Evaluation of tumour cells damage following radiotherapy by Tc-99m pertechnetate

Abstract

ABSTRACT

Radiotherapy has become the most important modality in treating cancer with approximately 50% of cancer patient undergo the treatment. However, more improvement to the radiotherapy treatment efficacy is required to deprive cancer. Assessment of tumor progress during treatment is important to accommodate the changes that occur during the fractionation course.  The objective of this study is to assess tumor cell damage after external beam radiotherapy by using technetium-99m pertechnetate (^99mTcO₄^-) as a tracer. In this study, HeLa cells were irradiated with 6 MV photon beam with different radiation dose ranging from 0.5 Gy to 10 Gy. The irradiated cells were recultured in 6-well plates and incubated for 10 days. After that, 2 mCi of ^99mTcO₄^- were prescribed to each cell colonies. The viable cells were separated from the rest and measured for ^99mTcO₄^- uptake using single head gamma camera with LEHR collimation. As results, the cells survival fractions clearly indicate diminishing effect to the cells at higher dose of irradiation. Good correlation were observed between ^99mTcO₄ uptake and survival fraction for cells irradiated at lower dose and less significant correlation were indicated at higher dose. In conclusion, there is potential for the efficacy of external beam radiotherapy in treating cancer to be assessed by using radioisotope as a non-invasive tracer. In this case, technetium-99m pertechnetate (^99mTcO₄) could be attached to the specific antibody so that better correlation between the cells uptake and possible cell damages could be observed.

ABSTRAK

 Radioterapi telah menjadi modaliti utama dalam merawat kaser, di mana lebih 50% pesakit kanser melalui kaedah rawatan ini. Namun yang demikian, masih banyak ruang penambahbaikan perlu dibuat untuk meningkatkan keberkesanan radioterapi dalam merawat kanser. Penilaian terhadap perubahan tumor adalah penting ketika membuat sebarang perubahan sepanjang prosedur rawatan berlangsung. Objektif kajian ini adalah untuk menilai kerosakan terhadap sel kanser akibat radioterapi dengan menggunakan technetium-99m pertechnetate (^99mTcO₄^-) sebagai penanda. Sel HeLa telah didedahkan dengan pancaran foton 6 MV, yang mempunyai dos radiasi antara 0.5 hingga 10 Gy. Sel HeLa tersebut kemudiannya dikultur semula dan diinkubasi selama 10 hari. Seterusnya sebanyak 2 mCi ^99mTcO₄^- telah dimasukkan kedalam setiap bekas sel. Sel yang hidup diasingkan untuk diukur kandungan ^99mTcO₄^- menggunakan kamera gamma berkolimasi LEHR. Hasil kajian jelas menunjukkan bahawa pecahan survival sel berkurangan apabila dos radiasi meningkat. Kolerasi antara survival sel dan penyerapan ^99mTcO₄^- adalah baik bagi dos rendah, namun kolerasi tersebut menurun apabila dos meningkat. Konlusinya, radioisotop mempunyai potensi untuk digunakan sebagai penanda bagi melihat keberkesanan radioterapi secara tidak invasif. Dalam kes ini, technetium-99m pertechnetate (^99mTcO₄^-) boleh disambung dengan antibody yang spesifik bagi meningkatkan kolerasi antara penyerapan ^99mTcO₄^- ke dalam sel dan kerosakan sel akibat radioterapi.