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All Journal Journal of Medical Physics and Biophysics Radioterapi & Onkologi Indonesia
Wahyu Edy Wibowo
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Point dose measurement on center and peripheral target for stereotactic treatment using Helical Tomotherapy Hi-Art Laras Ati Nur Fatimah; Nuruddin Nasution; Wahyu Edy Wibowo; Supriyanto Ardjo Pawiro
Journal of Medical Physics and Biophysics Vol 5, No 1 (2018)
Publisher : Indonesian Association of Physicists in Medicine (AIPM/AFISMI)

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (530.313 KB)

Abstract

Stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT) using tomotherapy were advanced radiotherapy technique with prescribing high dose on the peripheral target to get as steep as possible fall-off dose criteria on the target. These technique need an accurate and high precision treatment delivery also passing the criteria for patient specific quality assurance. Point dose measurement was a simple verification to ensure these goals. However, there are many issues for point dose measurement with ionisation chamber related to the problem of high dose gradient area on the peripheral target. Therefore, the purpose of this study was to verify the assessment criteria of ±3% discrepancies for center and peripheral target measurement. The work has been done by point dose verification for 11 patient with brain cancer using Helical Tomotherapy Hi-Art. Point dose measurement were done on the center and peripheral PTV, also brainstem for organ parameter in the off-axis area, using Exradin A1SL. The measurement results show that highest discrepancy compared to the dose plan for center and peripheral target reach 1.95% and 2.81%, respectively. The Higher discrepancies shows for peripheral target compared to the center target measurement. The measurement on the brainstem show a highest discrepancies reach 5.29%. This result occur because of the off-axis area of the brainstem location. In conclusion, the center and peripheral target measurement are meet the criteria ±3% by the dose plan with peripheral target measurement shows higher discrepancies influences by volume averaging effect and lack of particle equilibrium of the condition related to the chamber size.
Karakteristik berkas foton lapangan kecil setengah lapangan (half beam) dengan menggunakan wedge Elsa Angelina; Wahyu Edy Wibowo; Riana Dian Pertiwi; Supriyanto Ardjo Pawiro
Journal of Medical Physics and Biophysics Vol 5, No 1 (2018)
Publisher : Indonesian Association of Physicists in Medicine (AIPM/AFISMI)

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Penelitian ini bertujuan untuk mengetahui profil berkas foton lapangan kecil setengah lapangan (half beam) dengan menggunakan wedge yang dapat menjawab tantangan radioterapi tumor sino-nasal yang diketahui memiliki lokasi yang sangat kompleks. Pengukuran dilakukan dengan berkas foton 6MV menggunakan dosimeter film Gafchromic EBT3 yang dilakukan pada kedalaman 1.5 cm, 5 cm dan 10 cm untuk setiap lapangan penyinaran 0.8 × 0.8 cm2, 1.6 × 1.6 cm2, 2.4 × 2.4 cm2, 3.2 × 3.2 cm2 dan 4 × 4 cm2 dengan menggunakan physical wedge dengan besar sudut 15°, 30°, 45° dan 60° serta dilakukan variasi penyinaran yaitu daerah penyinaran wedge tipis dan tebal. Hasil pengukuran didapatkan bahwa nilai FWHM dan penumbra cenderung naik seiring dengan semakin dalamnya pengukuran. Selain itu, nilai FWHM cenderung lebih besar 1.59% saat daerah penyinaran wedge tipis. Penumbra memiliki rentang nilai 0.15 – 0.36 cm dengan anomali sebesar 80% (n=135) jika definisi penumbra merupakan jarak level isodosis 80% - 20% dan 0.24% (n=135) jika definisi penumbra merupakan jarak level isodosis 50% - 20%. Kesimpulannya, dari hasil pengukuran nilai deviasi FWHM dan penumbra (80% - 20%) terkecil masing-masing 0.92% dan 0.33 cm pada lapangan 0.8×0.8 cm2 wedge 60°, namun tidak ada hubungan yang pasti antara wedge dengan nilai FWHM dan penumbra pada lapangan kecil.
Lateral setup error analysis of dosimetric impact for nasopharynx carcinoma using intensity modulated radiotherapy treatment Syarifatul Ulya; Nuruddin Nasution; Wahyu Edy Wibowo; Supriyanto Ardjo Pawiro
Journal of Medical Physics and Biophysics Vol 5, No 1 (2018)
Publisher : Indonesian Association of Physicists in Medicine (AIPM/AFISMI)

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Abstract

Patients with nasopharyngeal carcinoma have been analyzed for lateral setup error. Systematic and randomized inter-fractional setup errors were evaluated in 48 patients with this case. Based on these errors, the margin was drawn from CTV to obtain the delineation of PTV structure, called PTV margin. MVCT system in tomotherapy has been used to get the number of error with four-degree direction setup. Moreover, the biggest error direction value was evaluated with in 6 patients and analyzed at D98 in each PTV and OARs. The result of PTV margin for the lateral, longitudinal, vertical, and rotation was 4.91 mm, 4.27 mm, 3.37 mm and 3.53 mm, respectively. According to the result of the PTV margin, a lateral direction showed the biggest value of error. So, achievable dose coverage of PTVs on the effect of the lateral shift were 87.04%, 60.19%, and 50% for 2, 4 and 6 mm, respectively. Furthermore, OAR dose in the right position is increasing with larger shift setup direction.
Perbandingan profil berkas wedge lapangan kecil foton 6 MV terhadap pengaruh jaw dan MLC sebagai pembentuk lapangan Riana Dian Pertiwi; Wahyu Edy Wibowo; Elsa Angelina; Supriyanto Ardjo Pawiro
Journal of Medical Physics and Biophysics Vol 5, No 1 (2018)
Publisher : Indonesian Association of Physicists in Medicine (AIPM/AFISMI)

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Abstract

Kanker sinonasal memiliki karakteristik yang unik berkaitan dengan anatomi yang berdekatan dengan OAR, sehingga memerlukan gradien dosis yang tinggi untuk melakukan treatment yang dapat diamati dengan melihat FWHM dan penumbra yang dihasilkan pada profil berkas pada lapangan wedge yang dihasilkan dengan menggunakan jaw dan MLC. Wedge yang digunakan merupakan physical wedge [L1] dengan sudut 15o, 30o, 45o, dan 60o  yang dilakukan di kedalaman 1.5 cm, 5 cm dan 10 cm pada lapangan 1 × 1 cm2, 2 × 2 cm2, 3 × 3 cm2 dan 4 × 4 cm2  dengan menggunakan film Gafchromic EBT3. Hasil menunjukkan nilai penumbra dan FWHM terbesar diperoleh dengan MLC sebagai pembentukan lapangan dan nilai terkecil dengan MLC (edge) sebagai pembentukan lapangan. Perbedaan hasil tersebut dikarenakan adanya perbedaan faktor transmisi jaw dan faktor transmisi MLC, dan adanya pengaruh dari kebocoran interleaf dan transmisi pada bagian tepi dari MLC. Penggunaan wedge pada profil berkas dapat mempengaruhi nilai FWHM dan penumbra yang dihasilkan sebagai akibat adanya efek beam hardening yang muncul dengan penggunaan physical wedge. Hasil studi ini menunjukkan pembentukan lapangan dengan menggunakan MLC (edge) merupakan pembentukan lapangan secara optimal, sedangkan penggunaan wedgedapat mempengaruhi nilai FWHM yang dihasilkan. [L1]Hindari kata berulang 
The lateral shift effect of gamma index evaluation on tomotherapy Yosi Sudarsi Asril; Nuruddin Nasution; Wahyu Edy Wibowo; Supriyanto Ardjo Pawiro
Journal of Medical Physics and Biophysics Vol 5, No 1 (2018)
Publisher : Indonesian Association of Physicists in Medicine (AIPM/AFISMI)

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Abstract

Fourteen patients with different cases have been planned and treated using helical Tomotherapy HI-ART system. To investigate the lateral shift effect on gamma index, the planning verification was evaluated for a point dose and a fluence dose measurement using ion chamber and Gafchromic EBT3 film, respectively. As a result, the difference between a measured and calculated point dose was under 3% for all interest organs, which account for 1.46±0.71% (parotid), 1.97±0.56% (pelvis and abdomen), 2.27±0.24% (brain), 1.56±0.51% (nasopharynx), and 1.43±1.3% (breast). In addition, Gamma index criteria used to evaluate fluence dose was 3mm (distance-to-agreement) and 3% (dose-difference) with 90% passed rate. Overall, the results, found in this study, shows that a lateral shift of the patient table resulted in an error beyond an acceptable tolerance if the table was shifted at more than 3mm. Gamma index criteria, then, is met if the lateral shift was within 3mm.
Dosimetric Parameter Analysis of Stereotactic Radiosurgery on Vestibular Schwannoma with Intensity-Modulated Radiotherapy Step-and-Shoot, Volumetric-Modulated Arc Therapy and Helical Tomotherapy Soehartati A. Gondhowiardjo; Aurika Sinambela; Handoko Handoko; Arie Munandar; Wahyu Edy Wibowo; Sri Mutya Sekarutami; Angela Giselvania
Radioterapi & Onkologi Indonesia Vol 12, No 2 (2021): VOLUME 12 NO.2 JULY 2021
Publisher : Perhimpunan Dokter Spesialis Onkologi Radiasi Indonesia (PORI)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32532/jori.v12i2.140

Abstract

Introduction: SRS is a non-invasive modality in management of vestibular schwannoma. There is limited study comparing dosimetric parameters between three techniques SRS in vestibular schwannoma cases, thus IMRT Step and Shoot (IMRT-SS), VMAT, and Helical Tomotherapy (HT). Aim: To compare the dosimetry parameters on SRS among IMRT-SS, VMAT, and HT techniques on Vestibular ScwhanomaMethod: Treatment planning with IMRT-SS, VMAT, and HT on eleven CT plan data for schwannoma vestibular cases. The marginal dose is 12 Gy with single fraction. Results: Mean tumor size was 8.23 cm + 5.08 cm3. No significant difference were found in the mean CI, GI, V100%, and V50% among three techniques. There was no significant difference in maximal dose to brainstem, ipsilateral cochlea, chiasma opticum, ipsilateral and contralateral optic nerve between the three techniques. There was significant difference of maximum dose on contralateral cochlea between IMRT-SS and VMAT techniques. The longest beam-on time was obtained with HT technique (1209,18 +390,20 second), followed by IMRT-SS technique (665,05 + 73,40 second), and the shortest was with VMAT technique (362,87 + 24,55 second). There was significant difference in mean MU and beam on time between three techniques. Conclusion: VMAT technique could be an option for SRS for vestibular schwannoma cases to provide conformity and gradient index as well as IMRT-SS and HT techniques, with better sparing to contralateral cochlea compared with IMRT-SS technique, and provides shorter beam-on time rather than IMRT-SS and HT.
Co-Authors Angela Giselvania Arie Munandar Aurika Sinambela Elsa Angelina Handoko Handoko Laras Ati Nur Fatimah Nuruddin Nasution Riana Dian Pertiwi Soehartati A. Gondhowiardjo Sri Mutya Sekarutami Supriyanto Ardjo Pawiro Syarifatul Ulya Yosi Sudarsi Asril