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"ABSTRAKFilm EBT3 merupakan model film radiochromic yang didisain khusus untuk keperluan radioterapi eksternal (external beam therapy, EBT) respon film terhadap radiasi pengion mengakibatkan perubahan pada spektrum serapan dan sifat optiknya membuat film radiochromic menjadi pilihan yang banyak digunakan dalam bidang oncologi. Responfilm terhadap radiasi biasanya diukur dalam hal perubahan kerapatan optik (netOD) yang nilainya bergantung dari banyaknya berkas yang melewati film dan juga panjang gelombang cahaya dari alat pembaca (densitometer optik). Penelitian ini bertujuan menyelidiki pengaruh penggunaan densitometer optik yang berbeda, yakni scanner, densitometer dan spektrofotometer dalam mengukur respon dosimeter film terhadap radiasi pengion. Penyelidikan respon film dilakukan dengan mengirradiasi film menggunakan pesawat Linac Varian Trilogy dengan energi 6 MV. netOD yang terbaca pada film dilakukan dengan mengekstrak mean pixel value dari kanal merah ketika menggunakan scanner. Ketika menggunakan densitometer netOD dihasilkan dariperubahan nilai OD yang terbaca secara langsung. Sedangkan nilai netOD didapat dengan melihat perubahan spektrum serapan film sesudah dan sebelum irradiasi menggunakan spektrofotometer. Evaluasi penggunaan metode dosimetri dilakukan menggunakanfantom homogen untuk evaluasi dosis uji dan juga untuk evaluasi pada variasi lapangan penyinaran, dan fantom non-homogen (rando) untuk implementasi metode pada perlakuan klinis radioterapi. Untuk mendapatkan hasil pengukuran yang optimum juga dilakukan penyelidikan karakteristik spektrum serapan pada variasi level dosis dan variasi waktu pengukuran pasca irradiasi. Hasil pengukuran respon film menunjukkan tidak terjadi perubahan pita serapan film terhadap perubahan level dosis ataupun terhadap perubahan waktu pasca irradiasi, yakni berada pada pusat pada panjang gelombang 635nm untuk pita serapan maksimum, dan pita serapan ke-dua berpusat pada 583 nm. Penyelidikan sensitivitas ketiga metode menghasilkan tren kurva sensitivitas yang mirip namum memiliki besar yang berbeda dimana sensitivitas tertinggi didapat ketika menggunakan spektrofotometer. Sementara ketidakpastian (1σ) netOD untuk ketigametode menghasilkan nilai ketidakpastian yang cukup besar untuk dosis dibawah 100 cGy dan nilai ketidakpastian mulai membaik ketika level dosis meningkat. Pada aplikasi klinis ketiga metode dosimeteri dievaluasi dengan melihat besar diskrepansi yang dihasilkan pada adaerah target kepala, paru-paru dan prostat. Penggunaan scanner danspektrofotometer menghasilkan rata-rata diskrepansi dibawah 2% untuk semua target pengukuran, sedangkan densitometer menghasilkan rata-rata diskrepansi sampai 3%.

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ABSTRACTEBT3 film is a radiochromic film model specially designed for external radiotherapy (EBT). The response of the film to ionizing radiation results in changes in the absorption spectrum and its optical properties making radiochromic films a widely used choice in oncology. The response of the film to radiation is usually measured in terms of the change in optical density (netOD) whose value depends on the number of beams passing through the film and also the wavelength of light from the reader (optical densitometer). This study aims to investigate the effect of using different optical densitometers, namely scanners, densitometers and spectrophotometers in measuring the response of film dosimeters to ionizing radiation. The investigation of the film response was carried out by irradiating the film using a Linac Varian Trilogy with an energy of 6 MV. The netOD read on the film was done by extracting the mean pixel value from the red channel when using a scanner. When using a densitometer the netOD results from changes in OD values that are read directly. While the netOD value was obtained by measuring changes in the absorption spectrum of the film after and before irradiation using a spectrophotometer. Evaluate the use of the dosimetric methods was carried out using homogeneous phantomfor the evaluation of test doses and also for evaluation of variations in the radiation field, and non-homogeneous phantom (rando) for the implementation of the method in clinical radiotherapy treatment. To obtain the optimum measurement results, an investigation of the characteristics of the absorption spectrum was also carried out at variations in dose levels and variations in measurement time after irradiation. The results of the measurement of the response of the film showed that there was no change in the absorption band of the film due to changes in dose levels or to changes in time after; irradiation, which was at the center at a wavelength of 635 nm for the maximumabsorption band, and the second absorption band was centered at 583 nm. The sensitivityinvestigation of the three methods resulted in a trend of similar sensitivity curves but different magnitudes with the highest sensitivity obtained when using a spectrophotometer. Meanwhile, the uncertainty (1σ) netOD for the three methods resultedin a fairly large uncertainty value for doses below 100 cGy and the uncertainty value began to decrease as the dose level increased. In clinical application, the three dosimetric methods were evaluated by measuring the resulting discrepancy in the target areas of thehead, lungs and prostate. The use of a scanner and a spectrophotometer resulted in an average discrepancy of below 2% for all measurement targets, while the use of a densitometer resulted in an average discrepancy of up to 3%."

"Penelitian ini bertujuan untuk memperoleh nilai parameter dosimetri sumber brakhiterapi intrakaviter Cs 137 model CSM40 milik Rumah Sakit Umum Pusat Persahabatan dengan menggunakan software Monte Carlo N Partikel versi 5 (MCNP5). Nilai parameter dosimetri yang ditentukan sesuai dengan rekomendasi AAPM TG43, yang meliputi : faktor geometri, air kerma strength, konstanta laju dosis, fungsi dosis radial, dan fungsi anisotropi. Berdasarkan nilai parameter yang diperoleh, laju dosis dapat dikalkulasi dengan menggunakan persamaan yang tersedia dalam TG43. Selanjutnya laju dosis dalam air sepanjang sumbu transversal (θ=90) ditentukan.Dari hasil simulasi dan perhitungan diperoleh bahwa air kerma strength dan konstanta laju dosis Cs 137 CSM40 berturut-turut 1840 cGy.h-1.cm2 dan 0.994 cGy.h-1.U-1. Selain itu laju dosis dalam air sepanjang sumbu transversal dikalkulasi dengan metode Sievert. Akhirnya, perhitungan laju dosis sepanjang θ=90 dengan ketiga metode dibandingkan. Diperoleh bahwa ratarata perbedaan antara metode monte carlo dengan Sievert sekitar 11% dan antara monte carlo dengan TG43 sekitar 0.4%.

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This study is aimed to calculate dosimetry parameters of brachytherapy intracavitary source Cs 137 CSM40 which is used by RSUP Persahabatan following the recommendation of AAPM TG43 and by using software Monte Carlo N Particle version 5 (MCNP5). The parameters which has been obtained are : geometry factor, air kerma strength, dose rate constant, radial dose function, and anisotropy function. After that, the calculation of dose rate will be enabled using TG43 formalism.

It has been obtained that the value of air kerma strength and dose rate constant are 1840 cGy.h-1.cm2 and 0.994 cGy.h-1.U-1 respectively. The value of dose rate in water along θ=90 also has been calculated using Sievert method and TG43 formalism. Finally, the result of the three methods is compared and it is found approximately 11% difference between monte carlo and Sievert method and 0.4% between monte carlo and TG43 method."

"Penelitian ini bertujuan untuk mengevaluasi perhitungan dosis berdasarkan citra Cone Beam Computed Tomography (CBCT) pada pasien dengan diagnosa tumor otak. Perencanaan dan perhitungan dosis berdasarkan citra CBCT fraksinasi ke-16 yang dilakukan terhadap 13 pasien yang disinari menggunakan pesawat linac Elekta Versa HD dan 7 pasien yang disinari menggunakan pesawat linac Halcyon 2.0. Perencanaan dan perhitungan dosis dilakukan pada Treatment Planning System (TPS) Eclipse dan TPS Monaco. Hasil perhitungan dosis berdasarkan citra CBCT dibandingkan dengan citra Computed Tomography (CT) simulator. Penelitian ini memiliki beberapa tahapan, (1) kalibrasi Hounsfield Unit (HU) citra CBCT menggunakan fantom CIRS CT electron density 062M untuk melakukan perhitungan dosis di TPS dengan nilai HU yang sesuai, (2) proses pengumpulan data citra pasien yang memenuhi kriteria penelitian dan dilanjutkan dengan proses registrasi dan perencanaan citra CBCT, (3) analisis Dose Volume Histogram (DVH) untuk mengevaluasi kualitas perencanaan dengan parameter dosis yaitu Conformity Index (CI) dan Homogeneity Index (HI), (4) analisis dosis Organ at Risk (OAR) terhadap dose-constraint (batas dosis) untuk OAR batang otak, kiasma, sumsum tulang belakang, saraf optik, mata dan lensa. Nilai CI pada perencanaan berdasarkan CT tidak berbeda secara signifikan, Berdasarkan CBCT dari pesawat linac Elekta Versa HD diperoleh CI sebesar 0,05±0,21 (p=0,08) dan -0,01 ± 0,06 (p=0,02) berdasarkan CBCT dari pesawat linac Halcyon 2.0. Sementara itu, nilai HI pada perencanaan berdasarkan CBCT diamati berbeda secara signifikan terhadap CT, Berdasarkan CBCT dari pesawat linac Elekta Versa HD diperoleh HI sebesar 0,25 ± 0,43 (p=0,01) dan 0,08 ± 0,04 (p=0,01) berdasarkan CBCT dari pesawat linac Halcyon 2.0.

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This research aims to evaluate dose calculations based on Cone Beam Computed Tomography (CBCT) images in patients diagnosed with brain tumors. Planning and dose calculations based on the 16th fraction of CBCT images were performed on 13 patients irradiated using Elekta Versa HD linear accelerator and 7 patients irradiated using Halcyon 2.0 linear accelerator. The planning and dose calculations were conducted using the Treatment Planning System (TPS) Eclipse and TPS Monaco. The results of the dose calculations based on CBCT images were compared with the Computed Tomography (CT) simulator images. The research comprised several stages: (1) calibration of Hounsfield Unit (HU) of CBCT images using CIRS CT electron density 062M phantom to perform dose calculations in TPS with appropriate HU values, (2) data collection of patient images meeting the research criteria followed by image registration and CBCT planning, (3) analysis of Dose Volume Histogram (DVH) to evaluate planning quality using dose parameters such as Conformity Index (CI) and Homogeneity Index (HI), (4) analysis of dose to Organs at Risk (OAR) against dose constraints for OARs such as brainstem, chiasm, spinal cord, optic nerves, eyes, and lenses. The CI values for the planning based on CT were not significantly different. Based on CBCT from Elekta Versa HD linear accelerator, the CI obtained was 0.05 ± 0.21 (p=0.08), and based on CBCT from Halcyon 2.0 linear accelerator, the CI obtained was -0.01 ± 0.06 (p=0.02). However, the HI values for planning based on CBCT significantly differed from CT. Based on CBCT from Elekta Versa HD linear accelerator, the HI obtained was 0.25 ± 0.43 (p=0.01), and based on CBCT from Halcyon 2.0 linear accelerator, the HI obtained was 0.08 ± 0.04 (p=0.01)."

"Karakteristik dari berkas proton secara teori lebih menguntungkan untuk jaringan normal dibanding dengan berkas foton. Karakteristik bragg peak dari berkas proton memungkinkan untuk mereduksi distribusi dosis pada jaringan normal. Oleh karena itu, penggunaan berkas proton mampu mengurangi kemungkinan terjadinya efek samping pada jaringan normal. Penggunaan Intensity Modulated Proton Therapy (IMPT) memungkinkan untuk memberikan dosis optimal pada PTV dengan tetap memberikan distribusi dosis yang baik, sehingga tujuan penelitian ini untuk mengetahui kemungkinan penggunaan IMPT untuk kasus vestibular schwannoma serta membandingkan kualitas pencitraan IMPT dengan IMRT, VMAT, dan TOMO. Setiap perencanaan dilakukan dengan menggunakan teknik stereotactic radiosurgery (SRS), perencanaan IMPT dilakukan dengan multifield optimizatin (MFO) dan single field optimization (SFO). Hasil perencanaan didapat nilai conformity indeks (CI) dari tertinggi ke terendah adalah 3MFO-NC, 5MFO-NC, 3MFO, 5MFO, IMRT, 3SFO-NC, VMAT, 3SFO, dan TOMO. Perencanaan proton memiliki gradient indeks lebih baik dari foton. Equivalent Unoform Dose (EUD) berkas proton lebih rendah dibandingkan dengan foton. Nilai Normal Tissue Complication Probability perencaan proton lebih rendah dari foton. Selain itu, perencanaan proton memiliki dosis pada OAR yang lebih rendah dibanding foton.

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The characteristics of the proton beam are theoretically more favorable for normal tissues than the photon beam. The characteristic of the proton beam Bragg Peak can provide minimum dose distribution in normal tissues. Therefore, the use of proton beams can reduce the possibility of side effects in normal tissues. In addition, Intensity Modulated Proton Therapy (IMPT) produces an optimal dose for PTV while still providing a good dose distribution. In this study, the purpose was to determine the quality of planning IMPT for cases of Vestibular Schwannoma and compare with planning with IMRT, VMAT, and TOMO. The stereotactic Radiosurgery (SRS) technique was employed for all treatment planning. Furthermore, IMPT planning was performed using Multifield Optimization (MFO) and Single Field Optimization (SFO). The study described Conformity Index (CI) values from the highest to the lowest are 3MFO-NC, 5MFO-NC, 3MFO, 5MFO, IMRT, 3SFO-NC, VMAT, 3SFO, and TOMO. Additionally, the Gradient Index (GI) of the proton beam is better than photons planning. However, the Equivalent Uniform Dose (EUD) and Normal Tissue Complication Probability (NTCP) of the proton beam are lower than that of the photon. In addition, proton plans have a lower OAR dose than photons."

"Radioterapi lapangan kecil mulai banyak digunakan pada radioterapi modern seperti Intensity modulated radiotherapy (IMRT), stereotactic radiosurgery (SRS), dan Volumetric modulated arc therapy (VMAT). Akurasi terhadap pengukuran profil berkas dan percentage depth dose (PDD) menjadi kompleks karena ketidakseimbangan elektron. Oleh karena itu, film Gafchromic EBT2 digunakan untuk dosimeter radioterapi lapangan kecil karena memiliki resolusi spasial yang tinggi. Analisa dosimetri pada film Gafchromic EBT2 sangat dipengaruhi oleh penggunaan resolusi spasial citra. Penggunaan resolusi yang terlalu tinggi dapat menyebabkan noise yang cukup besar sebaliknya resolusi citra yang terlalu rendah tidak mampu menampilkan hasil analisa yang cukup akurat. Dengan demikian penggunaan resolusi citra yang optimum menjadi parameter penting dalam analisa dosimetri pada film Gafchromic EBT2. Resolusi citra yang optimum dapat ditentukan dengan melakukan uji respon terhadap variasi resolusi citra yakni : 50, 75, 100, 150, dan 240 dpi pada saat melakukan scanning film dengan Epson Perfection V700 menggunakan orientasi film landscape. Analisa dosimetri dilakukan menggunakan algoritma MATLAB dan dibandingkan dengan penelitian sebelumnya menggunakan ImageJ, Monte Carlo dan PPC untuk melihat karakteristik dosimetri terhadap penggunaan resolusi. Secara keseluruhan hasil evaluasi menunjukkan kondisi optimum resolusi citra 150 dpi diperoleh pada TPR20,10 dengan S.D. 8.10 % dan dmax dengan S.D 4.78%. Hasil evaluasi profil berkas menunjukkan resolusi optimum untuk FWHM dan Penumbra dicapai pada resolusi 75 dpi dengan S.D. 7.0 2% dan 12.43%. Hasil evaluasi VACF menunjukkan resolusi optimum dicapai pada resolusi 50 dan 75 dpi. Hasil yang diperoleh dari masing-masing parameter dosimetri memiliki kecenderungan optimum pada resolusi citra75 dpi.

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Small field radiotherapy were increasing used in modern radiotherapy especially in intensity modulated radiotherapy (IMRT), stereotactic radiosurgery (SRS), and volumetric modulated arc therapy (VMAT). Accurate beam profile and percentage depth dose (PDD) measurements of such as beams were complicated due to the electron disequilibrium. Hence the EBT2 (external beam therapy) Gafchromic film was used for dosimetry small field radiotherapy because of its high spatial resolution. Spatial resolution influence dosimetric analyze for EBT2. More perturbation cause by using high spatial resolution otherwise low image spatial resolution couldn?t determined accurately. Such as, small field radiotherapy required the optimum image resolution for important parameter in dosimetric analyze EBT2. Optimum image resolution could be determine with testing dosimetric characterization to resolution response by 50, 75, 100, 150, and 240 dpi with landscape film orientation during film scanning by Epson Perfection V700. Dosimetric analyze was done by MATLAB algorithm and compare to ImageJ, Monte Carlo and PPC from prior research to evaluate dosimetry characteristic to image resolution. The results show that optimum image resolution was 150 dpi with S.D. 8.10 % and 4.78% for TPR20,10 and dmax respectively. Beam profile evaluation for FWHM dan Penumbra attained for 75 dpi with S.D. 7.0 2% and 12.43%. VACF evaluation show that optimum image resolution rich at 50 and 75 dpi. The result for each dosimetry parameter attained to optimum image resolution at 75 dpi"

"[ABSTRAKFilm gafchromic EBT2 dan EBT3 cocok digunakan untuk jaminan kualitas (QA) pada treatment planning systems (TPS) dan linear accelerator (LINAC) serta verifikasi radioterapi teknik IMRT dan VMAT. Namun generasi selanjutnya dari film gafchromic EBT yaitu EBT2 dan EBT3 ketika dilakukan scanning (pemindaian) menggunakan scanner flatbed masih terdapat artefak geometris yang dahulunya juga ditemukan pada film EBT sehingga memerlukan penanggulangan dan koreksi yang sesuai. Pada penelitian ini menggunakan scanner flatbed Epson expression 10000XL, Epson perfection V700 dan Mikrotek 1000XL plus yang dapat menangkap warna dengan rinci dan presisi. Perangkat lunak yang digunakan dalam koreksi ini adalah FilmQA Pro 2015. Hasil yang diperoleh yaitu Koefisien A dan B diterapkan untuk variasi posisi lateral terhadap nilai tanggapan di lokasi yang bersamaan, sehingga pengkoreksian tanggapan artifak lateral dapat dilakukan. Pada dosis maksimum nilai koreksinya <0,5% dan pada kasus <0.2%. Pada pengukuran ulang untuk setiap film, standar deviasi yang diperoleh untuk setiap film sekitar 0.19%. Pengujian dosimetri channel tunggal (merah) sebelum dan sesudah koreksi pada kasus IMRT didapatkan hampir 91% dari piksel memenuhi 3% / 3mm kriteria gamma keseluruhan dengan ambang batas dosis > 10%. Untuk pengujian kasus VMAT, film di scan dengan posisi di pusat scanner dan posisi ektrim tepi scanner, maka pengukuran di channel warna merah 4% lebih tinggi dibandingkan channel warna hijau dan biru. Rata-rata konsistensi pengukuran dosis selama daerah terkena dosis > 100 cGy adalah sekitar 21,8 cGy dan di daerah yang paling dekat dengan tepi scan window sekitar 10 mm dengan perbedaan dosis 35 cGy. Setelah dilakukan koreksi, rata-rata konsistensi dosis pada tiga channel di sekitar daerah terpapar sekitar 5,1 cGy. Perbedaan dosis antar channel sekitar 9 cGy. Hasil ini menunjukkan koreksi respon artefak lateral memang perlu dilakukan. Respon yang diukur tergantung pada posisi film pada pemindai dan dosis yang diberikan. Pengukuran pada channel warna merah menunjukkan sensitivitas yang lebih besar pada dosis rendah, sedangkan respon pada channel hijau atau biru memberikan perpanjangan jangkauan dinamis dari film ke dosis tinggi. Metode triple-channel dosimetri telah terbukti memiliki keuntungan signifikan atas single channel dosimetry dengan akurasi dosimetri yang baik.

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ABSTRACT

The film of gafchromic EBT2 and EBT3 are appropriate for quality assurance (QA) to the radiotherapy technics verification of IMRT and VMAT. In the next generations of EBT which are EBT2 and EBT3, are still attained the geometrical artifacts once scanning by flatbed scanner which is used to be found on EBT film in order to need an overcome ways and an appropriate correction. This research used a flatbed scanner EPSON expression 10000XL, EPSON perfection V700 and Microtech 1000XL plus and FilmQA Pro 2015 as a software for correcting it. The result shows that coefficient A and B were applied for lateral correction artifacts responses can be made. On the maximum dose, it has correction value as much as <0,5% and in case was <0.2%. The deviation standard was approximately 0,19% on re-measure for each film. Prior to the dosimetry measurement of single channel (red) and subsequent to the correction IMRT has got almost 91% of pixel which met with gamma criteria, 3% / 3mm, with dose threshold 10% TH. In the measurement of VMAT‟s case, film scanned on the center of scanner and the extreme position of the scanner edge. Thus, measurement in the red channel was 4% higher than green and blue channel. The average of dose measurement consistency during area exposed to doses > 100 cGy is approximately 21,8 cGy and the closest area with the edge of scan window is around 10 mm at difference doses 35 cGy. After correction, the average of doses consistency was 5,1 cGy on the three channel where exposed. The distinction of doses was approximately 9 cGy among channels. This result stated that the correction of artifacts lateral response is needed to carry on. The method of triple-channel dosimetry has the significant advantage on single-channel dosimetry with a good consistency. Through escalation dose and variation of lateral position, the distinct response would be increased on single-channel which is red channel. The measurement on red channel reveals the highest sensitivity on the slight dose. Whereas, a green or blue channel response provides a dynamic range extension of film to a high dose. Thus, the method of dosimetry triple-channel has the significant contribution of single-channel evidently with a good dosimetric accuracy., The film of gafchromic EBT2 and EBT3 are appropriate for quality assurance (QA) to the radiotherapy technics verification of IMRT and VMAT. In the next generations of EBT which are EBT2 and EBT3, are still attained the geometrical artifacts once scanning by flatbed scanner which is used to be found on EBT film in order to need an overcome ways and an appropriate correction. This research used a flatbed scanner EPSON expression 10000XL, EPSON perfection V700 and Microtech 1000XL plus and FilmQA Pro 2015 as a software for correcting it. The result shows that coefficient A and B were applied for lateral correction artifacts responses can be made. On the maximum dose, it has correction value as much as <0,5% and in case was <0.2%. The deviation standard was approximately 0,19% on re-measure for each film. Prior to the dosimetry measurement of single channel (red) and subsequent to the correction IMRT has got almost 91% of pixel which met with gamma criteria, 3% / 3mm, with dose threshold 10% TH. In the measurement of VMAT‟s case, film scanned on the center of scanner and the extreme position of the scanner edge. Thus, measurement in the red channel was 4% higher than green and blue channel. The average of dose measurement consistency during area exposed to doses > 100 cGy is approximately 21,8 cGy and the closest area with the edge of scan window is around 10 mm at difference doses 35 cGy. After correction, the average of doses consistency was 5,1 cGy on the three channel where exposed. The distinction of doses was approximately 9 cGy among channels. This result stated that the correction of artifacts lateral response is needed to carry on. The method of triple-channel dosimetry has the significant advantage on single-channel dosimetry with a good consistency. Through escalation dose and variation of lateral position, the distinct response would be increased on single-channel which is red channel. The measurement on red channel reveals the highest sensitivity on the slight dose. Whereas, a green or blue channel response provides a dynamic range extension of film to a high dose. Thus, the method of dosimetry triple-channel has the significant contribution of single-channel evidently with a good dosimetric accuracy.]"