International Journal of Medical Physics, Clinical Engineering and Radiation Oncology最新文献_第9页

Partial and Full Arc Volumetric Modulated Arc Therapy in Lung Cancer Stereotactic Body Radiotherapy with Different Definitions of Internal Target Volume Based on 4D CT 基于4D CT的不同内靶体积定义的肺癌立体定向放疗的部分和全弧体积调制弧治疗

International Journal of Medical Physics, Clinical Engineering and Radiation Oncology Pub Date : 2018-09-28 DOI: 10.4236/IJMPCERO.2018.74042

Wu Wang, Didi Chen, Ce Han, Xiaomin Zheng, Yongqiang Zhou, Changfei Gong, C. Xie, X. Jin

{"title":"Partial and Full Arc Volumetric Modulated Arc Therapy in Lung Cancer Stereotactic Body Radiotherapy with Different Definitions of Internal Target Volume Based on 4D CT","authors":"Wu Wang, Didi Chen, Ce Han, Xiaomin Zheng, Yongqiang Zhou, Changfei Gong, C. Xie, X. Jin","doi":"10.4236/IJMPCERO.2018.74042","DOIUrl":"https://doi.org/10.4236/IJMPCERO.2018.74042","url":null,"abstract":"Purpose: To investigate the feasibility of partial arc volumetric modulated arc therapy (VMAT) in lung cancer stereotactic body radiotherapy (SBRT), as well the volumetric and dosimetric effects of different internal target volume (ITV) definitions with 4D CT. Methods: Fourteen patients with primary and metastatic lung cancer underwent SBRT were enrolled. Full and partial arc VMAT plans were generated with four different ITVs: ITVall, ITVMIP, ITVAIP and ITV2phases, representing ITVs generated from all 10 respiratory phases, maximum intensity projection (MIP), average intensity projection (AIP), and 2 extreme respiratory phases. Volumetric and dosimetric differences, as well as MU and delivery time were investigated. Results: Partial arc VMAT irradiated more dose at 2 cm away from planning target volume (PTV) (P = 0.002), however, it achieved better protection on mean lung dose , lung V5, spinal cord, heart and esophagus compared with full arc VMAT. The average MU and delivery time of partial arc VMAT were 240 and 1.6 min less than those of full arc VMAT. There were no significant differences on target coverage and organ at risks (OARs) sparing among four ITVs. The average percent volume differences of ITVMIP, ITVAIP and ITV2phases to ITVall were 8.6%, 13.4%, and 25.2%, respectively. Conclusions: Although partial arc VMAT delivered more dose 2 cm out of PTV, it decreases the dose to lung, spinal cord, and esophagus, as well decreased the total MU and delivery time compared with full arc VMAT without sacrificing target coverage. Partial arc VMAT was feasible and more efficient for lung SBRT.","PeriodicalId":14028,"journal":{"name":"International Journal of Medical Physics, Clinical Engineering and Radiation Oncology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73999030","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Variability in Fluoroscopic Time during Interventional Non-Cardiac Procedures Performed Outside of the Radiology Department 在放射科以外进行的介入性非心脏手术中透视时间的变化

International Journal of Medical Physics, Clinical Engineering and Radiation Oncology Pub Date : 2018-09-28 DOI: 10.4236/IJMPCERO.2018.74039

Murdhi A. Al Harbi, A. Malki, S. Ahmari, K. Soliman

{"title":"Variability in Fluoroscopic Time during Interventional Non-Cardiac Procedures Performed Outside of the Radiology Department","authors":"Murdhi A. Al Harbi, A. Malki, S. Ahmari, K. Soliman","doi":"10.4236/IJMPCERO.2018.74039","DOIUrl":"https://doi.org/10.4236/IJMPCERO.2018.74039","url":null,"abstract":"Purpose: Increasing physician awareness of patient exposure to radiation is an important step towards the reduction of potentially harmful effects of radiation. Published studies demonstrated that providing physicians with feedback regarding their fluoroscopy time leads to a reduction in average fluoroscopy times. The aim of this work was to analyze and publish our medical center data observed during the past year; fluoroscopy time (FT), Dose Area Product (DAP) and cumulative dose (CD) were monitored for radiation protection purposes. Methods: Fluoroscopy time is one of multiple radiation dose indices used in radiation safety auditing. Such auditing is nowadays turning into requirement of patient care safety and quality improvement; as indicated by accreditation bodies both nationally and internationally. All non-cardiac procedures performed outside radiology department by surgeons and interventionists are viewed. FT, DAP and CD are extracted for analysis. Results: a total of 846 cases were studied (643 orthopedic, 99 others, 73 urology, 17 chest, 7 vascular and 4 ERCP cases). Mean FT was 1.3 minutes, mean CD to the patient was 12.98 mGy and the mean DAP was 4.53 Gy/cm2. The longest FT noted was 55 min. The maximum CD was 904 mGy and the maximum DAP was 689 Gy/cm2. Using spearman’s correlation test we found out that there is a significant correlation between FT and DAP (correlation coefficient = 0.615, p. value < 0.001). There is a significant correlation between FT and CD (correlation coefficient = 0.628, p. value < 0.001). Conclusion: Information about FT that used in each procedure can be used as a tool for patient dose optimization. As we found a significant correlation between DAP as well as CD. Reducing fluoroscopic time (FT) is a radiation protection goal, since it serves the purpose of protection for both the patient and the workers.","PeriodicalId":14028,"journal":{"name":"International Journal of Medical Physics, Clinical Engineering and Radiation Oncology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82295952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Organ at Risk Doses during High Dose Rate Intracavitary Brachytherapy for Cervical Cancer: A Dosimetric Study 宫颈癌高剂量率腔内近距离放射治疗中的危险器官剂量:剂量学研究

International Journal of Medical Physics, Clinical Engineering and Radiation Oncology Pub Date : 2018-09-28 DOI: 10.4236/ijmpcero.2018.74040

N. Vinin, Joneetha Jones, V. T. Ajas, G. Muttath, C. Suja, E. Yahiya, P. N. S. Nawaz, A. Narendran, P. Shimjith

{"title":"Organ at Risk Doses during High Dose Rate Intracavitary Brachytherapy for Cervical Cancer: A Dosimetric Study","authors":"N. Vinin, Joneetha Jones, V. T. Ajas, G. Muttath, C. Suja, E. Yahiya, P. N. S. Nawaz, A. Narendran, P. Shimjith","doi":"10.4236/ijmpcero.2018.74040","DOIUrl":"https://doi.org/10.4236/ijmpcero.2018.74040","url":null,"abstract":"Background: Treatment of Cervical cancer includes a combination of external beam radiotherapy (EBRT) with intracavitary brachytherapy (ICBT). ICBT helps to boost radiation dose to primary disease. Organs like rectum, bladder, sigmoid and small bowel lie close to the cervix region and these organs receive dose from EBRT as well as ICBT and we want to know the dose to these organ at risk (OAR). Materials & Methods: Dosimetric details of 174 ICBT applications done in 58 patients were retrospectively analysed. All patients received EBRT dose of 50.4 Gy in 28 fractions. All patients had ICBT, three sessions with 7 Gy prescribed to point A. Dosimetric data including dose to right and left point A and dose to OARs were recorded from Oncentra Planning System. Results: Mean dose to point A on right side was 6.89 Gy and left side was 6.91 Gy. Mean D2cc dose to rectum, bladder, sigmoid and small bowel was 3.5 Gy, 5.25 Gy, 4.75 Gy and 4.2 Gy respectively. Mean EQD2 dose combining EBRT and ICBT in point A was 78.7 Gy on right side and 79 Gy on left side. Mean EQD2 doses to D2cc of rectum, bladder, sigmoid and small bowel was 62 Gy, 74.4 Gy, 70.5 Gy and 66.5 Gy respectively. Conclusion: From the results of this dosimetric study it is evident that OARs like rectum, sigmoid, bladder & bowel are receiving only acceptable doses of radiation using point A prescribed CT based ICBT planning. Hence with regards to OAR doses, CT based ICBT planning with dose prescribed to point A is a feasible option.","PeriodicalId":14028,"journal":{"name":"International Journal of Medical Physics, Clinical Engineering and Radiation Oncology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75900588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

The Application of Image Guided Radiotherapy on the Precision of Intensity Modulated Radiotherapy in Patients with Locally Advanced Rectal Cancer 影像引导放疗在局部晚期直肠癌调强放疗精度中的应用

International Journal of Medical Physics, Clinical Engineering and Radiation Oncology Pub Date : 2018-09-28 DOI: 10.4236/IJMPCERO.2018.74041

Cheng-tao Wang, Zhenyu Wang, M. Min, X. Yu, Jun Dong, B. Wen

{"title":"The Application of Image Guided Radiotherapy on the Precision of Intensity Modulated Radiotherapy in Patients with Locally Advanced Rectal Cancer","authors":"Cheng-tao Wang, Zhenyu Wang, M. Min, X. Yu, Jun Dong, B. Wen","doi":"10.4236/IJMPCERO.2018.74041","DOIUrl":"https://doi.org/10.4236/IJMPCERO.2018.74041","url":null,"abstract":"Objective: To investigate the effect of onboard image (OBI) system-based image guided radiotherapy (IGRT) on the precision of fractionated intensity modulated radiotherapy (IMRT) for patients with locally advanced rectal cancer. Methods: The IGRT validation images of the 12 patients with rectal cancer were obtained after initial setup by the OBI system of Varian Novalis TX linear accelerator, and registered to the planning CT image system. Subsequently, the setup deviations on three translational directions [ventral-dorsal direction (VD), cranial-caudal direction (CD) and lateral direction (LD)] for the three-validation phase including Pre-treatment (Pre-RT1), repositioning (Pre-RT2) and Post-treatment (Post-RT) were obtained and comparatively analyzed. Results: The frequency of setup deviation of ≤2.0 mm in the lateral, cephalocaudal and ventral direction was 83.01%, 65.71%, and 68.91%, respectively for Pre-RT1; 100%, 98.72% and 100%, respectively for Pre-RT2; 100%, 97.76%, and 99.68%, respectively for Post-RT. Compared with the Pre-RT1 phase, the ranges of setup deviation on Pre-RT2 and Post-RT phases possessed a significant contraction trend. The absolute values of setup deviations on the three translation directions between the Pre-RT1 and Pre-RT2 or Post-RT were statistically significant (p < 0.05). Through positioning adjustment based on IGRT based on the OBI system, the setup deviations on the three translational directions decreased significantly. Conclusion: Application of OBI-based daily IGRT may help improve the precise delivery of fractionated IMRT by decreasing the inter- and intra-fractionated setup deviation in the ventral-dorsal direction, cranial-caudal direction and lateral direction for patients with locally advanced rectal cancer.","PeriodicalId":14028,"journal":{"name":"International Journal of Medical Physics, Clinical Engineering and Radiation Oncology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73162972","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Assessment of Organ Dose and Effective Dose from Head CT Examination in a Large Hospital in South-Southern Nigeria 尼日利亚南南部某大型医院头部CT检查器官剂量和有效剂量的评估

International Journal of Medical Physics, Clinical Engineering and Radiation Oncology Pub Date : 2018-09-28 DOI: 10.4236/ijmpcero.2018.74036

R. Obed, M. Ekpo

{"title":"Assessment of Organ Dose and Effective Dose from Head CT Examination in a Large Hospital in South-Southern Nigeria","authors":"R. Obed, M. Ekpo","doi":"10.4236/ijmpcero.2018.74036","DOIUrl":"https://doi.org/10.4236/ijmpcero.2018.74036","url":null,"abstract":"The magnitude of radiation dose imparted to \u0000patients who underwent Head Computed Tomography examination in a large tertiary \u0000hospital in South-Southern Nigeria has been estimated. CT-ExPO dosimetry \u0000software was used to determine the effective and organ doses to the head region \u0000of 40 adult patients. Scanning parameters were retrieved from the CT monitor \u0000for both contrast-enhanced and non-contrast head CT examinations. The tube \u0000potential ranged from 100 kVp to 120 kVp, while the mAs ranged from 127 mAs to \u0000202 mAs. The mean values of the volume Computed Tomography Dose Index (CTDIvol) and Dose Length Product (DLP) for the \u0000contrast-enhanced Head CT examination were 166.4 ± 39.6 mGy and 3568.6 ± 756.1 \u0000mGy·cm, respectively, while for the non-contrast \u0000examination they were 86.6 ± 30.4 mGy and 2102.3 ± 870.3 mGy·cm, respectively. The effective doses were higher for the \u0000contrast-enhanced study than for the non-contrast study by a factor of 1.6. Results \u0000were compared with the European Union reference doses and other published data \u0000and were found to be higher. Doses to the organs which comprise of brain, red bone marrow, thyroid and eye lens were \u0000also estimated. The high variation in the doses in this study may be due to \u0000differences in imaging protocols such as large range of mAs and scan lengths \u0000and also the algorithm of the scanner.","PeriodicalId":14028,"journal":{"name":"International Journal of Medical Physics, Clinical Engineering and Radiation Oncology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79839858","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Editorial: The Authorship of IJMPCERO Papers 社论:IJMPCERO论文的作者身份

International Journal of Medical Physics, Clinical Engineering and Radiation Oncology Pub Date : 2018-09-28 DOI: 10.4236/IJMPCERO.2018.74035

M. Chan, C. Shi

引用次数: 0

Monte Carlo Study of 3D Stray Radiation during Interventional Procedures 介入过程中三维杂散辐射的蒙特卡罗研究

International Journal of Medical Physics, Clinical Engineering and Radiation Oncology Pub Date : 2018-09-28 DOI: 10.4236/ijmpcero.2018.74038

K. Alzimami

{"title":"Monte Carlo Study of 3D Stray Radiation during Interventional Procedures","authors":"K. Alzimami","doi":"10.4236/ijmpcero.2018.74038","DOIUrl":"https://doi.org/10.4236/ijmpcero.2018.74038","url":null,"abstract":"In interventional medical procedures, other than the highly important issue of optimizing image quality and patient exposure using the primary beam, there remains a continuing need for the study of staff exposure from the scattered radiation. Herein, investigation is made of the 3D stray-radiation distribution, the simulation being made of a realistic interventional scenario through use of the Monte Carlo code Geant4 (version 10.3). The simulation is conducted based on the high definition reference Korean-man (HDRK-man) computational phantom and a GE Infinia 3/8” C-arm machine, focusing on the effect of variation of kVp and field of view (FoV) on the scattered particles’ spatial distribution. With direct measurement of the absorbed dose remaining challenging, not least in respect of the organs at risk, we computed the scatter fractions, defined as the ratio of the air kerma free-in-air to the entrance surface air kerma (ESAK), which are both easily quantifiable. Scatter fraction distributions were simulated for X-ray tube outputs (and half-value layers, HVL) of 60 kVp (2.3 mm Al), 80 kVp (3.2 mm Al) and 120 kVp (4.3 mm Al) and FoV of 15, 20, 25 and 30 cm. The distributions are obtained for different height levels, corresponding to the lens of the eye, and the lung and prostate, all radiosensitive organs. Investigations are made for eight likely locations around the patient. At fixed FoV results reveal an inverse relationship between ESAK and kVp, also that change in kVp from 60 to 80 has a greater effect than from 80 to 120. For change in FoV at fixed kVp, the scatter fraction remains constant. The particular staff locations are found to be optimal in seeking mitigation of dose. Moreover, the combined usage of numerical human model and Monte Carlo simulation can be considered as an added value to the radiation safety research field, especially to the interventional radiology staff and to the patient.","PeriodicalId":14028,"journal":{"name":"International Journal of Medical Physics, Clinical Engineering and Radiation Oncology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85878899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Automated Heuristic Optimization of Prostate VMAT Treatment Planning 前列腺VMAT治疗方案的自动启发式优化

International Journal of Medical Physics, Clinical Engineering and Radiation Oncology Pub Date : 2018-08-31 DOI: 10.4236/IJMPCERO.2018.73034

C. Fiandra, A. Alparone, E. Gallio, C. Vecchi, G. Balestra, S. Bartoncini, S. Rosati, R. Ragona, U. Ricardi

{"title":"Automated Heuristic Optimization of Prostate VMAT Treatment Planning","authors":"C. Fiandra, A. Alparone, E. Gallio, C. Vecchi, G. Balestra, S. Bartoncini, S. Rosati, R. Ragona, U. Ricardi","doi":"10.4236/IJMPCERO.2018.73034","DOIUrl":"https://doi.org/10.4236/IJMPCERO.2018.73034","url":null,"abstract":"Purpose: To investigate a genetic algorithm approach to automatic treatment planning. Methods: A Python script based on genetic algorithm (GA) was implemented for VMAT treatment planning of prostate tumor. The script was implemented in RayStation treatment planning system using Python code. Two different clinical prescriptions were considered: 78 Gy prescribed to planning target volume in 39 fractions (GROUP 1) and simultaneous integrated boost (70.2 Gy to prostate bed and 61.1 Gy to seminal vesicles) in 26 fractions (GROUP 2). The script automatically optimizes doses to PTV and OARs according to GA. A comparison with corresponding plans created with Monaco TPS (M) and Auto-Planning module of Pinnacle3 (AP) was carried out. The plans were evaluated with a total score (TS) of PlanIQ software in terms of target coverage and sparing of OARs as well as clinical score (CS) performed by a Radiation Oncologist. Results: In GROUP 1, mean value of TS were 150.6 ± 30.7, 146.3 ± 36.1 and 137.4 ± 35.7 for AP, GA and M respectively. For GROUP 2, mean value for TS were 163.5 ± 16.8, 163.4 ± 24.7 and 162.9 ± 16.6 for AP, GA and M respectively with no significance differences. In terms of CS, the highest value has been attributed to GA in four patients out of five for both GROUP 1 and 2. Conclusions: Genetic approach is practicable for prostate VMAT plan generation and studies are underway in other anatomical sites such as Head and Neck and Rectum.","PeriodicalId":14028,"journal":{"name":"International Journal of Medical Physics, Clinical Engineering and Radiation Oncology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84088860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

Relationship between Patient-Dependent Parameters and Radiation Dose Rates Measured around Patients Undergoing PET/CT Imaging Using 18 F-FDG 患者依赖参数与使用18f - fdg进行PET/CT成像患者周围测量的辐射剂量率的关系

International Journal of Medical Physics, Clinical Engineering and Radiation Oncology Pub Date : 2018-08-30 DOI: 10.4236/ijmpcero.2018.73033

K. Soliman, S. Qahtani, A. Alenezi

{"title":"Relationship between Patient-Dependent Parameters and Radiation Dose Rates Measured around Patients Undergoing PET/CT Imaging Using 18 F-FDG","authors":"K. Soliman, S. Qahtani, A. Alenezi","doi":"10.4236/ijmpcero.2018.73033","DOIUrl":"https://doi.org/10.4236/ijmpcero.2018.73033","url":null,"abstract":"Objectives: Patients undergoing 18F-FDG PET/CT imaging are considered external radiation sources. Accurate dose rate estimates are important for conducting realistic risk assessments and performing dose reconstruction in cases of accidental exposures. The patient radiation self-attenuation factor is assumed to be a function of the patient’s body size metrics, but we can use these metrics to predict the dose rate around the patients with accuracy. The objective of this work was first to measure the patient attenuation factor by performing direct dose rate measurements from patients undergoing PET/CT imaging studies using 18F-FDG. The second objective was to study the possible correlation between the measured dose rate constant per unit activity from the patients and their body size metrics; five metrics were tested in this work. The last objective was to measure the patients’ voiding factor. Methods: We have measured dose rates at one meter from 57 patients and noted the patient’s height (H), weight (W) and calculated patient size metrics namely: Equivalent Cylindrical Diameter (ECD), Equivalent Spherical Diameter (ESD) and the Body Mass Index (BMI). Results: The measured average dose rate was 92.2 ± 14 μSv·h-1·GBq-1 measured at one meter. Therefore, the dose rate constant of 92 μSv·h-1·GBq-1 proposed by the AAPM, TG-108 report is adequate for radiation protection purposes. There was no statistically significant correlation between the dose rate constant per unit activity and the patient body size metrics. We have measured a patient voiding factor of 0.89 ± 0.06 in comparison with 0.85 recommended by the AAPM. Conclusions: The presented data can be used by medical physicist working in nuclear medicine in formulating more accurate risk estimations resulting from radiation exposure from patients undergoing 18F-FDG PET/CT imaging.","PeriodicalId":14028,"journal":{"name":"International Journal of Medical Physics, Clinical Engineering and Radiation Oncology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88911907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Measurement of Electron Return Effect and Skin Dose Reduction by a Bolus in an Anthropomorphic Physical Phantom under a Magnetic Resonance Guided Linear Accelerator (MR-LINAC) System 磁共振引导直线加速器(MR-LINAC)系统下拟人物理模型中电子返回效应和皮肤剂量减少的测量

International Journal of Medical Physics, Clinical Engineering and Radiation Oncology Pub Date : 2018-08-14 DOI: 10.4236/IJMPCERO.2018.73028

E. Han, Z. Wen, Hannah J. Lee, A. Paulino, Choonsik Lee

{"title":"Measurement of Electron Return Effect and Skin Dose Reduction by a Bolus in an Anthropomorphic Physical Phantom under a Magnetic Resonance Guided Linear Accelerator (MR-LINAC) System","authors":"E. Han, Z. Wen, Hannah J. Lee, A. Paulino, Choonsik Lee","doi":"10.4236/IJMPCERO.2018.73028","DOIUrl":"https://doi.org/10.4236/IJMPCERO.2018.73028","url":null,"abstract":"Background: Magnetic resonance image-guided radiation therapy (MR-IGRT) promises more precise and effective \u0000radiation treatments compared to conventional IGRT by using real-time on-board \u0000MR imaging. Under the influence of a magnetic field, however, secondary electrons \u0000exiting a surface can be forced in a circular path and re-enter the medium, \u0000resulting in dose increase at a beam-exit surface, called the electron return \u0000effect (ERE). The purpose of the study is to compare the exit skin dose \u0000computed by Monte Carlo dose calculation with measurements using an adult \u0000anthropomorphic phantom and to measure the effect of skin dose reduction by \u0000adding 1 cm-thick bolus. Method: The plan was compared with measurements \u0000using an adult anthropomorphic phantom combined with radiochromic films and \u0000thermoluminescent dosimeters. We also measured the skin dose reduction by \u0000adding 1 cm-thick bolus on the frontal surface of the phantom. Results: We found that 1 cm-thick bolus reduced the skin dose by up to 20% both in \u0000measurements and calculations. The plan was found to overestimate the measured \u0000skin dose by about 10% and there was no significant difference in the bolus \u0000effect between the breast skin and the skin (without breast attachment) doses. Conclusion: In conclusion, we confirmed the ERE effect on the anthropomorphic phantom under \u0000the magnetic field and the exit \u0000skin dose reduction by adding a bolus. Skin dose measurements using \u0000anthropomorphic phantom may be helpful to evaluate more realistic skin dose and \u0000the bolus effect in the magnetic field.","PeriodicalId":14028,"journal":{"name":"International Journal of Medical Physics, Clinical Engineering and Radiation Oncology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84244594","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6