Sains Malaysiana 44(8)(2015): 1145–1151

Evaluation of Organ at Risk (OAR) Doses based on 2D Treatment Planning in Intracavitary Brachytherapy of Cervical Cancer

(Penilaian Dos Organ Berisiko berdasarkan Perancangan Rawatan 2 Dimensi Brakiterapi Intrarongga bagi Kanser Servik)

REDUAN ABDULLAH¹*, NUR AQILAH ABDUL SANI¹, CHEN SUK CHIANG¹, MAZURAWATI MOHAMED², NIK RUZMAN NIK IDRIS², AHMAD LUTFI YUSOFF²

& BHAVARAJU VMK²

¹School of Health Sciences, Health Campus, Universiti Sains Malaysia, 11800 Kubang Kerian, Kelantan Darul Naim, Malaysia

²Department of Nuclear Medicine, Radiotherapy and Oncology, School of Medical Sciences, Universiti Sains Malaysia, 11800 Kubang Kerian, Kelantan Darul Naim, Malaysia

Received: 28 January 2015/Accepted: 31 March 2015

ABSTRACT

Conventional two-dimensional (2D) treatment planning of intracavitary brachytherapy is still a common practice at the radiotherapy center. The purpose of this study was to evaluate the organ at risk (OAR) doses estimated based on International Commission on Radiation Units and Measurements (ICRU) reference-point in patients with cervical cancer treated with high-dose-rate (HDR) intracavitary brachytherapy (ICBT). Between January 2010 and April 2014, 21 cervical cancer patients were treated with 42 fractions of brachytherapy using tandem and ovoids and underwent post-implant two-dimensional (2D) radiograph scans. HDR brachytherapy was delivered to a dose of 18 Gy in two fractions. Using the Oncentra brachytherapy treatment planning system (BTPS) software version 4.1 (Nucletron, Netherlands), the bladder and rectum points were retrospectively reconstructed based on 42 orthogonal radiographs datasets. The ICRU bladder and rectum point doses were recorded. As for results, the mean percentage dose of rectum and bladder for selected patients treated with intracavitary brachytherapy treatment (ICBT) were 47.27 and 75.59%, respectively. Combinations of ovoid’s size, length of tandem and anatomy variation between each patient were factors that affected the dose to the OAR. Therefore, the ICRU reference points can still be used with the 2D brachytherapy treatment planning in evaluating the OAR doses.

Keywords: International Commission on Radiation Units and Measurements (ICRU) reference points; intracavitary brachytherapy treatment (ICBT); organ at risk (OAR) doses; two-dimensional (2D) treatment planning

ABSTRAK

Perancangan konvensional dua dimensi (2D) rawatan brakiterapi intrarongga masih merupakan amalan biasa di sesetengah pusat radioterapi. Tujuan kajian retrospektif ini dijalankan adalah untuk menilai dos pada organ berisiko (OAR) berdasarkan syor oleh Suruhanjaya Antarabangsa mengenai Unit Sinaran dan Pengukuran (ICRU) pada pesakit dengan kanser serviks dirawat dengan dos berkadar tinggi (HDR) brakiterapi intrarongga (ICBT). Antara Januari 2010 dan April 2014, 21 pesakit kanser serviks telah dirawat dengan 42 pecahan brakiterapi menggunakan tandem dan ovoid serta menjalani imbasan dua dimensi (2D) radiografi pasca-implan. Dos rawatan HDR brakiterapi yang digunakan adalah sebanyak 18 Gy dalam dua fraksi. Menggunakan perancangan rawatan brakiterapi Oncentra perisian 4.1 (Nucletron, Netherlands), titik pundi kencing dan rektum telah ditandakan semula pada 42 radiografi ortogonal dalam kajian retrospektif ini. Hasil kajian menunjukkan peratusan dos purata rektum dan pundi kencing bagi pesakit dipilih dirawat dengan ICBT masing-masing 47.27 dan 75.59%. Kombinasi saiz ovoid, panjang tandem dan anatomi yang berbeza antara pesakit merupakan beberapa faktor yang memberi kesan dos terhadap OAR. Oleh itu, titik rujukan ICRU dalam 2D perancangan rawatan brakiterapi masih boleh digunakan untuk menganggar dos OAR.

Kata kunci: Dos pada organ berisiko (OAR); mata rujukan Suruhanjaya Antarabangsa mengenai Unit Sinaran dan Pengukuran (ICRU); perancangan rawatan dua dimensi (2D); rawatan brakiterapi intrarongga (ICBT)

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*Corresponding author; email: reduan@usm.my