ESTRO 36 Abstract Book

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S550 ESTRO 36
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Purpose or Objective
Immobilization and positioning are necessary in radiation
therapy of head-and-neck patients. A 5-points mask offers
stability, although large shifts of the shoulder (>1cm)
routinely can occur. A wrong positioned shoulder can
cause coverage loss or an increased critical structure dose.
The purpose of this study was to decrease the
shouldershifts by increasing the awareness of the RTT’s.
Material and Methods
In the period January 2014 till June 2016 head-and-neck
patients were immobilized daily with a 5-points mask
(2014/2015: CIVCO Medical solutions: Posicast®, 2016:
Orfit Industries: Efficast® Push Pin)/Wedges 50 & 70
(Cablon Medical)/Head supports (2014/2015: CIVCO
Medical solutions: Posifix® Supine Headrests, 2016 Orfit
Industries: Raycast® Head supports regular density with
lateral neck flaps).
For each year, 10 patients with head-and-neck cancer
were selected randomly.
All patients had daily CBCT imaging (Varian Medical
Systems). The position of both shoulders on the CBCT
relative to the mask was quantified in inferior direction in
Offline Review (Varian Medical Systems). Measurements
were performed on the coronal plane, 1.5cm dorsal of the
isocenter (Figure 1).
Results
Three hundred CBCT scans (600 shoulder positions) were
examined. Table 1 shows the shoulder shifts in inferior
direction. In 2014 23% of the shoulders was positioned
≥15mm inferior relative to the mask. At the end of 2014
the results were presented at our institute. Extra
awareness of the RTT’s resulted in a decrease of the
shouldershifts ≥15mm (7%). After a second presentation in
December 2015, the percentage of shifts ≥15mm
decreased (3.5% vs. 7%) in 2016. The percentage of
shifts 5mm ≤ x < 10mm increased relative to 2015 (34.5%
vs. 24.5%). This might be due to lack of experience with
the new type of masks.
Conclusion
A presentation and discussion session is a simple and
efficient way to create more awareness. Extra awareness
of the RTT’s improved the setup of the shoulders in a 5-
points mask, but the immobilization of the shoulders
demands attention. The reason for the increase in shifts
5mm ≤ x < 10mm will be further investigated.
PO-0998 Comparison of the accuracy of different
pillow for radiation therapy of head and neck cancer
C.Y. Lin1, W.H. Yu1, C.Y. Lin1, J.T.C. Chang1
1Chang Gung Memorial Hospital, Department of
Radiation Oncology, Taoyuan, Taiwan
Purpose or Objective
Random error occurring in daily treatment is always a
serious concern in fractionated radiotherapy (RT). Image
guided radiotherapy can partially solve some of these
problems. However, the curvature of the cervical spine is
still a problem. Change of spine curvature can easily result
in a deviation of more than 3mm. Therefore, we initiate
this study to evaluate the accuracy of different pillow
used for radiotherapy and to eliminate the errors caused
by curvature change.
Material and Methods
With the agreement of institutional review board, 71 head
and neck patients were enrolled and randomly assigned to
use different pillow for either primary or postoperative
RT. The three different pillows including conventional
pillow (CP, Silverman Headrests, CIVCO, medical
solution), customized pillow with alpha cradle (AC,
Smithers Medical Products, Inc. ), and Moldcare Head
Cushion pillow (MP, Alcar Co, Inc.). All patients used head
and shoulder mask for fixation. Daily on-board image (OBI)
was acquired for evaluation and correction of set-up error.
Change of curvature was measured by the movement of
the vertebral body of first (C1) and 5 th (C5) cervical spine,
comparing to the location on digital reconstructed image
from CT simulation.
Results
Of all patients accrued, 34 patients received surgery and
postoperative radiotherapy, and 13, 11, and 10 patients
used CP, AC, and MP respectively. Thirty-seven patients
received primary radiotherapy without surgery, and 14,
11, and 12 of them used CP, AC, and MP respectively.
There were 1633 OBI acquired. In postoperative RT group,
the absolute movement of C1 were 0.07±0.03 cm,
0.07±0.03 cm, and 0.09±0.03 cm, when CP, AC, and MP
was used, respectively (p> 0.05). In RT group, the absolute
movements of C1 were 0.07±0.03 cm, 0.06±0.02 cm, and
0.08±0.08 cm, when CP, AC, and MP were used,
respectively (p> 0.05). In comparison the movement of C5,
the absolute movements were 0.15±0.04, 0.21±0.07, and
0.16±0.72, when CP, AC, and MP was used in postoperative
RT group, respectively (p> 0.05). In primary RT group, the
absolute movements were 0.23±0.09, 0.14±0.05, and
0.15±0.03, when CP, AC, and MP was used, respectively.
The movements of C5 in patients who used AC (p = 0.048)
or MP (p = 0.05) were significant lower than patients who
used CP in primary RT group.
Conclusion
Customized pillow could reduce setup error in patients
who received primary radiotherapy but not postoperative
radiotherapy.
PO-0999 Control of rectal volume with Kampo formula
during prostate radiotherapy: A prospective study
J. Kobayashi1, T. Tahara2, Y. Matsuzaki1, Y. Ono1, J.
Matsumoto1, H. Sato1, K. Onko1, Y. Kishimoto1, T.
Tanino2, H. Sakaguchi2, N. Uchida2
1Tottori University Hospital, Radiology, Yonago, Japan
2Tottori University Hospital, Radiation Oncology,
Yonago, Japan
Purpose or Objective
During intensity-modulated radiation therapy (IMRT) for
prostate cancer, volume and position of the prostatic
gland, bladder and rectum should be kept stable to
minimize adverse events such as radiation proctitis or
rectal bleeding. For this purpose, keeping the rectal
volume small is essential. Daikenchuto (DKT) is a
traditional Japanese herbal (Kampo) formula used to treat
patients with abdominal bloating or constipation and is