Preparation of tissue compensator and investigation of resultant dose distribution effects on treatments performed with Co-60 teletherapy machine

Abstract

OBJECTIVES In this study, it was purposed to design an aluminium material using compensator in order to obtain homogeneous dose distribution in irradiated volume on an irregular treatment field. METHODS For preparation of the compensator for large body curve, the anterior supra field of 25x26 cm and the lateral field of the face of 13x12 cm were selected. For the selected fields, the compensators were prepared using a man-shaped special phantom. The selected lateral face and anterior supra field without using the compensator and on Co-60 apparatus, dose distribution was obtained by film dosimetry method from man- shaped sagittal two-segmented special phantom. Findings were controlled using another measuring system thermoluminescent dosimeter. The experimental studies made without using the compensator were repeated with the compensator. The dose distributions obtained with and without compensator were compared and any positive contribution to dose distribution was investigated. RESULTS The data obtained from this study using compensator on the treatment field with excess surface irregularity, on lateral face, medial line and vertical axis, showed 5% more homogeneous dose distribution, and for supra field, parallel axis to radiation field to isodose distribution was 11.1% more homogeneous. CONCLUSION Consequently, in the case of curved or irregular treatment surfaces, a more homogeneous dose distribution can be produced using tissue compensators prepared for each patient separately. This will increase treatment quality in clinical use.

Keywords

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Co-60 teleterapi cihazı ile yapılan tedavilerde doku kompansatörü tasarlanması ve buna bağlı doz dağılımı etkisinin araştırılması

Abstract

AMAÇ Bu çalışmada, tedavi yüzeyinin eğri ya da düzensiz olması halinde ışınlanan volüm içindeki doz dağılımının homojen olmasını sağlamak amacıyla, alüminyum materyali kullanarak kompansatör dizayn edilmesi amaçlandı. GEREÇ VE YÖNTEM Kompansatör hazırlanması için vücut eğriliğinin fazla olduğu 13x12 cm büyüklüğünde yan yüz alanı, 25x26 cm büyüklüğünde ön supra alanı seçildi. Seçilen alanlar için insan şeklinde özel hazırlanmış fantom kullanılarak kompansatörler hazırlandı. Seçilen yan yüz, ön supra alanı için kompansatör kullanılmadan Co-60 cihazında, insan benzeri sagital iki simetrik parça halinde olan özel fantomda film dozimetri yöntemiyle doz dağılımları elde edildi ve bu doz dağılımlarının doğruluğu, bir başka doz ölçüm yöntemi olan termoluminesans dozimetre yöntemi ile kontrol edildi. Kompansatör kullanılmadan yapılan deneysel çalışmalar, kompansatör kullanılarak tekrar edildi. Kompansatör kullanılmadan ve kullanılarak elde edilen doz dağılımları karşılaştırıldı; kompansatör kullanımının doz dağılımına olumlu katkısı araştırıldı. BULGULAR Bu çalışmanın sonunda elde edilen veriler, yüzey eğriliği fazla olan tedavi alanlarında kompansatör kullanılması ile yan yüz alanlarda, orta hatta ışına dik eksende izodoz dağılımını %5 oranında daha homojen hale getirdiği, supra alanında radyasyon alanına paraleleksende izodoz dağılımını %11, 1 oranında daha homojen hale getirdiğini göstermektedir. SONUÇ Tedavi yüzeyinin eğri ya da düzensiz olması halinde hastaya özel hazırlanan kompansatörün, ışınlanan volüm içindeki doz dağılımını daha düzgün bir hale getirdiği, buna bağlı olarak klinik kullanımında tedavi kalitesini arttıracağı görülmüştür.

Keywords

• Doz dağılımı, kompansatör, radyoterapi

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