Target coverage and local recurrences after radiotherapy for sinonasal cancer in Denmark 2008–2015. A DAHANCA study

Purpose: To evaluate the usefulness of helical tomotherapy (HT) in the treatment of advanced esophageal cancer (EC) and compare target homogeneity, conformity and normal tissue doses between HT and fixed-field intensity-modulated radiotherapy (ff-IMRT).Methods: In all, 23 patients with cT3-4N0-1M0-1a thoracic EC (upper esophagus, 9 patients; middle esophagus, 6; distal esophagus, 6 and esophagogastric junction, 2) who were treated with ff-IMRT (60 Gy in 30 fractions) were re-planned for HT and ff-IMRT with the same clinical requireÂments. Comparisons were performed using the Wilcoxon matched-pair signed-rank test.Results: Compared with ff-IMRT, HT significantly reduced the homogeneity index for thoracic, upper, middle and distal ECs by 38%, 31%, 36% and 33%, respectively (P < 0.05). The conformity index was increased by HT for thoracic, upper and middle ECs by 9%, 9% and 18%, respectively (P < 0.05). Target coverage was improved by 1% with HT (P < 0.05). The mean lung dose was significantly reduced by HT for thoracic and upper ECs (P < 0.05). The V20 (volume receiving at least 20 Gy) and higher dose volumes of the lungs were decreased by HT in all cases, but the differences were significant for thoracic, upper and distal ECs (P < 0.05), with reductions of 2.1%, 3.1% and 2.2%, respectively. HT resulted in a larger lung V5 for thoracic, upper, middle and distal ECs, with increases of 3.5%, 1.5%, 7.2% and 3.2%, respectively. Heart sparing was significantly better with HT than with ff-IMRT in terms of the V30 and V40 for thoracic, upper, middle and distal ECs (P < 0.05).Conclusions: Compared to ff-IMRT, HT provides superior target coverage, conformity and homogeneity, with reduced the volume of high doses to the lungs and heart for advanced EC. HT may be a treatment option for advanced EC, especially upper EC.

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Use of hybrid shots in planning Perfexion Gamma Knife treatments for lesions close to critical structures

Journal of Neurosurgery ◽

10.3171/jns/2008/109/12/s7 ◽

2008 ◽

Vol 109 (Supplement) ◽

pp. 34-40 ◽

Cited By ~ 13

Author(s):

Paula L. Petti ◽

David A. Larson ◽

Sandeep Kunwar

Keyword(s):

Optic Nerve ◽

Gamma Knife ◽

Pituitary Tumor ◽

Metastatic Lesion ◽

Conformity Index ◽

Target Coverage ◽

Critical Areas ◽

Planning Technique ◽

Small Targets ◽

Critical Structure

Object The authors investigated the use of different collimator values in different sectors (hybrid shots) when treating patients with lesions close to critical structures with the Perfexion model Gamma Knife. Methods Twelve patients with various tumors (6 with a pituitary tumor, 3 with vestibular schwannoma, 2 with meningioma, and 1 with metastatic lesion) that were within 4 mm of the brainstem, optic nerve, pituitary stalk, or cochlea were considered. All patients were treated at the authors' institution between June 2007 and March 2008. The patients' treatments were replanned in 2 different ways. In the first plan, hybrid shots were used such that the steepest dose gradient was aligned with the junction between the target and the critical structure(s). This was accomplished by placing low-value collimators in appropriate sectors. In the second plan, no hybrid shots were used. Sector blocking (either manual or dynamic) was required for all plans to reduce the critical structure doses to acceptable levels. Prescribed doses ranged from 12 to 30 Gy at the periphery of the target. The plans in each pair were designed to be equally conformal in terms of both target coverage (as measured by the Paddick conformity index) and critical structure sparing. Results The average number of shots required was roughly the same using either planning technique (16.7 vs 16.6 shots with and without hybrids). However, for all patients, the number of blocked sectors required to protect critical areas was larger when hybrid shots were not used. On average, nearly twice as many blocked sectors (14.8 vs 7.0) were required for the plans that did not use hybrid shots. The number of high-value collimators used in each plan was also evaluated. For small targets (≤ 1 cm3), for which 8 mm was considered a high value for the collimator, plans employing hybrids used an average of 2.3 times as many 8-mm sectors as did their nonhybrid counterparts (7.4 vs 3.2 sectors). For large targets (> 1 cm3), for which 16 mm was considered a high value for the collimator, hybrid plans used an average of 1.4 times as many 16-mm sectors as did the plans without hybrids (10.7 vs 7.7 sectors). Decreasing the number of blocked sectors and increasing the number of high-value collimator sectors led to use of shorter beam-on times. Beam-on times were 1–39% higher (average 17%) when hybrid shots were not allowed. The average beam-on time for plans with and without hybrid shots was 67.4 versus 78.4 minutes. Conclusions The judicious use of hybrid shots in patients for whom the target is close to a critical structure is an efficient way to achieve conformal treatments while minimizing the beam-on time. The reduction in beam-on time with hybrid shots is attributed to a reduced use of blocked sectors and an increased number of high-value collimator sectors.

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Faculty Opinions recommendation of Prostate cancer transrectal HIFU ablation: detection of local recurrences using T2-weighted and dynamic contrast-enhanced MRI.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1165531.628533 ◽

2009 ◽

Author(s):

Uri Lindner

Keyword(s):

Prostate Cancer ◽

Dynamic Contrast Enhanced Mri ◽

Hifu Ablation ◽

Dynamic Contrast Enhanced ◽

Local Recurrences ◽

Enhanced Mri ◽

Contrast Enhanced ◽

Contrast Enhanced Mri

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LOCAL RECURRENCES AFTER THE TREATMENT OF SOFT TISSUE MALIGNANT FIBROUS HISTIOCYTOMA (UNCLASSIFIEDPLEOMORPHIC SARCOMA) OF THE LIMBS

Wiadomości Lekarskie ◽

10.36740/wlek201908120 ◽

2019 ◽

Vol 72 (8) ◽

pp. 1523-1526

Author(s):

Oleksandr O. Lytvynenko ◽

Volodymyr F. Konovalenko ◽

Anton Yu. Ryzhov

Keyword(s):

Soft Tissue ◽

Malignant Fibrous Histiocytoma ◽

Fibrous Histiocytoma ◽

Survival Rates ◽

Soft Tissue Sarcomas ◽

Primary Treatment ◽

Radical Excision ◽

Local Recurrences ◽

Results Of Treatment

Introduction: The treatment of patients with malignant fibrous histiocytoma as well as other soft tissue sarcomas is not sufficiently effective up to date, and has largely changed and reflects the alterations, occurred in oncology as a whole. The number of amputation decreased over the last 10-15 years. Some researchers associate the improvement of treatment outcomes with the development of combined and complex methods. The aim of the study is an improvement of the results of treatment of patients with soft tissue malignant histiocytoma on the basis of determination of factors, influencing local recurrence development. Materials and methods: The basis of our study was a comprehensive analysis of examination and treatment results of 130 patients with MFH of the soft tissue of limbs, of them in 84 patients (64.6%) the recurrences developed. The group included 45 (53.6%) males and 39 (46.4%) females. The major part of patients – 82.1% (60 patients) were older than 40 years. Results and conclusions: The number of recurrences after the treatment in general surgical facilities is 86.9%, whereas in the patients after the treatment in the specialized oncological facilities this figure is twice lower (40%). The characteristic of the medical facility where the patient receives his/her primary treatment largely affects the development of local recurrences, patients’ quality of life and overall survival rates. The surgical method remains the leading modality in the treatment of MFH of ST. Wide and radical excision of tumors in the specialized oncological facilities allows achieving better survival outcomes of the patients.

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The effect of beam divergence on target coverage

Medical Dosimetry ◽

10.1016/s0958-3947(99)00009-6 ◽

1999 ◽

Vol 24 (2) ◽

pp. 99-113 ◽

Cited By ~ 2

Author(s):

Gunilla C. Bentel ◽

Lawrence B. Marks ◽

Mitchell S. Anscher

Keyword(s):

Beam Divergence ◽

Target Coverage

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Dosimetric comparison of MR-linac-based IMRT and conventional VMAT treatment plans for prostate cancer

Radiation Oncology ◽

10.1186/s13014-021-01858-7 ◽

2021 ◽

Vol 16 (1) ◽

Author(s):

Vanessa Da Silva Mendes ◽

Lukas Nierer ◽

Minglun Li ◽

Stefanie Corradini ◽

Michael Reiner ◽

...

Keyword(s):

Prostate Cancer ◽

Target Volume ◽

Planning System ◽

Treatment Planning System ◽

Target Coverage ◽

Treatment Delivery ◽

Ptv Margin ◽

Delivery Times ◽

Low Field ◽

Treatment Plans

Abstract Background The aim of this study was to evaluate and compare the performance of intensity modulated radiation therapy (IMRT) plans, planned for low-field strength magnetic resonance (MR) guided linear accelerator (linac) delivery (labelled IMRT MRL plans), and clinical conventional volumetric modulated arc therapy (VMAT) plans, for the treatment of prostate cancer (PCa). Both plans used the original planning target volume (PTV) margins. Additionally, the potential dosimetric benefits of MR-guidance were estimated, by creating IMRT MRL plans using smaller PTV margins. Materials and methods 20 PCa patients previously treated with conventional VMAT were considered. For each patient, two different IMRT MRL plans using the low-field MR-linac treatment planning system were created: one with original (orig.) PTV margins and the other with reduced (red.) PTV margins. Dose indices related to target coverage, as well as dose-volume histogram (DVH) parameters for the target and organs at risk (OAR) were compared. Additionally, the estimated treatment delivery times and the number of monitor units (MU) of each plan were evaluated. Results The dose distribution in the high dose region and the target volume DVH parameters (D98%, D50%, D2% and V95%) were similar for all three types of treatment plans, with deviations below 1% in most cases. Both IMRT MRL plans (orig. and red. PTV margins) showed similar homogeneity indices (HI), however worse values for the conformity index (CI) were also found when compared to VMAT. The IMRT MRL plans showed similar OAR sparing when the orig. PTV margins were used but a significantly better sparing was feasible when red. PTV margins were applied. Higher number of MU and longer predicted treatment delivery times were seen for both IMRT MRL plans. Conclusions A comparable plan quality between VMAT and IMRT MRL plans was achieved, when applying the same PTV margin. However, online MR-guided adaptive radiotherapy allows for a reduction of PTV margins. With a red. PTV margin, better sparing of the surrounding tissues can be achieved, while maintaining adequate target coverage. Nonetheless, longer treatment delivery times, characteristic for the IMRT technique, have to be expected.

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Impact of Geometric Uncertainties on Dose Distribution During Intensity Modulated Radiotherapy of Head-and-neck Cancer: The Need for a Planning Target Volume and A Planning Organ-at-Risk Volume

Current Oncology ◽

10.3390/curroncol13030010 ◽

2006 ◽

Vol 13 (3) ◽

pp. 108-115 ◽

Cited By ~ 1

Author(s):

O. Ballivy ◽

W. Parker ◽

T. Vuong ◽

G. Shenouda ◽

H. Patrocinio

Keyword(s):

Spinal Cord ◽

At Risk ◽

Neck Cancer ◽

Intensity Modulated Radiotherapy ◽

Target Volume ◽

Ct Scans ◽

Target Coverage ◽

Geometric Uncertainties ◽

Intensity Modulated ◽

Organ At Risk

We assessed the effect of geometric uncertainties on target coverage and on dose to the organs at risk (OARS) during intensity-modulated radiotherapy (IMRT) for head-and-neck cancer, and we estimated the required margins for the planning target volume (PTV) and the planning organ-at-risk volume (PRV). For eight headand- neck cancer patients, we generated IMRT plans with localization uncertainty margins of 0 mm, 2.5 mm, and 5.0 mm. The beam intensities were then applied on repeat computed tomography (CT) scans obtained weekly during treatment, and dose distributions were recalculated. The dose–volume histogram analysis for the repeat CT scans showed that target coverage was adequate (V100 ≥ 95%) for only 12.5% of the gross tumour volumes, 54.3% of the upper-neck clinical target volumes (CTVS), and 27.4% of the lower-neck CTVS when no margins were added for PTV. The use of 2.5-mm and 5.0-mm margins significantly improved target coverage, but the mean dose to the contralateral parotid increased from 25.9 Gy to 29.2 Gy. Maximum dose to the spinal cord was above limit in 57.7%, 34.6%, and 15.4% of cases when 0-mm, 2.5-mm, and 5.0-mm margins (respectively) were used for PRV. Significant deviations from the prescribed dose can occur during IMRT treatment delivery for headand- neck cancer. The use of 2.5-mm to 5.0-mm margins for PTV and PRV greatly reduces the risk of underdosing targets and of overdosing the spinal cord.

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The impact of tumour regression in locally advanced carcinoma cervix during external beam radiotherapy and the need for adaptive planning

10.1055/s-0039-1685287 ◽

2016 ◽

Keyword(s):

Ct Scan ◽

Locally Advanced ◽

Target Volume ◽

Ct Images ◽

Tumour Regression ◽

Target Coverage ◽

Carcinoma Cervix ◽

Advanced Carcinoma ◽

The Impact ◽

Planning Ct

Aim: To study the impact of tumour regression occurring during IMRT for locally advanced carcinoma cervix and study dose distribution to target volume and OARs and hence the need for any replanning. Materials and Methods: 40 patients undergoing IM-IGRT and weekly chemotherapy were included in the study. After 36 Gy, a second planning CT-scan was done and target volume and OARs were recontoured. First plan (non-adaptive) was compared with second plan (adaptive plan) to evaluate whether it would still offer sufficient target coverage to the CTV and spare the OARs after having delivered 36 Gy. Finally new plan was created based on CT-images to investigate whether creating a new treatment plan would optimize target coverage and critical organ sparing. To measure the response of the primary tumour and pathologic nodes to EBRT, the differences in the volumes of the primary GTV and nodal GTV between the pretreatment and intratreatment CT images was calculated. Second intratreatment IMRT plans was generated, using the delineations of the intratreatment CT images. The first IMRT plan (based on the first CT-scan or non adaptive plan) was compared with second IMRT plan (based on the second CT-scan or adaptive plan). Results: 35% patients had regression in GTV in the range of 4.1% to 5%, 20% in the range of 1.1%-2%, 15% in the range of 2.1%-3% and 20% in the range of 6%-15%. There was significant mean decrease in GTV of 4.63 cc (p=0.000). There was a significant decrease in CTV on repeat CT done after 36 Gy by 23.31 cc (p=0.000) and in PTV by 23.31 cc (p=0.000). There was a statistically significant increase in CTV D98, CTV D95, CTV D50 and CTV D2 in repeat planning CT done after 36 Gy. There was no significant alteration in OARs doses. Conclusion: Despite tumour regression and increased target coverage in locally advanced carcinoma cervix after a delivery of 36 Gy there was no sparing of OARs. Primary advantage of adaptive RT seems to be in greater target coverage with non-significant normal tissue sparing.

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