DOSIMETRIC COMPARISON OF 3 DIFFERENT TREATMENT TECHNIQUES IN PANCREATIC CANCER RADIOTHERAPY: RETROSPECTIVE STUDY

Year 2018, Volume: 44 Issue: 2, 111 - 116, 01.08.2018

Burcu İbicioğlu , Meral Kurt , Sema Gözcü Tunç , Candan Demiröz Abakay Sibel Kahraman Çetintaş Abdulhamit Turan , Ece Ayfer Cura Habibe Altaş

https://doi.org/10.32708/uutfd.431268

Abstract

In our study, our aim is to treat 20
patients with pancreatic cancer who had radiotherapy, with conformal
radiotherapy (3D-CRT), intensity modulated radiotherapy (IMRT), volume
modulated arc therapy (VMAT) planning and comparison of the techniques in terms
of dosimetric. In this study, 20 patients with primary pancreatic head tumor
who were treated in our clinic between 2012-2017 were retrospectively
evaluated. Five different treatment techniques were planned for each patient’s
tumor, around of tumor  and regional
lymph nodes, and all plans were implemented so that target volume doses would
be 54/45 Gy. Plans were prepared using 6 MV X-rays for VMAT and IMRT and 15 MV
X-rays for 3BKRT. Techniques were compared in
terms of planned target volume doses (PTV), conformity index (CI), homogeneity
index (HI), organs at risk (kidneys, spinal cord, liver). The mean CI indices
VMAT 1 arc plans for PTV₅₄  and PTV₄₅ were found to be 1.16 and
1.03 for VMAT 2 arc 1.01 and 1.00. Although there was no significant difference
between the two groups in terms of CI, the most appropriate CI value was found
in VMAT 2 arc plans (p = 0.806 for PTV₄₅ and p = 0.595 for PTV₅₄). There was no difference in
terms of CI between IMRT and 3D-CRT techniques, the best value being obtained
from IMRT technique. Doses of VMAT 2 arc plans were found to be
lower, although there was no statistical difference between VMAT 1 arc and VMAT
2 arc plans in terms of critical organ doses. Since pancreatic tumors are
located close to critical organs such as kidneys and liver as a settlement, 3DCRT
plans can be accepted in terms of liver; but the kidneys have not succeeded in
terms of protection. The VMAT 2 arc technique excelled in dose sprinning, CI,
HI and critical organ doses according to other techniques. Therefore, VMAT may
be preferred as a treatment technique when side effects are taken into account.

Keywords

VMAT, Pancreatic Cancer, 3D-CRT, IMRT

Pankreas Kanseri Radyoterapisinde 3 Farklı Tedavi Tekniğinin Dozimetrik Karşılaştırılması: Retrospektif Çalışma

Abstract

Çalışmamızda
amacımız pankreas kanseri tanısıyla radyoterapi görmüş, 20 hastaya konformal
radyoterapi (3B-KRT), yoğunluk ayarlı radyoterapi (IMRT), hacimsel ayarlı ark terapi
(VMAT) teknikleri ile tedavi planlaması yapılarak tekniklerin dozimetrik açıdan
karşılaştırılmasıdır. Bu çalışmada 2012-2017 yılları arasında kliniğimizde
tedavi görmüş, primer pankreas başı tümörü olan 20 hasta retrospektif olarak
değerlendirilmiştir. Her hastaya tümör, tümör çevresi ve bölgesel lenf
nodlarına yönelik 5 farklı tedavi tekniği planlanmış, tüm planlar hedef hacim
dozları 54/45 Gy olacak şekilde seçilmiştir. Planlar VMAT ve IMRT için 6 MV X-ışını,
3BKRT için 6/15 MV X-ışını kullanılarak hazırlanmıştır. Planlanan hedef hacim
dozları (PTV), Conformite indeksi (CI), Homojenite indeksi (HI), riskli organlar
(böbrekler, spinal cord, karaciğer) açısından teknikler karşılaştırılmıştır.
PTV₅₄ ve PTV₄₅ için ortalama CI indeksleri VMAT 1 ark
planlarında sırasıyla 1,16 ve 1,03 VMAT 2 arkda ise 1,01 ve 1,00 bulunmuştur.
CI açısından iki grup arasında anlamlı fark olmamasına rağmen en uygun CI değeri
VMAT 2 ark planlarında bulunmuştur (PTV₄₅ için p=0,806-PTV₅₄
için p=0,595). IMRT ile 3B-KRT teknikleri arasında CI açısından fark
bulunamamış, en uygun değer IMRT tekniğinden elde edilmiştir. Kritik organ
dozları açısından VMAT 1 ark ve VMAT 2 ark planları arasında istatistiksel
farklılık olmamasına rağmen VMAT 2 ark planlarının dozları daha düşük
bulunmuştur. Pankreas tümörleri yerleşim yeri olarak böbrekler ve karaciğer
gibi kritik organlara yakın oluşundan 3BKRT planları karaciğer açısından kabul edilebilir;
ancak böbrekleri koruma açısından yeterli değildir. VMAT 2 ark tekniği diğer
tekniklere göre doz sarımı, CI, HI ve kritik organ dozlarında üstünlük
sağlamıştır. Bu yüzden yan etkiler göz önüne alındığında tedavi tekniği olarak
VMAT tercih edilebilir.

Keywords

VMAT, Pankreas Kanseri, 3BKRT, IMRT

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