Pankreas kanseri radyoterapisinde 3 farklı tedavi tekniğinin dozimetrik karşılaştırılması: Retrospektif çalışma
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Date
2018-07-16
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Uludağ Üniversitesi
Abstract
Bu çalışmada 2012-2017 yılları arasında kliniğimizde definitif radyoterapi uygulanmış, primer pankreas başı tümörü olan inopere hastalar retrospektif olarak değerlendirilmiştir. Her hastaya tümör, tümör çevresi ve bölgesel lenf nodlarına yönelik 3 farklı tedavi tekniği kullanılarak 5 farklı planlama yapılmış, tüm planlar hedef hacim dozları 54/45 Gy olacak şekilde seçilmiştir. Planlar Volümetrik Ark Tedavi (VMAT) ve Yoğunluk Ayarlı Radyoterapi (IMRT) için 6 MV X-ışını, 3 Boyutlu Konformal Radyoterapi (3BKRT) için 6/15 MV X-ışını kullanılarak hazırlanmıştır. Planlanan hedef hacim dozları (PTV), Konformite indeksi (CI), Homojenite indeksi (HI), riskli organlar (böbrekler, spinal kord, 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 hedef hacimler 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 3BKRT teknikleri arasında CI değeri açısından fark bulunamamış, en uygun değer IMRT tekniğinde 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 dozun hedefi sarımı, CI, HI ve kritik organ dozlarında üstünlük sağlamıştır. Bu yüzden yan etkiler göz önüne alındığında tedavi tekniği olarak VMAT tercih edilebilir.
In this study, inoperable patients with primary pancreatic head tumor who underwent definitive radiotherapy in our clinic between 2012-2017 were evaluated retrospectively. Five different plannings were done using 3 different treatment techniques for tumor, tumor periphery and regional lymph nodes in each patient, and plans were selected so that the target volume doses would be 54/45 Gy. Volumetric Arc Therapy (VMAT) and Intensity Modulated Radiotherapy (IMRT) plans were prepared using 6 MV X-rays and for 3DCRT plans 6/15 MV X-rays were used. 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 CI indices for PTV54 and PTV45 were found to be 1.16 and 1.03 for VMAT 1 arc plans and 1.01 and 1.00 for VMAT 2 arc, respectively. The optimal CI value was found in the VMAT 2 arc plans, although there was no significant difference between the target volumes in terms of CI (PTV45 p=0,806 - PTV54 p=0,595). There was no difference in terms of CI value between IMRT and 3D-CRT techniques, and the most appropriate value was obtained by 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 close to critical organs such as the kidneys and liver, 3DCRT plans can be accepted in terms of liver; but not enough for the kidney protection. VMAT 2 arc technique was superior in dose targeting, CI, HI and critical organ doses when all tecniques are compared. Therefore, VMAT may be a preferred treatment technique when side effects are taken into account.
In this study, inoperable patients with primary pancreatic head tumor who underwent definitive radiotherapy in our clinic between 2012-2017 were evaluated retrospectively. Five different plannings were done using 3 different treatment techniques for tumor, tumor periphery and regional lymph nodes in each patient, and plans were selected so that the target volume doses would be 54/45 Gy. Volumetric Arc Therapy (VMAT) and Intensity Modulated Radiotherapy (IMRT) plans were prepared using 6 MV X-rays and for 3DCRT plans 6/15 MV X-rays were used. 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 CI indices for PTV54 and PTV45 were found to be 1.16 and 1.03 for VMAT 1 arc plans and 1.01 and 1.00 for VMAT 2 arc, respectively. The optimal CI value was found in the VMAT 2 arc plans, although there was no significant difference between the target volumes in terms of CI (PTV45 p=0,806 - PTV54 p=0,595). There was no difference in terms of CI value between IMRT and 3D-CRT techniques, and the most appropriate value was obtained by 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 close to critical organs such as the kidneys and liver, 3DCRT plans can be accepted in terms of liver; but not enough for the kidney protection. VMAT 2 arc technique was superior in dose targeting, CI, HI and critical organ doses when all tecniques are compared. Therefore, VMAT may be a preferred treatment technique when side effects are taken into account.
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Keywords
Pankreas kanseri, VMAT, IMRT, 3BKRT, Radyoterapi, Pancreatic cancer, Radiotherapy, 3D-CRT
Citation
İbicioğlu, B. vd. (2018). ''Pankreas kanseri radyoterapisinde 3 farklı tedavi tekniğinin dozimetrik karşılaştırılması: Retrospektif çalışma''. Uludağ Üniversitesi Tıp Fakültesi Dergisi, 44(2), 111-116.