• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.252-254
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• 2002

A new protocol for dosimetry in external beam radiotherapy is published by the Japan Society of Medical Physics (JSMP) in 2002. The protocol deals with proton and heavy ion beams as well as photon and electron beams, in accordance with IAEA Technical Report Series No. 398. To establish inter-institutional uniformity in proton beam dosimetry, an intercomparison program was carried out with the new protocol. The absorbed doses are measured with different cylindrical ionization chambers in a water phantom at a position of 30-mm residual range for a proton beam, that had range of 155 mm and a spread out Bragg peak (SOBP) of 60-mm width. As a result, the intercomparison showed that the use of the new protocol would improve the +/- 1.0 % (one standard deviation) and 2.7 % (maximum discrepancy) differences in absorbed doses stated by the participating institutions to +/- 0.3% and 0.9 %, respectively. The new protocol will be adopted by all of the participants.

• Progress in Medical Physics
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• v.29 no.4
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• pp.164-172
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• 2018

We evaluated the performance of various detectors for small-field dosimetry with field sizes defined by a high-definition (HD) multileaf collimator (MLC) system. For small-field dosimetry, diodes referred to as "RAZOR detectors," MOSFET detectors, and Gafchromic EBT3 films were used in this study. For field sizes less than $1{\times}1cm^2$, percent depth doses (PDDs) and lateral profiles were measured by diodes, MOSFET detectors, and films, and absolute dosimetry measurements were conducted with MOSFET detectors. For comparison purposes, the same measurements were carried out with a field size of $10{\times}10cm^2$. The dose distributions were calculated by the treatment planning system Eclipse. A comparison of the measurements with calculations yielded the percentage differences. With field sizes less than $1{\times}1cm^2$, it was shown that most of the percentage difference values were within 5% for 6-MV and 15-MV photon beams with the use of diodes. The measured lateral profiles were well matched with those calculated by Eclipse as the field sizes increased. Except for the depths of 0.5 cm and 20 cm, there was agreement in terms of the absolute dosimetry within 10% when MOSFET detectors were used. There was good agreement between the calculations and measurements conducted using diodes and EBT films. Both diode detectors and EBT3 films were found to be appropriate options for relative measurements of PDDs and for lateral profiles.

• Journal of Yeungnam Medical Science
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• v.39 no.2
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• pp.108-115
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• 2022

Background: This study was aimed at comparing and analyzing the results of FractionLab (Varian/Mobius Medical System) with those of portal dosimetry that uses an electronic portal imaging device. Portal dosimetry is extensively used for patient-specific quality assurance (QA) in intensity-modulated radiotherapy (IMRT). Methods: The study includes 29 patients who underwent IMRT on a Novalis-Tx linear accelerator (Varian Medical System and Brain-LAB) between June 2019 and March 2021. We analyzed the multileaf collimator DynaLog files generated after portal dosimetry to evaluate the same condition using FractionLab. The results of the recently launched FractionLab at various gamma indices (0.1%/0.1 mm-1%/1 mm) are analyzed and compared with those of portal dosimetry (3%/3 mm). Results: The average gamma passing rates of portal dosimetry (3%/3 mm) and FractionLab are 98.1% (95.5%-100%) and 97.5% (92.3%-99.7%) at 0.6%/0.6 mm, respectively. The results of portal dosimetry (3%/3 mm) are statistically comparable with the QA results of FractionLab (0.6%/0.6 mm-0.9%/0.9 mm). Conclusion: This paper presents the clinical performance of FractionLab by the comparison of the QA results of FractionLab using portal dosimetry with various gamma indexes when performing patient-specific QA in IMRT treatment. Further, the appropriate gamma index when performing patient-specific QA with FractionLab is provided.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.17-18
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• 2002

Last year, a three-year research program was started in order to establish an external audit system to radiotherapy QA in Japan. It consists of questionnaire surveys, mailed (off-site) dosimetry and visited (on-site) dosimetry at radiotherapy facilities in Japan. The first questionnaire was sent to all Japanese radiotherapy facilities in October 2001, surveying basic QA procedures at each facility. 628 answers were returned with the return rate of 87%. In February 2002, the second questionnaire was sent. Off-site and on-site dosimetry have been tested in several facilities, and will be started soon. We anticipates that this program will gradually grow to a radiotherapy quality control center similar to Radiological Physics Center at MD Anderson Hospital.

• Nuclear Engineering and Technology
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• v.55 no.4
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• pp.1265-1268
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• 2023

One important issue in using radiopharmaceuticals as therapeutic and imaging agents is predicting different organ absorbed dose following their injection. The present study aims at extrapolating dosimetry estimates to a female phantom from the animal data of ⁸⁹Zr radionuclide accumulation using the Sparks-Idogan relationship. The absorbed dose of ⁸⁹Zr radionuclide in different organs of the human body was calculated based on its distribution data in mice using both MIRD method and the MCNP simulation code. In this study, breasts, liver, heart wall, stomach, kidneys, lungs and spleen were considered as source and target organs. The highest and the lowest absorbed doses were respectively delivered to the liver (4.00E-02 and 3.43E-02 mGy/MBq) and the stomach (1.83E-03 and 1.66E-03 mGy/MBq). Moreover, there was a good agreement between the results obtained from both MIRD and MCNP methods. Therefore, according to the dosimetry results, [⁸⁹Zr] DFO-CR011-PET/CT seems to be a suitable for diagnostic imaging of the breast anomalies for CDX-011 targeting gpNMB in patients with TNBC in the future.

• Progress in Medical Physics
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• v.31 no.4
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• pp.145-152
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• 2020

Purpose: In ionization-chamber dosimetry for high-dose-rate electron beams-above 20 mGy/pulse-the ion-recombination correction methods recommended by the International Atomic Energy Agency (IAEA) and the American Association of Physicists in Medicine (AAPM) are not appropriate, because they overestimate the correction factor. In this study, we suggest a practical ion-recombination correction method, based on Boag's improved model, and apply it to reference dosimetry for electron beams of about 100 mGy/pulse generated from an electron linear accelerator (LINAC). Methods: This study employed a theoretical model of the ion-collection efficiency developed by Boag and physical parameters used by Laitano et al. We recalculated the ion-recombination correction factors using two-voltage analysis and obtained an empirical fitting formula to represent the results. Next, we compared the calculated correction factors with published results for the same calculation conditions. Additionally, we performed dosimetry for electron beams from a 6 MeV electron LINAC using an Advanced Markus^® ionization chamber to determine the reference dose in water at the source-to-surface distance (SSD)=100 cm, using the correction factors obtained in this study. Results: The values of the correction factors obtained in this work are in good agreement with the published data. The measured dose-per-pulse for electron beams at the depth of maximum dose for SSD=100 cm was 115 mGy/pulse, with a standard uncertainty of 2.4%. In contrast, the k_s values determined using the IAEA and AAPM methods are, respectively, 8.9% and 8.2% higher than our results. Conclusions: The new method based on Boag's improved model provides a practical method of determining the ion-recombination correction factors for high dose-per-pulse radiation beams up to about 120 mGy/pulse. This method can be applied to electron beams with even higher dose-per-pulse, subject to independent verification.

• Radiation Oncology Journal
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• v.12 no.2
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• pp.219-223
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• 1994

This paper describes the basic data measurements for total body irradiation with 6 Mv photon beam including compensators design. The technique uses bilateral opposing fields with tissue compensators for the head, neck, lungs, and legs from the hip to toes. In vivo dosimetry was carried out for determining absorbed dose at various regions in 7 patients using diode detectors(MULTIDOSE,k Model 9310, MULTIDATA Co., USA). As a results, the dose uniformity of${\pm}3.5{\%}$(generally, within${\pm}10{\%}$can be achieved with out total body irradiation technique.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2006.08a
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• pp.127-127
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• 2006

• Progress in Medical Physics
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• v.6 no.2
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• pp.35-40
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• 1995

Purpose: We have developed new film dosimetry algorithm for personal dosimetry and examined its characteristics. Materials and methods: Agfagaevart personal monitoring 2/10 films are used. Films which are in the film badges filtered with Cu 0.3mm, plastic 1.5mm, Aluminum 0.6mm and tin 0.8mm, were exposed by standard dosimetry laboratory. Irradiated energy categories are ANSI N13.1l Category III, and IV. Manual type film precessor and X-rite film densitometor was used. Filtered densities to energy relations and does to transformed densities relations can be obtained ofter transformation of H＆D curves to linear shape by polynomal fitting. Reults : Personal dose be determined within 25％ error for category m and 15％ for category IV. And we are able to evaluate the exposed energy. Conclusion : New algorithm developed in this study is good for personal dosimetry within 30％ error range for catergory III and IV. It is expectd to be complete personal dosimetry algorithm with further study for categrory, I, Dand II V.

• The Journal of Korean Society for Radiation Therapy
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• v.27 no.2
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• pp.167-174
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• 2015

Purpose : The pre-treatment QA using Portal dosimetry for Volumetric Arc Therapy To analyze whether maintaining the reproducibility depending on various factors. Materials and Methods : Test was used for TrueBeam STx$^{TM}$ (Ver.1.5, Varian, USA). Varian Eclipse Treatment planning system(TPS) was used for planning with total of seven patients include head and neck cancer, lung cancer, prostate cancer, and cervical cancer was established for a Portal dosimetry QA plan. In order to measure these plans, Portal Dosimetry application (Ver.10) (Varian) and Portal Vision aS1000 Imager was used. Each Points of QA was determined by dividing, before and after morning treatment, and the after afternoon treatment ended (after 4 hours). Calibration of EPID(Dark field correction, Flood field correction, Dose normalization) was implemented before Every QA measure points. MLC initialize was implemented after each QA points and QA was retried. Also before QA measurements, Beam Ouput at the each of QA points was measured using the Water Phantom and Ionization chamber(IBA dosimetry, Germany). Results : The mean values of the Gamma pass rate(GPR, 3%, 3mm) for every patients between morning, afternoon and evening was 97.3%, 96.1%, 95.4% and the patient's showing maximum difference was 95.7%, 94.2% 93.7%. The mean value of GPR before and after EPID calibration were 95.94%, 96.01%. The mean value of Beam Output were 100.45%, 100.46%, 100.59% at each QA points. The mean value of GPR before and after MLC initialization were 95.83%, 96.40%. Conclusion : Maintain the reproducibility of the Portal Dosimetry as a VMAT QA tool required management of the various factors that can affect the dosimetry.