Search results for: Radiotherapy.

Authors: R.M.V. Silva, D.N. Souza

Abstract:

This paper presents a model for the characterization and selection of beeswaxes for use as base substitute tissue for the manufacture of objects suitable for external radiotherapy using megavoltage photon beams. The model of characterization was divided into three distinct stages: 1) verification of aspects related to the origin of the beeswax, the bee species, the flora in the vicinity of the beehives and procedures to detect adulterations; 2) evaluation of physical and chemical properties; and 3) evaluation of beam attenuation capacity. The chemical composition of the beeswax evaluated in this study was similar to other simulators commonly used in radiotherapy. The behavior of the mass attenuation coefficient in the radiotherapy energy range was comparable to other simulators. The proposed model is efficient and enables convenient assessment of the use of any particular beeswax as a base substitute tissue for radiotherapy.

Keywords: Beeswaxes, characterization, model, radiotherapy

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Authors: Ahmed Mostafa, Mohamed Mahmoud, Nesreen H. Hafez, Mohamed Fahim

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This retrospective study includes 60 patients with pre-invasive breast cancer. Aim of the study: Evaluation of premalignant lesions of the breast (DCIS), different treatment methods and outcome. Patients and methods: 60 patients with DCIS were studied from the period between 2005 to 2012, for 38 patients the primary surgical method was wide local resection (WLE) (63.3%) and the other cases (22 patients, 36.7%) had mastectomy, fourteen cases from those who underwent local excision received radiotherapy, while no adjuvant radiotherapy was given for those who underwent mastectomy. In case of hormonal receptor positive DCIS lesions hormonal treatment (Tamoxifen) was given after local control. Results: No difference in overall survival between mastectomy & breast conserving therapy (wide local excision and adjuvant radiotherapy), however local recurrence rate is higher in case of breast conserving therapy, also no role of Axillary evacuation in case of DCIS. The use of hormonal therapy decreases the incidence of local recurrence by about 98%. Conclusion: The main management of DCIS is local treatment (wide local excision and radiotherapy) with hormonal treatment in case of hormone receptor positive lesions.

Keywords: Ductal carcinoma in situ, surgical treatment, radiotherapy, breast conserving therapy, hormonal treatment.

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Authors: M. Umar Farooq, T. Ahmad Afridi, M. Zia-Ul-Islam Arsalan, U. Hussain Haider, S. Ullah

Abstract:

Cancer, a leading fatal disease worldwide, can be treated with various techniques including radiation therapy. It involves the use of ionizing radiation to target cancer cells. On basis of source placement, radiation therapy is of two types i.e., Brachytherapy and External Beam Radiotherapy (EBRT). EBRT has evolved from 2-D conventional therapy to 3-D Conformal radiotherapy (3D-CRT) and then Intensity-Modulated Radiotherapy (IMRT). IMRT improves dose conformity and sparing of organs at risk. Volumetric Modulated Arc Therapy (VMAT) is a modern technique that uses treatment delivery in arcs with rotation of the gantry. In this report, a dosimetry comparison was performed between IMRT and VMAT. This study was conducted in the Radiotherapy Department of the Institute of Nuclear Medicine and Oncology Lahore (INMOL). Ten patients with Prostate Carcinoma were selected for this study to compare the methods. Simulation of these patients was done with help of a CT Simulator. All target volumes and organs were delineated by the oncologists. Then suitable fields/arcs were applied which cover volumes effectively. This was followed by the optimization of plans for both techniques for every patient. Finally, a comparison of evaluating parameters e.g., Conformity Index (CI), Volume Coverage, Homogeneity Index (HI), Organ Doses, and MUs (Monitor Units) was performed. We obtained better results of target conformity indices from VMAT (CI = 1.16) than IMRT (CI = 1.24). VMAT was better in organ sparing too. Also, VMAT shows fewer MUs (733 MUs) as compared to IMRT (2149 MUs). From this study, it is concluded that VMAT is a better treatment technique than IMRT. This technique will enhance treatment efficiency as it takes less time in obtaining the required results. Also, a very less scatter dose will be delivered to the patient.

Keywords: 2-D Conventional Radiotherapy, 3-D Conformal Radiotherapy, Intensity Modulated Radiotherapy, Prostate Carcinoma, Radiotherapy, Volumetric Modulated Arc Therapy.

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Authors: A. Taqaddas

Abstract:

Purpose: This E-survey was carried out to facilitate the implementation and Education of VMAT (Volumetric Modulated Arc Therapy) in Radiotherapy-RT departments and reasons for not using IMRT (Intensity Modulated Radiotherapy). VMAT Skills in demand were also identified. Method: E-Survey was distributed to NHS hospitals across UK by email. Thirty NHS and related centres in England, 21 in Scotland, 3 in Ireland and 1 in Wales were contacted. This Survey was intended for those working in RT and Medical Physics and who were responsible for Treatment Planning and training. Results: This E-survey have indicated pathways adopted by staff to acquire VMAT skills, strategies to efficiently implement VMAT in RT departments and for obtaining VMAT Education. Conclusion: Despite poor survey response this survey has managed to highlight requirements for education and implementation of VMAT that are also applicable to IMRT. Other RT centres in world can also find these results useful.

Keywords: IMRT, Radiotherapy, Treatment Planning, VMAT.

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Authors: Loredana G. Marcu, David Marcu, Sanda M. Filip

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Advanced head and neck cancers are aggressive tumours, which require aggressive treatment. Treatment efficiency is often hindered by cancer cell repopulation during radiotherapy, which is due to various mechanisms triggered by the loss of tumour cells and involves both stem and differentiated cells. The aim of the current paper is to present in silico simulations of radiotherapy schedules on a virtual head and neck tumour grown with biologically realistic kinetic parameters. Using the linear quadratic formalism of cell survival after radiotherapy, altered fractionation schedules employing various treatment breaks for normal tissue recovery are simulated and repopulation mechanism implemented in order to evaluate the impact of various cancer cell contribution on tumour behaviour during irradiation. The model has shown that the timing of treatment breaks is an important factor influencing tumour control in rapidly proliferating tissues such as squamous cell carcinomas of the head and neck. Furthermore, not only stem cells but also differentiated cells, via the mechanism of abortive division, can contribute to malignant cell repopulation during treatment.

Keywords: Radiation, tumour repopulation, squamous cell carcinoma, stem cell.

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Authors: A. Taqaddas

Abstract:

Medulloblastoma (MB) is one of the most prevalent brain tumours among paediatrics. Although its management has evolved over time still there is need to find new therapeutic targets for MB that can result in less normal tissue toxicity while improving survival and reducing recurrence. This literature review is aimed at finding new potential therapeutic targets for MB focusing on viruses that can be used as potential targets for MB. The review also gives an over-view of management of paediatric Medulloblastoma focusing on Radiotherapy management.

Keywords: Cytomegalovirus, Measles Virus, Medulloblastoma, Radiotherapy.

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Authors: A. Taqaddas

Abstract:

Chemotherapy and radiotherapy are one of the major treatment modalities that play important role in the management of a number of different cancers. This study for the first time evaluates the toxicity of these treatment modalities and its impact on quality of life of cancer patients in Pakistan. The study also for the first time determines what cancer patients of different ages and cancer stages believe would be an effective intervention to manage their psychosocial needs and treatment induced toxicity. The article also provides evidence based approach for the use of variety of interventions to mange cancer treatment induced morbidity and toxicity. In light of the present study and reviewed research data, evidence based recommendations are also made for selection of appropriate interventions to manage Pain, Nausea and Vomiting, Anxiety and Depression, Fatigue and Overall QOL of cancer survivors.

Keywords: Chemotherapy Toxicity, Psycho-Social Interventions, Quality of Life, Radiotherapy Toxicity.

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Authors: Seid Ali Asghar Terohid, Vahid Fayaz

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Thyroid cancer-s overall contribution to the worldwide cancer burden is relatively small, but incidence rates have increased over the last three decades throughout the world. This trend has been hypothesised to reflect a combination of technological advances enabling increased detection, but also changes in environmental factors, including population exposure to ionising radiation from fallout, diagnostic tests and treatment for benign and malignant conditions. The Thyroid dose received apparently shielded by cerrobend blocks was about 8cGy in 100cGy Expose

Keywords: Absorbed Dose, Thyroid, Radiotherapy

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Authors: Ravi Kiran Pothamsetty, Radha Rani Ghosh, Baby Paul Thaliath

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Radiation therapy has undergone many advancements and evloved from 2D to 3D. Recently, with rapid pace of drug discoveries, cutting edge technology, and clinical trials has made innovative advancements in computer technology and treatment planning and upgraded to intensity modulated radiotherapy (IMRT) which delivers in homogenous dose to tumor and normal tissues. The present study was a hospital-based experience comparing two different conformal radiotherapy techniques for brain tumors. This analytical study design has been conducted at Regional Cancer Centre, India from January 2014 to January 2015. Ten patients have been selected after inclusion and exclusion criteria. All the patients were treated on Artiste Siemens Linac Accelerator. The tolerance level for maximum dose was 6.0 Gyfor lenses and 54.0 Gy for brain stem, optic chiasm and optical nerves as per RTOG criteria. Mean and standard deviation values of PTV98%, PTV 95% and PTV 2% in IMRT were 93.16±2.9, 95.01±3.4 and 103.1±1.1 respectively; for 3DCRT were 91.4±4.7, 94.17±2.6 and 102.7±0.39 respectively. PTV max dose (%) in IMRT and 3D-CRT were 104.7±0.96 and 103.9±1.0 respectively. Maximum dose to the tumor can be delivered with IMRT with acceptable toxicity limits. Variables such as expertise, location of tumor, patient condition, and TPS influence the outcome of the treatment.

Keywords: IMRT, 3D CRT, Brain, tumors, OARs, RTOG.

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Authors: Mohammad Hassan Heidari, Amir Hossein Goodarzi, Majid Azarniush

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Radiation doses to tissues and organs were measured using the anthropomorphic phantom as an equivalent to the human body. When high-energy X-rays are externally applied to treat laryngeal cancer, the absorbed dose at the laryngeal lumen is lower than given dose because of air space, which it should pass through, before reaching the lesion. Specially, in case of high-energy X-rays, the loss of dose is considerable. Three-dimensional absorbed dose distributions have been computed for high-energy photon radiation therapy of laryngeal and hypopharyngeal cancers, using a coaxial pair of opposing lateral beams in fixed positions. Treatment plans obtained under various conditions of irradiation.

Keywords: 3D Treatment Planning, anthropomorphic phantom, larynx cancer, radiotherapy.

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Authors: Vahid Fayaz , Asieh Tavakol

Abstract:

To investigate the applicability of the EDR-2 film for clinical radiation dosimetry, percentage depth-doses, profiles and distributions in open and dynamically wedged fields were measured using film and compared with data from a Treatment Planning system.The validity of the EDR2 film to measure dose in a plane parallel to the beam was tested by irradiating 10 cm×10 cm and 4 cm×4 cm fields from a Siemens, primus linac with a 6MV beam and a source-to-surface distance of 100 cm. The film was placed Horizontally between solid water phantom blocks and marked with pin holes at a depth of 10 cm from the incident beam surface. The film measurement results, in absolute dose, were compared with ion chamber measurements using a Welhoffer scanning water tank system and Treatment Planning system. Our results indicate a maximum underestimate of calculated dose of 8 % with Treatment Planning system.

Keywords: 6MV Photon , EDR-2 film, Radiotherapy, TreatmentPlanning system

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Authors: Hui-Min Ting, Tsair-Fwu Lee, Ming-Yuan Cho, Pei-Ju Chao, Chun-Ming Chang, Long-Chang Chen, Fu-Min Fang

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To evaluate the ability to predict xerostomia after radiotherapy, we constructed and compared neural network and logistic regression models. In this study, 61 patients who completed a questionnaire about their quality of life (QoL) before and after a full course of radiation therapy were included. Based on this questionnaire, some statistical data about the condition of the patients’ salivary glands were obtained, and these subjects were included as the inputs of the neural network and logistic regression models in order to predict the probability of xerostomia. Seven variables were then selected from the statistical data according to Cramer’s V and point-biserial correlation values and were trained by each model to obtain the respective outputs which were 0.88 and 0.89 for AUC, 9.20 and 7.65 for SSE, and 13.7% and 19.0% for MAPE, respectively. These parameters demonstrate that both neural network and logistic regression methods are effective for predicting conditions of parotid glands.

Keywords: NPC, ANN, logistic regression, xerostomia.

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Authors: Devasis Ghosh

Abstract:

The main hindrance to total cure of cancer is a) the failure to control continued production of cancer cells, b) its sustenance and c) its metastasis. This review study has tried to address this issue of total cancer cure in a more innovative way. A 10-pronged “CRAB METHOD”, a novel holistic scientific approach of Cancer treatment has been hypothesized in this paper. Apart from available Chemotherapy, Radiotherapy and Oncosurgery, (which shall not be discussed here), seven other points of interference and treatment has been suggested, i.e. 1. Efficient stress management. 2. Dampening of ATF3 expression. 3. Selective inhibition of Platelet Activity. 4. Modulation of serotonin production, metabolism and 5HT receptor antagonism. 5. Auxin, its anti-proliferative potential and its modulation. 6. Melatonin supplementation because of its oncostatic properties. 7. HDAC Inhibitors especially valproic acid use due to its apoptotic role in many cancers. If all the above stated seven steps are thoroughly taken care of at the time of initial diagnosis of cancer along with the available treatment modalities of Chemotherapy, Radiotherapy and Oncosurgery, then perhaps, the morbidity and mortality rate of cancer may be greatly reduced.

Keywords: ATF3 dampening, auxin modulation, cancer, platelet activation, serotonin, stress, valproic acid.

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Authors: Sadegh Masoudi, Ali Asghar Yousefi, Somayeh Nourollahi, Fatemeh Noughani

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Two different testicular tissues have to be distinguished in regard to radiation damage: first the seminiferous tubules, corresponding to the sites of spermatogenesis, which are extremely radiosensitive. Second the testosterone secreting Leydig cells, which are considered to be less radiosensitive. This study aims to estimate testicular dose and the associated risks for infertility and hereditary effects from Abdominal and pelvic irradiation. Radiotherapy was simulated on a humanoid phantom using a 15 MV photon beam. Testicular dose was measured for various field sizes and tissue thicknesses along beam axis using an ionization chamber and TLD. For transmission Factor Also common method of measuring the absorbed dose distribution and electron contamination in the build-up region of high-energy beams for radiation therapy is by means of parallel-plate Ionisation chambers. Gonadal dose was reduced by placing lead cups around the testes supplemented by a field edge block. For a tumor dose of 100 cGy, testicular dose was 2.96-8.12 cGy depending upon the field size and the distance from the inferior field edge. The treatment at parameters, the presence of gonad shield and the somatometric characteristics determine whether testicular dose can exceed 1 Gy which allows a complete recovery of spermatogenesis.

Keywords: Absorbed Dose, Abdominal and pelvic, gonads men, Radiotherapy.

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Authors: Manjusha R. Vagal, Shyam K. Shrivastava, Umesh Mahantshetty, Sudeep Gupta, Supriya Chopra, Reena Engineer, Amita Maheshwari, Atul Buduk

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Vaginal stenosis is a common side effect associated with pelvic radiotherapy in cervical cancer patients which contributes negatively to woman’s health and prevents adequate vaginal/cervical examination. Vaginal dilation with a dilator is routine practice and is internationally advocated as a prophylactic measure to preserve vaginal patency. This retrospective study was carried out with the aim to know the usefulness of vaginal dilation following pelvic radiation therapy in cervical cancer patients in India. Data from medical records of 183 cervical cancer patients, which met the study criteria, were collected related to the stage of the disease, treatment received, commencement period of dilation post radiation therapy, sexual status and side effects associated to dilation practice. Data related to vaginal dimensions as per the length of insertion of a small, medium and large dilator were collected on regular follow-ups until 36 months and/or more. Vaginal dimensions as measured with the length of medium dilator insertion were used for analysis of dilation therapy results using paired t-test. Patients who underwent vaginal dilation with dilator maintained vaginal patency, also the mean vaginal length significantly increased, from 8.02 cm ± 2.69 to 9.96 ± 2.89 cm with a p value <0.001. There was no significant difference found on vaginal patency with different intervals of initiation of dilation therapy. At the third year and more following dilation therapy, significant increase in vaginal length observed with a p value of 0.0001 in both sexually active and inactive patients. Compilation of vaginal dosage during brachytherapy was inadequate, and hence, the secondary objective of the study to determine the effect of radiotherapy on the outcome of rehabilitation intervention was not studied in detail. This retrospective study has found that dilation therapy with vaginal dilators post pelvic radiotherapy is effective in preventing vaginal stenosis and improving vaginal patency and cannot be substituted with vaginal intercourse. Sexual quality of life assessment in the Indian population needs much attention.

Keywords: Dilator, sexually active, vaginal dilation, vaginal stenosis.

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Authors: N. Chegeni, M. J. Tahmasebi Birgani

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Nowadays, in most radiotherapy departments, the commercial treatment planning systems (TPS) used to calculate dose distributions needs to be verified; therefore, quick, easy-to-use and low cost dose distribution algorithms are desirable to test and verify the performance of the TPS. In this paper, we put forth an analytical method to calculate the phantom scatter contribution and depth dose on the central axis based on the equivalent square concept. Then, this method was generalized to calculate the profiles at any depth and for several field shapes regular or irregular fields under symmetry and asymmetry photon beam conditions. Varian 2100 C/D and Siemens Primus Plus Linacs with 6 and 18 MV photon beam were used for irradiations. Percentage depth doses (PDDs) were measured for a large number of square fields for both energies, and for 45^º wedges which were employed to obtain the profiles in any depth. To assess the accuracy of the calculated profiles, several profile measurements were carried out for some treatment fields. The calculated and measured profiles were compared by gamma-index calculation. All γ–index calculations were based on a 3% dose criterion and a 3 mm dose-to-agreement (DTA) acceptance criterion. The γ values were less than 1 at most points. However, the maximum γ observed was about 1.10 in the penumbra region in most fields and in the central area for the asymmetric fields. This analytical approach provides a generally quick and fairly accurate algorithm to calculate dose distribution for some treatment fields in conventional radiotherapy.

Keywords: Dose distribution, equivalent field, asymmetric field, irregular field.

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Authors: Panos D. Kotsas, Tony Dodd

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2D/3D registration is a special case of medical image registration which is of particular interest to surgeons. Applications of 2D/3D registration are [1] radiotherapy planning and treatment verification, spinal surgery, hip replacement, neurointerventions and aortic stenting. The purpose of this paper is to provide a literature review of the main methods for image registration for the 2D/3D case. At the end of the paper an algorithm is proposed for 2D/3D registration based on the Chebyssev polynomials iteration loop.

Keywords: Medical image registration, review, 2D/3D

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Authors: O. Sotolongo-Grau, D. Rodriguez-Perez, J. A. Santos-Miranda, M. M. Desco, O. Sotolongo-Costa, J. C. Antoranz

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The use of the oncologic index ISTER allows for a more effective planning of the radiotherapic facilities in the hospitals. Any change in the radiotherapy treatment, due to unexpected stops, may be adapted by recalculating the doses to the new treatment duration while keeping the optimal prognosis. The results obtained in a simulation model on millions of patients allow the definition of optimal success probability algorithms.

Keywords: Mathematical model, radiation oncology, dynamical systems applications.

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Authors: Faten A. Khorshid

Abstract:

Breast cancer is the most common malignancy in the world among women. Many therapies have been designed to treat this disease. Mamectomy, chemotherapy and radiotherapy are still the main therapies of breast cancer. However, the results were unsatisfactory and still far from the ideal treatment. PM 701is a natural product, has anticancer activity. The bioactive fraction PMF and subfraction PMFK had been isolated from PM701. PM 701 and its fractions were proved to have a cytotoxic properties against different cancer cell lines. This article is directed for the further examination of lyophilized PM701 and its active fractions on the growth of breast cancer cells (MCF-7). PM 701, PMF or PMFK were adding to the cultural medium, where MCF-7 is incubated. PM 701, PMF or PMFK were able to inhibit significantly the proliferation of MCF-7 cells, Moreover these new agents were proved to induce apoptosis of the breast cancer cells; through its direct effect on the nuclei.

Keywords: Anticancer agent, breast carcinoma, MCF-7 cell line, PM 701

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Authors: Shivayogi Charantimath

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Radiotherapy and chemotherapy are effective for treating malignancies but are associated with side effects like oral mucositis. Chlorhexidine gluconate is one of the most commonly used mouthwash in prevention of signs and symptoms of mucositis. Evidence shows that chlorhexidine gluconate has side effects in terms of colonization of bacteria, bad breadth and less healing properties. Thus, it is essential to find a suitable alternative therapy which is more effective with minimal side effects. Curcumin, an extract of turmeric is gradually being studied for its wide-ranging therapeutic properties such as antioxidant, analgesic, anti-inflammatory, antitumor, antimicrobial, antiseptic, chemo sensitizing and radio sensitizing properties. The present study was conducted to evaluate the efficacy and safety of topical curcumin gel on radio-chemotherapy induced oral mucositis in cancer patients. The aim of the study is to evaluate the efficacy and safety of curcumin gel in the management of oral mucositis in cancer patients undergoing radio chemotherapy and compare with chlorhexidine. The study was conducted in K.L.E. Society’s Belgaum cancer hospital. 40 oral cancer patients undergoing the radiochemotheraphy with oral mucositis was selected and randomly divided into two groups of 20 each. The study group A [20 patients] was advised Cure next gel for 2 weeks. The control group B [20 patients] was advised chlorhexidine gel for 2 weeks. The NRS, Oral Mucositis Assessment scale and WHO mucositis scale were used to determine the grading. The results obtained were calculated by using SPSS 20 software. The comparison of grading was done by applying Mann-Whitney U test and intergroup comparison was calculated by Wilcoxon matched pairs test. The NRS scores observed from baseline to 1^st and 2^nd week follow up in both the group showed significant difference. The percentage of change in erythema in respect to group A was 63.3% for first week and for second week, changes were 100.0% with p = 0.0003. The changes in Group A in respect to erythema was 34.6% for 1^st week and 57.7% in second week. The intergroup comparison was significant with p value of 0.0048 and 0.0006 in relation to group A and group B respectively. The size of the ulcer score was measured which showed 35.5% [P=0.0010] of change in Group A for 1^st and 2^nd week showed totally reduction i.e. 103.4% [P=0.0001]. Group B showed 24.7% change from baseline to 1^st week and 53.6% for 2^nd week follow up. The intergroup comparison with Wilcoxon matched pair test was significant with p=0.0001 in group A. The result obtained by WHO mucositis score in respect to group A shows 29.6% [p=0.0004] change in first week and 75.0% [p=0.0180] change in second week which is highly significant in comparison to group B. Group B showed minimum changes i.e. 20.1% in 1^st week and 33.3% in 2^nd week. The p value with Wilcoxon was significant with 0.0025 in Group A for 1^st week follow up and 0.000 for 2^nd week follow up. Curcumin gel appears to an effective and safer alternative to chlorhexidine gel in treatment of oral mucositis.

Keywords: Curcumin, chemotherapy, mucositis, radiotherapy.

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Authors: Sadegh Masoudi , Vahid Fayaz , Hassan Zandi, Asieh Tavakol

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The overall penumbra is usually defined as the distance, p20–80, separating the 20% and 80% of the dose on the beam axis at the depth of interest. This overall penumbra accounts also for the fact that some photons emitted by the distal parts of the source are only partially attenuated by the collimator. Medulloblastoma is the most common type of childhood brain tumor and often spreads to the spine. Current guidelines call for surgery to remove as much of the tumor as possible, followed by radiation of the brain and spinal cord, and finally treatment with chemotherapy. The purpose of this paper was to present results on an Uniformity of dose distribution in radiation fields surrounding the spine using film dosimetry and comparison with 3D treatment planning software.

Keywords: Absorbed Dose , Spine , Radiotherapy, 3D treatment planning software

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Authors: Pradip Deb

Abstract:

Quantitative radiobiological models can be used to assess the optimum clinical outcome from sophisticated therapeutic modalities by calculating tumor control probability (TCP) and normal tissue complication probability (NTCP). In this study two 3D-CRT and an IMRT treatment plans were developed with an initial prescription dose of 60 Gy in 2 Gy/fraction to prostate. Sensitivity of TCP and Complication free tumor control probability (P+) to the different values of α/β ratio was investigated for various prescription doses planned to be delivered in either a fixed number of fractions (I) or in a fixed dose per fraction (II) in each of the three different treatment plans. High dose/fraction and high α/β value result in comparatively smaller P+ and IMRT plans resulted in the highest P+, mainly due to the decrease in NTCP. If α/β is lower than expected, better tumor control can be achieved by increasing dose/fraction but decreasing the number of fractions.

Keywords: Linear Quadratic Model, TCP, NTCP, α/β ratio.

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Authors: Jayesh K., Ganesh T., Suganthi D., Mohan R., Rakesh C. J., Sarojkumar D. M., Jacob S. J.

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Prior to the use of detectors, characteristics comparison study was performed and baseline established. In patient specific QA, the portal dosimetry mean values of area gamma, average gamma and maximum gamma were 1.02, 0.31 and 1.31 with standard deviation of 0.33, 0.03 and 0.14 for IMRT and the corresponding values were 1.58, 0.48 and 1.73 with standard deviation of 0.31, 0.06 and 0.66 for VMAT. With ImatriXX 2-D array system, on an average 99.35% of the pixels passed the criteria of 3%-3 mm gamma with standard deviation of 0.24 for dynamic IMRT. For VMAT, the average value was 98.16% with a standard deviation of 0.86. The results showed that both the systems can be used in patient specific QA measurements for IMRT and VMAT. The values obtained with the portal dosimetry system were found to be relatively more consistent compared to those obtained with ImatriXX 2-D array system.

Keywords: Gamma, IMRT, QA, TPS, VMAT.

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Authors: Sajjad A. Memon, Sadaf T. Qureshi, Naeem A. Laghari, Noor M. Khuhro

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The present study represents the occupational radiation doses received by selected workers of Nuclear Institute of Medicine and Radiotherapy (NIMRA) Jamshoro Pakistan and conducted to discuss about how we be careful and try to avoid make ourselves overconscious. Film badges with unique identification number were issued to radiation worker to detect occupational radiation doses. In this study, only 08 workers with high radiation doses were assessed amongst 35 radiation workers during the period of January 2012 to December 2012. The selected radiation workers’ occupational doses were according to designated work areas and in the range of 1.21 to 7.78 mSv (mili Sieveret) out of the annual dose limit of 20 mSv. By the comparison of different studies and earth’s HNBR (High Natural Background Radiation) locations’ doses, it is concluded that the worker’s high doses are of magnitude of HNBR Regions and were in the acceptable range of National and International regulatory bodies so we must not to show any type of overconsciousness but be careful in handling the radioactive sources.

Keywords: Natural background radiation, Occupational dose, Overconscious, Personal monitoring.

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Authors: Alireza Osareh, Bita Shadgar

Abstract:

Segmenting the lungs in medical images is a challenging and important task for many applications. In particular, automatic segmentation of lung cavities from multiple magnetic resonance (MR) images is very useful for oncological applications such as radiotherapy treatment planning. However, distinguishing of the lung areas is not trivial due to largely changing lung shapes, low contrast and poorly defined boundaries. In this paper, we address lung segmentation problem from pulmonary magnetic resonance images and propose an automated method based on a robust regionaided geometric snake with a modified diffused region force into the standard geometric model definition. The extra region force gives the snake a global complementary view of the lung boundary information within the image which along with the local gradient flow, helps detect fuzzy boundaries. The proposed method has been successful in segmenting the lungs in every slice of 30 magnetic resonance images with 80 consecutive slices in each image. We present results by comparing our automatic method to manually segmented lung cavities provided by an expert radiologist and with those of previous works, showing encouraging results and high robustness of our approach.

Keywords: Active contours, breast cancer, fuzzy c-means segmentation, treatment planning.

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Authors: Todsaporn Fuangrod, Daryl J. O'Connor, Boyd MC McCurdy, Peter B. Greer

Abstract:

An electronic portal image device (EPID) has become a method of patient-specific IMRT dose verification for radiotherapy. Research studies have focused on pre and post-treatment verification, however, there are currently no interventional procedures using EPID dosimetry that measure the dose in real time as a mechanism to ensure that overdoses do not occur and underdoses are detected as soon as is practically possible. As a result, an EPID-based real time dose verification system for dynamic IMRT was developed and was implemented with MATLAB/Simulink. The EPID image acquisition was set to continuous acquisition mode at 1.4 images per second. The system defined the time constraint gap, or execution gap at the image acquisition time, so that every calculation must be completed before the next image capture is completed. In addition, the <=-evaluation method was used for dose comparison, with two types of comparison processes; individual image and cumulative dose comparison monitored. The outputs of the system are the <=-map, the percent of <=<1, and mean-<= versus time, all in real time. Two strategies were used to test the system, including an error detection test and a clinical data test. The system can monitor the actual dose delivery compared with the treatment plan data or previous treatment dose delivery that means a radiation therapist is able to switch off the machine when the error is detected.

Keywords: real-time dose verification, EPID dosimetry, simulation, dynamic IMRT

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Authors: V. R. Ahire, A. Kumar, B. N. Pandey, K. P. Mishra, G. R. Kulkarni

Abstract:

Radiation therapy is an effective vital strategy used globally in the treatment of cervical cancer. However, radiation efficacy principally depends on the radiosensitivity of the tumor, and not all patient exhibit significant response to irradiation. A radiosensitive tumor is easier to cure than a radioresistant tumor which later advances to local recurrence and metastasis. Herbal polyphenols are gaining attention for exhibiting radiosensitization through various signaling. Current work focuses to study the radiosensitization effect of ellagic acid (EA), on HeLa cells. EA intermediated radiosensitization of HeLa cells was due to the induction γ-H2AX foci formation, G1 phase cell cycle arrest, and loss of reproductive potential, growth inhibition, drop in the mitochondrial membrane potential and protein expression studies that eventually induced apoptosis. Irradiation of HeLa in presence of EA (10 μM) to doses of 2 and 4 Gy γ-radiation produced marked tumor cytotoxicity. EA also demonstrated radio-protective effect on normal cell, NIH3T3 and aided recovery from the radiation damage. Our results advocate EA to be an effective adjuvant for improving cancer radiotherapy as it displays striking tumor cytotoxicity and reduced normal cell damage instigated by irradiation.

Keywords: Apoptotic radiosensitivity, ellagic acid, mitochondrial potential, cell-cycle arrest.

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Authors: A. Taqaddas

Abstract:

Purpose: Planning and dosimetry of different VMAT algorithms (SmartArc, Ergo++, Autobeam) is compared with IMRT for Head and Neck Cancer patients. Modelling was performed to rule out the causes of discrepancies between planned and delivered dose. Methods: Five HNC patients previously treated with IMRT were re-planned with SmartArc (SA), Ergo++ and Autobeam. Plans were compared with each other and against IMRT and evaluated using DVHs for PTVs and OARs, delivery time, monitor units (MU) and dosimetric accuracy. Modelling of control point (CP) spacing, Leaf-end Separation and MLC/Aperture shape was performed to rule out causes of discrepancies between planned and delivered doses. Additionally estimated arc delivery times, overall plan generation times and effect of CP spacing and number of arcs on plan generation times were recorded. Results: Single arc SmartArc plans (SA4d) were generally better than IMRT and double arc plans (SA2Arcs) in terms of homogeneity and target coverage. Double arc plans seemed to have a positive role in achieving improved Conformity Index (CI) and better sparing of some Organs at Risk (OARs) compared to Step and Shoot IMRT (ss-IMRT) and SA4d. Overall Ergo++ plans achieved best CI for both PTVs. Dosimetric validation of all VMAT plans without modelling was found to be lower than ss-IMRT. Total MUs required for delivery were on average 19%, 30%, 10.6% and 6.5% lower than ss-IMRT for SA4d, SA2d (Single arc with 2⁰ Gantry Spacing), SA2Arcs and Autobeam plans respectively. Autobeam was most efficient in terms of actual treatment delivery times whereas Ergo++ plans took longest to deliver. Conclusion: Overall SA single arc plans on average achieved best target coverage and homogeneity for both PTVs. SA2Arc plans showed improved CI and some OARs sparing. Very good dosimetric results were achieved with modelling. Ergo++ plans achieved best CI. Autobeam resulted in fastest treatment delivery times.

Keywords: Dosimetry, Intensity Modulated Radiotherapy, Optimization Algorithms, Volumetric Modulated Arc Therapy.

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