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Abstrak :
Simulator perilaku hidrodinamika aliran sungai menggunakan metode numerik dengan basis partikel seperti metode Smoothed Particle Hydrodynamics (SPH) dapat menjadi salah satu alternatif yang tersedia untuk menyimulasikan perilaku hidrodinamika dan morfodinamika pada sungai meander yang tidak mampu dihasilkan oleh simulator yang menggunakan metode numerik berbasis grid. Penelitian ini bertujuan untuk membuat simulator hidrodinamika pada sungai meander dengan menggunakan metode SPH pada platform sederhana seperti MS. Excel yang menggunakan bahasa program Visual Basic dengan menghasilkan keluaran hidrodinamika secara tiga dimensi. Untuk mengetahui perilaku hidrodinamika dari penyebab terjadinya aliran helikal pada sungai meander dilakukan beberapa tahapan simulasi seperti fluid at rest, sloshing, dan simulasi aliran helikal. Dari hasil penelitian ini aliran helikal terbentuk karena adanya gangguan pada morfologi dan kecepatan partikel di dalam aliran sungai. ...... The simulator uses particle-based numerical methods, Smoothed Particle Hydrodynamics (SPH), may be one of the alternatives that is available to simulate the behavior of hydrodynamics and morphodynamics in meander that are not able to simulate by simulators that use grid-based numerical methods. This study aims to make simulator that can simulates hydrodynamic behavior in meander by using simple platform, MS. Excel, and Visual Basic programming language. This simulator also generate a three-dimensional hydrodynamics data as the result. To determine the causes of helical flow in the river meanders, some stages of simulation such as fluid at rest, sloshing, and helical flow simulation are done. From the results of this study, the helical flow is formed due to disturbance in morphology and particle velocity in the river flow.

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Vorrex lube adalah ala! yang dapa! memisahlcan energi yang ada yang ada pada fluida. Sekalrpun efsiensinya lebih rendah cibandingkan dengan ala! pendingin konvensional, narmm ada keunizmgan yang diberikan oleh vorfex lube, seperli; geomerri/konstrnlrsi yang sederhana, lidak memerlulcan rejryeran dan ridak ada bagian yang bergerak. Peneltian aliran vorteks yang diadakan di jurusan Mesin FTU1' sejauh ini hanya pada vortex tube berpenampang lingkaran biasa. Penelirian pada perzambahan inlemya pun masih berlrisar pada sam penampang saja. Apa yang redadi apabila penambahan inlet tangensial terbenlur masalah desain/mamjaktur ? Apalcah perlu umuk memenuhi seluruh lingkaran penampang swirl generalor zmiuk mendapalkan pemmman remperalur yang lebih oplimal ? Peneliiian perrambahan inlet tangensial secara aksial dlanggqp perlu zmluk menjawab pertanyaan seperri av alas. Bagaimana pengaruh pemzmbahan inlet rangensial dalam arah sumbu vorler-Mya. Uniuk visualisasi yang Iebih jelas teniarrg bagaimana pola aliran dalam labung vorlelas, digunakan pemodelan 3D dalam simulasi ini. Beberapa data eksperimen jnga digunakcm untuk mencari nilai awal seperti inlensilas lurbnlen, kecepalan, dan sebagaiqya. Simulasi ini menggzmakan model nlrbnlen RNG K-a Model mrlmlen ini memberikan beberapa kelebihan balk dalam lfeakuralan, penghemalan grid maupwn dalcrm pergrelesaian lcasusjluida yang didominasl aliran berpufar. Penambahan jumlah inle! langensial pada arah aksial menunjuklran kerzailcan lemperalur drop sampai pada balas~balas terlenlu. T emperalur drop lidak lranya dilenlukan oleh kecepatan udara berpular, namzm bagaimana rancangan suam vorlex tube dapal menjaga keslabilan pularan (vorleks) dalam tabzmg tersebur. ......Vortex Tube is a device that can seperates fluid 's energi into hot and cold one. Although the ejiciency of vortex tube is relativebf less than the one in the conventional cooler, still there 's some advantages offered by vortex tube, i.e,° simple geometry/construction, no rejrigeran 's needed and non-moving part(s) of it. So far, research on vortex flow held in F TU] ont)/for ordinary circle section at the swirl generator. Research on the increment of the inlet tangential is also in one section. What will happen if incremental of the tangential inlet limited by the abiligv of desain/manufacture ? Is it necessary to malre the tangential inlet all over the place Hn one section of course) to get the optimal result of temperature drop ? The research on the increment of tangential inlet is considered important according the question above. What is the eject of tangential inlet in the direction of its vortex ?s axis. To have relatively clearer visualisation of the flow pattern in this helical vortex tube, we 'll use 3D simulation. Some of the experimental data will be used too, to have the initial value such as turbulence intensigv, velocity and so on. This simulation accomplished by using turbulence RNG if-e model. This kind of turbulence model offers some better result in accuracy, grid conservation and even in the case of solving fluid dominated by swirling flows. The increment of tangential inlet in axial direction shows some increasing ternpreature drop for some limit. Temperature drop is not only ejected by the velocigv of the swirling _/low, but also by how the design of the vortex tube can maintain the swirling flow to remain at it is axis.

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ABSTRAK
Latar Belakang: Kasus kehilangan gigi molar pertama yang disertai dengan mesial tipping dari gigi molar kedua sering ditemui, sehingga penegakan gigi merupakan salah satu mekanika yang sering dilakukan oleh klinisi. Namun, sebagian besar literatur yang tersedia mengenai penegakan gigi merupakan laporan kasus yang memaparkan mengenai hasil perawatan dengan mekanika tertentu, sesuai dengan pengalaman masing-masing klinisi. Efisiensi dalam perawatan ortodonti, khususnya penegakan gigi, dapat dicapai apabila pergerakan gigi dapat diprediksi. Tujuan: Menganalisis gambaran distribusi stress pada ligamen periodontal gigi molar kedua, pada model 3D mandibula, serta menganalisis perpindahan inisial gigi molar kedua (dalam arah bukolingual, vertikal, dan mesiodistal) ketika diaplikasikan gaya penegakan gigi dengan menggunakan initial archwire, helical uprighting spring, T-loop, serta dengan retromolar miniscrew. Metode: Konstruksi model tiga dimensi mandibula dilakukan dalam satu kuadran, dengan konfigurasi kehilangan gigi molar pertama dan gigi molar kedua tipping 30º. Empat buah model kerja dibuat sesuai dengan metode penegakan gigi yang akan diuji yaitu dengan initial archwire, helical uprighting spring, T-loop, serta dengan retromolar miniscrew. Hasil: Terdapat perbedaan bermakna intensitas stress dan perpindahan inisial pada keempat kelompok mekanika yang diuji. Distribusi stress dan perpindahan inisial gigi molar kedua pada penggunaan initial archwire sangat kecil dibandingkan dengan ketiga mekanika lain yang diuji. Pada penggunaan T-loop, helical uprighting spring, dan retromolar miniscrew, area tension terbentuk paling besar di area servikal akar mesial, sedangkan area compression terbentuk pada area servikal akar distal. Pada analisis perpindahan inisial gigi molar kedua, penggunaan helical uprighting spring menunjukkan ekstrusi yang paling besar, diikuti oleh T-loop, dan retromolar miniscrew. Selain itu, terlihat adanya pergerakan akar pada penggunaan retromolar miniscrew, yang tidak ditemukan pada penggunaan mekanika lainnya. Kesimpulan: Intensitas stress ekuivalen paling besar dihasilkan dari penggunaan helical uprighting spring, T-loop, dan retromolar miniscrew secara berurutan. Analisis perpindahan inisial gigi menunjukkan penggunaan retromolar miniscrew menyebabkan mesial root movement, dibandingkan dengan distal tipping mahkota gigi pada mekanika lain.

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ABSTRACT
Introduction: One of the most frequently encountered clinical situation in adult patients would be the tipping of mandibular second molar which normally occurred due to early loss of the first molar. Previous studies reported different uprighting mechanics were mainly case report and only a few that aimed to describe the efficacy of the various available mechanics. A profound understanding of the efficacy and predictability of the various mechanics would improve tooth movement and prevent unwanted side effects that may arise. The aim of this study was to analyse and compare the stress distribution as well as initial displacement of mandibular second molar using various uprighting mechanics. Methods: A three-dimensional model was constructed and analysed using Finite Element Analysis (FEA) with tipped mandibular second molar set at 30º. Four mandibular models were assembled according to different uprighting mechanics, as follows: initial continuous archwire, helical uprighting spring, T-loop and retromolar miniscrew. Results: Stress distribution and initial displacement resulted from the use of initial archwire were insignificant compared to other mechanics tested. The highest tensile stress were observed on the cervical area of mesial root and the highest compressive stress were observed on the cervical area of distal root on the application of T-loop, helical uprighting spring, and retromolar miniscrew mechanics. Analysis of initial tooth displacement showed that helical uprighting spring caused the largest degree of extrusion, followed by T-loop, and retromolar miniscrew. Root movement was observed on the usage of retromolar miniscrew. Conclusion: Greatest equivalent stress were observed on the usage of helical uprighting spring, T-loop, and retromolar miniscrew in consecutive order. Analysis of initial displacement of the second molar showed that the application of retromolar miniscrew caused mesial root movement, while other mechanics showed distal tipping of the crown.

Abstrak :
Two kinds of stresses in the gear teeth are root bending stress and tooth contact stress. These two stresses results in the failure of gear teeth. The root bending stress results in fatigue failure and contact stress results in pitting failure at the contact surface. The stress analysis used to minimize gear failure in the design of helical gear. It is also optimize the design of helical gear on the transmission system of the truck motor vehicle, where the power transmission is required at heavy loads with smoother and noiseless operation. In this paper bending stress and contact stress estimated using analytical method while modeling of gears used the numerical solution. Method of beam strength based on modified Lewis calculation used to predict the bending strength of helical gears. Contact stress was estimated using related method of AGMA contact stress. Stress modeling of helical gears is done by ANSYS 14.5, which is a finite element analysis package. The results are then compared with both AGMA and ANSYS procedures. The values of bending strength and contact stress determined using AGMA method found to be compatible with ANSYS simulation.

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Wireless power transmission is being investigated as a means to operate tiny medical devices such as the capsular endoscope, which is able to exist for a long period during diagnostic procedures within the body. In this paper, we examine the wireless power transmission to a capsular endoscope by electromagnetic waves to show its usability for medical applications. A modified helical antenna inside the endoscope is proposed as a power receiving antenna, operating at 915 MHz. By calculating a maximum received power in the stomach using such antenna, the results show that adequate power can be well received.

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ABSTRAK
Adanya pengaruh pada pergerakan target akibat dari proses pernapasan maupun parameter pitch dan faktor modulasi pada pesawat tomoterapi, maka penelitian ini dilakukan untuk menginvestigasi pengaruh dari manajemen pergerakan menggunakan citra yang didapatkan dari hasil fusi antara metode pemindaian statik dan dinamik pada fantom CIRS Thoraks. Teknik pemindaian dilakukan dengan menggunakan dua teknik yakni aksial dan helikal. Variasi amplitudo yaitu 10 mm, 15 mm, dan 20 mm. Selanjutnya dilakukan planning menggunakan TPS TomoPlan dengan variasi pitch 0.25-0.5 dan MF 2 dan 3 . Evaluasi planning menggunakan parameter dosis pada target dan OAR, HI, serta nilai mean LOT. Perubahan volume organ target untuk amplitudo 10 mm, 15 mm, dan 20 mm sebesar 10.9 cc, 10.3 cc, 16.1 cc untuk teknik aksial dan 6.6 cc, 8.5 cc, 14.9 cc untuk teknik helikal dari volume target statik sebesar 3.53 cc. Didapatkan perubahan volume yang lebih besar untuk teknik pemindaian aksial dibandingkan dengan helikal. Hasil parameter optimum yang didapatkan pada planning yaitu dengan nilai pitch 0.5 dan MF 3 berdasarkan evaluasi mean LOT dan HI. Oleh karena itu perlu adanya manajemen pergerakan untuk organ target yang bergerak selama penyinaran dengan pertimbangan pada penambahan volume target akibat adanya pergerakan pernapasan agar target menerima dosis preskripsi yang cukup.

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ABSTRACT
The influence on target motion resulted from the respiratory process, the pitch and modulation factor presented in Tomotherapy. This study was aimed to investigate the effect of motion management using CT images obtained from the fusion process between static and dynamic scanning mode on the CIRS Thorax Phantom. The images were scanned using axial and helical modes. The amplitude were varied from 10 mm, 15 mm, and 20 mm. Then, the organ structures were planned using TomoPlan TPS with variation of pitch ranging from 0.25 to 0.5, and the MF in the range 2 to 3. Furthermore, evaluation of radiotherapy planning was performed using dose parameters on target and OAR, HI, and mean LOT. Target volume for static mode was 3.53 cc, where target volume has changed to 10.9 cc, 10.3 cc, 16.1 cc for axial and 6.6 cc, 8.5 cc, 14.9 cc for helical scanning. The optimum parameters were pitch 0.5 and MF 3 based on evaluation of mean LOT and HI. Therefore, motion management was needed during irradiation for the moving target organs with consideration of the target volume increment due to the movement of the respiratory system so the target volume would precisely accept the prescription dose.

Abstrak :
Méandres se produire même sans le transport des sédiments, elle est causée par une turbulence à grande échelle (da Silva, 2006). La recherche de méandre des chaînes en général est séparé, mais toujours corrélée, en deux approches : la dynamique géomorphologiques et fluide, où la modélisation des flux 3D reçoivent plus d'attention pour sa capacité à simuler le mouvement hélicoïdal, même si elle est élevée dans les efforts de calcul et limitée à une géométrie simple (Camporeal, et al, 2007). Un modèle développé avec un finis méthodes d'éléments pour l'écoulement en trois dimensions est appelé Resource Modelling Associates (RMA), pour modéliser ; flux de densité stratifié (RMA-10), et la qualité de l'eau dans les estuaires et les ruisseaux (RMA-11) (King, 2013). Smoothed particle hydrodynamics (SPH) est une méthode libre de maille la plus perceptible et devenu très populaire, en particulier pour les flux de surface libre, il est une méthode robuste et puissant pour décrire les médias déformation (Gomez-Gesteira, et al, 2010). SPH est une méthode très prometteuse pour répondre à la modélisation des flux 3D dans le dynamique méandre. Objectif de cette recherche est modèles d'écoulement hélicoïdaux de simulation d'écoulement avec 3D méthode SPH d'écoulement presque incompressible est comparable à écouler simulation avec écoulement stratifié 3D méthode des éléments finis. Approches dans cette recherche est divisé en deux grandes parties ; (1) modélisation du dynamique méandre avec RMA afin de déterminer ses caractéristiques de base, et (2) développement de la méthode de SPH pour simuler l'écoulement hélicoïdal dans un canal. Modèle éléments finis utilisé dans cette étude, RMA a montré sa capacité à simuler les caractéristiques clés de méandres et sont convenus avec les expériences de Hasegawa (1983), et Xu et Bai (2013). Ces résultats sont utilisés comme référence pour développer le modèle du dynamique méandre. Procédures de SPH sont élaborées à partir du modèle d'écoulement du fluide 3D, gestion des collisions entre les particules de l'eau, et des conditions aux limites de canal courbes. La caractéristique fondamentale dans le dynamique méandre est écoulement hélicoïdal. Avec simulation de SPH, écoulement hélicoïdal est initiée par l'addition des flux de tourbillon et visqueux aux conditions initiales. Formation d'écoulement hélicoïdal est généré en hémisphères partie aval du canal courbé. Motif d'écoulement hélicoïdal à partir du modèle SPH peut être comparé avec des modèles de flux hélicoïdaux de modèle RMA. Le modèle d'écoulement hélicoïdal est compatible avec les modèles de l'investigation très récente de l'expérience par Wang et Liu (2015), et l?esquisse théorique de flux secondaires dans un canal courbe par Wu (2008). Ainsi, SPH est capable pour développer écoulement hélicoïdal du fait de la courbure, d'accord avec Camporeal et al. (2007), et même sans le transport des sédiments, convenu avec da Silva (2006) et Yalin (1993). Notre contribution en présente recherche est le développement de la méthode SPH pour la modélisation de l'écoulement hélicoïdal dans un canal courbé dans le but de simuler le dynamique méandre. Ceci est tout le long avec l'avancement de SPH en hydraulique où quatre grands défis dans les applications de SPH, selon la communauté SPHERIC (Violeau et Rogers, 2015), sont la convergence, la stabilité numérique, la condition limite, et l'adaptabilité. Cette recherche participe aux deux défis de SPH ; la condition limite et l?adaptabilité. Nous avons utilisé des géométries simples basées sur la loi de Snell pour représenter la réponse basique des particules du mur de canal courbé, et adapté SPH pour flux presque incompressible comme un phénomène basique de l'hydraulique dans un canal courbé qui est note bene un flux incompressible. Mots-clés: smoothed particle hydrodynamics, RMA, écoulement hélicoïdal, simulation d'écoulement du fluide 3D, canal courbé, les méandres.

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Meanders occur even without sediment transport, it is caused by a large-scale turbulence (da Silva, 2006). Meandering channels research in general is separated, but still correlated, into two approaches: geomorphologic and fluid dynamics, where 3D flow modeling receives more attention for its ability to simulate helicoidal motion even though it is high in computational efforts and limited to simple geometry (Camporeal, et al., 2007). One developed model with a finite element method for three-dimensional flow is called Resource Modelling Associates (RMA), to model; density stratified flow (RMA- 10), and water quality in estuaries and streams (RMA-11) (King, 2013). Smoothed particle hydrodynamics (SPH) is one most noticeable meshfree method and now become very popular, particularly for free surface flows, it is a robust and powerful method for describing deforming media (Gomez-Gesteira, et al., 2010). SPH is a very promising method to answer 3D flow modeling in meander dynamics. Objective of this research that helical flow patterns from flow simulation with 3D nearly incompressible flow SPH method is comparable to flow simulation with 3D stratified flow finite element method. Approaches in this research is divided into two big parts; (1) modeling meander dynamics with RMA to determine its basic characteristics, and (2) development smoothed particle hydrodynamics (SPH) method to simulate helical flow in a curved channel. The finite element model using in this study, RMA has shown its capability to simulate the meander key characteristics and are agreed with experiments of Hasegawa (1983), and Xu and Bai (2013). These results are used as a reference in developing a method to model meander dynamics. SPH procedures are developed from 3D fluid flow model, collision handling between water particles, and curved channel boundary conditions. The very basic characteristic in meander dynamics is helical flow. With SPH simulation, helical flow is initiated by adding up viscous flow and vorticity at initial conditions. Formation of helical flow is generated at downstream hemispheres part of the curved channel. Helical flow pattern from SPH model can be compared with helical flow patterns from RMA model. The helical flow pattern is consistent with the patterns from very recently experiment investigation by Wang and Liu (2015), and theoretical sketch of secondary flows in a curved channel by Wu (2008). Thus, SPH method is able to develop helical flow as a result of curvature, agreed with Camporeal et al. (2007), and even without sediment transport, agreed with da Silva (2006) and Yalin (1993). Our contribution with this research is developing SPH method for modeling helical flow in a curved channel with the aim of simulating meandering dynamics. This is all along with advancement of SPH in Hydraulics where four grand challenges in SPH applications, according to SPHERIC community (Violeau & Rogers, 2015), are convergence, numerical stability, boundary conditions, and adaptivity. This research participates to the two of SPH challenges; boundary conditions and adaptivity. We used simple geometries based on Snell?s law to represent basic particle responses to channel walls. We adapted SPH for nearly incompressible flow as a basic hydraulics phenomenon in a curved channel that is note bene an incompressible flow.

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Latar Belakang: Hingga saat ini belum pernah dilakukan studi untuk menganalisis parameter dosimetri diantara teknik Three Dimentional Conformal Radiotherapy (3D-CRT), Intensity Modulated Radiotherapy-Step and Shoot (IMRT-SS), IMRT-Helical Tomotherapy (HT) dan Volumetric Modulated Arc Therapy (VMAT) pada kanker prostat di Departemen Radioterapi RSUPN Cipto Mangunkusumo. Metode: Studi eksperimental eksploratorik dengan melakukan intervensi pada 10 data CT plan pasien kanker prostat yang diradiasi di Departemen Radioterapi RSUPN-CM. Dosis 78 Gy diberikan pada PTV dalam 39 fraksi. Hasil: rerata V75Gy rektum dan buli antara teknik 3D-CRT dengan tiga teknik lainnya, seluruhnya memperlihatkan perbedaan yang bermakna (p <0,05). Rerata V5Gy RVR antara teknik 3D-CRT vs VMAT dan HT, IMRT-SS vs HT dan VMAT vs HT bermakna secara statistik dengan nilai p<0,0001. Rerata durasi penyinaran paling tinggi didapatkan dengan teknik HT (rerata 4,70±0,84 menit). Kesimpulan: Angka V75Gy Rektum dan buli antara teknik 3D-CRT berbeda signifikan dibandingkan dengan tiga teknik lainnya. Teknik IMRT-SS menggunakan 5 arah sinar ko-planar mampu memberikan distribusi dosis yang baik terhadap PTV dan organ kritis meskipun tidak superior dibandingkan dengan teknik HT dan VMAT. Teknik HT memiliki konformitas yang lebih inferior dibandingkan dengan teknik VMAT. Durasi penyinaran terpendek dengan menggunakan teknik VMAT, berbeda signifikan dibandingkan dengan 3 teknik lainnya. Background: There is limited study comparing dosimetry parameters between four different techniques; Three Dimentional Conformal Radiotherapy (3D-CRT), Intensity Modulated Radiotherapy-Step and Shoot (IMRT-SS), IMRT-Helical Tomotherapy (HT) and Volumetric Modulated Arc Therapy (VMAT) in relation to prostate cancer in Radiotherapy Department RSUPN Cipto Mangunkusumo. Method: Experimental study with intervention on 10 prostate cancer patients' CT planning data. All the subjects underwent radiation in radiotherapy department RSUPN-CM. 78 Gy dose in 39 fractions was given for PTV. Results: The mean V75Gy rectum and bladder between 3D-CRT and the other three above mentioned techniques all showed significant results (p <0.05). V5Gy RVR between 3D-CRT vs VMAT and HT, IMRT-SS vs HT and VMAT vs HT is statistically significant (p <0.0001). The longest radiation time was done with HT (mean 4.70±0.84 minutes). Conclusion: V75Gy rectum and bladder between 3D-CRT is statistically significant compared with the other three techniques. Even though, it is not superior compared to HT and VMAT, IMRT-SS using 5 co-planar beams are able to provide good dose distribution for PTV and critical organs. HT have inferior conformity compared to VMAT. Shortest radiation time was done using VMAT (statistically significant compared to three other techniques).

Abstrak :
Latar Belakang: Radiasi kraniospinal adalah metode radiasi yang sering digunakan pada kasus keganasan sistem saraf pusat yang menyebar ke cairan cerebrospinal, sehingga area radiasinya sangat luas meliputi seluruh otak dan canalis spinalis. Akibat daerah radiasi yang luas, area radiasi harus dibagi menjadi beberapa lapangan yang menghasilkan kesulitan dalam mengatasi junction antar lapangan tersebut.Kesulitan lain adalah banyaknya organ kritis yang terlibat dan usiapasien yang mayoritas anak-anak. Saat ini belum terdapat data penelitian yang menganalisis radiasi kraniospinal dengan teknik Three Dimentional Conformal Radiotherapy 3D-CRT, Intensity Modulated Radiotherapy IMRT, dan IMRT-Helical Tomotherapy HT di Indonesia. Metode: studi eksperimental eksploratorik dengan melakukan intervensi planning terhadap 10 data CT plan pasien kraniospinal yang diradiasi di Departemen Radioterapi RSUPN Cipto Mangunkusumo. Dosis 36 Gy diberikan dalam 20 fraksi.Cakupan PTV kranial dan spinal dievaluasi menggunakan indeks konformitas CI dan indeks homogenitas HI.Dilakukan pencatatan parameter organ kritis lensa mata, mata, kelenjar parotis, kelenjar submandibula, tiroid, paru-paru, jantung, ginjal, testis dan ovarium, serta paparan radiasi pada seluruh tubuh.Selain itu juga dilakukan pencatatan jumlah MU dan durasi sinar beam on time. Hasil: Teknik HT adalah teknik terbaik dalam pencapaian angka HI dan CI serta perlindungan terhadap organ kritis, namun memiliki paparan radiasi seluruh tubuh tertinggi dibandingkan teknik 3D CRT dan IMRT selain nilai MU tertinggi dan durasi penyinaran terlama sehingga harus dipertimbangkan penggunaannya pada pasien anak-anak karena resiko secondary malignancy yang tinggi. Teknik 3D CRT dengan arah sinar opposing lateral untuk lapangan kranial dan dari posterior untuk lapangan spinal memiliki nilai HI dan CI terburuk dengan keterbatasan kemampuan melindungi organ kritis namun memiliki paparan radiasi seluruh tubuh dan MU terendah serta durasi penyinaran terpendek.

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Background: Craniospinal radiation is a method of radiation that is often used in cases of malignancy of the central nervous system that spread to cerebrospinal fluid, so that the area of ??radiation is very broad covering the entire brain and spinal canal. Due to the large area of radiation, the radiation area must be divided into several fields that produce difficulty in overcoming the inter-field junction. In addition, the number of critical organs involved and the age of patients with the majority of children result in separate considerations in the choice of craniospinal radiation techniques. Currently there is no research data that analyzes craniospinal radiation with Three Dimentional Conformal Radiotherapy 3D-CRT, Intensity Modulated Radiotherapy-Step and Shoot IMRT-SS, and IMRT-Helical Tomotherapy HT techniques in Indonesia. Method: exploratory experimental study by planning intervention on 10 CT plan data of craniospinal patients radiated in Radiotherapy Department of Cipto Mangunkusumo General Hospital. Dose 36 Gy is given in 20 fractions. Cranial and spinal PTV coverage was evaluated using the conformity index CI and homogeneity index HI. Performed recording of critical organ parameters of lens, eye, parotid gland, submandibular gland, thyroid, lung, heart, kidney, testis and ovary, and exposure to radiation throughout the body. In addition, also recorded the number of MU and the duration of the beam. Results: The HT technique is the best technique for achieving HI and CI figures and protection of critical organs, but has the highest body-wide radiation exposure compared to CRT and IMRT 3D techniques in addition to the highest MU values and longest exposure duration so should be considered in children high risk of secondary malignancy. 3D CRT technique with opposite lateral beam direction for the cranial field and from the posterior to the spinal field has the worst HI and CI values with limited ability to protect critical organs but has the lowest total body radiation and MU exposure as well as the shortest duration of irradiation.

Abstrak :
Latar Belakang: Radiasi eksterna seringkali digunakan untuk mengurangi gejala dari metastasis otak. Teknik radiasi paliatif Whole Brain masih merupakan terapi standar bagi pasien kanker dengan metastasis otak, namun teknik radiasi ini dapat menyebabkan penurunan fungsi neurokognitif yang diakibatkan oleh inflamasi akibat radiasi pada daerah hipokampus. Hal ini memicu penggunaan Hippocampal Sparing Whole Brain Radiotherapy (HS-WBRT) untuk mengurangi efek samping penurunan neurokogntif yang terkait hipokampus. Thesis ini membahas perbandingan dosimetri teknik radiasi Intensity Modulated Radiotherapy (IMRT), Volumetric Modulated Arc Therapy (VMAT), dan Helical Tomotherapy (HT) pada Hippocampal Sparing Whole Brain Radiotherapy (HS-WBRT) untuk menilai apakah ada perbedaan parameter dosimetri dari ketiga teknik radiasi tersebut. Penelitian ini merupakan studi eksperimental eksploratif dengan melakukan intervensi pada data CT-plan pasien metastasis otak secara in silico. Parameter dosimetri yang dinilai adalah Conformity Index, Homogenity Index, Treatment Time, D98% PTV, D2% PTV, D50% PTV, D100% Hipokampus, dan Dmax Hipokampus. Hasil penelitian ini menunjukkan adanya perbedaan yang signifikan secara statistik dalam parameter Homogenity Index, D98% PTV, D2% PTV, dan D50% PTV pada semua kelompok data teknik radiasi, dimana Helical Tomotherapy (HT) memiliki nilai rerata yang paling baik dibandingkan kedua teknik radiasi lainnya. Untuk parameter yang lainnya baik Intensity Modulated Radiotherapy (IMRT) maupun Volumetric Modulated Arc Therapy (VMAT) memiliki nilai rerata yang tidak berbeda bermakna, kedua teknik radiasi tersebut masih memungkinkan sebagai tehnik pilihan dalam HSWBRT. Masih diperlukan penelitian lebih lanjut dengan jumlah sampel yang lebih besar guna menilai dengan baik teknik radiasi mana yang paling unggul untuk digunakan dalam perencanaan HS-WBRT serta menghasilkan perencanaan radiasi yang lebih baik.

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Background: Radiation therapy is still a standard treatment in brain metastases cases. Whole brain radiation therapy is widely used to reduce debilitating symptoms, on the other hand this treatment could decrease neurocognitif function due to radiationinduced inflammation of the hippocampus. This is the ground reason to apply Hippocampal Sparing Whole Brain Radiotherapy (HS-WBRT), in order to reduce hippocamus related side effects. The focus in this study is to analyze dosimetric parameter between Intensity Modulated Radiotherapy (IMRT), Volumetric Modulated Arc Therapy (VMAT), and Helical Tomotherapy (HT) in Hippocampal Sparing Whole Brain Radiotherapy (HS-WBRT) to asses any differences in dosimetric values. This study is an experimental study on CT and delivered treatment planing data, recalculated in silico as a hippocampal sparing treatment planning to be compared. The dosimetric parameter that were used in this study are Conformity Index, Homogenity Index, Treatment Time, D98% PTV, D2% PTV, D50% PTV, D100% Hippocampus, dan Dmax Hippocampus. The dosimetric comparisons between the three modalities resulted in statistically significant differences in Homogenity Index, D98% PTV, D2% PTV, D50% PTV, D100% where Helical Tomotherapy (HT) has a better mean value among the rest of the group. In other dosimetric comparisons, Intensity Modulated Radiotherapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) does not have any significant differences, as such both modalities allows for sparing of the hippocampus with acceptable means value in many dosimetric parameters. Further research is nedeed, particularly with larger sample to assess superiority in HS-WBRT modalities, as such to increase efficacy in its treatment planning.