A Comparison of Volumetric Modulated Arc Therapy and Conventional Intensity-Modulated Radiotherapy for High Grade Glial Tumors

Abstract

The aim of radiotherapy is to protect critical organs sensitive to radiation and surrounding healthy tissues as much as possible, while giving the most appropriate dose on the specified target volume. The aim of this study is to provide the best plans of 10 brain tumor patients, whose computed tomography (CT) image was taken, using the best plans created using the VMAT technique in the Eclipse treatment planning system and the best plans created using the seven-field IMRT technique to compare doses in terms of target volume, duration of treatment and monitor unit (MU) values. The study is a retrospective study and patients were not treated with the plans and techniques used in the studies. Plans have been made so that 100% of the dose defined for the target volume will take at least 95% of the target volume. Using the Radiation Therapy Oncology Group (RTOG) protocol, the results obtained with the minitab program were statistically evaluated using the t-test for the matched data. PTV coverage, conformity and homogeneity index were equivalent for VMAT and IMRT plans. VMAT plans compared to IMRT, PTV max. 64,835±0,504 (p=0,039), Brain max. 64,378±0,565 (p=0,025), and Eye L. max. 20,39± 12,17 (p=0,046) The difference between the mean doses is statistically significant. Brain mean 26,74±3,42 (p=0,096), Brainstem max. 32,44±18,70 (p=0,178), Eye R. max. 32,90± 16,84 (p=0,076), Optic Nerve L.max. 23,17± 15,45 (p=0,851), Optic Nerve R. max. 22,63± 17,98 (p=0,688), Optic Chiasma max. 25,25± 20,24 (p=0,531) were found lower in VMAT plans but it was not statistically significant. It may be preferred in plans made with the VMAT technique due to less monitor units (MU) and shorter treatment time.

Keywords

• Brain tumors
• High- grade glioma
• Intensity- modulated radiotherapy (IMRT)
• Volumetric modulated arc therapy (VMAT)

Yüksek Dereceli Glial Tümörlerin Radyoterapisinde VMAT Tekniği İle IMRT Tekniğinin Karşılaştırılması

Öz

Radyoterapide amaç, belirlenen hedef hacim üzerine en uygun dozu verirken, radyasyona hassas kritik organları ve civarındaki sağlıklı dokuları mümkün olduğunca korumaktır. Bu çalışmanın amacı, Bilgisayarlı tomografi (BT) görüntüsü alınmış 10 beyin tümörü tanılı hastanın, Eclipse tedavi planlama sisteminde VMAT tekniği kullanılarak oluşturulan en iyi planlarla, yedi alanlı IMRT tekniği kullanılarak oluşturulan en iyi planları kritik organ dozları, hedef hacim, tedavi süreleri ve monitör unit (MU) değerleri açısından karşılaştırmaktır. Çalışma retrospektif bir çalışma olup, hastalar çalışmalarda geçen plan ve tekniklerle tedavi edilmemiştir. Hedef hacim için tanımlanan dozun %100’ü hedef hacmin en az %95’ini alacak şekilde planlamalar yapılmıştır. Elde edilen doz-volüm histogramları aracılığıyla çalışılan farklı planların hedef hacim ve kritik organ dozları Radiation Therapy Oncology Group (RTOG) protokolünden faydalanarak, eşleşmiş veriler için t – testi kullanılarak minitab programı ile alınan sonuçlar istatistiksel olarak değerlendirilmiştir. PTV kapsamı, konformite ve homojenite indeksi VMAT ve IMRT planları için eşdeğerdi. VMAT planları IMRT ile karşılaştırıldığında PTV max. 64,835±0,504 (p=0,039), Beyin max. 64,378±0,565 (p=0,025), ve Eye L. max. 20,39± 12,17 (p=0,046) için ortalama dozları arasında fark istatistiksel olarak anlamlıdır. Beyin ortalama 26,74±3,42 (p=0,096), Beyin Sapı max. 32,44±18,70 (p=0,178), Eye R. max. 32,90± 16,84 (p=0,076), Optik Nerve L. max. 23,17± 15,45 (p=0,851), Optic Nerve R. max. 22,63± 17,98 (p=0,688), Optik Kiazma max. 25,25± 20,24 (p=0,531) dozları VMAT planlarında daha düşük bulunmasına karşılık istatistiksel olarak anlamlı değildir. VMAT tekniği ile yapılan planlarda daha az monitor unit (MU) ve daha kısa tedavi süresi olması nedeniyle tercih edilebilinir.

Anahtar Kelimeler

• Beyin tümörleri
• Yüksek dereceli Glioma
• Yoğunluk ayarlı radyasyon tedavisi(IMRT)
• Volumetrik modüle ark tedavisi (VMAT)

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