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Verifikasi Distribusi Dosis Menggunakan Detektor 2D-Array sebagai Evaluasi Hasil Kalkulasi Algoritma Collapsed Cone dan Monte Carlo pada TPS Monaco
INTISARI
Penelitian kali ini akan dilakukan verifikasi dosis dengan membandingkan distribusi dosis hasil kalkulasi dosis pada TPS terhadap dosis pengukuran pada slab phantom. Kalkulasi dosis pada TPS menggunakan algoritma monte carlo dan collapsed cone, sedangkan pengukuran pada slab phantom menggunakan detektor 2D-array Octavius 729. Hasil pada penelitian kali ini sebagai berikut, pada tahap pertama perbandingan hasil kalkulasi distribusi dosis algoritma collapsed cone terhadap algoritma monte carlo untuk variasi luas lapangan standar 3x3, 5x5, 10x10, 15x15, 20x20 cm berturut turut yaitu 0%, 0%, 0,7%, 1,2%, 1,1%. Pada tahap kedua yaitu hasil kalkulasi distribusi dosis masing-masing algoritma dibandingkan dengan hasil pengukuran sebenarnya pada slab phantom untuk variasi luas lapangan penyinaran standar 3x3, 5x5, 10x10, 15x15, 20x20 dan nilai MU (Monitor Unit didapat perbedaan untuk algoritma collapsed cone dan monte carlo terhadap hasil pengukuran sebagai berikut: untuk 50 MU collapsed cone 4,8%, 6,5%, 3,8%, 7,1%, dan 2,4% sedangkan untuk monte carlo 0%, 0%, 1,3%, 2,6%, dan 6,3%. Nilai 100 MU collapsed Cone 9,5%, 6,5%, 4,4%, 7,6%, dan 2,4% sedangkan monte carlo 0%, 2,2%, 1,9%, 3,2%, dan 6,3%. Nilai 150 MU collapsed cone 9,5%, 6,5%, 4,4%, 7,9%, dan 2,7% sedangkan monte carlo 0%, 2,2%, 3,8%, 2,9%, dan 6,8%. Nilai 200 MU collapsed cone 9,5%, 8,7%, 4,4%, 7,9%, dan 2,9% sedangkan monte carlo 0%, 2,2%, 4,4%, 2,6%, dan 5,8%. Tahap perbandingan kalkulasi distribusi dosis masing-masing algoritma dengan pengukuran dosis pada slab phantom menggunakan QA plan untuk tiga pasien didapat sebagai berikut collapsed cone 13,6%, 16,1%, dan 1,7% sedangkan monte carlo 5,1%, 6,2%, dan 0%. Sehingga dapat disimpulkan bahwa algoritma monte carlo lebih akurat dalam mengalkulasi distribusi dosis untuk variasi lapangan standar maupun planning pada pasien dibanding algoritma collapsed cone.
Kata kunci: Radioterapi, QA Plan, 2D-Array, Monte Carlo, Collapsed Cone
ABSTRACT
Research this time will verify the dose by comparing the planned dose on TPS with actual measured dose on slab phantom. Dose calculation on TPS uses monte carlo and collapsed cone algorithm, meanwhile the measurement on slab phantom using detector 2D-array Octavius 729 First step of this research is Direct comparison between dose distribution of collapsed cone algorithm against monte carlo algorithm for standard field size variation. The result for first step comparison obtained that the difference between these two algorithms for standard field size 3x3, 5x5, 10x10, 15x15, 20x20 variation is 0%, 0%, 0,7%, 1,2%, 1,1%. next step is to compare the result of dose calculation using each algorithm against the result of measurement on slab phantom with standard field size 3x3,5x5,10x10,15x15,20x20 and 50,100,150, 200monitor unit output in variation. Comparison result for 50 MU and standard field size obtained that the difference for collapsed cone against actual measurement on slab phantom are 4,8%, 6,5%, 3,8%, 7,1%, 2,4%, meanwhile for monte Carlo algorithm are 0%, 0%, 1,3%, 2,6%, 6,3%. Comparison result for 100 MU obtained that the difference for collapsed cone against actual measurement on slab phantom are 9,5%, 6,5%, 4,4%, 7,6%, 2,4%, meanwhile for monte carlo algorithm are 0%, 2,2%, 1,9%, 3,2%, 6,3%. Comparison result for 150 MU obtained that the difference for collapsed cone against actual measurement on slab phantom are 9,5%, 6,5%, 4,4%, 7,9%, 2,7%, meanwhile for monte carlo algorithm are 0%, 2,2%, 3,8%, 2,9%, 6,8%. Comparison result for 200 MU obtained that the difference for collapsed cone against actual measurement on slab phantom are 9,5%, 8,7%, 4,4%, 7,9%, 2,9%, meanwhile for monte carlo algorithm are 0%, 2,2%, 4,4%, 2,6%, 5,8%. the third step comparison is to compare the result of dose calculation using each algorithm against the result of dose measurement on slab phantom using variation is patient planning. Comparison result using three patient planning obtained that the difference for collapsed cone algorithm against actual measurement on slab phantom are 13,6%, 16,1%, 1,7%, meanwhile for monte carlo algorithm are 5,1%, 6,2%, 0%. So, it can be inferred that the monte carlo algorithm more accurate in calculating dose distributions for variation of standard field size and patient planning than collapsed cone algorithms
Keywords: Radiotherapy, QA Plan, 2D-Array, Monte Carlo, Collapsed Cone
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