Yoğunluk ayarlı radyoterapi tekniği kullanılarak tedavi edilen baş-boyun kanserli hastaların tedavi planlarının dozimetrik olarak incelenmesi
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Date
2012
Authors
Yüce, Şilem
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Journal ISSN
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Publisher
Uludağ Üniversitesi
Abstract
Bu çalışmada amaç, Yoğunluk Ayarlı Radyoterapi (YART) tekniği kullanılarak tedavi edilen baş-boyun kanserli hastaların doz dağılımlarının, farklı dozimetrik ekipmanlar kullanılarak doğrulanması ve bu ekipmanların uygulanabilirlik açısından birbirleriyle karşılaştırılmasıdır.Uludağ Üniversitesi Tıp Fakültesi Radyasyon Onkolojisi Anabilim Dalı'nda tedavi edilen 20 baş-boyun kanserli hastanın BT görüntüleri 3 mm kesit aralıkları ile taranmıştır. Taranan görüntüler konturlama bilgisayarına aktarılıp radyasyon onkoloğu tarafından hedef hacim ve riskli organlar konturlandıktan sonra üç boyutlu görüntüleri elde edilmiştir. Elde edilen görüntüler CMS XIO Tedavi Planlama Sistemi'ne (TPS) aktarılarak her hasta için hedef hacme ve bu hedefin sağlıklı organlarla komşuluğuna bağlı olarak YART planları tersten planlama (inverse planning) yöntemi kullanılarak oluşturulmuştur. 0.015 hacimli PinPoint (PTW, Freiburg, Germany) silindirik iyon odası ile merkezi doz doğrulaması yapılırken, PTW 2D ARRAY (seven29) ve Elektronik Portal Görüntüleme Cihazı (EPID) ile plan doğrulaması yapılmıştır. Gamma indeksi yönteminde doz farkı (DD) %3 ve doz mesafe uyumu (DTA) 3 mm kriterleri kabul edilmiştir.Pinpoint iyon odası ile merkezi doz doğrulamasında, TPS' den alınan doz değerleri ile ölçülen dozlar arasında en yüksek yüzde fark %3,07, en düşük yüzde fark %1,08, ortalama fark %2,29 ve standart sapma değeri 0.41 olarak bulunmuştur. TPS ile 2D Array karşılaştırmasında gamma indeks yöntemine göre %3 doz farkı (DD) ve 3 mm doz mesafe uyumu (DTA) kriterleri dikkate alınarak yapılan değerlendirmede geçen noktaların yüzdesi en yüksek %97,73 ve en düşük %88,55, ortalama değer %94,09 ve standart sapma değeri 2,27 olarak bulunmuştur. Elektronik Portal Görüntüleme Cihazı (EPID) ile elde edilen doz haritaları ile TPS karşılaştırmasında ise, yapılan değerlendirme sonucu geçen noktaların yüzdesi en yüksek %98,84 ve en düşük %91,59, ortalama değer %96,05 ve standart sapma değeri 1,63 olarak bulunmuştur.Sonuç olarak, YART planlarının doğrulaması için elde ettiğimiz sonuçların TPS ile uyumlu ve kabul sınırları içerisinde olduğu saptanmıştır. İki boyutlu iyon odası (2D ARRAY seven 29) ile EPID' in birbirlerine alternatif yöntemler olduğu görülmüştür. Ayrıca, YART doğrulaması için yapılan rutin uygulamalarda EPID sisteminin daha az zaman aldığı ve uygulanabilirlik açısından daha pratik olduğu tespit edilmiştir.
The purpose of this study is to verify the dose distributions of head and neck cancer patients treated with Intensity Modulated Radiation Therapy (IMRT) technique by using various dosimetric equipments and to compare these equipments in terms of their applicability.CT images of 20 patients who were treated in Uludag University School of Medicine Department of Radiation Oncology were scanned with 3 mm slice intervals. The scanned images were transferred to contouring computer and their three dimensional images were obtained after contouring the target volume and organs at risk. After transferring these images to the treatment planning system, IMRT plans were done for each patient by using inverse planning method depending on the target volume and neighborhood of target with healthy organs. The verification of central dose was done by using PinPoint (PTW, Freiburg, Germany) ionization chamber which have 0.015 volume and the plan verification was done by using PTW 2D ARRAY (seven29) and Electronic Portal Imaging Device (EPID). 3% dose difference and 3 mm distance to aggreement criteria were adopted while using Gamma index method.During the verification of central dose with Pinpoint ionization chamber, the difference between the values taken from TPS and measured dose values were highest 3,07%, lowest 1,08% and mean difference and standard deviation were found 2,29% and 0,41, respectively. While comparing TPS with 2D Array 3% dose difference and 3 mm distance to aggrement criteria were taken into consideration and the percentage of the points passed were found maximum 97,73%, minimum 88,55% and mean and standard deviation values were 94,09% and 2,27, respectively. While comparing the dose maps obtained with Electronic Portal Imaging Device (EPID), as a result of the evaluation the perccentage of points passed were found maximum 98,84%, minimum 91,59% and mean and standard deviation values were 96,05% and 1,63, respectively.Consequently, the results we obtained for the verification of IMRT plans were within the limits of acceptance and compatible with the TPS. It was seen that the two-dimensional ionization chamber (2D array, seven 29) and EPID were alternative methods to each other. InIXaddition, it was determined that EPID has taken less time and was more practical in terms of applicability during routine verification of IMRT plans.
The purpose of this study is to verify the dose distributions of head and neck cancer patients treated with Intensity Modulated Radiation Therapy (IMRT) technique by using various dosimetric equipments and to compare these equipments in terms of their applicability.CT images of 20 patients who were treated in Uludag University School of Medicine Department of Radiation Oncology were scanned with 3 mm slice intervals. The scanned images were transferred to contouring computer and their three dimensional images were obtained after contouring the target volume and organs at risk. After transferring these images to the treatment planning system, IMRT plans were done for each patient by using inverse planning method depending on the target volume and neighborhood of target with healthy organs. The verification of central dose was done by using PinPoint (PTW, Freiburg, Germany) ionization chamber which have 0.015 volume and the plan verification was done by using PTW 2D ARRAY (seven29) and Electronic Portal Imaging Device (EPID). 3% dose difference and 3 mm distance to aggreement criteria were adopted while using Gamma index method.During the verification of central dose with Pinpoint ionization chamber, the difference between the values taken from TPS and measured dose values were highest 3,07%, lowest 1,08% and mean difference and standard deviation were found 2,29% and 0,41, respectively. While comparing TPS with 2D Array 3% dose difference and 3 mm distance to aggrement criteria were taken into consideration and the percentage of the points passed were found maximum 97,73%, minimum 88,55% and mean and standard deviation values were 94,09% and 2,27, respectively. While comparing the dose maps obtained with Electronic Portal Imaging Device (EPID), as a result of the evaluation the perccentage of points passed were found maximum 98,84%, minimum 91,59% and mean and standard deviation values were 96,05% and 1,63, respectively.Consequently, the results we obtained for the verification of IMRT plans were within the limits of acceptance and compatible with the TPS. It was seen that the two-dimensional ionization chamber (2D array, seven 29) and EPID were alternative methods to each other. InIXaddition, it was determined that EPID has taken less time and was more practical in terms of applicability during routine verification of IMRT plans.
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Keywords
YART, Dozimetrik doğrulama, 2D Array, EPID, Gamma indeksi, IMRT, Dosimetric verification, Gamma index
Citation
Yüce, Ş. (2012). Yoğunluk ayarlı radyoterapi tekniği kullanılarak tedavi edilen baş-boyun kanserli hastaların tedavi planlarının dozimetrik olarak incelenmesi. Yayınlanmamış yüksek lisans tezi. Uludağ Üniversitesi Sağlık Bilimleri Enstitüsü.