Dosimetric Comparison of Different Dose Calculation Algorithms in Postmastectomy Breast Cancer Patients Using Conformal Planning Techniques.

Background: The aim of the current study was to compare three different dose-calculating algorithms, i.e., superposition (SP), fast SP (FSP), and convolution (CV), for breast cancer patients treated with intensity-modulated radiotherapy (IMRT) and field-in-Field forward plan IMRT (FiF-FP-IMRT). Materials and Methods: The current retrospective study involved 100 postmastectomy breast cancer patients who were given radiotherapy using IMRT and FiF-FP-IMRT planning techniques. All the initially SP-calculated plans were recalculated with the same monitor units for FSP and CV algorithm without change in any of the other planning parameters. The isodose distribution and various plan evaluating parameters, for example, conformity index (CI), homogeneity index, and uniformity index target volume and normal structure doses were compared and analyzed for all the different algorithm calculated plans. Results: In the IMRT plans, all the target and normal structure dose-volume parameters showed a significant difference between all the three different algorithms with P < 0.05. In the FiF-FP-IMRT plans, CV algorithm showed a significant difference in most of the target and normal structure dose-volume parameters. Among quality indexes, only CI showed a significant difference between all the algorithms in both the planning techniques. R50 showed a significant difference with the CV algorithm in both the planning techniques. Conclusion: The change in the dose calculation algorithm resulted in dosimetric changes which must be evaluated by the medical physicists and oncologists while evaluating treatment plans. In the current study with breast patients, the results obtained for target and normal structure doses using the CV algorithm are overestimated as compared to SP and FSP algorithms, producing variable results in air and bony normal structures. However, the ipsilateral lung V5 parameter and the ipsilateral humeral head mean dose were found to be underestimated by the CV algorithm as compared to the SP and FSP algorithm in both the planning techniques.

Dose Agreement Analysis of Treatment Planning System-Calculated Doses and Markus Chamber-Measured Doses in the Near-Surface Region for Breast Cancer Patients' Conformal Treatment Plans.

Background: Surface/skin dose measurement is one of the most challenging tasks for clinical dosimetry in radiotherapy and comparison with almost all the commercially available treatment planning systems (TPSs) brings a significant variation with the measured dose. Aims and Objectives: In the current study, doses calculated from the TPS in the near-surface region for conformal plans (both three-dimensional conformal radiotherapy [3DCRT] and intensity-modulated radiotherapy [IMRT]) of 35 breast cancer patients were evaluated and compared with the doses measured with Markus chamber. Materials and Methods: The computed tomography (CT) images of a solid water slab phantom with a Markus chamber (at different depths ranging from 1 mm to 5 mm from the surface) were taken and imported into the TPS. All the conformal treatment plans made in TPS were executed on a linear accelerator and dose agreements between TPS calculated and chamber measured doses were analysed. Results: Results showed that this TPS underestimated the calculated doses in the superficial region by up to 26% and 21%, respectively, with respect to mean and maximum dose values obtained within the effective volume of the chamber used. Conclusion: The uncertainty of doses in the superficial region should be kept in mind when evaluating treatment plans for superficial tumours in TPS.

Dosimetric and radiobiological evaluation of treatment plan for cervical cancer high-dose-rate intracavitary brachytherapy.

Purpose: The purpose of the study was to consider and calculate dosimetric parameters during treatment planning to improve radiobiological outcomes for cervical cancer patients treated with high-dose-rate (HDR) intracavitary brachytherapy (ICBT). Material and methods: In the present study, dose volume histograms (DVH) of 30 cervical cancer patients treated with HDR brachytherapy using computer tomography (CT)-based planning were analyzed. High-risk clinical target volume (HR-CTV) was contoured as the main target volume for all the patients, with an assumption that there was no presence of gross tumor at the time of brachytherapy. Values of target coverage volumes (100%, 150%, and 200%) were obtained from DVH, which was used to calculate different quality indices (QIs), including coverage index (CI), dose homogeneity index (DHI), overdose volume index (ODI), and dose non-uniformity ratio (DNR). Values of these QIs were further used to calculate tumor control probability (TCP). Statistical correlation between all QIs with TCP was established. Also, normal tissue complication probabilities for bladder (NTCP_B) and rectum (NTCP_R) were calculated. Results: The mean values of the various calculated parameters, including CI, DHI, ODI, DNR, TCP, NTCP_B and NTCP_R were 0.92 ±0.07, 0.26 ±0.10, 0.50 ±0.10, 0.74 ±0.10, 0.92 ±0.07, 0.08 ±0.25, and 0.36 ±0.27, respectively. Pearson's product moment correlation coefficient between CI, DHI, ODI, and DNR with regards to TCP was +0.85, -0.85, +0.84, and +0.85, respectively. Conclusions: The correlation between dosimetric and radiobiological parameters was found statistically significant, which shows the influence of dosimetric parameters on the radiobiological outcome. Therefore, these parameters should be considered during the treatment planning to improve the radiobiological outcome.

Analysis of Clinical, Radiographic, and Treatment Profile of 10 Cases of Neurogenic Tumors and Tumor-Like Lesions of the Oral and Maxillofacial Region: An Observational Study.

BACKGROUND: Soft tissues of the head and neck areas are a very frequent site of occurrence of certain benign tumors of the peripheral nerve sheath, especially the neurofibromas. Hence, the present study was conducted for assessing clinical, radiographic, and treatment profile of 10 cases of neurogenic tumors and tumor-like lesions of the oral and maxillofacial region. MATERIALS AND METHODS: Data records of a total of 10 patients who were diagnosed with tumors of neurogenic origin were enrolled in the present study. Data files were analyzed over a time period of 2 years, and complete clinical and radiographic details were evaluated. All the patients in which incomplete information was present in the record files were excluded from the present study. The assessment of the histopathologic reports was done, and final diagnosis was recorded separately in the master chart. RESULTS: Neurofibroma was the diagnosis in two cases. In another set of two cases, final diagnosis of traumatic neuroma was achieved. A single case Schwannoma of mandible depicting multilocular radiolucency was present. Granular cell tumor was present in three cases. It was present clinically in the form of swelling, ulcerative nodule, and nodular growth in the three respective cases. Surgical excision was carried out in all the cases, and follow-up records did not depict any case of recurrence of complication posttreatment. CONCLUSION: Neurogenic tumors of oral and maxillafacial region are a rare phenomenon and mainly present in the form of benign neoplasm. However, careful recognition and diagnosis of these lesions are necessary to rule any possible malignant changes.

To Evaluate the Role of Positron Emission Tomography-Computerized Tomography in Initial Staging of Carcinoma Breast.

BACKGROUND: Breast cancer is the most common cancer in urban and second common in rural Indian women. In India, in spite of the best treatment available being given to the patients they lose their lives because of paucity of diagnostic aids and lack of an organized breast cancer screening program. Early detection, accurate staging, and initiation of appropriate therapy are the key factors for improving the treatment outcome and prognosis of the disease for the patients. Traditional staging methods include clinical examination, blood tests, chest X-ray, ultrasound of the abdomen, and/or skeletal survey. As these tests lack sensitivity and specificity, these are being scaled down. The hybrid positron emission tomography-computerized tomography (PET-CT) is a unique tool in the field of imaging modalities that combines the effectiveness of PET and CT. This study was undertaken to assess the efficacy and accuracy of PET-CT as a single-session staging modality in the very initial stage itself and if it can replace the conventional means of staging. METHODS: This was a cross-sectional study conducted in the Radiotherapy department at GGS Medical College and Hospital Faridkot from March 2014 to October 2015. 52 patients with newly diagnosed and histopathologically proven carcinoma breast were staged by conventional modalities (clinical examination, blood tests, X-ray chest, mammography, ultrasonography abdomen, skeletal survey) and by 18F-fluorodeoxyglucose (18F FDG) PET/CT. PET-CT images were used for the detection, localization, staging of tumors and detection, evaluation, and diagnosis of metastatic lesions, disease burden and organ function along with treatment planning and planning therapeutic procedures. Following the completion of initial study, the results of 18F FDG PET-CT staging in comparison with conventional staging method were assessed. Along with this, the accuracy, changes in staging of cases of carcinoma breast and cost-effectiveness of 18F-FDG PET-CT were also studied. RESULTS: All the pathologic entities identified by conventional imaging were also perceived with 18F-FDG PET/CT. Therefore, we recommend the use of PET/CT as an important imaging modality for initial diagnosis of carcinoma breast.