% (cc)
Range
Iso 90% (cc)
Range
Iso 100% (cc)
Range
Boost Iso 25% (cc)
Range
Boost Iso 50% (cc)
Range
Boost Iso 90% (cc)
Range
Boost Iso 100% (cc)
Range
0.092
<.001
0.021
<.001
<.001
<.001
0.145
8
Table 3
Average
G2
G1
G3
G1-G2
t-test
G1-G3
G2-G3
VMAT
CI Large Deviation from 1.0 (%)
Range
CI Boost Deviation from 1.0 (%)
Range
L Kidney Mean (Gy)
Range
R Kidney Mean (Gy)
Range
5.1
14.2
6.5
22.9
16.2
9.7
14.7
15.0
4.2
1.3
3.1
2.3
13.9
11.7
14.1
10.3
4.3
1.2
3.0
3.6
16.7
8.0
16.3
6.7
0.694
0.719
0.932
0.403
0.347
0.825
0.352
0.788
0.288
0.709
0.515
0.109
Liver Mean (Gy)
Range
Spine Max (Gy)
Range
Integral Dose
Range
10.4
13.0
36.6
17.1
103713.7
78871.9
14.2
14.6
33.3
19.2
182662.9
140025.2
14.3
12.4
35.5
15.1
222495.3
121199.9
0.139
0.327
0.994
0.342
0.775
0.627
0.001
<.001
0.005
HT
CI Large Deviation from 1.0 (%)
5.1
4.2
4.3
0.053
0.505
0.803
Range
CI Boost Deviation from 1.0 (%)
Range
L Kidney Mean (Gy)
Range
R Kidney Mean (Gy)
13.8
6.5
5.6
28.1
11.4
24.5
13.4
3.1
10.8
28.7
10.8
28.1
8.8
3.0
58.6
28.8
5.9
29.7
0.009
0.216
0.515
0.867
0.668
0.967
0.141
0.136
0.361
Range
Liver Mean (Gy)
Range
Spine Max (Gy)
15.3
26.0
21.0
36.9
8.5
30.2
2.3
40.0
3.1
30.4
1.6
41.2
0.280
0.252
0.700
0.386
0.322
0.637
Range
Integral Dose
18.3
135165.0
7.4
204448.0
14.5
277335.2
0.002
<.001
0.012
Range
111707.8
138507.4
143466.2
*G1 averaged a tumor volume of 438.0cm3, G2 717.6 cm3, and G3 1075.1
cm3
9
Table 4
Average
G2
G1
t-test
G1-G2
VMAT
CI Large Deviation from 1.0 (%)
Range
CI Boost Deviation from 1.0 (%)
Range
L Kidney Mean (Gy)
Range
R Kidney Mean (Gy)
Range
4.9
14.2
5.0
23.5
16.5
9.7
15.0
15.0
4.2
1.0
3.4
3.6
14.7
13.6
15.1
9.8
0.654
Liver Mean (Gy)
13.2
Range
14.7
PTV Mean
60.4
Range
5.3
Spine Max (Gy)
37.1
Range
17.1
Integral Dose (Gy) 124808.7
Range 111398.8
12.7
15.5
61.5
4.2
33.1
19.6
214439.3
147400.0
0.822
0.640
HT
CI Large Deviation from 1.0 (%)
Range
CI Boost Deviation from 1.0 (%)
Range
L Kidney Mean (Gy)
8.1
16.8
5.4
14.2
28.6
6.9
8.8
15.5
55.0
28.4
Range
R Kidney Mean (Gy)
Range
Liver Mean (Gy)
10.3
26.1
19.1
27.5
12.1
28.8
4.7
30.2
Range
PTV Mean
22.0
54.4
2.4
56.7
0.548
0.291
0.939
0.195
0.191
0.002
0.107
0.857
0.131
0.267
0.509
Range
28.6
11.3
Spine Max (Gy)
38.7
40.1
0.495
Range
18.3
16.4
Integral Dose (Gy) 157574.5 248668.9
0.009
Range 133810.5 223766.0
*G1 averaged a patient circumference of 295cm, G2 averaged
541cm
10