Dosimetric control of dose distribution calculated in computerized treatment planning system/Tedavi planlama sisteminde hesaplanan doz dagilimlarinin dozimetrik kontrolu

• Published in: Türk onkoloji dergisi 2011-12, Vol.26 (4), p.167
• Main Authors: Sahin, Sevim, Gurler, Orhan, Gozcu, Sema, Kurt, Meral, Sengul, Kansu, Altay, Ali, Cetintas, Sibel Kahraman, Ozkan, Lutfi
• Format: Article
• Language: Turkish
• ISSN: 1300-7467
• DOI: 10.5505/tjoncol.2011.597

OBJECTIVES The purpose of this study is providing dosimetric control by comparing dose values calculated in computerized treatment planning system (CTPS) and measured by Linear 2D-Array and ion chambers of various volumes. METHODS Fields measured by Farmer, Semiflex and PinPoint ion chambers were created in CTPS. Using Linear 2D-Array, measurements were done in open, isocentric, oblique and wedge filtered fields which created in CTPS. Dose values were compared. RESULTS PinPoint ion chamber measured top dose values whereas Farmer ion chamber measured low values. The most compatible results with CTPS were obtained by Semiflex ion chamber. However, in 2D-Array measurements, concordance was observed with CTPS in central axis, difference reached 20% in build-up and penumbra regions. CONCLUSION The most compatible results with CTPS were obtained by Semiflex ion chamber. Reasons of discordance in 2D-Array measurements were found as; varible dose around build-up region, and not to obtain the exact superpose of profiles' penumbra region. Key words: Computerized treatment planning system; linear 2D-array; quality assurence in radiotherapy. AMAC Calismanin amaci, bilgisayarli tedavi planlama sisteminde (BTPS) hesaplanan doz degerleri ile farkli volumlu iyon odalari ve linear 2D-Array kullanilarak olculen dozlari karsilastirarak dozimetrik kontrolu saglamaktir. GEREC VE YONTEM Farmer, Semiflex ve PinPoint iyon odalariyla olcumleri alinan alanlar BTPS'de olusturuldu. 2D-Array ile acik alan, izosentrik, oblik ve wedge filtreli alanlarda olcumler alindi. Bu alanlar BTPS'de olusturularak nokta doz okumalari yapildi ve profilleri olusturuldu. Olculen ve planlanan izodoz dagilimlari karsilastirildi. BULGULAR PinPoint iyon odasinin en yuksek, Farmer iyon odasinin ise en dusuk doz okumasi yaptigi goruldu. BTPS ile en uyumlu sonuclar Semiflex iyon odasiyla elde edildi. 2D-Array kullanilarak yapilan okumalarda merkezi eksende BTPS ile uyum gozlenirken, build-up ve penumbra bolgelerinde %20'lere cikan fark gozlendi. SONUC Iyon odasi olcumleri incelendiginde, BTPS'ye en yakin sonuclar Semiflex iyon odasi ile elde edilmistir. 2D-Array kullanilarak yapilan okumalarda gozlenen uyumsuzlugun nedenleri; build-up bolgesindeki doz degiskenligi ve isin modellemesinde olculen profiller ile algoritma tarafindan olusturulan profillerin penumbra bolgelerinde tam olarak cakismamasi olarak bulundu. Anahtar sozcukler: Bilgisayarli tedavi planlama sistemi; lineer 2D-Array; radyoterapide kalite ko