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The aim of this paper is to compare the dosimetric difference between intensity-modulated arc therapy (IMAT) and conventional intensity-modulated radiation therapy (IMRT) for radiotherapy of nasopharyngeal carcinoma (NPC) using si...
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The aim of this paper is to compare the dosimetric difference between intensity-modulated arc therapy (IMAT) and conventional intensity-modulated radiation therapy (IMRT) for radiotherapy of nasopharyngeal carcinoma (NPC) using simultaneously integrated boost (SIB) protocol. Ten patients with nasopharyngeal carcinoma underwent SIB protocol were retrospectively studied. The plan target volume (PTV) of NPC contained nasopharynx gross target volume and the positive neck lymph nodes, PTV1 contained the high-risk sites of microscopic extension and the whole nasopharynx and PTV2 contained the low-risk sites. The prescription dose of PTV was 66 Gy/30 fractions, and for PTV1 60 Gy/30 fractions and for PTV2 54 Gy/30 fractions. IMAT (two 358° arcs) and IMRT (7 fields) plans were designed for each patients using SIB strategies. The monitor unit (MU), treatment time (T) and dosimetric difference between IMRT and IMAT were compared. IMAT can achieve better conformal index (CI) than IMRT (P<0.05) for all PTVs, while no significant difference were found in homogeneity index (HI) (P > 0.05). There's no significant difference found in radiation dose of brain stem, lenses and parotids, while the maximum dose of spinal cord of IMAT was higher than IMRT (P < 0.05). The monitor unit of IMRT (1308 ±213) was more than IMAT (606± 96) (P< 0.05), while the treatment time of IMRT (540 ±160S) was more than IMAT (160 ±10S). This study shows that IMAT using SIB strategies for NPC radiotherapy can achieve similar target coverage with better conformity with less MU and delivery time comparing to IMRT.
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The major benefits of modern radiation therapy (eg, intensity-modulated [x-ray] radiation therapy [IMRT]) for oropharyngeal cancer are reduced xerostomia and better quality of life. Intensity-modulated proton therapy may provide a...
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The major benefits of modern radiation therapy (eg, intensity-modulated [x-ray] radiation therapy [IMRT]) for oropharyngeal cancer are reduced xerostomia and better quality of life. Intensity-modulated proton therapy may provide additional advantages over IMRT by reducing radiation beam-path toxicities. Several acute and late treatment-related toxicities and symptom constellations must be kept in mind when designing and comparing future treatment strategies, particularly because currently most patients with oropharyngeal carcinoma present with human papillomavirus-positive disease and are expected to have a high probability of long-term survival after treatment.
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Objective of the present study was to investigate the tolerant radiation dose of nasal mucosa by observing and analyzing patients who received intensity-modulated radiation therapy (IMRT). Patients with nasopharyngeal carcinoma (N...
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Objective of the present study was to investigate the tolerant radiation dose of nasal mucosa by observing and analyzing patients who received intensity-modulated radiation therapy (IMRT). Patients with nasopharyngeal carcinoma (N = 66) were selected for this study. The modified saccharin assay, endoscopy test, magnetic resonance imaging, and sino-nasal outcome test-20 (SNOT-20) survey were performed for the patients before and at 0 (T0), 3 (T1), 6 (T2), and 12 (T3) months after radiotherapy. The threshold doses of IMRT before radiotherapy and at T0, T1, T2, and T3 were determined as, respectively, 37 Gy, 37 Gy, 39 Gy, and 37 Gy for the saccharin test; 38 Gy, 37 Gy, 40 Gy, and 38 Gy for the endoscopy test; and 39 Gy, 37 Gy, 39 Gy, and 39 Gy for the nasal-related symptom scoring test. The modified saccharin assay, endoscopy test, and SNOT-20 survey revealed that a low dose (< threshold dose) of IMRT was associated with higher mucocilia transport rate (MRT), better endoscopy test score, and improved SNOT-20 score. The patients who received IMRT at a dose less than the threshold had the least damaged nasal mucosa morphology, and functional impairment scores were highest at T1 of IMRT. We conclude that nasal mucosa showed the most serious damage within 3 months after IMRT. If the radiation dose can be controlled within the threshold, the nasal mucosa can recover in the following few months, but recovery will be difficult otherwise.
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Introduction: Prostate and colorectal cancers are the two most prevalent cancers in men and diagnosis of synchronous tumours is increasingly common. Dependent on a number of factors including patient preference, tumour stage and l...
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Introduction: Prostate and colorectal cancers are the two most prevalent cancers in men and diagnosis of synchronous tumours is increasingly common. Dependent on a number of factors including patient preference, tumour stage and localization, different management strategies are utilized for both tumours. External beam radiotherapy (EBRT) is frequently required in their management and IMRT enables simultaneous delivery of different dose levels to separate structures. We report our experience of delivering 2-phase EBRT utilising IMRT to this group of patients.
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Modern radiation therapy treatment planning and delivery is a complex process that relies on advanced imaging and computing technology as well as expertise from the medical team. The process begins with simulation imaging, in whic...
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Modern radiation therapy treatment planning and delivery is a complex process that relies on advanced imaging and computing technology as well as expertise from the medical team. The process begins with simulation imaging, in which three-dimensional computed tomography images (or magnetic resonance images in some cases) are used to characterize the patient anatomy. From there, the radiation oncologist delineates the relevant target/tumor volumes and normal tissue and communicates the goals for treatment planning. The planning process attempts to generate a radiation therapy treatment plan that will deliver a therapeutic dose of radiation to the tumor while sparing nearby normal tissue.
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Because of its sharp lateral penumbra and steep distal fall-off, proton therapy offers dosimetric advantages over photon therapy. In head and neck cancer, proton therapy has been used for decades in the treatment of skull-base tum...
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Because of its sharp lateral penumbra and steep distal fall-off, proton therapy offers dosimetric advantages over photon therapy. In head and neck cancer, proton therapy has been used for decades in the treatment of skull-base tumors. In recent years the use of proton therapy has been extended to numerous other disease sites, including nasopharynx, oropharynx, nasal cavity and paranasal sinuses, periorbital tumors, skin, and salivary gland, or to reirradiation. The aim of this review is to present the physical properties and dosimetric benefit of proton therapy over advanced photon therapy; to summarize the clinical benefit described for each disease site; and to discuss issues of patient selection and cost-effectiveness. (C) 2017 Published by Elsevier Inc.
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Purpose. Intensity-modulated radiation therapy (IMRT) is the state-of-the-art treatment for patients with malignant pleural mesothelioma (MPM). The goal of this work was to assess whether intensity-modulated proton therapy (IMPT) ...
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Purpose. Intensity-modulated radiation therapy (IMRT) is the state-of-the-art treatment for patients with malignant pleural mesothelioma (MPM). The goal of this work was to assess whether intensity-modulated proton therapy (IMPT) could further improve the dosimetric results allowed by IMRT. Patients and methods. We re-planned 7 MPM cases using both photons and protons, by carrying out IMRT and IMPT plans. For both techniques, conventional dose comparisons and normal tissue complication probability (NTCP) analysis were performed. In 3 cases, additional IMPT plans were generated with different beam dimensions. Results. IMPT allowed a slight improvement in target coverage and clear advantages in dose conformity (p < 0.001) and dose homogeneity (p = 0.01). Better organ at risk (OAR) sparing was obtained with IMPT, in particular for the liver (Dmean reduction of 9.5 Gy, p = 0.001) and ipsilateral kidney (V20 reduction of 58%, p = 0.001), together with a very large reduction of mean dose for the contralateral lung (0.2 Gy vs 6.1 Gy, p = 0.0001). NTCP values for the liver showed a systematic superiority of IMPT with respect to IMRT for both the esophagus (average NTCP 14% vs. 30.5%) and the ipsilateral kidney (p = 0.001). Concerning plans obtained with different spot dimensions, a slight loss of target coverage was observed along with sigma increase, while maintaining OAR irradiation always under planning constraints. Conclusion. Results suggest that IMPT allows better OAR sparing with respect to IMRT, mainly for the liver, ipsilateral kidney, and contralateral lung. The use of a spot dimension larger than 3 x 3 mm (up to 9 x 9 mm) does not compromise dosimetric results and allows a shorter delivery time.
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Background: The aim of this study was to compare the dosimetric parameters, clinical complications, and efficacy of volumetric modulated arc therapy (VMAT) and fixed-field intensity-modulated radiotherapy (f-IMRT) in radical radio...
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Background: The aim of this study was to compare the dosimetric parameters, clinical complications, and efficacy of volumetric modulated arc therapy (VMAT) and fixed-field intensity-modulated radiotherapy (f-IMRT) in radical radiotherapy for cervical cancer without lymphadenectasis. Methods: 84 cervical cancer patients undergoing treatment with VMAT and f-IMRT were selected. Dose-volume histograms were used to evaluate the dose distribution in the planning target volume (PTV) and organs at risk. The clinical complications and efficacy were observed. Results: The homogeneity index (HI) and the conformity index (CI) of VMAT plans were both superior to the HI and CI of f-IMRT plans (p = 0.043, 0.025). VMAT plans resulted in a reduction in the V30 of the rectum and V40 of the bladder (p = 0.002). Furthermore, the monitor units (MUs) for VMAT were less than a quarter of those for f-IMRT. The treatment time for VMAT was less than a half of that for f-IMRT. Both clinical complications and efficacy showed no significant differences. Conclusion: VMAT plans showed superior dose coverage of the PTV, better protection of the rectum and bladder in dosimetry, and significantly reduced MUs and treatment time compared with f-IMRT. Clinical results were similar for both plans. (c) 2018 S. Karger GmbH, Freiburg
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Purpose: To define the roles of radiotherapy and chemotherapy on the risk of Grade 3+ mucositis during intensity-modulated radiation therapy (IMRT) for oropharyngeal cancer. Methods and Materials: 164 consecutive patients treated ...
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Purpose: To define the roles of radiotherapy and chemotherapy on the risk of Grade 3+ mucositis during intensity-modulated radiation therapy (IMRT) for oropharyngeal cancer. Methods and Materials: 164 consecutive patients treated with IMRT at two institutions in nonoverlapping treatment eras were selected. All patients were treated with a dose painting approach, three dose levels, and comprehensive bilateral neck treatment under the supervision of the same radiation oncologist. Ninety-three patients received concomitant chemotherapy (cCHT) and 14 received induction chemotherapy (iCHT). Individual information of the dose received by the oral mucosa (OM) was extracted as absolute cumulative dose-volume histogram (DVH), corrected for the elapsed treatment days and reported as weekly (w) DVH. Patients were seen weekly during treatment, and peak acute toxicity equal to or greater than confluent mucositis at any point during the course of IMRT was considered the endpoint. Results: Overall, 129 patients (78.7%) reached the endpoint. The regions that best discriminated between patients with/without Grade 3+ mucositis were found at 10.1 Gy/w (V10.1) and 21 cc (D21), along the x-axis and y-axis of the OM-wDVH, respectively. On multivariate analysis, D21 (odds ratio [OR] = 1.016, 95% confidence interval [CI], 1.009-1.023, p < 0.001) and cCHT (OR = 4.118, 95% CI, 1.659-10.217, p = 0.002) were the only independent predictors. However, V10.1 and D21 were highly correlated (rho = 0.954, p < 0.001) and mutually interchangeable. cCHT would correspond to 88.4 cGy/w to at least 21 cc of OM. Conclusions: Radiotherapy and chemotherapy act independently in determining acute mucosal toxicity; cCHT increases the risk of mucosal Grade 3 toxicity ≈4 times over radiation therapy alone, and it is equivalent to an extra ≈6.2 Gy to 21 cc of OM over a 7-week course.
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The present study intends to explore the influence of intensity-modulated radiation therapy on the quality of life for patients with nasopharyngeal carcinoma, which provides a theoretical basis and practical foundation for clinica...
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The present study intends to explore the influence of intensity-modulated radiation therapy on the quality of life for patients with nasopharyngeal carcinoma, which provides a theoretical basis and practical foundation for clinical practice. The present study randomly enrolled 130 cases of patients with nasopharyngeal carcinoma (NPC) in different stages who were admitted in The Second Affiliated Hospital of Fujian Medical University and the First Affiliated Hospital of Chongqing Medical University from September 2007 to August 2012, including 65 cases in IMRT group who received intensity-modulated radiation therapy and 65 cases in CRT group who received conventional radiation therapy. The prescribed dose in the target region of radical radiation therapy was 72 Gy/36 f; the prescribed dose in the target region at high risk was 60-64 Gy/30-32 f; the prescribed dose in the target region at low risk was 50-54 Gy/25-27 f and 2 Gy/f, with conventional fractionated irradiation of 1 f/d and 5 f/w. The data of the quality of life for patients with NPC who received intensity-modulated radiation therapy and conventional radiation therapy were collected and analyzed by filling in the questionnaire survey, including the Quality of Life Questionnaire of Head and Neck 35 (QLQ-H&N35) and Shot Form 36 Health Survey Questionnaire (SF-36). RP, VT, BP, SF, and RE scores in eight fields in SF-36 Scale were declined during the radiation therapy and risen again after radiation therapy, and those measured at 6 months after radiation therapy were higher than those before radiation therapy (all P < 0.05). The scores in IMRT group measured at two and six months after radiation therapy were all higher than those in CRT group (all P < 0.05). The scores of head and neck pain, pararthria, dysphagia, social difficulty, sensory difficulty, difficulty in feeding, xerostomia, cough, sticky saliva, and sensory discomfort during the radiation therapy were lower than those before radiation therapy (all P < 0.05). Except for the scores of sticky saliva and xerostomia, the other scores measured at 6 months after radiation therapy were all lower than those before radiation therapy, and the scores of dysphagia, sticky saliva, and xerostomia in MRT group were lower than those in CRT group (all P < 0.05). Conventional radiation therapy and intensity-modulated radiation therapy can cause a decline the quality of life for the patient with head and neck cancer, but intensity-modulated radiation therapy can improve local tumor control rate and significantly reduce the incidence of adverse reactions.
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