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All Journal Journal of Medical Physics and Biophysics Journal of Mathematical and Fundamental Sciences Journal of Physics: Theories and Applications YARSI Medical Journal PROSIDING SEMINAR NASIONAL FISIKA (E-JOURNAL) Indonesian Journal of Physics (IJP)
Rena Widita
Institut Teknologi Bandung
Astronomy Chemistry Computer Science & IT Earth & Planetary Sciences Education Electrical & Electronics Engineering Energy Engineering Materials Science & Nanotechnology Mathematics Medicine & Pharmacology Physics Other

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 1 
Comparison between Image Correlation and Projection Correlation in CT Image Reconstruction with Limited Data Widita, Rena
Jurnal Kedokteran YARSI Vol 17, No 2 (2009): MEI - AGUSTUS 2009
Publisher : Lembaga Penelitian Universitas YARSI

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (350.198 KB) | DOI: 10.33476/jky.v17i2.204

Abstract

Since the improvement in radiotherapy impacts on cancers at their most curable stages, radiotherapy-related research has a high strategic priority and a great capacity for improving the overall cure rates of the disease. However, some of the treatments involve the delivery of relatively high radiation dose to patients. Thus, it is important to be able to verify the success of the treatment by determining the dose deposited in the patient at each fraction. One possibility to achieve this would be to obtain an image while the patient is on the treatment couch. The aim of this study was to develop an image reconstruction algorithm by collecting limited information while the patient is on the treatment couch. Two methods, image correlation and projection correlation, were developed and compared here. The effectiveness and practicality of each of these methods were compared. The results showed that the projection correlation presents several advantages. It can be applied without any interations, and it produces a fast algorithm. With more advanced image reconstruction software, this method could potentially be used in a clinical environment.
Dose Volume Product (DVP) As Descriptor for Estimating Total Energy Imparted to Patient Undergoing CT Examination Choirul Anam; Freddy Haryanto; Rena Widita; Idam Arif; Geoff Dougherty
Journal of Medical Physics and Biophysics Vol 3, No 1 (2016)
Publisher : Indonesian Association of Physicists in Medicine (AIPM/AFISMI)

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (545.031 KB)

Abstract

The purpose of this study is to expand a descriptor for estimating the total energy imparted to a patient undergoing a CT examination and to investigate its relationship to the currently used descriptor. Estimating the total energy imparted to a patient has previously been characterized by dose length product (DLP). We propose a descriptor which we call the dose volume product (DVP), defined as the product of the size specific-dose estimate (SSDE) and the volume irradiated in the patient (V). We also present algorithm to automate the calculation of DVP. There are several steps in calculating the DVP: the first is to contour the patient automatically, the second is to calculate the area of patient in every single slice, the third is to calculate the volume of the radiated part of the patient, the fourth is to calculate the water equivalent diameter (DW) automatically, the fifth is to calculate the SSDE, and the last is to calculate the DVP. To investigate the effectiveness of the algorithm, we used it on images of phantoms and patients. The results of this study show that the automated calculations of DVP for both body and head phantoms were in good agreement with theoretical calculations. The differences between them were within 2%. DVP and DLP had a linear relationship with R2 = 0.971 (slope 1099 cm2, 95% confidence interval (CI), 1047 to 1157 cm2) and R2 = 0.831 (slope 248.6 cm2: CI, 237.6 to 259.7 cm2), for thorax and head patients respectively.
Scatter index measurement using a CT dose profiler Choirul Anam; Freddy Haryanto; Rena Widita; Idam Arif; Toshioh Fujibuchi; Takatoshi Toyoda; Geoff Dougherty
Journal of Medical Physics and Biophysics Vol 4, No 1 (2017)
Publisher : Indonesian Association of Physicists in Medicine (AIPM/AFISMI)

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (626.874 KB)

Abstract

The CT dose index (CTDI) is usually measured using a pencil chamber with a length of 100 mm on a CTDI phantom with a length of 150 mm. The scattering radiation dose beyond 100 mm is usually still significant despite using a small beam width (below 10 mm). This study aims to measure the scattering index of CT dose for several variations of input parameters. The scatter index measurements were performed on a multi-slice CT (MSCT) Alexion™ using a CT dose profiler detector connected to a Black Piranha electrometer (RTI Electronic, Sweden). The measurements used the helical mode and a beam width of 2 x 4 mm, and resulted in 150 mm dose profiles. Values of CTDI150, CTDI130 and CTDI100 were calculated and used to obtain values of the scatter indices (SI130 and SI150). We varied input parameters, such as tube voltage, tube current, and pitch, and used two types of CTDI phantoms, i.e. body and head. In the tube voltage variation (from 80 to 135 kV), we found SI130 and SI150 values of 1.13 ± 0.01 and 1.19 ± 0.01 for the body CTDI phantom; and  SI130 and SI150 values of 1.08 ± 0.01 and 1.11 ± 0.01 for the head CTDI phantom. For tube current variations from 25 to 120 mA, and pitch variations from 0.75 to 1.5, SI130 and SI150 values were 1.14 ± 0.00 and 1.20 ± 0.00 for the body CTDI phantom; and 1.08 ± 0.00 and 1.11 ± 0.00 respectively for the head CTDI phantom. We showed that the more frequently used CTDI100 value is too small because it ignores scattering beyond the 100 mm boundary, even for beam widths less than 10 mm. The scatter index values were strongly influenced by the size of the CTDI phantom, and were slightly affected by the tube voltage. Variations in tube currents and pitch did not affect the value of the scatter index. The scatter index values of SI130 and SI150 were significantly different, and suggests that the use of SI150 is even more appropriate for describing the scattering dose.
Beam Positions Optimization to Achieve Improved CT Images with Limited Data Rena Widita
Journal of Mathematical and Fundamental Sciences Vol. 38 No. 2 (2006)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2006.38.2.4

Abstract

 In radiotherapy planning, margins are used to account for the uncertainties due to internal organ and patient motion as well as set-up error. Improvement in radiotherapy treatments may be achieved by reducing the set-up uncertainty and thus treatment margins allowing a higher dose to be delivered to the target volume. It is important to be able to verify the success of the treatment by determining the position of patient and the dose deposited in the patient at each fraction. One possibility for achieving this would be to collect limited information while the patient is on the treatment couch. The aim of this study is to develop a method for determining intelligent angles to use to reconstruct an image for dose verification.A method optimizing the angles based on an objective function is required. The methods developed here are based on image correlation and projection correlation that have been investigated previously. Two optimization methods, deterministic and stochastic (simulated annealing), were also assessed. The effectiveness and practicality of each of these combinations were compared.
PENGUKURAN WAKTU PARUH EFEKTIF I-131 PADA KANKER TIROID Yuanita Puspita Dewi Sudarso; Rena Widita; Rini Shintawati
PROSIDING SEMINAR NASIONAL FISIKA (E-JOURNAL) Vol 10 (2022): PROSIDING SEMINAR NASIONAL FISIKA (E-JOURNAL) SNF2021
Publisher : Program Studi Pendidikan Fisika dan Program Studi Fisika Universitas Negeri Jakarta, LPPM Universitas Negeri Jakarta, HFI Jakarta, HFI

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (216.572 KB) | DOI: 10.21009/03.SNF2022.01.FA.01

Abstract

Abstrak Iodin 131 digunakan dalam proses terapi dan diagnosis pada pasien penderita kanker tiroid yang menyebabkan adanya paparan radiasi yang diberikan oleh pasien kepada lingkungannya, sehingga pasien terapi I-131 akan diisolasi selama beberapa hari hingga laju paparan dari tubuhnya berkurang hingga mencapai batas yang ditetapkan. Berkurangnya laju paparan setiap pasien berbeda-beda yang menyebabkan waktu pulang dan penanganan selanjutnya untuk tiap pasien berbeda-beda. Penentuan lama pasien diisolasi dapat diperkirakan dengan waktu paruh efektif Iodin 131. Pengukuran waktu paruh efektif I-131 dilakukan dengan mengukur laju paparan tubuh pasien disertai dengan pengukuran laju paparan urin pasien menggunakan alat surveimeter 2 jam setelah pemberian Iodin 131 dan dilanjutkan setiap 12 jam selama 3 hari. Laju paparan tubuh digunakan untuk mengetahui waktu paruh efektif dan laju paparan urin pasien digunakan untuk mengetahui waktu washing out pasien. Dari penelitian diketahui bahwa semakin besar dosis yang diberikan pada pasien maka waktu paruh efektifnya semakin cepat dan begitu pula dengan waktu washing outnya. Kata-kata kunci: I-131, Kanker Tiroid, Waktu Paruh Efektif. Abstract Thyroid cancer patient usually undergoes Iodine 131 therapy. By giving I-131, there might be an exposure from patient’s body to the environment, to prevent the exposure to healthy people; usually patient will be isolated in hospital for a few days until the exposure rate from their body reduced and safe for their environment. Decreasing time of exposure rate might be different for each person and will affect their discharge time and/or treatment time. To determine the exact discharge time of the patient, effective half-life of I-131 become important. Effective half-life of I-131 is determined by measuring exposure rate of body and urine from the patient. Exposure rate of the body of the patient were taken 2 hours after dose administration and every 12 hours on the next day in 3 days using survey meter for 1 minute. Exposure rate of the urine of the patient is used for obtaining the washing out time. From this research, it found that the greater dose given to the patient, the faster the effective half-life and the washing out time. Keywords: I-131, Effective Half-life, Thyroid Cancer.
A Method for Beam Positions Determination in Image Reconstruction Rena Widita
Indonesian Journal of Physics Vol 17 No 3 (2006): Vol. 17 No. 3, July 2006
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (641.986 KB)

Abstract

From one treatment to the next, considerable effort is made to accurately position the patient consistent with the plan, but some variation is unavoidable. The target volume and the organ at risks may move within the patient and/or change shape during the treatment. Thus, it is important to be able to verify the success of the treatment by determining the position of patient and the dose deposited in the patient at each fraction. One possibility to achieve this would be to obtain an image while the patient is on the treatment couch. The aim of this study was to develop a method for determining beam positions to use to reconstruct an image for dose verification by collecting limited information while the patient is on the treatment couch. Two methods, image correlation and projection correlation, were developed and compared here. The effectiveness and practicality of each of these methods were compared. The results show that the projection correlation presents several advantages. It can be applied without any iterations, and it produces a fast algorithm. With more advanced image reconstruction software, this method could potentially be used in a clinical environment.
Projection Correlation Optimization using Simulated Annealing in CT Image Reconstruction Rena Widita
Indonesian Journal of Physics Vol 17 No 4 (2006): Vol. 17 No. 4, October 2006
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (372.574 KB)

Abstract

Image reconstruction without analytical continuation is possible if and only if all projections cover entire object. In medical CT (Computed Tomography) applications, this condition is clearly not achievable. The new algorithm for image reconstruction using a few beam positions (projection correlation method) has been proved offer several advantages. . One drawback of using a few beam positions is a low quality image yielded. Thus, an objective function to rank the image quality is required to automate the decision process in determining the optimum beam positions. In this work, two optimization methods, gradient-descent method and simulated annealing, using projection correlation value as the objective function, were developed and compared to obtain the optimum beam positions. The effectiveness and practicality of each of these methods were compared. The results show that the simulated annealing presents superior results. This method could potentially be used in a clinical environment.
Analysis of the Effect of Tube Current, Slice Thickness, and Tube Voltage on Ct Scan Image Noise using the Noise Power Spectrum (NPS) Method Kirei, Anggita Ananda; Widita, Rena
Indonesian Journal of Physics Vol 34 No 2 (2023): vol 34 no 2 2023
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itb.ijp.2023.34.2.3

Abstract

This study was conducted to analyze CT scan images in order to determine the effect of tube current, slice thickness, and tube voltage on noise using the Noise Power Spectrum (NPS) method. Moreover, this study was also aimed to identify the optimal range of tube current, slice thickness, and tube voltage values to minimize noise formation in CT scan images while maintaining the safe dose for the patients. The research parameters included variations in tube current values with slice thickness variations, using tube voltages of 80 kV and 120 kV. The tube current (mAs) variations used were 150 mAs, 200 mAs, 250 mAs, 300 mAs, and 350 mAs, while the slice thickness variations were 0.8 mm, 1.6 mm, 3.2 mm, 4.8 mm, and 9.6 mm. A Phillips 16-slice access CT scan with a water phantom was utilized as the material for the research. The obtained image data were analyzed using ImQuest and ImageJ software. The results show that as the variations in tube current (mAs), slice thickness (mm), and tube voltage (mV) increase, the noise values decrease. This was demonstrated by the smallest area under the curve (AUC) values, which were 24.46 variance for the tube current variation at 120 kV and 3.57 variance for the slice thickness variation at 120 kV. Thus, to minimize the noise, it is recommended to increase the tube current, slice thickness, and tube voltage.
Determination of Fractionation Scheme Based on Repair Effect Using Equivalent Uniform Dose (EUD) Model Pratista, Tiara Andrina; Widita, Rena
Indonesian Journal of Physics Vol 34 No 2 (2023): vol 34 no 2 2023
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itb.ijp.2023.34.2.2

Abstract

Radiotherapy treatment planning is required to obtain an optimal balance between delivering a high dose to target volume and a low dose to organ at risks. In this planning, it is also necessary to determine the appropriate fractionation scheme for each patient. One of the commonly used methods to determine the fractionation scheme is calculating the Normal Tissue Complication Probability (NTCP) and Tumor Control Probability (TCP) parameters. In this study, the Equivalent Uniform Dose (EUD) model is used to calculate NTCP and TCP. This model is based on a non-uniform dose distribution that is sensitive to the biological factors of cells. The biological factor examined in this research is the repair effect, which is the ability of cells to repair themselves after being radiated. Thus, the objective of this research is to determine the fractionation scheme based on NTCP calculations using the EUD model while taking into account the repair effect. The data used in this study were obtained from 10 patients with glioblastoma brain cancer in the form of cumulative DVH (dose-volume histogram) and total time of radiation. Based on the NTCP calculations, the average risk of organ complication for each patient appears to be close to zero, with a range of values from 2 x 10-6% to 1 x 10-1%. These results indicate that the treatment planning conducted is proven to be safe and there are no complications for the patients. Furthermore, based on the NTCP and TCP calculations, the best fractionation scheme is hypofractionation, which remains safe while considering the dose limit for each normal organ surrounding the target.
The Effect of Volume Target on Quality of Radiotherapy using 3DCRT and IMRT: Dosimetry and Radiobiological Evaluation Lutfin, Nursakinah Annisa; Widita, Rena
Journal of Physics: Theories and Applications Vol 7, No 1 (2023): Journal of Physics: Theories and Applications
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/jphystheor-appl.v7i1.71608

Abstract

The main goal of radiotherapy is to deliver the maximum possible dose to the target volume and the minimum possible to the surrounding healthy tissue. In this study, planning was carried out on the TPS Eclipse Varian Medical System using 3DCRT and IMRT techniques for 14 cancer patients. 6 cases of lung cancer with PTV were in the range of 175.1 cc - 875.5 cc, and eight brain cancer patients with a PTV range of 148.5 cc - 841.2 cc. This study aims to determine the effect of target volume on the quality of radiation therapy planning using the 3DCRT and IMRT techniques. The evaluation was carried out using dosimetry and radiobiology analysis. Dosimetry assessment analyzes the average dose, D98, D50, D2, CI, and HI on PTV and the average dose on OAR. Radiobiological evaluation by calculating the value of TCP, NTCP, and UTCP. The results showed that based on dosimetry and radiobiology evaluation, the IMRT technique provides better planning quality for radiation therapy by increasing the probability of cancer cells dying at PTV and reducing the risk of OAR compared to planning using the 3DCRT technique. The effect of PTV on planning quality using statistical regression tests showed that PTV did not significantly impact the quality of radiation therapy planning results either using the 3DCRT technique or the IMRT technique.
Co-Authors Choirul Anam AM Diponegoro Freddy Haryanto Freddy Haryanto Geoff Dougherty Geoff Dougherty Idam Arif Idam Arif Kirei, Anggita Ananda Nursakinah Annisa Lutfin Pratista, Tiara Andrina Rini Shintawati Takatoshi Toyoda Toshioh Fujibuchi Yuanita Puspita Dewi Sudarso