Irfan et al. This is an open access article distributed under the terms of the Creative Commons Attribution License CC-BY 4.0., which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Purpose: A comparative study was performed about the plan parameters and quality indices between volumetric arc therapy (VMAT) and intensity-modulated radiotherapy (IMRT) for the treatment of high-risk prostate cancer patients. The aim of this retrospective study was to compare the two methods of external beam radiotherapy IMRT and VMAT in terms of plan quality and efficacy. Material and method: Fifteen high-risk prostate patients were planned for radiotherapy using 6 MV photon. Three dose levels were contoured having Planning Tumour Volume 1 (PTV1 = 48 Gy), Planning Tumour Volume 2 (PTV2 = 57.6 Gy) and Planning Tumour Volume 3 (PTV3 = 60 Gy). Setup margins were given using the CHIP trial method. The prescribed PTV3 dose was 60 Gy in 20 fractions which is biologically equivalent to 74 Gy in 37 fractions using α/β = 3. In case of IMRT, seven fixed beam angles 30, 60, 105, 180, 255, 300 and 330 were used and the dose was optimised using the sliding window method. In case of rapid arc technique, one or two full arcs were used for dose optimisation while keeping all the dose constraints and other planning parameters same used in IMRT. The plan evaluation parameters and Organ at risks (OARs) doses were calculated using a dose volume histogram (DVH). Results: The average D2, D5, D95 and PTVmean for PTV3 were 61.22, 61.13, 58.12, 60.00 Gy and 62.41 62.24 59.53 61.12 Gy for IMRT and VMAT, respectively. The averages V60 for bladder and V30 for rectum were 22.81, 25 and 67, 65% for IMRT and VMAT, respectively. The average homogeneity index (HI), conformity index (CI) and gradient index (GI) were 1.04, 1.4833, 14.79 and 1.04, 1.704, 7.89 for IMRT and VMAT, respectively. Conclusion: VMAT takes less dose-delivery time and lesser number of monitoring units than IMRT, thus it compensates the intrafractional movements during dose delivery. The Dose GI in VMAT was much better than IMRT. This indicates sharper dose fall off near the normal tissue. No other major differences were observed in terms of plan evaluation parameters between IMRT and VMAT techniques. So, we conclude that VMAT technique is more efficient than IMRT in terms of plan quality and dose delivery.
The radiotherapy of left-sided breast cancers is challenging because of neighboring critical organs, posing an increased risk of complications. Various radiation delivery techniques have been used to deliver the desired dose of radiation to the target area while keeping the doses to nearby structures within constraints.The main aim of this study is to quantify doses delivered to the organs at risk (OARs) including heart, left lung, spinal cord, and contralateral breast, and to the planning target volume (PTV) using Field-in-Field (FIF) and Volumetric Modulated Arc Therapy (VMAT). Patients and methodsA retrospective review of 15 left-sided breast cancer patients was done. All the patients underwent breastconserving surgery and adjuvant radiation. For every patient, two different radiation treatment plans were formulated and compared for the PTV coverage and doses to OARs, including heart, ipsilateral lung, spinal cord, and contralateral breast.The radiation treatment techniques utilized for this purpose were FIF and VMAT. The homogeneity index (HI), and conformity index (CI) required for the treatment planning were also calculated. Data was analyzed using Statistical Package for the Social Sciences (IBM Corp., Armonk, USA). An Independent T-test was used for statistical analysis. ResultsThe mean age was 41 years and the majority of them were stage II. Total nine patients were given 4005centi Gray (cGy) in 15 fractions (fr) followed by 10Gy boost, hence receiving a total dose of 5005cGy in 20fr. While remaining six patients were given a total dose 4005cGy in 15fr without any boost.All patients were hypofractionated and the dose was delivered at a rate of 267cGy per fr. The FIF technique utilized in breast cancer radiation significantly reduced the mean doses to OARs: mean heart dose (3.81cGy), ipsilateral lung dose (V16-15cGy), mean contralateral breast dose (0.03cGy), and maximum spinal cord dose (0.18cGy); as compared to VMAT technique which delivered comparatively higher doses: mean heart dose (8.85cGy), ipsilateral lung dose (V16-19.82cGy), mean contralateral breast dose (4.59cGy), and maximum spinal cord dose (7.14cGy).There was a significant mean difference between doses of OARs and all p-values were statistically significant (p<0.005). Moreover, the FIF technique also improves the dose distribution of PTV in terms of dose homogeneity. However, the conformity index is more enhanced with VMAT as opposed to FIF. ConclusionThe FIF technique is more advantageous than the VMAT planning technique because it provides better dose distribution in terms of PTV coverage and significantly lower doses to OARs in radiotherapy to left-sided breast cancer.
Mirels' scoring system quantifies the risk of sustaining a pathologic fracture in osseous metastases of weight bearing long bones. Conventional Mirels' scoring is based on radiographs. Our pilot study proposes Tc MDP bone SPECT-CT based modified Mirels' scoring system and its comparison with conventional Mirels' scoring. Cortical lysis was noted in 8(24%) by SPECT-CT versus 2 (6.3%) on X-rays. Additional SPECT-CT parameters were; circumferential involvement [1/4 (31%), 1/2 (3%), 3/4 (37.5%), 4/4 (28%)] and extra-osseous soft tissue [3%]. Our pilot study suggests the potential role of SPECT-CT in predicting risk of fracture in osseous metastases.
Purpose: The purpose of this study was to assess the outcomes in glioblastoma patients treated with hypofractionated radiotherapy.Materials and Methods: We reviewed all glioblastoma patients treated at our specialist cancer centre over 7 and a 1⁄2 years using hypofractionated radiotherapy (HRT) postoperatively. The HRT regimen was 48 Gy given at 3 Gy/ fractions in 16 fractions. We calculated overall survival using time to event analyses. Results: A total of 62 patients were identi ed of whom 44 (71%) were male. The median age of these patients was 50 years (range: 20–71 years). Eastern Cooperative Oncology Group (ECOG) performance status was 0 in 47 (76%) and 1 in 15 (24%) patients. 7 (11%) of the patients underwent gross total resection, 52 (83%) had subtotal resection and 3 (5%) had a biopsy only. Response assessment on magnetic resonance imaging at 3-month post-HRT showed that 14 (22%) patients had regression, 21 (34%) were stable and 22 (35%) had a progressive primary tumour. 5 (8%) patients were lost to follow up. With a median follow-up of 7.8 months, the median overall survival was 9 months. Patients with ECOG-0 showed a median survival of 7 months as compared to 6 months for those with ECOG-1. Patients with stable or partial response showed a median overall survival of 8 months in comparison to 6 months for those with progressive disease. There were no signi cant differences in median survival based on the extent of surgery. A Cox multivariate model con rmed signi cant correlation of age and response to radiotherapy with survival. Conclusion: HRT consisting of 48 Gy in 3 weeks can be used for selected glioblastoma patients to reduce the overall treatment time of conventional radiotherapy by 35–40% without apparent increased toxicity or decrement in survival in a low resource environment. Key words: Chemoradiation, glioblastoma, hypofractionated radiotherapy, survival
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