Meme Kanseri Radyoterapisinde IMRT ve Konformal Radyoterapi Uygulamaları için Tedavi Planlama Sisteminde Planlanan Doz Dağılımının Rando Fantomda Ölçülen Doz Dağılımıyla Uyumunun Araştırılması

Year 2021, Volume: 12 Issue: 2, 244 - 250, 01.04.2021

Özlem Göksel Evren Ozan Göksel Halil Küçücük Melahat Garipağaoğlu

https://doi.org/10.31067/acusaglik.849386

Abstract

Amaç
Bu çalışmada, meme kanseri radyoterapisinde kullanılan 3B konformal radyoterapi (3BKRT), Alan içinde alan (Field in Field,FinF) ve yoğunluk ayarlı radyoterapi (IMRT) tekniklerinin planlanan-ölçülen doz farklarının araştırılması amaçlanmıştır.

Gereç ve Yöntem
Bu çalışma için su eşdeğeri bolus materyalinden meme şeklinde fantomlar (MŞF) oluşturularak, Alderson rando fantom üzerine yerleştirilmiş ve planlama amaçlı bilgisayarlı tomografisi çekilmiştir. Hedef yapı ve kritik organlar konturlandıktan sonra3BKRT, FinF ve IMRT teknikleri için planlama (Varian Eclipse 8,6, PencilBeam) yapılmıştır.MŞF‘nın izomerkezden geçen sagital ve transvers düzlemlerine ayrı ayrı Gafchromic EBT2 filmler yerleştirilmiş ve her bir teknik için fantom ikişer kez ışınlanmıştır.İzomerkezden ve izomerkezin 1’er cm anterior-posterir, superior – inferior ve sağ-solundan geçen eksenlerden film üzerinden ölçülen dozlar aynı eksenlerde tedavi planlama sisteminden (TPS) okunan dozlarla kaşrılaştırılmıştır.

Bulgular
Uygulanan tekniklerde planlanan-ölçülen doz farkı en yüksek %4.5 ile FinF tekniğinde, en az %0.05 ile IMRT tekniğinde bulunmuştur. Farkların %66.6‘sında ölçülen doz planlanandan daha yüksek bulunurken, bütün farkların %93‘ünde fark %3‘ün altında bulunmuştur. En az fark izomerkezden geçen eksenler boyunca görülürken, izomerkezden uzaklaştıkça farkın artığı bulunmuştur. Eksenlerle farklar arasında anlamlı bir ilişki bulunamamıştır.

Sonuç
TPS’te hesaplanan doz dağılımları rando fantom üzerinde film ile ölçülen doz dağılımlarıyla karşılaştırıldığında, en iyi IMRT için olmak üzere her üç teknik için de uyumlu bulunmuştur.

Keywords

Meme Kanseri, Film Dozimetri, Radyoterapi Tedavi Planlaması, Rando Fantom, Bolus Meme Fantomu

Investigation of The Compliance of Planned Dose Distribution on The Treatment Planning System with Measured Dose Distribution in Rando Phantom For IMRT and Conformal Radiotherapy Applications

Abstract

Purpose
This study investigates planned and measured dose differences for 3 dimensional conformal radiotherapy (3DCRT), Field in Field (FinF) and Intensity-Modulated Radiation Therapy (IMRT) techniques for breast cancer radiotherapy.

Material and Method
Breast shaped phantom (BSP) was fabricated with water equevelent bolus material and BSP was placed on Alderson rando phantom, then planning computerized tomography (CT) images were obtained. Target volume andnormal tissues were delineated on these images. Treatment planning was performed for 3DCRT, FinF and IMRT techniques (Varian, Eclipse 8,6, PencilBeam). EBT2 films were placed into sagittal and transverse planes of BSP which intersect with the isocenter. After thatfilms were irradiated for each calculated plans in two times. The measured doses with film from the isocenter and from the axes passing 1 cm anterior-posterior, superior – inferior and right-left of the isocenter were compared with the doses read from the treatment planning system (TPS) on the same axes.

Results
Among applied techniques, the maximum and minimum dose differences for measured and calculated doses were 4.5 % and 0.05 % for FinF and IMRT techniques, respectively. Measured doses were higher than calculated doses for 66.6% of all points; however 93% of total points had a difference less than 3 %. Dose differences were minimum on axes that intersect with the isocenter and were directly correlated with the distance from the isocenter. There was no relation between dose differences and directions on axes.

Conclusion
Dose distributions calculated in TPS were found to be compatible for all three techniques when compared to dose distributions measured by film on rando Phantom. The best compliance was found for IMRT technique.

Keywords

Breast Cancer, Film Dosimetry, Treatmet Planning, RANDO phantom, Breast Phantom

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