Comparison of Acute Toxicities, Overall Treatment Time and Quality of Life in Head and Neck Cancer Patients Treated with IMRT and Helical Tomotherapy.

INTRODUCTION: Technical innovations in radiation therapy treatment planning and delivery over the last two decades have changed the practice of radiation therapy dramatically. The benefit of improved dose homogeneity and better sparing of critical structures in helical tomotherapy compared with conventional linac-based IMRT has been reported. This study was conducted to compare acute toxicities (skin, mucous membrane, salivary gland and hematological) during treatment and overall treatment time in Head and Neck Cancer patients treated with IMRT and Helical Tomotherapy and to assess the quality of life of patients during treatment between two groups. MATERIALS AND METHODS: The study involved thirty patients with histologically proven Squamous cell carcinomas of Head and Neck. They were treated with concurrent chemoradiotherapy, to a dose of 60-70 Gray in 30-35 fractions. The study consists of 2 arms which are standard IMRT and Tomotherapy arm. Fifteen consecutive patients were treated under IMRT and 15 patients were treated under Helical tomotherapy, along with concurrent chemotherapy. After completion of planning, plans were evaluated and dose to the targets, organs at risk were tabulated. Patients were assessed weekly for acute toxicities (skin reactions, mucositis, xerostomia, haematological toxicities) during the course of the treatment as per RTOG criteria. Quality of life of patients were assessed using FACT/ NCCN HNSI questionnaire in local language at day 1, day 21 and at completion of radiotherapy. RESULTS: Grade 2-3 skin reactions, mucositis, anemia, leukopenia and thrombocytopenia were predominant in both arms. Treatment time from start of radiotherapy to completion of radiotherapy varied from 39 days to 68 days. Majority of patients completed radiotherapy within 50-56 days. Mean quality of life score did not show much difference between IMRT and tomotherapy arms. CONCLUSION: The study did not show any statistically significant difference in overall treatment time, acute toxicities- skin reactions, xerostomia, mucositis& hematological toxicities and quality of life of patients during radiotherapy between IMRT and Helical Tomotherapy. Dosimetric benefits of Tomotherapy over IMRT do not translate into clinical benefit in terms of reduced acute toxicities, lesser overall treatment time and better quality of life of patients. KEY WORDS: Head and Neck Carcinoma, IMRT, Tomotherapy, RTOG, toxicity, FACT/ NCCN HNSI, quality of life.

An experimental investigation on the effect of beam angle optimization on the reduction of beam numbers in IMRT of head and neck tumors.

In static intensity-modulated radiation therapy (IMRT), the fundamental factors that determine the quality of a plan are the number of beams and their angles. The objective of this study is to investigate the effect of beam angle optimization (BAO) on the beam number in IMRT. We used six head and neck cases to carry out the study. Basically the methodology uses a parameter called "Beam Intensity Profile Perturbation Score" (BIPPS) to determine the suitable beam angles in IMRT. We used two set of plans in which one set contains plans with equispaced beam configuration starting from beam numbers 3 to 18, and another set contains plans with optimal beam angles chosen using the in-house BAO algorithm. We used quadratic dose-based single criteria objective function as a measure of the quality of a plan. The objective function scores obtained for equispaced beam plans and optimal beam angle plans for six head and neck cases were plotted against the beam numbers in a single graphical plot for effective comparison. It is observed that the optimization of beam angles reduces the beam numbers required to produce clini-cally acceptable dose distribution in IMRT of head and neck tumors. Especially N0.1 (represents the beam number at which the objective function reaches a value of 0.1) is considerably reduced by beam angle optimization in almost all the cases included in the study. We believe that the experimental findings of this study will be helpful in understanding the interplay between beam angle optimization and beam number selection process in IMRT which, in turn, can be used to improve the performance of BAO algorithms and beam number selection process in IMRT.

A hybrid algorithm for instant optimization of beam weights in anatomy-based intensity modulated radiotherapy: A performance evaluation study.

The study aims to introduce a hybrid optimization algorithm for anatomy-based intensity modulated radiotherapy (AB-IMRT). Our proposal is that by integrating an exact optimization algorithm with a heuristic optimization algorithm, the advantages of both the algorithms can be combined, which will lead to an efficient global optimizer solving the problem at a very fast rate. Our hybrid approach combines Gaussian elimination algorithm (exact optimizer) with fast simulated annealing algorithm (a heuristic global optimizer) for the optimization of beam weights in AB-IMRT. The algorithm has been implemented using MATLAB software. The optimization efficiency of the hybrid algorithm is clarified by (i) analysis of the numerical characteristics of the algorithm and (ii) analysis of the clinical capabilities of the algorithm. The numerical and clinical characteristics of the hybrid algorithm are compared with Gaussian elimination method (GEM) and fast simulated annealing (FSA). The numerical characteristics include convergence, consistency, number of iterations and overall optimization speed, which were analyzed for the respective cases of 8 patients. The clinical capabilities of the hybrid algorithm are demonstrated in cases of (a) prostate and (b) brain. The analyses reveal that (i) the convergence speed of the hybrid algorithm is approximately three times higher than that of FSA algorithm; (ii) the convergence (percentage reduction in the cost function) in hybrid algorithm is about 20% improved as compared to that in GEM algorithm; (iii) the hybrid algorithm is capable of producing relatively better treatment plans in terms of Conformity Index (CI) [~ 2% - 5% improvement] and Homogeneity Index (HI) [~ 4% - 10% improvement] as compared to GEM and FSA algorithms; (iv) the sparing of organs at risk in hybrid algorithm-based plans is better than that in GEM-based plans and comparable to that in FSA-based plans; and (v) the beam weights resulting from the hybrid algorithm are about 20% smoother than those obtained in GEM and FSA algorithms. In summary, the study demonstrates that hybrid algorithms can be effectively used for fast optimization of beam weights in AB-IMRT.

Performance evaluation of an algorithm for fast optimization of beam weights in anatomy-based intensity modulated radiotherapy.

This study aims to evaluate the performance of a new algorithm for optimization of beam weights in anatomy-based intensity modulated radiotherapy (IMRT). The algorithm uses a numerical technique called Gaussian-Elimination that derives the optimum beam weights in an exact or non-iterative way. The distinct feature of the algorithm is that it takes only fraction of a second to optimize the beam weights, irrespective of the complexity of the given case. The algorithm has been implemented using MATLAB with a Graphical User Interface (GUI) option for convenient specification of dose constraints and penalties to different structures. We have tested the numerical and clinical capabilities of the proposed algorithm in several patient cases in comparison with KonRad((R)) inverse planning system. The comparative analysis shows that the algorithm can generate anatomy-based IMRT plans with about 50% reduction in number of MUs and 60% reduction in number of apertures, while producing dose distribution comparable to that of beamlet-based IMRT plans. Hence, it is clearly evident from the study that the proposed algorithm can be effectively used for clinical applications.

An algorithm for fast beam angle selection in intensity modulated radiotherapy.

PURPOSE: This article aims to introduce a novel algorithm for fast beam angle selection in intensity modulated radiotherapy (IMRT). METHODS: The algorithm models the optimization problem as a beam angle ranking problem and chooses suitable beam angles according to their rank. A new parameter called "beam intensity profile perturbation score (BIPPS)" is used for ranking the beam angles. The BIPPS-based beam angle ranking implicitly accounts for the dose-volume effects of the involved structures. A simulated phantom case with obvious optimal beam angles is used to verify the validity of the presented technique. In addition, the efficiency of the algorithm was examined in three clinical cases (prostate, pancreas, and head and neck) in terms of DVH and dose distribution. In all cases, the judgment of the algorithm's efficiency was based on the comparison between plans with equidistant beams (equal-angle-plan) and plans with beams obtained using the algorithm (suitable-angle-plan). RESULTS: It is observed from the study that the beam angle ranking function over BIPPS instantly picks up a suitable set of beam angles for a specific case. It takes only about 15 min for choosing the suitable beam angles even for the most complicated cases. The DVHs and dose distributions confirm that the proposed algorithm can efficiently reduce the mean or maximum dose to OARs, while guaranteeing the target coverage and dose uniformity. On the average, about 17% reduction in the mean dose to critical organs, such as rectum, bladder, kidneys and parotids, is observed. Also, about 12% (averaged) reduction in the maximum dose to critical organs (spinal cord) is observed in the clinical cases presented in this study. CONCLUSIONS: This study demonstrates that the algorithm can be effectively applied to IMRT scenarios to get fast and case specific beam angle configurations.

Dose escalation in image-guided, intensity-modulated radiotherapy of carcinoma prostate: initial experience in India.

BACKGROUND: Increasing incidence and significant stage migration from distant metastases to a localized disease, due to screening application of PSA, is taking place in carcinoma prostate. Also, role of radiotherapy is increasing in carcinoma prostate due to rapid strides in technology. AIM: The present retrospective study, evaluates escalating the dose in the treatment of localized carcinoma prostate using integration of multiple advanced techniques. SETTINGS AND DESIGN: The settings designed are: a) use of gold seed internal fiducial markers: b) clinical application of emerging Megavoltage Cone Beam Computed Tomography (MVCBCT) technology for Image Guided Radiotherapy (IGRT); c) Intensity Modulated Radiotherapy (IMRT); d) adopting biochemical method for follow-up. METHODS AND MATERIAL: Twelve consecutive, biopsy proven localized cancer of prostate patients, treated with dose escalation IMRT & IGRT protocol between August 2006 and January 2008, were analyzed. Gold seed markers in prostate were used for daily localization with MVCBCT or Electronic Portal Imaging (EPI). All patients underwent clinical and biochemical follow-up. STATISTICAL ANALYSIS & RESULTS: Planned dose of 7740 cGy was delivered in 10 out of 12 patients (83%). While one patient had migration of maximum of 3 mm, two others had 1 mm migration of one seed during course of treatment. One patient (8%) developed Grade II proctitis at 12th month. During the mean follow-up duration of 12.2 months, 92% (11/12) had biochemical control within 3 months of treatment. CONCLUSIONS: IGRT technique using MVCBCT for implanted fiducial gold seed localization was feasible for IMRT dose escalation in carcinoma prostate with excellent results.