International Journal of Medical Physics, Clinical Engineering and Radiation Oncology, 2013, 2, 92-97
http://dx.doi.org/10.4236/ijmpcero.2013.23013 Published Online August 2013 (http://www.scirp.org/journal/ijmpcero)
Effect of Breathing on Exposed Lung Volumes
and Doses in Patients with Breast
Carcinoma Receiving Radiotherapy*
Evren Ozan Göksel1#, Evrim Tezcanli2, Melahat Garipağaoğlu2, Öznur Şenkesen1,
Halil Küçücük1, Meriç Şengoz2, Nuran Beşe3, Işık Aslay4
1Department of Radiation Oncology, Acibadem Kozyatagi Hospital, Istanbul, Turkey
2Department of Radiation Oncology, Acibadem Univer sity, Istanbu l , T u r k ey
3Oncology Institute, Istanbul University, Istanbul, Turkey
4Department of Radiation Oncology, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey
Email: #evrenozangoksel@yahoo.com, tezcanlievrim@gmail.com, melahat.garipagaoglu@gmail.com,
osenkesen@gmail.com, halilkucucuk@gmail.com, msengoz@asg.com.tr,
nuranbese@superonline.com, isik.aslay@gmail.com
Received March 8, 2013; revised April 10, 2013; accepted May 27, 2013
Copyright © 2013 Evren Ozan Göksel et al. This is an open access article distributed under the Creative Commons Attribution Li-
cense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ABSTRACT
Introduction: Th is study evaluates the changes in th e lung volume (LV) exposed radiation dur ing the breath cycle and
whether these volume differences have an effect on both lung and target doses in breast carcinoma patients. Material
and Methods: Ten patients with left breast carcinoma underwent breast conservative surgery or mastectomy receiving
radiotherapy (RT) (breast or chest wall and regional lymph nodes) were included. For this study, planning computerized
tomography (CT) images were obtained during deep inspiration (DI) and end of expiration (EE), besides free breathing
(FB) to simulate breath cycles. Three-dimensional conformal or intensity-modulated RT planning was done to obtain
dose-volume information using CT series taken FB, DI and EE. The treatment plan was done with FB images and ex-
ported to the DI and EE scans and re-calculated. Volume changes and calculated dose differences according to breath
cycles were compared. Results: There were significant differences in the whole LV, ipsilateral LV and contralateral LV
between FB-DI and EE-DI while no significant difference was seen between FB and EE. V20 was lower during DI than
FB and EE but the difference was not significant. There was no significant variation in whole breast dose although sig-
nificant dose variations were observed in mean MI, supraclaviculary and level III axillary lymph node doses between
breath cycles. Conclusion: Breath cycle had no significant effect on whole breast dose although significantly changed
regional lymph node doses in patients with breast carcinoma receiving whole breast and regional lymph nodes radio-
therapy. V20 dose was lower during DI than FB and EE, but the difference was not significant.
Keywords: Radiotherapy; Treatment Planning; Breast Carcinoma; Lung Volume; Lung Dose; Breath Cycle
1. Introduction
Radiotherapy (RT) is an indispensable treatment option
for most patients with breast carcinoma because of its
benefits of local disease control and on improving sur-
vival rates. However, 5% - 30% of the ipsilateral lung is
exposed to radiation during RT [1,2]. Radiation induced
lung side effects can occur during and after completion
of radiotherapy [3]. These side effects can manifest with
different clinical symptoms such as radiation pneumoni-
tis (shortness of breath) or physical changes such as
bronchial stricture; they can also be detected using im-
aging techniques e.g. density changes in computerized
tomography (CT) and perfusion-ventilation defects in
SPECT scintigraphy [3,4]. According to the normal tis-
sue control probability model, the incidence of clinical
symptoms and severity of disease depend on both radia-
tion dose and the volume of ex posed lung [5-8]. In order
to reduce the radiation exposed hearth and lung volume,
sophisticated radiotherapy techniques such as respira-
tory-gate d r adiotherap y have been us ed [9,10].
The targets in the treatment of breast carcinoma com-
prise the chest wall, breast and/or regional lymph nodes.
*This study presen ted as a poster in UROK 2010 and ESTRO 29.
#Corresponding author.
C
opyright © 2013 SciRes. IJMPCERO
E. O. GÖKSEL ET AL. 93
Tangential fields are often used to irradiate the breast
and/or chest wall in order to protect the lungs and heart.
Tangential beam axis passes through target-lung-target.
A decrease in the lung tissue density results in an in-
crease in electron scattering, which subsequently leads to
an increase in the radiation dose in areas beyond and in
front of the lung [11,12]. Therefore, tissue density het-
erogeneity correction is considered during RT planning
in clinical practice. RT planning is based on a series of
CT images obtained without breath control (FB), which
might not include all anatomical changes during a whole
breath cycle. In other words, this CT series may not in-
clude peak phases of breathing, namely the end of expi-
ration (EE) and deep inspiration (DI). To our knowledge,
there is only one study examined whether organ-tissue
motion during breathing has an effect on the target dose
in patients with breast carcinoma. They reported target
dose was not significantly affected by breath cycles.
However they looked for whole breast dose. Their study
did not include regional lymph node doses [13].
This study evaluates the changes in the lung volume
exposed radiation during the breath cycle and whether
these volume differences have an effect on both lung and
target doses in breast carcinoma patien ts.
2. Patients and Methods
Ten consecutive patients with left breast carcinoma who
underwent breast conservative surgery (BCS) or mastec-
tomy (M), receiving radiotherapy (breast, chest wall and
regional lymph nodes) were included.
All patients were positioned supine on a carbon fiber
breast board having a fixed base with adjustable tilting,
and a body cast was fabricated to immobilize the pa-
tient’s shoulder, in order to en sure daily set-up accuracy.
Planning CT images were obtained from the upper neck
to the upper abdomen at 3 mm intervals with a multi-
detector 16 slices CT (Siemens Sensation 16 Erlangen,
Germany), while the patient was in the treatment position
on a flat tabletop. Because lung volumes vary with brea-
thing and planning images taken during one particular
moment of breath cycle such as expirium, inspirium, and
these images do not represent whole breath cycles.
Therefore the estimation of lung side effects based on
DVH parameters is not precise. In this study, to simulate
the lung volumes changes during the respiratory cycle,
DI and EE series were also acquired, apart from FB im-
age series, in same sequence to obtain unchanged DICOM
coordinates as used in previous studies [14,15]. DI and
EE image series were registered to FB, according to
DICOM coordin ates using ECLIPSE version 8.6 (Varian,
Palo Alto, USA) radiotherapy planning system (Figure
1). The target and organs at risk (OAR) volumes were
contoured by primary Radiation Oncologist; on 3 differ-
ent sets of images taken, according to RTOG breast con-
Figure 1. FB and DI CT images registration according to
DICOM coordinates. Lung volume changes and targets re-
placement between FB and DI.
touring atlas [16]. The target volumes were the breast or
chest wall, lymph nodes namely level I, II, III axillaries,
supraclaviculary and internal mammary (MI). Lung
(whole, contralateral and ipsilateral), heart, left anterior
descending artery (LAD) and contralateral breast were
OAR. The lung volumes were automatically contoured
by ECLIPSE using Hounsfield unit data and were manu-
ally corrected.
Target prescription dose was 4600 - 5000 cGy for this
dosimetric study. Further planning requirements: 95% of
the target volume receiving 95% of the prescription dose
(4350 - 4750 cGy) and 110% of pr escription do se ( 5060 -
5500 cGy) should not exceed 5% of CTV volume. The
dose constraints for OAR were: volume receiving 20 Gy
(V20) < 30% for the ipsilateral lung, mean dose 3.5 Gy
and V20 < 1% for heart and mean dose should not ex-
ceed 1 Gy, for contralateral breast V3.5 < 1%. Primarily,
three-dimensional conformal planning was used for all
patients using CT slices were taken during FB series for
each patient. However planning requirements were not
achieved for 4 patients. Consequently IMRT planning
was done for these particular 4 patients. Then, all plans
were exported to DI and EE image series to obtain that
dose-volume information changes depending on respira-
tory motion. Any parameter difference such as beam an-
gles, wedges, field size, etc. of FB pla n was not al lowed in
planning for DI and EE series. In order to avoid the effect
of heterogeneity difference during recalculation, MU
values from FB plan were entered for each field, in DI and
EE plan. Modified Batho heterogeneity correction algo-
rithm was on during all calculations.
The absolute and percentages of whole, ipsilateral and
contralateral lung V5, V20 and prescription dose (PD)
volumes belong to different breath cycle namely FB, DI
Copyright © 2013 SciRes. IJMPCERO
E. O. GÖKSEL ET AL.
94
and EE were calculated and compared each other. Whe-
ther there was a difference between V20 among breath
cycles was studied. Furthermore, target coverage, min,
mean and max targets doses for different breath cycles
namely FB, DI and EE were calculated and compared
each other. Parts of this study examining hearth and con-
tralateral breast volume-dose changes during breath cycle
were publ ishe d and bein g pu bli shed el sewhe re sepa rate ly.
The significance of dose and volume changes was inves-
tigated using Wilcoxon test (PASW statistics 18) [13].
3. Results
The absolute and perce ntages of V5, V20 and PD volum es
of whole, ipsilateral and contralateral lung during FB, DI
and EE are listed in Table 1. The differences between
FB-DI were found significant for criteria namely absolute
whole, ipsilateral and contralateral lung volumes, whole
lung V5, ipsilateral lung V5, whole lung V20, lung vol-
ume receiving PD, ipsilateral lung volume receiving PD,
% lung volume receiving PD and % ipsilateral lung vol-
ume receiving PD. However, contralateral lung volume
was the only significant factor between FB-EE (Figure
2).
Calculated min, max and mean target namely whole
breast, axillary level I-III, supraclaviculary, infraclavicu-
lary and M I for diffe rent breat h cycle and a re shown i n the
Table 2. Average targets coverage was adequate for all
breath cycle while target coverage was not adequate for 6
out of 10 patie nts. No significant difference was foun d be-
tween whole breast doses. However there was a signifi-
cant differences between mean MI and level III axillary
lymph node doses belo ngs to FB and DI a nd mean l evel II
axillary doses belongs to FB and EE (Figure 3).
4. Discussion
In the present study, there were significant differences
between FB-DI for absolute whole, ipsilateral, contralat-
eral, V5, V20 lung volumes and volume exposed PD as
reported previously [13,14]. On the other hand, absolute
lung volumes were not significantly differ between FB
and EE except contralateral lung volume. As known,
absolute lung volume increases during inspiration in
comparison to FB, because lung inflates. Percent lung
volume is better than absolute volume to estimate radia-
tion related side effects. Both exposed dose and % vol-
ume are determine radiation side effects [17,18]. Lung
functions permanently damage when exposed radiation
doses greater than 20 Gy which is accepted as tolerance
dose for lung [16]. Recently, Stranzl et al. reported sig-
nificant dose decrease in both exposed heart and lung in
their study examining benefit of radiotherapy during
deep inspirium breath-hold in patients with breast carci-
(a)
(b)
Data are shown as median values; 1) Whole lung volume (ml); 2) Ipsilateral
lung volume (ml); 3) Contralateral lung volume (ml); 4) Lung volume re-
ceiving 5 Gy (ml); 5) Ipsilateral lung volume receiving 5 Gy (ml); 6) Lung
volume receiving 20 Gy (ml); 7) Lung volume receiving prescription dose
(ml); 8) % Lung volume receiving prescription dose; 9) % Ipsilateral lung
volume receiving prescription dose.
Figure 2. (a) Absolute lung volume and exposed absolute
lung volume; (b) Percentage of exposed lung volume dif-
ferences during breath cycle.
Dat a a re sh o wn a s m ed i an va lu e s; 1) Mean axillary (Level III) dose (cGy); 2)
Mean (Supraclaviculary) dose (cGy); 3) Mean (MI) dose.
Figure 3. Target (lymph nodes) dose differences according
to breath cycle.
noma receiving RT [19]. They reported significant de-
crease in % ipsilateral lung V20 during deep inspirium
breath-hold, average ipsilateral V20 values changes %
.5 for whole group. However decrease were seen in 8 2
Copyright © 2013 SciRes. IJMPCERO
E. O. GÖKSEL ET AL.
Copyright © 2013 SciRes. IJMPCERO
95
Table 1. Organ at risk dose and volume variations according to breath cycles. Significant of differences were shown as “p*
and “p**” values representing variation between FB-DI and F B-EE respectively.
FB DI p* EE p**
Med (max-min) Med (max-min) Med (max-min)
Whole lung volume (ml) 2822.5 (4134 - 17 22)4863 (6019 - 1665)0.007 2525.5 (3950.2 - 1710)0.059
Ipsilateral lung volume (ml) 1289 (1823 - 853) 2443.5 (2753 - 82 5)0.007 1189 (1725.1 - 73 8) 0.083
Contralateral lung volume (ml) 1478.5 (2311 - 87 1)2389.5 (3247 - 840)0.074 1219.5 (2224.5 - 774)0.007
Lung volume receiving 5 Gy (ml) 451.5 (1279 - 365 )904.5 (1789 - 355)0.007 508.5 (1166.8 - 367)0.646
% Lung volume receiving 5 Gy 20.2 (31 - 14) 20 (31.5 - 15) 0.440 21.7 (29.6 - 14.6) 0.066
Ipsilateral lung volume receiving 5 Gy (ml) 451.5 (1256 - 366 )873.5 (1676 - 0) 0.037 501 (1158 - 367) 0.646
Lung volume receiving 20 Gy (ml) 304.5 (598 - 230) 593 (1053 - 261) 0.007 345 (582 - 234) 0.799
% Lung volume receiving 20 Gy 13.1 (17.6 - 8.3) 13.9 (17.5 - 10) 0.109 14.1 (19.6 - 9) 0.308
% Ipsilateral lung volume receiving 20 Gy 30.4 (41.5 - 19) 29.2 (38 - 22) 0.721 29.4 (40.2 - 20) 0.200
Lung volume receiving prescription dose (ml) 50.3 (147 - 4) 244.8 (371 - 100) 0.007 23 (174 - 0) 0.959
% Lung volume receiving prescription dose 1.4 (5.8 - 0.1) 5.2 (7 - 2.5) 0.005 0.9 (6.2 - 0) 0.444
% Ipsilateral lung volume receiving prescription dose 4.4 (11.8 - 0.1) 11 (15 - 5.4) 0.005 2.1 (12,5 - 0) 0. 508
p*” and “p**” values represent the significance; (FB) free breathing, (DI) deep inspiration, (EE) end of expiration.
Table 2. Target dose differences according to breath cycle. Significant of differences were shown as “p*” and “p**” values
representing variation between FB-DI and FB-EE respectively.
FB DI p* EE p**
Med (max-min) Med (max-min) Med (max-min)
Mean breast dose (cGy) 5097.5 (5176 - 4913) 5128.5 (5573.4 - 4677)0.203 5026 (5250 - 507) 0.114
Mean (Level I) dose (cGy) 4907.5 (5146 - 46 27) 4923 (5082 - 469 3) 0.333 4898.5 (5045 - 4616) 0.169
Mean (Level II) dose (cGy) 5032 (5300 - 4740) 5112 (5407 - 4426) 0.575 5016.5 (5306 - 4574) 0.760
Mean (Level III) dose (cGy) 5181.5 (5341 - 48 86) 5179.5 (5423 - 5091) 0.047 5154.5 (5365 - 4983) 0.203
Mean (Supraclaviculary) dose (cGy) 5217 (5409 - 4981) 5147 (5430 - 4900) 0.203 5070.5 (53 31 - 4634) 0.009
Mean (MI) dose (cGy) 4205.5 (5409 - 24 18) 5232 (6164 - 502 6) 0.011 4412.5 (5210 - 2446) 0.721
p*” and “p**” values represent the significance; (FB) free breathing, (DI) deep inspiration, (EE) end of expiration.
out of 11 patients. Likewise, Vikstrom et al. reported
significant ipsilateral lung V20 decrease during breath-
hold in their study, which is searching for heart, and lung
dose changes during breath-hold in patients with breast
carcinoma receiving RT. Yet, the amount of decrease
was limited to 2.2% [13]. In present study breath cycle
did not have a significant effect on % ipsilateral lung
V20 while there was 1.2% average decrease in DI in
comparison to FB. Decreases were seen 5 out of 10 pa-
tients. One speculates that, there was a tendency to de-
crease in ipsilateral lung V20, but this differen ce was not
statistically significant. Target selection differences
could be the reason of dissimilar result. Whole breast-
chest wall and all regional lymph nodes were within tar-
get in present study while whole breast and MI alongside
whole breast was targeted in Stranzl study and whole
breast was only targeting in Vikstrom study.
IMRT incr eases low dose area arising scattering radia-
tion doses, have been used more common in breast car-
cinoma because of its benefit of heart and lung protection
[20]. Then V5 became an issue, yet the long term effect
on lung function is not known. As seen on table, there
were no significant differences between V5 and V20.
There was a tendency to increase % lung volume ex-
posed to prescription dose. However the amount of dif-
ference is limited.
According to the results of this study, the ipsilateral
lung V20 is approximately 28% - 29% in all phases of
breathing. This result is compatible with previous studies
[1]. Radiation Therapy Oncology Group recommends
that, ipsilateral V20 volumes should be restricted to 10%
patients receiving radiotherapy for “breast only” and
30% for “breast plus regional lymph nodes” respectively
[21-23].
E. O. GÖKSEL ET AL.
96
Individual organ motion could affect treatment plan-
ning, target dose and determined dose limits. Therefore,
organ motion should be considered and treatment plan-
ning tailored accordingly. Dose differences between
plans using FB and DI images arise both from organ mo-
tion and heterogeneity differences. It would be ideal for
the organ position to be constant during planning and the
course of treatment. Respiratory-gated radiotherapy could
help to obtain an even level during the breath cycle and
achieve treatment execution within the determined dose
limits.
Because patients with breast carcinoma have higher
life expectancy, side effects are a very important factor to
be considered. Lung side effects could manifest months
to years after completion of radiotherapy [3]. Although
there are some approaches to relieve symptoms, chronic
breathing problems related to radiation therapy are ire-
versible and progressive. They could affect the patient’s
quality of life. Lung side effects can be particularly seri-
ous in patients receiving a combination of chemotherapy
and radiotherapy. Therefore these patients should be fol-
lowed-up carefully.
Although there were dose differences for some targets,
except for MI lymph nodes, these changes we re lim ited t o
200 cGy, dur ing differen t phases of the respiration cycle.
However the MI lymph nodes are required to irradiate
only in selected higher stage cases. For example, in this
study, t hose dif ferences wer e studi ed; howe ver, MI lymph
nodes were treated with only 1 out of 10 patients.
5. Conclusion
The results of this study suggest that, heterogeneity cor-
rection without considering breath control is adequate to
estimate the target dose during the whole breath cycle.
Furthermore, radiotherapy planning to use FB is suffi-
cient to estimate lung side effects. Because there is no
significant difference in V20 values for planning im-
ages obtained in the FB, DI and EE phases.
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