Yüksek enerjili fotonlarda fiziksel ve sanal kama filtrelerin dozimetrik özelliklerinin karşılaştırılması
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Date
2016-01-27
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Uludağ Üniversitesi
Abstract
Çalışmamızda, radyoterapide doz dağılımını modifiye etmek için kullanılan fiziksel ve sanal kama filtrelerin dozimetrik özelliklerini inceleyerek, uygulamadaki avantaj ve dezavantajlarının saptanması amaçlandı. Fiziksel ve sanal kama filtrelerin kama faktörleri (WF), yüzde derin doz (%DD) eğrileri, yüzey ve çevre dozların verilerini karşılaştırmak amacıyla elde edildi. Ölçümler Siemens Artiste cihazında 6 MV ve 15 MV X-Işın enerjileri kullanılarak 5x5, 10x10, 15x15 ve 20x20 cm2 alanlarda, SSD: 100 cm’de su ve katı su fantomunda farklı iyon odaları ile yapıldı. Kama faktör ölçümleri 5 cm derinlikte Farmer iyon odası ile yapılırken, %DD eğrileri Semifleks iyon odası ve yüzey dozu ölçümlerinde ise Markus paralel plak iyon odası kullanıldı. Çevre dozu ölçümleri için 2-D Array kullanılarak dmax ve 5 cm derinliklerde alındı. Aynı derinlikte, küçük alanlardan büyüğe doğru gidildikçe WF’leri fiziksel ve sanal kama için artığı görüldü. Sanal kama filtrelerin çevre dozu fiziksel kama filtreye göre yüksek bulundu. Sanal kama için küçük alanlarda kama açısının çevre dozlarına etkisinin olmadığı ancak büyük alanlarda kama açısıyla birlikte etkinin arttığı görüldü. Fiziksel kama için derinlik ve alan boyutu arttıkça çevre dozunun arttığını buna karşın kama açısı arttıkça çevre dozunun azaldığını saptandı. Sonuç olarak sanal kama filtreler set-up kolaylığı ve tedavi süresinin kısalması sebebiyle tercih edilebilir. Ayrıca daha fazla açı alternatifi sunması planlamada avantaj sağlar.
The aim of this study is to determine the advantages and disadvantages of physical and virtual wedge filters used in radiothreapy for modifing dose distribution by investigating the dosimetric features of them. In order to comparing the wedge factors (WF), percent depth dose (%DD) curves, surface and the environment dose values were obtained. Tha measuements were performed in Siemens Artiste lineer accelerator at the energies of 6 MV and 15 MV with the fields of 5x5, 10x10, 15x15 ve 20x20 cm2 at SSD 100 cm by using different ion chambers in water and solid water fantoms. The WF measurements were done at 5 cm depth by Farmer ion chamber, while the percent DD curves and surface dose values were measured by Semifleks ion chamber and Marcus paralel plate ion chamber, respectively. The environment dose measurements using the 2-D Array at dmax and 5 cm depth were performed. It was found that the physical and the virtual WFs were increased from small to large fields in the same depth. The environment dose values of the virtual wedge was higher than the physical wedge. For the virtual wedge, the effect of wedge angle on environment dose was negligable unlike large fields. For the physical wedge, the environment dose was deacreased by increasing wedge angle and increased by increasing depth and field size. As a result, virtual wedge filters would be preferred due to the ease of setup and shortening of treatment time. Additionally virtual wedge filters were provided more angle alternatives compared to physical wedge filters.
The aim of this study is to determine the advantages and disadvantages of physical and virtual wedge filters used in radiothreapy for modifing dose distribution by investigating the dosimetric features of them. In order to comparing the wedge factors (WF), percent depth dose (%DD) curves, surface and the environment dose values were obtained. Tha measuements were performed in Siemens Artiste lineer accelerator at the energies of 6 MV and 15 MV with the fields of 5x5, 10x10, 15x15 ve 20x20 cm2 at SSD 100 cm by using different ion chambers in water and solid water fantoms. The WF measurements were done at 5 cm depth by Farmer ion chamber, while the percent DD curves and surface dose values were measured by Semifleks ion chamber and Marcus paralel plate ion chamber, respectively. The environment dose measurements using the 2-D Array at dmax and 5 cm depth were performed. It was found that the physical and the virtual WFs were increased from small to large fields in the same depth. The environment dose values of the virtual wedge was higher than the physical wedge. For the virtual wedge, the effect of wedge angle on environment dose was negligable unlike large fields. For the physical wedge, the environment dose was deacreased by increasing wedge angle and increased by increasing depth and field size. As a result, virtual wedge filters would be preferred due to the ease of setup and shortening of treatment time. Additionally virtual wedge filters were provided more angle alternatives compared to physical wedge filters.
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Keywords
Bilgisayarlı tedavi planlama, Yüksek enerjili X-Işını, Konformal radyoterapi, Sanal kama filtre, Fiziksel kama filtre, Dozimetri, Radiotherapy treatment planning, High energy X-Ray, Conformal radiotherapy, Virtual wedge filter, Physical wedge filter, Dosimetry
Citation
Şahin, A. vd. (2016). “Yüksek enerjili fotonlarda fiziksel ve sanal kama filtrelerin dozimetrik özelliklerinin karşılaştırılması”. Uludağ Üniversitesi Tıp Fakültesi Dergisi, 42(1), 1-7.