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Brekner MC, Imhoff D, Rödel C, Filmann N, Licher J, Ramm U, Köhn J. Stereotactic body radiotherapy with volumetric intensity-modulated arc therapy and flattening filter-free beams: dosimetric considerations. Strahlenther Onkol 2024; 200:346-357. [PMID: 38092967 DOI: 10.1007/s00066-023-02181-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 11/01/2023] [Indexed: 03/27/2024]
Abstract
PURPOSE The present study comparatively evaluates the impact of energy-matched flattening filter-free (FFF) photon beams with different energy levels on the physical-dosimetric quality of lung and liver stereotactic body radiotherapy (SBRT) treatment plans. METHODS For this purpose, 54 different lung and liver lesions from 44 patients who had already received SBRT combined with volumetric modulated arc therapy (VMAT) were included in this retrospective planning study. Planning computed tomography scans already available were used for the renewed planning with 6 MV, 6 MV-FFF, 10 MV, and 10 MV-FFF under constant planning objectives. The treatment delivery data, dosimetric distributions, and dose-volume histograms as well as parameters such as the conformity index and gradient indices were the basis for the evaluation and comparison of treatment plans. RESULTS A significant reduction of beam-on time (BOT) was achieved due to the high dose rates of FFF beams. In addition, we showed that for FFF beams compared to flattened beams of the same energy level, smaller planning target volumes (PTV) require fewer monitor units (MU) than larger PTVs. An equal to slightly superior target volume coverage and sparing of healthy tissue as well as organs at risk in both lung and liver lesions were found. Significant differences were seen mainly in the medium to lower dose range. CONCLUSION We found that FFF beams together with VMAT represent an excellent combination for SBRT of lung or liver lesions with shortest BOT for 10 MV-FFF but significant dose savings for 6 MV-FFF in lung lesions.
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Affiliation(s)
- Mark Christoph Brekner
- Department of Radiation Oncology, University Hospital, Johann Wolfgang Goethe University Frankfurt, Theodor Stern Kai 7, 60590, Frankfurt, Germany.
| | - Detlef Imhoff
- Department of Radiation Oncology, University Hospital, Johann Wolfgang Goethe University Frankfurt, Theodor Stern Kai 7, 60590, Frankfurt, Germany
| | - Claus Rödel
- Department of Radiation Oncology, University Hospital, Johann Wolfgang Goethe University Frankfurt, Theodor Stern Kai 7, 60590, Frankfurt, Germany
| | - Natalie Filmann
- Institute for Biostatistics and Mathematical Modeling, University Hospital, Goethe University, 60590, Frankfurt, Germany
| | - Jörg Licher
- Department of Radiation Oncology, University Hospital, Johann Wolfgang Goethe University Frankfurt, Theodor Stern Kai 7, 60590, Frankfurt, Germany
| | - Ulla Ramm
- Department of Radiation Oncology, University Hospital, Johann Wolfgang Goethe University Frankfurt, Theodor Stern Kai 7, 60590, Frankfurt, Germany
| | - Janett Köhn
- Department of Radiation Oncology, University Hospital, Johann Wolfgang Goethe University Frankfurt, Theodor Stern Kai 7, 60590, Frankfurt, Germany
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Tarek I, Hafez A, Fathy MM, Fahmy HM, Abdelaziz DM. Efficacy of flattening filter-free beams with the acuros XB algorithm in thoracic spine stereotactic body radiation therapy. Med Dosim 2024:S0958-3947(24)00005-0. [PMID: 38336567 DOI: 10.1016/j.meddos.2024.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Revised: 12/25/2023] [Accepted: 01/06/2024] [Indexed: 02/12/2024]
Abstract
This study aimed to determine the dosimetric value of flattening filter-free (FFF) beams compared to flattening filter (FF) beams using different algorithms in the treatment planning of thoracic spine stereotactic body radiation therapy (SBRT). A total of 120 plans were created for 15 patients using the Anisotropic Analytical Algorithm (AAA) and the Acuros External Beam (AXB) algorithm with FF and FFF beams at 6 MV and 10 MV energies. Various dosimetric parameters were evaluated, including target coverage, dose spillage, and organs-at-risk sparing of the spinal cord and esophagus. Treatment delivery parameters, such as the monitor units (MUs), modulation factors (MFs), beam-on time (BOT), and dose calculation time (DCT), were also collected. Significant differences were observed in the dosimetric parameters when AXB was used for all energies (P < 0.05). 6 XFFF energy was the best option for target coverage, dose spillage, and organs-at-risk sparing. In contrast, dosimetric parameters had no significant difference when using the AAA. The AAA and AXB calculations showed that the 6 XFFF beam had the shortest DCT. The treatment delivery parameters indicated that 10 XFF beam required the fewest MUs and MFs. In addition, the 10 XFFF beam demonstrated the shortest BOT. For effective treatment of the thoracic spine using SBRT, it is recommended to use the 10 XFFF beam because of the short BOT. Moreover, the AXB algorithm should be used because of its accurate dose calculation in regions with tissue heterogeneity.
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Affiliation(s)
- Islam Tarek
- Department of Biophysics, Faculty of Science, Cairo University, Cairo, Egypt; Department of Radiotherapy, Baheya center for early detection and treatment of breast cancer, Giza, Egypt.
| | - Abdelrahman Hafez
- Department of Radiotherapy, Baheya center for early detection and treatment of breast cancer, Giza, Egypt
| | - Mohamed M Fathy
- Department of Biophysics, Faculty of Science, Cairo University, Cairo, Egypt.
| | - Heba M Fahmy
- Department of Biophysics, Faculty of Science, Cairo University, Cairo, Egypt
| | - Dina M Abdelaziz
- Department of Radiotherapy, Baheya center for early detection and treatment of breast cancer, Giza, Egypt; Department of Radiotherapy, National cancer institute, Cairo University, Cairo, Egypt
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Gill A, Hirst AL, Rowshanfarzad P, Gill S, Bucknell N, Dass J, Sabet M. Stereotactic body radiotherapy for early-stage lung cancer: a systematic review on the choice of photon energy and linac flattened/unflattened beams. Radiat Oncol 2024; 19:1. [PMID: 38167095 PMCID: PMC10762943 DOI: 10.1186/s13014-023-02392-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 12/15/2023] [Indexed: 01/05/2024] Open
Abstract
SBRT is an effective local treatment for patients with early-stage non-small cell lung cancer (NSCLC). This treatment is currently used in patients who have poor lung function or who decline surgery. As SBRT usually has small PTV margins, reducing the beam-on-time (BOT) is beneficial for accurate dose delivery by minimising intrafraction motion as well as improved patient comfort. Removal of the linear accelerator flattening filter can provide a higher dose rate which results in a faster treatment. In addition, the choice of photon energy can also affect the dose distribution to the target and the organs-at-risk (OAR). In this systematic review, studies analysing the choice of various photon beam energies, with a flattening filter or flattening filter free (FFF), were compared for their overall dosimetric benefit in the SBRT treatment for early-stage NSCLC. It was found that FFF treatment delivers a comparatively more conformal dose distribution, as well as a better homogeneity index and conformity index, and typically reduces BOT by between 30 and 50%. The trade-off may be a minor increase in monitor units for FFF treatment found in some studies but not others. Target conformity and OAR sparing, particularly lung doses appear better with 6MV FFF, but 10MV FFF was marginally more advantageous for skin sparing and BOT reduction. The favourable beam modality for clinical use would depend on the individual case, for which tumour size and depth, radiotherapy technique, as well as fractionation scheme need to be taken into account.
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Affiliation(s)
- Ashlesha Gill
- School of Physics, Mathematics and Computing, The University of Western Australia, Crawley, WA, 6009, Australia.
| | - Andrew L Hirst
- Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, WA, 6009, Australia
| | - Pejman Rowshanfarzad
- School of Physics, Mathematics and Computing, The University of Western Australia, Crawley, WA, 6009, Australia
| | - Suki Gill
- School of Physics, Mathematics and Computing, The University of Western Australia, Crawley, WA, 6009, Australia
- Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, WA, 6009, Australia
| | - Nicholas Bucknell
- Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, WA, 6009, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, VIC, 3000, Australia
| | - Joshua Dass
- Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, WA, 6009, Australia
| | - Mahsheed Sabet
- School of Physics, Mathematics and Computing, The University of Western Australia, Crawley, WA, 6009, Australia
- Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, WA, 6009, Australia
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Cai X, Shen Y, Yang Y, Wang W, Qian L, Cai J, Chi R, Yu S, Li K, Wei Z, Chen T, Fei Y, Han Y, Chen X, Liu M, Liu Y, Wang D, Jiang M, Li YG. Renal Denervation by Noninvasive Stereotactic Radiotherapy Induces Persistent Reduction of Sympathetic Activity in a Hypertensive Swine Model. J Am Heart Assoc 2021; 10:e020068. [PMID: 34369204 PMCID: PMC8475062 DOI: 10.1161/jaha.120.020068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Background We have previously reported the feasibility of noninvasive stereotactic body radiotherapy (SBRT) as a novel approach for renal denervation. Methods and Results Herein, from a translational point of view, we assessed the antihypertensive effect and chronological evolution of SBRT‐induced renal nerve injury within 6 months in a hypertensive swine model. Hypertension was induced in swine by subcutaneous implantation of deoxycorticosterone acetate pellets in combination with a high‐salt diet. A single dose of 25 Gy with SBRT was delivered for renal denervation in 9 swine within 3.4±1.0 minutes. Blood pressure levels at baseline and 1 and 6 months post‐SBRT were comparable to control (n=5), whereas renal norepinephrine was significantly lower at 6 months (P<0.05). Abdominal computed tomography, performed before euthanasia and renal function assessment, remained normal. Standard semiquantitative histological assessment showed that compared with control (1.4±0.4), renal nerve injury was greater at 1 month post‐SBRT (2.3±0.3) and peaked at 6 months post‐SBRT (3.2±0.8) (P<0.05), along with a higher proportion of active caspase‐3–positive nerves (P<0.05). Moreover, SBRT resulted in continuous dysfunction of renal sympathetic nerves and low level of nerve regeneration in 6 months by immunohistochemistry analysis. Conclusions SBRT delivering 25 Gy for renal denervation was safe and related to sustained reduction of sympathetic activity by aggravating nerve damage and inhibiting nerve regeneration up to 6 months; however, its translation to clinical trial should be cautious because of the negative blood pressure response in the deoxycorticosterone acetate–salt hypertensive swine model.
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Affiliation(s)
- Xingxing Cai
- Department of Cardiology Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine China
| | - Yichen Shen
- Department of Oncology Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine China
| | - Yuli Yang
- Department of Cardiology Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine China
| | - Wei Wang
- Department of Oncology Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine China
| | - Li Qian
- Department of Pathology Affiliated Hospital of Nantong University China
| | - Jing Cai
- Department of Radiology Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine China
| | - Runmin Chi
- Department of Radiology Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine China
| | - Shunxuan Yu
- Department of Oncology Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine China
| | - Keke Li
- Department of Oncology Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine China
| | - Zhixing Wei
- Department of Cardiology Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine China
| | - Taizhong Chen
- Department of Cardiology Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine China
| | - Yudong Fei
- Department of Cardiology Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine China
| | - Yaqin Han
- Department of Cardiology Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine China
| | - Xiu Chen
- Department of Cardiology Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine China
| | - Ming Liu
- Department of Radiology Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine China
| | - Yifei Liu
- Department of Pathology Affiliated Hospital of Nantong University China
| | - Dengbin Wang
- Department of Radiology Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine China
| | - Mawei Jiang
- Department of Oncology Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine China
| | - Yi-Gang Li
- Department of Cardiology Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine China
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Tuğrul T. Effect of different target materials of LINAC head on photon spectrum. JOURNAL OF RADIATION RESEARCH AND APPLIED SCIENCES 2021. [DOI: 10.1080/16878507.2021.1921964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Taylan Tuğrul
- Department of Radiation Oncology, Medicine Faculty of Van Yüzüncü Yıl University, Van, Turkey
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Dai G, Xu X, Wu X, Lei X, Wei X, Li Z, Xiao Q, Zhong R, Bai S. Application of 3D-print silica bolus for nasal NK/T-cell lymphoma radiation therapy. JOURNAL OF RADIATION RESEARCH 2020; 61:920-928. [PMID: 32960262 PMCID: PMC7674672 DOI: 10.1093/jrr/rraa084] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 06/28/2020] [Accepted: 06/23/2020] [Indexed: 02/05/2023]
Abstract
The aim of the study was to evaluate the clinical feasibility of a 3D-print silica bolus for nasal NK/T-cell lymphoma radiation therapy. Intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) plans were designed using an anthropomorphic head phantom with a 3D-print silica bolus and other kinds of bolus used clinically, and the surface dose was measured by a metal oxide semiconductor field-effect transistor (MOSFET) dosimeter. Four nasal NK/T patients with or without 3D-print silica bolus were treated and the nose surface dose was measured using a MOSFET dosimeter during the first treatment. Plans for the anthropomorphic head phantom with 3D-print bolus have more uniform dose and higher conformity of the planning target volume (PTV) compared to other boluses; the homogeneity index (HI) and conformity index (CI) of the VMAT plan were 0.0589 and 0.7022, respectively, and the HI and CI of the IMRT plan were 0.0550 and 0.7324, respectively. The MOSFET measurement results showed that the surface dose of the phantom with 3D-print bolus was >180 cGy, and that of patients with 3D-print bolus was higher than patients without bolus. The air gap volume between the 3D-print bolus and the surface of patients was <0.3 cc. The 3D-print silica bolus fitted well on the patient’s skin, effectively reducing air gaps between bolus and patient surface. Meanwhile, the 3D-print silica bolus provided patients with higher individuation, and improved the conformity and uniformity of the PTV compared to other kinds of boluses.
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Affiliation(s)
- Guyu Dai
- Department of Radiation Oncology, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
| | - Xin Xu
- Department of Obstetrics and Gynecology, West China Second University Hospital, Sichuan University/Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
| | - Xiaohong Wu
- Department of Oncology, The affiliated Hospital of Panzhihua University, Panzhihua, China
| | - Xiaolin Lei
- Department of Oncology, The affiliated Hospital of Panzhihua University, Panzhihua, China
| | - Xing Wei
- Department of Obstetrics and Gynecology, West China Second University Hospital, Sichuan University/Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
| | - Zhibin Li
- Department of Radiation Oncology, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
| | - Qing Xiao
- Department of Radiation Oncology, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
| | - Renming Zhong
- Department of Radiation Oncology, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
| | - Sen Bai
- Department of Radiation Oncology, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
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Comparison of radiotherapy techniques with flattening filter and flattening filter-free in lung radiotherapy according to the treatment volume size. Sci Rep 2020; 10:8983. [PMID: 32488150 PMCID: PMC7265285 DOI: 10.1038/s41598-020-66079-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Accepted: 05/13/2020] [Indexed: 11/23/2022] Open
Abstract
In external radiotherapy (RT), the use of flattening filter-free (FFF) radiation beams obtained by removing the flattening filter (FF) in standard linear accelerators is rapidly increasing, and the benefits of clinical use are the issue of research. Advanced treatment techniques have increased the interest in the operation of linear accelerators in FFF mode. The differences of the beams with non-uniform dose distribution created by removing FF compared to the beams with uniform dose distribution used as a standard were examined. These differences were compared in the treatment plans of lung patients who have different planning target volumes (PTV). Clinac IX linear accelerator units were used. Twenty patients with previously completed treatment were divided into two groups depending on the size of the target volume. All patients underwent two different intensity-modulated RT (IMRT) plans using FF and FFF beams. The Wilcoxon Signed-Rank test was used to compare two different techniques (Significance p < 0.05). There was no statistically significant difference between the two techniques when looking at the D2%(Gy), D98%(Gy), D50%(Gy), homogeneity (HI), and conformity index (CI) data for both groups. When the critical organ doses were evaluated, there was a statistically significant difference only in the V20(%) values of the lungs, but these differences were not very large. Monitor unit (MU) data were found to be lower in FF planning, and treatment time was lower in FFF planning. Except for shorter treatment times, and of the lungs V20(%) value, in standard fractionated RT of lung cancer, there was no significant difference between the use of FFF and FF techniques for large and small target volumes.
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Three-dimensional dose comparison of flattening filter (FF) and flattening filter-free (FFF) radiation therapy by using NIPAM gel dosimetry. PLoS One 2019; 14:e0212546. [PMID: 30789968 PMCID: PMC6383886 DOI: 10.1371/journal.pone.0212546] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Accepted: 02/05/2019] [Indexed: 12/21/2022] Open
Abstract
Intensity-modulated radiotherapy and volumetric modulated arc therapy are modern radiation therapy technologies that can create the desired dose distribution by multileaf collimator movement and dose-rate control. However, the homogeneous dose delivery of small-field irradiation techniques shows disagreement with that of treatment planning system. The removal of the flattening filter by flattening filter free (FFF) beam irradiation increases dose conformity and further reduces treatment delivery time in radiosurgery. This study aims to investigate the dose distribution of FFF and flattened beams for small-field irradiation by using the 3D gel dosimeter. The N-isopropylacrylamide (NIPAM) polymer gel dosimeter was employed to record the 3D dose distribution. In addition, flattened and FFF beams were compared using the gamma evaluation technique. The use of an FFF accelerator resulted in excellent radiation treatments with short delivery times and low doses to normal tissues and organs. Results also showed that the passing rate increased with the decrease of field size (30 × 30, 20 × 20, and 10 × 10 mm2) at post-irradiation times of 24, 48, 72, and 96 h. The passing rates for each field size were retained at the same level when gamma criteria, namely, distance-to-agreement (DTA) = 3 mm/dose difference (DD) = 3%, were used. Nevertheless, the passing rates for each field size decreased slowly after 48 h when DTA = 2 mm/DD = 2%. The Wilcoxon signed-rank test was used to determine statistical difference with a significant level of p < 0.05. The passing rates of flattened and FFF beams showed no significant difference. The edge enhancement effect in the flattened beam was more evident than in the FFF beam. The 3D NIPAM gel dosimeter can be used for dose verification of small field for radiation therapy with high dose rate.
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Edvardsson A, Scherman J, Nilsson MP, Wennberg B, Nordström F, Ceberg C, Ceberg S. Breathing-motion induced interplay effects for stereotactic body radiotherapy of liver tumours using flattening-filter free volumetric modulated arc therapy. ACTA ACUST UNITED AC 2019; 64:025006. [DOI: 10.1088/1361-6560/aaf5d9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Kong Y, Yan T, Sun Y, Qian J, Zhou G, Cai S, Tian Y. A dosimetric study on the use of 3D-printed customized boluses in photon therapy: A hydrogel and silica gel study. J Appl Clin Med Phys 2019; 20:348-355. [PMID: 30402935 PMCID: PMC6333182 DOI: 10.1002/acm2.12489] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 08/29/2018] [Accepted: 09/24/2018] [Indexed: 12/26/2022] Open
Abstract
PURPOSE The aim of the study was to compare the dose differences between two kinds of materials (silica gel and hydrogel) used to prepare boluses based on three-dimensional (3D) printing technologies and commercial bolus in head phantoms simulating nose, ear, and parotid gland radiotherapy. METHODS AND MATERIALS We used 3D printing technology to make silica gel and hydrogel boluses. To evaluate the clinical feasibility, intensity modulated radiation therapy (IMRT) plans were created for head phantoms that were bolus-free or had a commercial bolus, a silica gel bolus, or a hydrogel bolus. Dosimetry differences were compared in simulating nose, ear, and parotid gland radiotherapy separately. RESULTS The air gaps were smaller in the silica gel and hydrogel bolus than the commercial one. In nose plans, it was shown that the V95% (relative volume that is covered by at least 95% of the prescription dose) of the silica gel (99.86%) and hydrogel (99.95%) bolus were better than the commercial one (98.39%) and bolus-free (87.52%). Similarly, the homogeneity index (HI) and conformity index (CI) of the silica gel (0.06; 0.79) and hydrogel (0.058; 0.80) bolus were better than the commercial one (0.094; 0.72) and bolus-free (0.59; 0.53). The parameters of results (HI, CI, V95% ) were also better in 3D printing boluses than in the commercial bolus or without bolus in ear and parotid plans. CONCLUSIONS Silica gel and hydrogel boluses were not only good for fit and a high level of comfort and repeatability, but also had better parameters in IMRT plans. They could replace the commercial bolus for clinical use.
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Affiliation(s)
- Yuehong Kong
- Department of Radiotherapy and OncologyThe Second Affiliated Hospital of Soochow UniversitySuzhouChina
- Institute of Radiotherapy and OncologySoochow UniversitySuzhouChina
| | - Tengfei Yan
- Department of Radiotherapy and OncologyThe Second Affiliated Hospital of Soochow UniversitySuzhouChina
- Institute of Radiotherapy and OncologySoochow UniversitySuzhouChina
| | - Yanze Sun
- Department of Radiotherapy and OncologyThe Second Affiliated Hospital of Soochow UniversitySuzhouChina
- Institute of Radiotherapy and OncologySoochow UniversitySuzhouChina
| | - Jianjun Qian
- Department of Radiotherapy and OncologyThe Second Affiliated Hospital of Soochow UniversitySuzhouChina
- Institute of Radiotherapy and OncologySoochow UniversitySuzhouChina
| | - Gang Zhou
- Department of Radiotherapy and OncologyThe Second Affiliated Hospital of Soochow UniversitySuzhouChina
- Institute of Radiotherapy and OncologySoochow UniversitySuzhouChina
| | - Shang Cai
- Department of Radiotherapy and OncologyThe Second Affiliated Hospital of Soochow UniversitySuzhouChina
- Institute of Radiotherapy and OncologySoochow UniversitySuzhouChina
| | - Ye Tian
- Department of Radiotherapy and OncologyThe Second Affiliated Hospital of Soochow UniversitySuzhouChina
- Institute of Radiotherapy and OncologySoochow UniversitySuzhouChina
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A Monte Carlo Study of the Photon Spectrum due to the Different Materials Used in the Construction of Flattening Filters of LINAC. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2017; 2017:3621631. [PMID: 28769998 PMCID: PMC5523462 DOI: 10.1155/2017/3621631] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 05/14/2017] [Indexed: 11/18/2022]
Abstract
Different types the spectrum of photons were studied; they were emitted from the flattening filter of a LINAC Varian 2100 C/D that operates at 15 MV. The simplified geometry of the LINAC head was calculated using the MCNPX code based on the studies of the materials of the flattening filter, namely, SST, W, Pb, Fe, Ta, Al, and Cu. These materials were replaced in the flattening filter to calculate the photon spectra at the output of this device to obtain the spectrum that makes an impact with the patient. The different spectra obtained were analyzed and compared to the emission from the original spectra configuration of the LINAC, which uses material W. In the study, different combinations of materials were considered in order to establish differences between the use of different materials and the original material, with the objective of establishing advantages and disadvantages from a clinical standpoint.
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