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"[Studi ini telah dilakukan untuk mengetahui karakteristik dari EPID dosimetri yang digunakan sebagai verifikasi pasien IMRT dan VMAT. Penelitian ini dilakukan dengan membandingkan indeks gamma dari hasil verifikasi 5 pasien brain, 5 pasien cervix, 5 pasien kepala dan leher serta 5 pasien paru menggunakan EPID dosimetri dengan MatriXX 2D array pada dua Linac yang berbeda di instalasi radioterapi MRCCC SHS dan Siloam Hospital TBS. Dari penelitian ini dihasilkan nilai indeks gamma untuk kasus IMRT di MRCCC 99.59% ± 0.46 untuk EPID dosimetri dan 99.13% ± 0.75 untuk MatriXX 2D array, sedangkan di Siloam Hospital TBS 99.8% ± 0.20 untuk EPID dosimetri dan 99.71% ± 0.14 untuk MatriXX 2D array. Pada kasus VMAT di MRCCC 97.71% ± 1.27 untuk EPID dosimetri dan 99.50% ± 0.39 untuk MatriXX 2D array, sedangkan di SiloamHospital TBS 97.78% ± 1.45 untuk EPID dosimetri dan 98.66% ± 1.26 untuk MatriXX 2D array. Kesimpulan dari penelitian ini adalah perbedaan antara EPID dosimetri dan MatriXX 2D array di kedua rumah sakit menunjukan nilai kurang dari 1% untuk kasus IMRT dan kurang dari 2% untuk kasus VMAT.

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This work was aimed to study the characteristics of EPID dosimetry in use as patient specific QA for IMRT and VMAT. We compare result of gamma index from patient specific QA with each 5 cases of brain, cervix, head and neck, lung

using EPID dosimetry and MatriXX 2D array in two different linacs at MRCCC SHS and Siloam Hospital TBS. Calculated gamma index from IMRT case in MRCCC SHS ware 99.59% ± 0.46 for EPID dosimetry and 99.13% ± 0.75 for MatriXX 2D array, meanwhile at Siloam Hospital TBS the calculated gamma index were 99.8% ± 0.20 for EPID dosimetry and 99.71% ± 0.14 for MatriXX 2D array.Gamma index from VMAT cases in MRCCC were 97.71% ± 1.27 for EPID dosimetry and 99.50% ± 0.39 for MatriXX 2D array, and in Siloam Hospital TBS the value were 97.78% ± 1.45 for EPID dosimetry and 98.66% ± 1.26 for MatriXX 2D array. We conclude that the difference between EPID dosimetry and Matrixx 2D arrays at two hospitals were less than 1% and less than 2% for IMRT and VMAT cases, respectively. This work was aimed to study the characteristics of EPID dosimetry in use as patient specific QA for IMRT and VMAT. We compare result of gamma index from patient specific QA with each 5 cases of brain, cervix, head and neck, lung using EPID dosimetry and MatriXX 2D array in two different linacs at MRCCC SHS and Siloam Hospital TBS. Calculated gamma index from IMRT case in MRCCC SHS ware 99.59% ± 0.46 for EPID dosimetry and 99.13% ± 0.75 for

MatriXX 2D array, meanwhile at Siloam Hospital TBS the calculated gamma index were 99.8% ± 0.20 for EPID dosimetry and 99.71% ± 0.14 for MatriXX 2D array.Gamma index from VMAT cases in MRCCC were 97.71% ± 1.27 for EPID dosimetry and 99.50% ± 0.39 for MatriXX 2D array, and in Siloam Hospital TBS the value were 97.78% ± 1.45 for EPID dosimetry and 98.66% ± 1.26 for MatriXX 2D array. We conclude that the difference between EPID dosimetry and Matrixx 2D arrays at two hospitals were less than 1% and less than 2% for IMRT and VMAT cases, respectively.;This work was aimed to study the characteristics of EPID dosimetry in use as

patient specific QA for IMRT and VMAT. We compare result of gamma index

from patient specific QA with each 5 cases of brain, cervix, head and neck, lung

using EPID dosimetry and MatriXX 2D array in two different linacs at MRCCC

SHS and Siloam Hospital TBS. Calculated gamma index from IMRT case in

MRCCC SHS ware 99.59% ± 0.46 for EPID dosimetry and 99.13% ± 0.75 for

MatriXX 2D array, meanwhile at Siloam Hospital TBS the calculated gamma

index were 99.8% ± 0.20 for EPID dosimetry and 99.71% ± 0.14 for MatriXX 2D

array.Gamma index from VMAT cases in MRCCC were 97.71% ± 1.27 for EPID

dosimetry and 99.50% ± 0.39 for MatriXX 2D array, and in Siloam Hospital TBS

the value were 97.78% ± 1.45 for EPID dosimetry and 98.66% ± 1.26 forMatriXX

2D array. We conclude that the difference between EPID dosimetry and Matrixx

2D arrays at two hospitals were less than 1% and less than 2% for IMRT and

VMAT cases, respectively., This work was aimed to study the characteristics of EPID dosimetry in use as

patient specific QA for IMRT and VMAT. We compare result of gamma index

from patient specific QA with each 5 cases of brain, cervix, head and neck, lung

using EPID dosimetry and MatriXX 2D array in two different linacs at MRCCC

SHS and Siloam Hospital TBS. Calculated gamma index from IMRT case in

MRCCC SHS ware 99.59% ± 0.46 for EPID dosimetry and 99.13% ± 0.75 for

MatriXX 2D array, meanwhile at Siloam Hospital TBS the calculated gamma

index were 99.8% ± 0.20 for EPID dosimetry and 99.71% ± 0.14 for MatriXX 2D

array.Gamma index from VMAT cases in MRCCC were 97.71% ± 1.27 for EPID

dosimetry and 99.50% ± 0.39 for MatriXX 2D array, and in Siloam Hospital TBS

the value were 97.78% ± 1.45 for EPID dosimetry and 98.66% ± 1.26 forMatriXX

2D array. We conclude that the difference between EPID dosimetry and Matrixx

2D arrays at two hospitals were less than 1% and less than 2% for IMRT and

VMAT cases, respectively.]"

"Verifikasi dosis harus dilakukan pada setiap pra-terapi yang menggunakan teknik IMRT. Salah satu alat ukur dosimetri IMRT adalah matriks jenis ion chamber matriXX-FFF,IBA yang memberikan hasil pengukuran dosis secara real-time, serta tidak diperlukan kalibrasi berkala. Tetapi, dosimetri tersebut memiliki resolusi spasial terbatas, tergantung pada ukuran dan bentuk detektor serta ada efek transport elektron sekunder dari dinding detektor ke dalam volume detektor, sehingga seringkali mengakibatkan hasil verifikasi cukup rendah. Hal tersebut salah satunya dapat diatasi dengan metode back projection yang diusulkan oleh Poppe et al. Pada penelitian ini metode tersebut diterapkan dengan menggunakan fungsi kernel dari lapangan tunggal, kemudian diaplikasikan pada variasi lapangan persegi, kondisi No-BuildUp NBU dan BuildUp BU, posisi Extended-SSD, serta kasus IMRT dengan energi 6 MV dan 10 MV. Analisis indeks gamma Dose Difference/DD dan Dose to Agreement/DTA digunakan untuk memverifikasi efektivitas metode ini. Fungsi kernel diperoleh dari lapangan persegi 4 cm dengan dekonvolusi perbandingan MatriXX-FFF dan TPS. Hasil menunjukan terjadi peningkatan nilai passing grade secara keseluruhan 0 - 15.9, = 4.84, ? = 4.81, dimana nilai tertinggi pada lapangan persegi 4 cm dan 5 cm, baik kondisi NBU dan BU. Hal tersebut mengindikasikan adanya ketergantungan kernel terhadap ukuran lapangan. Hasil penerapan pada kasus IMRT juga memberikan kecenderungan peningkatan nilai passing grade. Kedepannya perlu dilakukan penelitian yang lebih lanjut mengenai hubungan fungsi kernel terhadap ukuran lapangan serta penerapan pada kasus IMRT lebih banyak.

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Verification process has to be carried out every pre treatment by using Intensity Modulated Radiotherapy IMRT . One of dosimetry tools for IMRT is matrix detector type of ionization chamber that gives the result of dose measurement in real time, and is not required calibration periodically. But, the dosimetry has finite spatial resolution, depends on size and shape of detector, and occur the effect of secondary electron transpot from detector wall to detector volume, so that often gives the result of gamma parameter low enough. One of solutions, it can be solved by back projection method proposed by Poppe et al. In this research, that method could be applied by using kernel function of single field, then be used for variations of square field, no BuildUp NBU and BuildUp BU condition, extended SSD position, and IMRT case with 6 MV and 10 MV. Analysis of gamma parameter Dose Difference DD and Dose to Agreement DTA is used to verify the effectiveness of this method. The kernel function is obtained from square field of 4 cm by deconvolution from comparison of MatriXX FFF and TPS. The results show increasing passing grade value for all of fields 0 15.9, 4.84, 4.81 , where the highest values are on square field of 4 cm and 5 cm at NBU and BU condition. All of those indicate the dependence kernel function to size of field. Application result of IMRT cases also give the same trend of increasing passing grade value. For the next, it needs to do research more about the relationship kernel function to size of field and the application of this method on IMRT case."