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The Existence of Symptomatic Localized Lesion(s) and ≤4 Lesions Are Indications for radiotherapy: Screening Computed Tomography Images of Patients with Metastatic/Recurrent/Inoperable Cancer in a Single Japanese Institution Observational Study

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International Journal of Medical physics, clinical Engineering and Radiation oncology 2016年第1期5卷 110-119页

作者： Shinsaku Yamaguchi Yuichi Matsuki Shinji Yotsumoto Hiroaki Satou Michiko Watanabe Sachie Yotsumoto department of Radiology Kitakyushu General Hospital Kitakyushu Japan department of Forensic Medicine School of Medicine University of Occupational and En-vironmental Health Kitakyushu Japan

Background: To investigate the prevalence of indications for radiotherapy (RT) in patients with metastatic/recurrent/inoperable cancer. We also sought to analyze such patients’ clinical and radiological characteristics for indications of radiotherapy in those patients who had either surveillance or an initial assessment done by computed tomography (CT). Methods: Two diagnostic radiologists and a radiation oncologist evaluated a total of 13,225 consecutive patients from January 2012 to December 2012 at a single Japanese institution. Patients with metastatic/recurrent/ inoperable cancer were selected for further study. After two diagnostic radiologists identified patients with a detectable cancerous lesion, a radiation oncologist subsequently investigated whether there was any indication for RT. The oncologist also evaluated the relationship between patients’ clinical/radiological factors, and patients with or without indications for RT. Results: Two diagnostic radiologists selected 329 patients showing a detectable gross cancerous lesion. In this patient group, a radiation oncologist identified 196 patients with metastatic/recurrent/inoperable cancer, of which 96 patients (49%) showed an indication for RT. According to both univariate and multivariate analyses, ≤4 lesions were significantly associated with patients who showed an indication for RT (P = 0.0002 and P 0.001, respectively). Conclusions: In screening CT images, approximately half of all patients with metastatic/recurrent/inoperable cancer showed an indication for RT. Moreover, ≤4 lesions and/or the existence of a symptomatic, localized lesion were highly suggestive of an indication for RT. These findings would be of considerable interest to radiation oncologists planning appropriate treatments for cancer patients.

关键词： Surveillance CT Radiation Oncologist Indication for radiotherapy

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Predicting Delivery Error Using a DICOM-RT Plan for Volumetric Modulated Arc Therapy

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International Journal of Medical physics, clinical Engineering and Radiation oncology 2014年第2期3卷 82-87页

作者： Hideharu Miura Masao Tanooka Masayuki Fujiwara Yasuhiro Takada Hiroshi Doi Soichi Odawara Kengo Kosaka Norihiko Kamikonya Shozo Hirota department of Radiological Technology Hyogo College of Medicine College Hospital Hyogo Mukogawa-cho Nishinomiya City Hyogo Japan department of Radiology Hyogo College of Medicine 1-1 Mukogawa-cho Nishinomiya City Hyogo Japan

The purpose of this study was to investigate the prediction of mechanical error using DICOM-RT plan parameters for volumetric modulated arc therapy (VMAT). We created plans for gantry rotation arcs of 360° and 180° (full-arc and half-arc VMAT) for six maxillary sinus cancer cases using a Monaco treatment planning system, and delivered the doses with a linear accelerator. We calculated DICOM-RT plan parameters, including gantry, multileaf collimator (MLC) positions and Monitor Units (MU). We compared plans with regard to gantry angle per MU (degrees/MU) and MLC travel per MU (mm/MU) for each segment. Calculated gantry angle/MLC position speeds and errors were evaluated by comparison with the log file. On average, the half-arc VMAT plan resulted in 47% and 35% fewer degrees/MU and mm/MU than the full-arc VMAT plan, respectively. The root mean square (r.m.s.) gantry and MLC speeds showed a linear relationship with calculated degrees/MU and mm/MU, with coefficients of determination (R2) of 0.86 and 0.72, respectively. The r.m.s. gantry angle and MLC position errors showed a linear relationship with calculated degrees/MU and mm/MU with R2 of 0.63 and 0.76, respectively. Deviations from plan parameters were related to mechanical error for VMAT, and provided quantitative information without the need for VMAT delivery. These parameters can be used in the selection of treatment planning.

关键词： Volumetric-Modulated Arc Therapy DICOM-RT Plan Patient-Specific QA radiotherapy Planning Computer-Assisted

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A Post-Mastectomy Radiation Therapy Dose Distribution Study

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International Journal of Medical physics, clinical Engineering and Radiation oncology 2017年第4期6卷 457-467页

作者： Xin Qian Kalpana Vaidya Lindsay Puckett Ferney Diaz Xiaoli Tang Lucille Lee Eric Klein department of Radiation Medicine Northwell Health New York NY USA MSKCC New York NY USA

Purpose: For post-mastectomy radiation therapy, skin dose must be accurately estimated to assess skin reactions, such as: erythema, desquamation, and necrosis. Even with advanced algorithms, planning systems do not always provide accurate dosimetry for target volumes distal to skin. Methods and Materials: In this study, a female anthropomorphic (ART) phantom and the newest generation of optically stimulated luminescence dosimeters (OSLD) (nanoDots, Landauer Inc.) were deployed to measure chest wall dose distribution. Since actual dose to patients’ lung and heart cannot be measured using in-vivo dosimetry, film was also used to verify the dose distribution to the left lung and heart. The treatment planning was performed using tolerance limits of 95% to 107% of prescription dose. The ART phantom was irradiated according to 3 three-dimensional (3D) conformal radiotherapy plans for 200 cGy dose per fraction using 6 MV medial and lateral tangential photon beams. The dose distribution provided by treatment planning was studied using nanoDots and film. Results: Results show that the largest surface dose difference between nanoDots measurement and prescribed dose for medial and lateral tangential beams, are 3.8% and 9.8%, respectively. This difference may be due to higher effective point of measurement and angular dependence of the nanoDots. The maximum differences in measured dose compared with prescribed dose, using film for heart and the left lung, were 6.2% and 7.5% respectively. Conclusions: Both nanoDots and film provided reasonable estimation of dose distribution in post-mastectomy radiation therapy.

关键词： Breast radiotherapy Post-Mastectomy Chest-Wall Surface Dose OSLD NanoDot

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X-Ray Induced Mutation Frequency at the <i>Hypoxanthine Phosphoribosyltransferase</i>Locus in clinically Relevant Radioresistant Cells

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International Journal of Medical physics, clinical Engineering and Radiation oncology 2017年第4期6卷 377-391页

作者： Yoshikazu Kuwahara Mehryar Habibi Roudkenar Yusuke Urushihara Yohei Saito Kazuo Tomita Amaneh Mohammadi Roushandeh Tomoaki Sato Akihiro Kurimasa Manabu Fukumoto Division of Radiation Biology and Medicine Faculty of Medicine Tohoku Medical and Pharmaceutical University Sendai Japan department of Applied Pharmacology Graduate School of Medical and Dental Sciences Kagoshima University Kagoshima Japan Medical Biotechnology Research Center Paramedicine Faculty Guilan University of Medical Science Rasht Iran Fukushima Project Headquarters National Institute for Quantum and Radiological Science and Technology Fukushima Japan department of Radiopharmacy Faculty of Pharmaceutical Science Tohoku Medical and Pharmaceutical University Sendai Japan department of Anatomical Sciences School of Medicine Hamadan University of Medical Sciences Hamadan Iran department of Molecular Pathology Tokyo Medical University Tokyo Japan

To elucidate the molecular mechanisms underlying cellular radioresistance, clinically relevant radioresistant cell lines were established via long-term exposure to X-rays with stepwise dose escalation. Established cells continue to proliferate despite exposure to 2 Gy X-rays/day for more than 30 days, a standard protocol in cancer radiotherapy. DNA repair fidelity in radioresistant and the parental cells by evaluating the mutation frequency at the hypoxanthine phosphoribosyltransferase (HPRT) locus after exposure to X-rays was determined. Mutation spectrum at the HPRT locus was examined by multiplex polymerase chain reaction. Rejoining kinetics of X-ray-induced DNA double strand breaks (dsbs) was evaluated by the detection of phosphorylated histone H2AX (γH2AX) after X-irradiation. The fold increase in the HPRT mutation frequency due to acute radiation was similar between radioresistant and the parental cell lines. However, fractionated radiation (FR) consisting of 2 Gy X-rays/day increased the mutation frequency at the HPRT locus in parental but not in radioresistant cells. Analysis of the FR-induced mutations at the HPRT locus revealed a high frequency of deletion mutations (>70%) in parental but not in radioresistant cells. As assessed by γH2AX immunostaining, DNA dsbs induced by acute exposure to 10 Gy of X-rays were repaired to the control level within 7 days in radioresistant but not in the parental cells. Moreover, 2 Gy × 5 FR increased the number of γH2AX-positive cells in parental cultures but not in radioresistant cultures. DNA dsbs induced by 2 Gy/day FR are repaired with fidelity in radioresistant but not in parental cells.

关键词： clinically Relevant Radioresistant (CRR) Cell Hypoxanthine Phosphoribosyltransferase (HPRT) Mutation Frequency Phosphorylated Histone H2AX (γH2AX) X-Rays

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Thermal Equilibration in the Cavity Volume of a Farmer Ion Chamber for Routine Dosimetry

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International Journal of Medical physics, clinical Engineering and Radiation oncology 2015年第4期4卷 268-272页

作者： Yuichi Kato Hiraku Fuse Kazuya Shinoda Katsumi Miyamoto Tatsuya Fujisaki Graduate School of Radiological Sciences Ibaraki Prefectural University of Health Sciences Ami Town Japan department of Radiological Sciences Ibaraki Prefectural University of Health Sciences Ami Town Japan department of Radiological Technology Tsukuba Medical Center Hospital Tsukuba City Japan

A Farmer ion chamber with an air cavity volume is the most widely used dosimeter for accurate dose determinations in radiotherapy. The quantity of ionization in the cavity volume occurred a given radiation dose has to be corrected to the cavity air temperature according to a dosimetry protocol because the mass of air in the cavity volume is subject to atmospheric variations. In the present study, we aim to measure the thermal equilibration time in the cavity volume of a Farmer ion chamber for the routine dosimetry. The Farmer ion chamber’s electrode was replaced by a thin thermocouple and coated by the PMMA for a waterproofing so that the measurement of the temperature in the cavity performed in water. As a result of the measurement, A Farmer ion chamber in thermal equilibrium with waterproofing equilibrates rapidly, followed by an exponential fall-off. In water, equilibration to less than 10% of the initial temperature difference required only a few minutes. Thermal equilibrium time is hardly affected by the room temperature change.

关键词： Farmer Ion Chamber Thermal Equilibrium Time Temperature Characteristic Routine Dosimetry

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Examination of the Run-Time Differences between the EGSnrc and the EGS5 Monte Carlo Codes

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International Journal of Medical physics, clinical Engineering and Radiation oncology 2020年第1期9卷 14-23页

作者： Shlomi Caduri Itzhak Orion department of Nuclear Engineering Ben-Gurion University of the Negev Beer-Sheva Israel Clalit Biomedical Engineering LTD Or Yehuda Israel

EGS5 Monte Carlo code is a general-purpose code for calculating photons and electrons transport for complex geometries in a wide range of energies. EGSnrc Monte Carlo code (BEAMnrc enclosed) was specially developed for medical physics usage, in particular for Linac modeling and dose calculations. Both EGS5 an EGSnrc were developed based on the former EGS4 code. For each of the codes, changes were made in the electron transport methods and in the geometrical utilities. Conformity between EGS5 calculation results and EGSnrc code results for Linac modelling was shown in recent work in our group. However, a large simulation run-time difference was found for the same conditions and statistical precision between these two codes. The EGS5 code took a longer period to obtain the same results compared to the EGSnrc code for Linac modelling. The electron transport in EGSnrc is based on the ESTEPE parameter, which is the maximum fractional energy loss per electron step. We investigated the ESTEPE parameter influence on the run-time and on the results accuracy. A set of variety simulations were performed using both codes in order to inspect the codes performance. We found that the EGSnrc run-time is strongly influenced by choosing different ESTEPE parameter values. While setting larger fractional energy losses per step, reduced simulation run-time was achieved. Hence, for optimal dose, one should define the optimal ESTEPE step-size parameter to achieve the desired dose results resolution. The use of the EGS5 code, based on the electron transport method improvements, is automatically adapted to the desired dose results quality without any user interference. Choosing the proper ESTEPE parameter for the use of EGSnrc for a given simulation resulted in similar run-time duration as with the use of EGS5. In conclusion, some cases that were tested in this study on the EGS5 and on the EGSnrc showed that the EGS5 is faster and more fluent to use between these two codes.

关键词： Simulation Dose Radiation Step-Size radiotherapy

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Comparison of the Motion Accuracy of a Six Degrees of Freedom radiotherapy Couch with and without Weights

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International Journal of Medical physics, clinical Engineering and Radiation oncology 2013年第3期2卷 69-75页

作者： Akihiro Takemura Shinichi Ueda Kimiya Noto Hironori Kojima Naoki Isomura department of Radiology Kanazawa University Hospital Kanazawa Japan Faculty of Health Sciences Institute of Medical Pharmaceutical and Health Sciences Kanazawa University Kanazawa Japan

In this study, we compared the motion accuracy of six degrees of freedom (6D) couch for precision radiotherapy with or without weights attached to the couch. Two digital cameras were focused on the iso-center of a linear accelerator. Images of a needle which had been fixed to the 6D couch were obtained using the cameras when the couch moved in translation and rotation around each axis. The three-dimensional (3D) coordinates of the needle were calculated from coordinate values in the images. A coordinate error of the needle position relative to the theoretical position was calculated. The errors were obtained with or without a 60 kg weight attached to the 6D couch, and these errors were compared with each other. The mean distance of the 3D error vectors for the weighted test was 0.21 ± 0.11 mm, and >0.16 ± 0.09 mm for the non-weighted test (p

关键词： 6D Couch IGRT Accuracy Assessment

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