Dosimetric Evaluation of Out-of-Field Breast Doses with TLD in Endometrial Cancer Radiotherapy

Öz

Objective: Unwanted doses may occur in distant organs, outside of the region where we want to be irradiated in patients treated with radiotherapy. These doses may not be accurately calculated by the treatment planning system (TPS). This study aims to measure out-of-field doses using thermoluminescence dosimetry (TLD) in field in field conformal radiotherapy (FIF) and intensity modulated radiotherapy (IMRT) techniques on a phantom imitating the real patient receiving radiotherapy for endometrial cancer. Material and Methods: Endometrium region on Alderson female rando phantom was selected as the target treatment volume. Plans were created by simulating the Alderson Rando phantom and using three different techniques (FIF, 5A-IMRT, 7A-IMRT) in a Varian DHX linear accelerator with 45 Gy in 25 fractions After TLD-100 dosimeters were placed in the breast volume in the phantom, the phantom was irradiated. TLD dose measurements obtained for each technique and TPS doses were compared. Results: The mean TLD dose measurements of the right breast were measured as 20.60±0.26 cGy, 23.32±0.16 cGy, and 27.11±0.28 cGy for the FIF, 5A-IMRT, and 7W-IMRT techniques, respectively. The mean TLD dose measurements of the left breast were found to be 20.17±0.13 cGy, 22.35±0.18 cGy, and 26.13±0.10 cGy for the FIF, 5A-IMART, and 7A-IMRT techniques, respectively. The mean dose values obtained from TPS for the right and left breasts were found to be 0 cGy. A significant difference was found in the mean dose values of the right breast and left breast for the 5A-IMRT and 7A-IMRT techniques (p=0.000). Conclusion: Radiation-sensitive tissues such as the breast may be affected by out-of-field dose in radiotherapy treatment. When choosing the most appropriate treatment technique in endometrial cancer radiotherapy, paying attention to out-of-field doses will make a positive contribution to the treatment.

Anahtar Kelimeler

• out of field dose
• endometrıum cancer
• dosimeter

Endometrium Kanseri Radyoterapisinde Alan Dışı Meme Dozlarının TLD İle Dozimetrik Olarak İncelenmesi

Öz

Amaç: Radyoterapi alan hastalarda tedavi bölgesi dışında uzak organlarda istenmeyen dozlar meydana gelmektedir. Bu dozlar tedavi planlama sistemi (TPS) tarafından doğru olarak hesaplanmayabilir. Bu çalışma endometrium kanseri nedeniyle radyoterapi alan gerçek bir hastayı taklit eden bir fantom üzerinde alan içi alan konformal radyoterapi (FIF) ve yoğunluk ayarlı radyoterapi (YART) tekniklerinde termolüminesans dozimetre (TLD) kullanılarak alan dışı dozları ölçmeyi amaçlamaktadır. Gereç ve Yöntem: Alderson kadın rando fantom üzerinde endometrium bölgesi hedef tedavi hacmi olarak seçilmiştir. Alderson Rando fantom simüle edilerek ve 25 fraksiyonda 45 Gy ile Varian DHX lineer hızlandırıcıda üç farklı teknikde planlar oluşturulmuştur (FIF, 5A-YART, 7A-YART). Fantomda meme hacmi içerisine TLD-100 dozimetreleri yerleştirildikten sonra fantom ışınlanmıştır. Her bir teknik için elde edilen doz ölçümleri TPS dozları ile karşılaştırılmıştır. Bulgular: Sağ memenin TLD doz ölçümlerinin ortalaması FIF, 5A-YART ve 7A-YART teknikleri için sırasıyla 20.60±0.26 cGy, 23.32±0.16 cGy ve 27.11±0.28 cGy olarak ölçülmüştür. Sol memenin TLD doz ölçümlerinin ortalaması FIF, 5A-YART ve 7A-YART teknikleri için sırasıyla 20.17±0.13 cGy, 22.35±0.18 cGy ve 26.13±0.10 cGy olarak bulunmuştur. Sağ ve sol meme için TPS’ den alınan ortalama doz değerleri 0 cGy olarak bulunmuştur. Sağ meme ve sol meme ortalama doz değerlerinde 5A-YART ve 7A-YART teknikleri için anlamlı fark bulunmuştur (p=0.000). Sonuç: Meme gibi radyasyona duyarlı dokular radyoterapi tedavisinde alan dışı dozdan etkilenebilmektedir. Endometrium kanseri radyoterapinde en uygun tedavi tekniği seçilirken alan dışı dozlara dikkat edilmesi tedaviye pozitif katkı sağlayacaktır.

Anahtar Kelimeler

• Alan dışı doz,
• endometrium kanseri,
• termolüminesans dozmetri

Kaynakça

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