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... To achieve a given clinical goal using VMAT and DCAT embedded TPS, competitive plans can be generated for the same patient from different solutions with different dose distributions 11 . The variation in dose distribution can be quantified by the Conformity Index (CI) that attributes a score to measure the fitting between the prescription isodose volume and the target volume, the Gradient Index (GI) that shows the rapidness of dose decline beyond the target, and the Homogeneity Index (HI) that accounts for the uniformity of dose distribution in the target volume [12][13][14] . ...
This paper presents a clinical comparison of the target dose, normal tissue complication probability (NTCP), and plan quality between volumetric modulated conformal arc therapy (VMAT) against dynamic conformal arc therapy (DCAT) techniques to facilitate clinical decision-making in multiple brain metastases (MBM) treatment. A total of 11 cases having 33 lesions were recruited at the Union Oncology Centre, Union Hospital, Hong Kong SAR. With CT images available, all plans were optimized using both HyperArc (HA) and Brainlab Elements Multiple Brain Metastases (Elements MBM). Target coverage, normal tissue sparing, and dose distribution were compared pairwise between VMAT and DCAT. Results showed that the plans generated using both techniques achieved adequate target coverage to meet up with the oncologist’s prescription. With similar levels of NTCP, the normal brain received low doses of radiation using both techniques and the risk of brain necrosis was kept equally low. This indicated that VMAT and DCAT produced similar high-quality treatment plans with low risks of brain necrosis. Meanwhile, VMAT showed better homogeneity which could potentially be more useful for large targets, while DCAT showed better target conformity especially for targets smaller than 1 cc. In general, both HA and Elements MBM demonstrated ability to generate high-quality clinical plans.
... The higher the conformity index, the better the radiation dose is applied to the target, which means that the radiation dose is more effective in killing cancer cells and minimizing the effect on healthy tissue. This is important because applying an ineffective dose can increase the risk of side effects and worsen the outcome of therapy [8]. In addition, CI can ensure that tumor cells receive the optimal radiation dose while minimizing damage to the surrounding normal tissue. ...
One of the most prevalent cancers in both men and women is breast cancer. A number of choice therapy covers surgery, radiotherapy, chemotherapy, and hormonal therapy. Radiotherapy is typically used as a cancer treatment because it can eliminate cancer cells and aid in preventing cancer recurrence following surgery. Dose planning must be completed before irradiating the patient. Planning is carried out in a treatment planning system (TPS) with several available technique options. In this study, we chose intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) techniques. To determine the quality of the dose planning of these two techniques, a comparison of the heterogeneity index (HI) and conformity index (CI) parameters was carried out. The results of the comparison between IMRT and VMAT show that VMAT is superior to IMRT in terms of homogeneity and conformity. This is consistent with the HI results on VMAT showing a mean of 1.060 while IMRT shows a mean of 1.081. In addition, the CI results at VMAT showed a mean of 0.641 while IMRT showed a CI value of 0.519.
Published radiotherapy data for canine intraventricular tumours are limited. In this retrospective, longitudinal study (9/2011–2018), 11 dogs with intraventricular masses were treated with stereotactic radiotherapy (SRT). Pathologic diagnosis was available from surgery or necropsy in 6/11 cases, revealing choroid plexus papilloma (3) or carcinoma (2), and ependymoma (1). The remainder were magnetic resonance imaging (MRI)‐diagnosed as suspected choroid tumours or ependymomas. Tumours were located in the third or lateral ventricle (8), fourth ventricle (2), and cerebellopontine angle (1). Surgery was performed in three dogs prior to radiotherapy, and all showed gross residual/recurrent disease at treatment. Dogs received 8 Gray × 3 fractions (7), or 15 Gray × 1 fraction (4). Ten dogs were deceased at analysis, and one was living. The estimated median overall survival time (OS) from first SRT treatment was 16.9 months (515 days, 95% CI 33–1593 days). The survival time for two pathology‐diagnosed carcinoma dogs were 24 and 133 days, respectively, and survival time for dogs with moderate to marked ventriculomegaly (4/11) ranged from 24 to 113 days. A total of 10/11 showed clinical improvement per owner or clinician, but two had short‐lived benefits and were euthanized within 6 weeks of SRT. Limited conclusions on radiation‐specific complications are possible due to the small dataset and limited follow‐up imaging. This study provides preliminary evidence that radiotherapy outcomes are variable with intraventricular tumours, and some long‐term survivors are noted.
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