Dose Planning Evaluation of Intensity-Modulated Proton Therapy (IMPT) Technique Based on In-House Dynamic Thorax Phantom

One of the drawbacks of the Intensity Modulated Radiation Therapy (IMRT) technique is that the absorbed dose in healthy tissue is relatively high. Proton beam has characteristics that can compensate for these drawbacks. The Bragg peak characteristic of a proton beam allows the administration of high radiation doses to the target organ only. Non-Small Cell Lung Cancer (NSCLC) cases are located in the vicinity of many vital organs, so radiation doses that exceed a certain limit will have a significant impact on these organs. Proton is a heavy particle that exhibits interaction patterns with tissue heterogeneity that differ from that of photon. This study aims to determine the distribution of proton beam planning doses in the NSCLC cases with the Intensity Modulated Proton Therapy (IMPT) technique and compare its effectiveness with the IMRT technique. Treatment planning was done by using TPS Eclipse on the water phantom and on the in-house thorax dynamic phantom. The water phantom planning parameters used are one field at 0° and three fields at 45°, 135°, and 225°. In this study, a single, sum, and multiple field techniques on the in-house thorax dynamic phantom were used. The evaluation was performed by calculating Conformity Index (CI), Homogeneity Index (HI), and Gradient Index (GI) parameters for each treatment planning. As a result, a bit of difference in the CI the HI values are shown between IMPT and IMRT planning. The GI values of IMPT planning are in the range between 4.15-4.53, while the GI value of IMRT is 7.89. The histogram results of the planar dose distribution show that the IMPT treatment planning provides fewer off-target organ doses than the IMRT planning. Evaluation was also carried out on the    IMPT treatment planning of target organs in five areas of interest and four OAR positions. The evaluation results were then compared with the IMRT measurement data. As a result, the value of the point doses at the target organ      did not differ significantly. However, the absorbed dose with the IMPT technique at four OAR positions is nearly zero, which had a large difference compared to the IMRT technique

Pengaruh Ketidakhomogenan Medium Pada Radioterapi

Telah dilakukan pengukuran Percentage Depth Dose (PDD) pada medium homogen dan nonhomogen dengan menggunakan bilik ionisasi plan paralel Markus. Phantom homogen dibuat dari susunan lapisan akrilik setebal 30 cm, dan phantom nonhomogen dibuat dengan menyisipkan lapisan gabus ekivalen paru-paru setebal 4 cm yang dimasukkan ke dalam susunan akrilik. Penyinaran dilakukan dengan sinar-X 6 MV dan 10 MV yang diproduksi oleh LINAC Varian 2100C. Perbedaan prosentase dosis kedalaman (PDD) pada medium homogen dan nonhomogen rata-rata sebesar 4,3% pada sinar-X 6 MV dan 3,7% pada sinar-X 10 MV. Pemberian gabus pada akrilik mengakibatkan peningkatan dosis sampai 11,7% pada sinar-X 6 MV dan 10,2% pada sinar-X 10 MV. Faktor koreksi yang dihasilkan sebagai akibat adanya material ekivalen paru-paru/gabus mencapai 1,19 pada sinar-X 6 MV dan 1,15 pada sinar-X 10 MV

Perbandingan Verifikasi Akurasi Posisi Pasien Radioterapi Secara Manual Dan Semiotomatis Berbasis Citra DRR/EPID

Radiotherapy is one of common treatment modality for Nasopharyngeal Cancer. The development of intensity modulated radiotherapy (IMRT technique) gives satisfactory results in the nasopharyngeal cancer treatment, both clinically and dosimetry. IMRT can reduce the effects of acute and chronic, with a maximum dose coverage to the tumor and minimal dose to the organ or normal tissue surrounding target value. The purpose of this study is to compare theaccuracy of patient positioning verification of Nasopharyngeal Cancer IMRT with DRR / EPID image registration. Retrospective data analysis of the AP and Lateral projections DRR and EPID images 35 patients (140 images) were then manually verified by simulative applied fusion semiautomatic with FIJI program. FIJI program improved the image quality of the DRR and EPID to facilitate the image registration. Results of this study shows no statistically significantdifference between the manual verification and semiautomatic fusion method of nasopharyngeal cancer patients, but there is a tendency that the semiautomatic method with FIJI program provides verification geometry radiotherapy better a result than manual methods

Verifikasi Dosimetri Teknik Stereotactic Body Radiotherapy (SBRT) Metastasis Tulang: Studi Kasus Menggunakan Fantom Homogen dan Inhomogen

Kanker menyebabkan 13% dari total semua kasus penyebab kematian, dan matastasis tulang adalah komplikasi umum dari kanker yang terjadi diatas 40% pada pasien onkologi. Sekitar 70% metastasis akan melibatkan tulang belakang. Stereotactic body radiotherapy (SBRT) adalah salah satu teknik yang dapat menangani metastasis tulang karena dapat memberikan dosis radiasi tinggi pada volume kecil dengan margin yang sangat rapat. Dalam perencanaan radioterapi untuk foton energi tinggi sering tidak sesuai dalam memperkirakan distribusi dosis dengan keberadaan material tidak homogen. Oleh karena itu dibandingkan hasil dosis pada fantom homogen (CIRS Model 002 H9K) dengan fantom inhomogen (CIRS Model 002 LFC) menggunakan tiga dosimeter, yaitu mikrochamber exradin A16, film gafchromic EBT3, dan TLD LiF: Mg, Ti rods. Hasil yang didapatkan dari pengukuran kedua fantom membuktikan bahwa film gafchromic EBT3 merupakan dosimeter terbaik dalam pengukuran dosis pada lapangan kecil dengan masing-masing deskripansi -0,30% pada fantom homogen dan -1,57% pada fantom inhomogen. Mikrochamber juga memperlihatkan kemampuannya dengan mendapatkan deskripansi tidak begitu jauh dengan film gafchromic EBT3 yaitu -0,52% pada fantom homogen dan -3,87% pada fantom inhomogen. Sedangkan menggunakan TLD LiF:Mg, Ti rods masing-masing deskripansinya -11,96% dan -13,88% pada fantom homogen dan inhomogen

Dose Evaluation of Head and Neck Cancer IMRT Treatment Planning Based on Gamma Index Analysis of Varian Halcyon 2.0 Linac

Varian Halcyon 2.0 linear accelerator was launched and became available for clinical use in 2018. Therefore, it is necessary to evaluate the accuracy of exit fluence of the Halcyon 2.0 for quality assurance (QA) of head and neck cancer treatment planning, pretreatment, and treatment. The accuracy of the exit fluence for twenty treatment plannings has been evaluated by conducting gamma analysis for QA pretreatment and treatment in each field and composite field by using criteria for gamma index 3 %/3 mm and 2 %/2 mm. The QA pretreatment results are in the average value for each criterion for each field and composite fields on actual gantry angle and null gantry angle with gamma passing rate (GPR) of over 99 % (range 99.78 %-99.95 %) The total treatments consisted of 2717 fractions. The analysis results of GPR for fields were 99.32 % and 97.74 % for gamma indexes of 3 %/3 mm and 2 %/2 mm, respectively. In addition, the analysis results of GPR for composites were 95.46 % and 81.38 % for gamma indexes of 3 %/3 mm and 2 %/2 mm, respectively. Based on this result, the average GPRs of QA pretreatment are ≈ 99 % of the total pixels. This means the prediction dose of Varian Halcyon 2.0 is accurate. The average GPRs of treatment is nearly  90 %, showing that Varian Halcyon 2.0 is effective for creating treatment plans for complex cases

Brief histories of medical physics in Asia-Oceania

The history of medical physics in Asia-Oceania goes back to the late nineteenth century when X-ray imaging was introduced, although medical physicists were not appointed until much later. Medical physics developed very quickly in some countries, but in others the socio-economic situation as such prevented it being established for many years. In others, the political situation and war has impeded its development. In many countries their medical physics history has not been well recorded and there is a danger that it will be lost to future generations. In this paper, brief histories of the development of medical physics in most countries in Asia-Oceania are presented by a large number of authors to serve as a record. The histories are necessarily brief; otherwise the paper would quickly turn into a book of hundreds of pages. The emphasis in each history as recorded here varies as the focus and culture of the countries as well as the length of their histories varies considerably

Brief histories of medical physics in Asia-Oceania

The history of medical physics in Asia-Oceania goes back to the late nineteenth century when X-ray imaging was introduced, although medical physicists were not appointed until much later. Medical physics developed very quickly in some countries, but in others the socio-economic situation as such prevented it being established for many years. In others, the political situation and war has impeded its development. In many countries their medical physics history has not been well recorded and there is a danger that it will be lost to future generations. In this paper, brief histories of the development of medical physics in most countries in Asia-Oceania are presented by a large number of authors to serve as a record. The histories are necessarily brief; otherwise the paper would quickly turn into a book of hundreds of pages. The emphasis in each history as recorded here varies as the focus and culture of the countries as well as the length of their histories varies considerably