Commissioning and Acceptance Testing of the existing linear accelerator upgraded to volumetric modulated arc therapy

AbstractAimThe RapidArc commissioning and Acceptance Testing program will test and ensure accuracy in DMLC position, precise dose-rate control during gantry rotation and accurate control of gantry speed.BackgroundRecently, we have upgraded our linear accelerator capable of performing IMRT which was functional from 2007 with image guided RapidArc facility. The installation of VMAT in the existing linear accelerator is a tedious process which requires many quality assurance procedures before the proper commissioning of the facility and these procedures are discussed in this study.Materials and methodsOutput of the machine at different dose rates was measured to verify its consistency at different dose rates. Monitor and chamber linearity at different dose rates were checked. DMLC QA comprising of MLC transmission factor measurement and dosimetric leaf gap measurements were performed using 0.13cm3 and 0.65cm3 Farmer type ionization chamber, dose 1 dosimeter, and IAEA 30cm×30cm×30cm water phantom. Picket fence test, garden fence test, tests to check leaf positioning accuracy due to carriage movement, calibration of the leaves, leaf speed stability effects due to the acceleration and deceleration of leaves, accuracy and calibration of leaves in producing complex fields, effects of interleaf friction, etc. were verified using EDR2 therapy films, Vidar scanner, Omnipro accept software, amorphous silicon based electronic portal imaging device and EPIQA software.1–8ResultsAll the DMLC related quality assurance tests were performed and evaluated by film dosimetry, portal dosimetry and EPIQA.7ConclusionResults confirmed that the linear accelerator is capable of performing accurate VMAT

ECOFRIENDLY NUTRIENT MANAGEMENT PRACTICES FOR YIELD AND QUALITY OF BANANA

Banana owing to its large size and rapid growth rate require relatively large amount of nutrients for higher yield of quality fruits and it is estimated that 50 tonnes of banana in one hectare removes 320kg N, 32kg P2O5 and 925 kg K2O every year (Lahav and Turner, 1983). Application of inorganic fertilizers though increases the yield substantially but could not able to sustain the fertility status of the soil (Bharadwaj and Omanwar, 1994) and have caused several undesirable consequences in the fragile soil eco-system, leading to gradual decline in productivity. Considering the present situation of soil quality and environmental security, it is necessary to go for an integrated nutrient management, involving various sources of organic manures, organic cakes and bio-fertilizers besides using chemical fertilizers in banana. In today’s cultivation many commercial organic manures are being used because of their application in lesser volume and also enriched with nutrients. One such commercial organic manure used in the study is Wellgro. Wellgro organic manure is a unique product with a blend of neem and non-timber forest produce and a rich source of nutrients. Hence, this study was under taken to find out the influence of ecofriendly nutrient management practices on yield and quality parameters of banana under irrigated conditions

Comparative Evaluation of Fluoride Release and Compressive Strength of Modified Biodentine Using 7 Wt % Sodium Fluorosilicate and 1o W/V % of 20 % Hydrofluoric Acid: An Invitro study

ABSTRACT AIM : The aim of this study is to evaluate the fluoride releasing properties and compressive strength of Biodentine modified with 7 wt% sodium fluorosilicate and with 10 w/v % of 20 % hydrofluoric acid using Spadns spectrophotometer & Instron Universal Testing machine respectively. MATERIALS AND METHODS: The study comprised of a total of 80 samples divided into 4 groups of 20 samples in each group. Out of the 20 samples, 10 samples were allocated for fluoride analysis and 10 samples were destined for compressive strength analysis. Group A -Biodentine powder only modified with 7wt% Na2[SiF6],Group B -Biodentine liquid only modified with 10 w/v % of 20% HF ,Group C - Biodentine powder modified with 7wt% Na2[SiF6] & Biodentine liquid modified with 10 w/v % of 20% HF ,Group D - Glass Ionomer cement type II (positive control). Fluoride release was assessed at 24 hr, 3rd day, 7th day and cumulatively thereafter on 2nd, 3rd & 4th weeks. The 24 hr compressive strength was assessed by Instron Universal Testing machine. RESULTS : At 24 hour, the fluoride release of Group A was higher than Group D which was statistically significant..On 3rd day Group C showed higher fluoride release than Group D which was not statistically significant. On, 7th 14th & 21st days the Group C showed higher fluoride release than Group D .On 28th day Group A had higher fluoride release followed by Group C & Group D which was not statistically significant. The 24 hr compressive strength found to be highest for Group Dfollowed by Group B, Group A and the least compressive strength was for Group C. CONCLUSION : The powder only modified Biodentine showed appreciable fluoride release without much compromise in the compressive strength.Hence the powder only modified Biodentine can be used as dentin substitute in posterior restorations tapping the fluoride release properties successfully

Clinical profile and the outcome of corrosive injury of GI tract

Background: Corrosive substances are common household substances that can be ingested either accidentally or intentionally with suicidal intent. The present study was conducted to analyse the clinical profile of 50 cases of corrosive injury of GI tract and to analyse the outcome of 50 cases of corrosive injury of GI tract.Methods: The Cross-sectional study was conducted on 50 cases admitted in the toxicology ward in Rajiv Gandhi Government General Hospital, madras medical college, Chennai over a period of six months. Patients with history of corrosive ingestion presenting within 24 hours of ingestion subjected to Upper GI endoscopy within 24 hours of admission. Patients presenting after 24 hours, with respiratory distress, suspected perforation either radiologically clinically and normal findings in Upper GI endoscopy were excluded. The patients were serially followed and were subjected for a re-look upper GI endoscopy after 6 weeks and the findings were compared.Results: Corrosive ingestion was more common in the age group 20-30 years and more common in males. Acid ingestion was almost twice as common as alkali ingestion. Suicidal ingestion was the most common circumstance of consumption and associated with higher grade of injury. Patients with ingestion of more than 50 ml had higher grades of injury and also were at higher risk of strictures. The spectrum of injury to the GI tract revealed esophageal injury of grade II b to be the most common finding with the duodenum being spared in majority of the cases.Conclusions: In our study, Patients with ingestion of more than 50ml had higher grades of injury and also were at higher risk of strictures. While the lesser grade injuries (0, I, IIa) were associated with complete recovery with no sequelae, the more severe grades (IIb and IIIa) were associated with higher incidence of strictures especially the circumferential lesions.  Oesophageal strictures are commonly associated with suicidal corrosive ingestion. All patients with corrosive ingestion should be subjected to early UGIE and after 6 weeks to identify stricture formation

Analysis of low dose level volumes in intensity modulated radiotherapy and 3-D conformal radiotherapy

Purpose: To analyze the low dose volume regions in four facets: Analysis 1: low dose volume regions were compared between 3-dimensional conformal radiotherapy (3DCRT) and intensity modulated radiotherapy (IMRT) plans for each case; Analysis 2: the effect on low dose volume in 3DCRT as the number of fields are increased; Analysis 3: the same effect in IMRT, and Analysis 4: above two analysis were inter-compared between the two modalities. Methods: For this work 18 patients were taken for which both 3DCRT and IMRT plans with varying number of beams were planned using Anisotropic Analytical Algorithm (AAA) in Eclipse 10 Version Treatment Planning System with two to nine beams and five to nine beams, respectively. The plans were analyzed on the basis of conformity index and dose to the critical structures.Results: In Analysis 1, 5 Gy volume region was greater for IMRT than for 3DCRT but the 10 Gy, 15 Gy and 20 Gy volume regions were smaller for IMRT plans. In Analysis 2 and 3 shows that as the number of fields increases the low dose volume regions also increases. In Analysis 4, the effect pronounced due to increase in the beam portals is similar in 3DCRT as well as IMRT. Also it was seen that with same number of beams for both IMRT and 3DCRT, low dose volume region is higher in 3DCRT than IMRT. Conclusion: Low dose volume regions are a major concern in 3DCRT and IMRT plans with multiple beams because of its risk of secondary cancer incidence. This study concludes that by increasing number of beams low dose volume regions increases in 3DCRT and IMRT. It shows that the low dose volume regions are slightly higher in IMRT than 3DCRT, however with proper optimization the volume of tissue receiving 10 Gy, 15 Gy and 20 Gy can be reduced.-----------------------Cite this article as: Ekambaram V, Velayudham R. Analysis of low dose level volumes in intensity modulated radiotherapy and 3-D conformal radiotherapy. Int J Cancer Ther Oncol 2014; 2(3):02032. DOI: 10.14319/ijcto.0203.2</p

Integrated scoring approach to assess radiotherapy plan quality for breast cancer treatment

Background: Proposal of an integrated scoring approach assessing the quality of different treatment techniques in a radiotherapy planning comparison. This scoring method incorporates all dosimetric indices of planning target volumes (PTVs) as well as organs at risk (OARs) and provides a single quantitative measure to select an ideal plan. Materials and methods: The radiotherapy planning techniques compared were field-in-field (FinF), intensity modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT), hybrid IMRT (H-IMRT), and hybrid VMAT (H-VMAT). These plans were generated for twenty-five locally advanced left-sided breast cancer patients. The PTVs were prescribed a hypofractionation dose of 40.5 Gy in 15 fractions. The integrated score for each planning technique was calculated using the proposed formula. Results: An integrated score value that is close to zero indicates a superior plan. The integrated score that incorporates all dosimetric indices (PTVs and OARs) were 1.37, 1.64, 1.72, 1.18, and 1.24 for FinF, IMRT, VMAT, H-IMRT, and H-VMAT plans, respectively. Conclusion: The proposed integrated scoring approach is scientific to select a better plan and flexible to incorporate the patient-specific clinical demands. This simple tool is useful to quantify the treatment techniques and able to differentiate the acceptable and unacceptable plans

Performance characteristics and commissioning of MOSFET as an in-vivo dosimeter for high energy photon external beam radiation therapy

AimIn vivo dosimetry is an essential tool of quality assurance programmes in radiotherapy. In fact, the assessment of the final uncertainty between the prescribed dose and the dose actually delivered to the patient is an effective way of checking the entire dosimetric procedure. Metal oxide semiconductor field effect transistors (MOSFETs) have recently been proposed for use in radiation therapy. The purpose of this work is to study the performance characteristics and to carry out the commissioning of MOSFET as an in-vivo dosimeter for high-energy photon external beam radiation therapy.Material and MethodsCharacterization and commissioning of low sensitivity TN502RD and high sensitivity TN1002RD MOSFETs for entrance and exit dosimetry respectively for application in in-vivo dosimetry in radiotherapy was carried out. The MOSFETs were characterized in terms of reproducibility, short-term constancy, long-term constancy, linearity, angular dependence, energy dependence, source to skin distance (SSD) dependence and field size dependence.ResultsThe reproducibility of standard sensitivity MOSFET is about 1.4% (1 SD) and 1.98% (1 SD) for high sensitivity detectors. The linearity of both MOSFETs was excellent (R2 = 0.996). The response of MOSFETs varies linearly for square fields from 3 × 3 cm2 to 30 × 30 cm2. For beam incidence ranging from ±45° the MOSFET response varies within ±3%. Commissioning of both MOSFETs was carried out in terms of entrance dose calibration factor, exit dose calibration factor, SSD correction factor, field size correction factor, wedge correction factor and shielding tray correction factor. The average calibration factor for low and high sensitivity MOSFET detectors is 0.9065 cGy/mV and 0.3412 cGy/mV respectively. The average SSD correction factors are quite small and vary between 0.968 and 1.027 for both types of detectors for the range of clinical SSDs from 80 cm to 120 cm. The field size correction factor varies from 1.00 to 1.02 for both types of detectors. The wedge and the shielding tray correction factors for both the detectors also show quite small variation. MOSFET characteristics are suitable for in vivo dosimetry of entrance and exit dose measurement relevant to 6 MV treatment.ConclusionIt can be concluded that MOSFET dosimetry's low energy dependence, high sensitivity and immediate readout make it a good replacement for TLD in radiation therapy dosimetry

Fetal MRI assessment of head & neck vascular malformation in predicting outcome of EXIT-to-airway procedure

Objectives: The objective of this clinical case report is to highlight the MRI features and staging system which may guide clinicians in determining further management. Case presentation: Three different cases with fetal head and neck vascular malformation diagnosed during prenatal screening were presented. MRI demonstrates large cystic neck masses which may compromise fetal airway during delivery. Thus, this required multidisciplinary team management among obstetricians, otolaryngologists, pediatricians, anesthesiologists, and radiologists. A decision for complex birth delivery through the cesarean section aided with EXIT-to-airway procedure was made. Each of these procedures demonstrates the different challenges and outcomes of the neonates which correlated with the characterization and staging based on prenatal MRI. Conclusions: EXIT-to-airway procedure in head and neck malformation may be beneficial in transiting complicated and potentially catastrophic delivery situations to a more controlled environment. However, it also needs to align with prenatal MRI evaluation, which provides a more objective assessment guide for the clinicians