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Gowri Balan, Anu Radha Chandrasekaran, Ramasubramanian Velayudham, Gopiraj Annamalai and Mohan Ramachandran

Abstract

Purpose: To estimate the midpoint dose delivered to cervical cancer patients treated by conventional technique using Electronic Portal Imaging Device (EPID).

Materials and Methods: Clinac 2100 equipped with aS500 EPID was used in this study. A methodology was developed to generate a Gy/Calibration Unit (CU) look up table for the determination of midpoint dose of patients. 25 patients of cervical cancer were included in this study and the delivered dose to the midpoint of the patients was estimated using EPID. The deviation between the prescribed and the measured dose was calculated and analysed.

Results: EPID showed a linear response with increase in Monitor unit and the Gy/CU look up table was validated for different field sizes and depth. 250 fields were measured for 25 patients, 10 measurements per patient, weekly once and for 5 weeks. The results show that out of 250 measurements, 98% of the measurements are within ±5% and 83.2% are within ±3% for with a standard deviation of 1.66%.

Conclusion: The outcome of this study proves the efficacy of this methodology for the estimation of midpoint dose using EPID with minimal effort, time and without any inconvenience to the patients unlike other in-vivo dosimeters.

Open access

Hanna Goszczyńska, Leszek Królicki, Adam Bajera, Ewa Zalewska, Leszek Kowalczyk, Piotr Walerjan, Andrzej Rysz and Krystyna Kolebska

The Procedure for SPECT and BEAM Images Adjustment Visualisation of EEG Electrodes in SPECT Images

Preliminary results of research to devise a method allowing spatial alignment of BEAM maps obtained from EEG examinations with SPECT data are presented. The main concept of the method presented lies in simultaneous recording of multi-channel EEGs during SPECT examination, and also in visualizing location of EEG electrodes on SPECT images that provide spatial three dimensional coordinates assignment. The proposed methodology of simultaneous SPECT and EEG examinations could be a significant complement to results of epileptic focus localisation obtained with the ISAS method used for the last few years. The ISAS method allows localisation of focuses with 80% confidence, but it requires carrying out MRI examinations for alignment of compared anatomical structures on two SPECT images. Complementing these results with a BEAM map analysis would improve significantly the effectiveness of the examinations. This work presents results of experiments carried out on the Jaszczak phantom.

Open access

Tomasz Pliszczyński, Katarzyna Ciszewska, Małgorzata Dymecka, Jakub Ośko and Zbigniew Haratym

Institute, www.atom.kaeri.re.kr [5] N. Vajda, C.K. Kim, Determination if radiostrontium isotopes: A review of analytical methodology, Appl Radiat Isotopes, 2010;68:2306-2326

Open access

Jerrin Amalraj, Ramasubramanian Velayudham and Pichandi Anchineyan

Abstract

Shielded silicon diodes are commonly employed in commissioning of Cyberknife 6 MV photon beams. This study aims to measure output factors, off centered ratio (OCR), percentage depth dose (PDD) of 6 MV photons using shielded and unshielded diodes and to compare with Gafchromic EBT3 film measurements to investigate whether EBT3 could effectively characterize small 6 MV photon beams. Output factors, OCR and PDD were measured with shielded and unshielded silicon detectors in a radiation field analyzer system at reference condition. Water equivalent solid phantom were used while irradiating EBT3 films. From multiuser data, diodes underestimated output factor by 3% for collimator fields ≤ 10 mm, while EBT3 underestimated the output factor by 3.9% for 5 mm collimator. 1D Gamma analysis of OCR between diode and film, results in gamma ≤ 1 for all measured points with 1 mm distance to agreement (DTA) and 1% relative dose difference (DD). Dose at surface is overestimated with diodes compared to EBT3. PDD results were within 2% relative dose values between diode and EBT3 except for 5 mm collimator. Except for small collimator fields of up to 10 mm, results of output factor, OCR, PDD of all detectors used in this study exhibited similar results. Relative dose measurements with Gafchromic EBT3 in this work show that EBT3 films can be used effectively as an independent tool to verify commissioning beam data of small fields only after careful verification of methodology for any systematic errors with appropriate readout procedure.

Open access

A. Slavchev, S. Avramova-Cholakova and J. Vassileva

National protocol for quality assurance in DXA-bone densitometry

Osteoporosis becomes largely one of the most important socially significant and costly diseases. Modern techniques (DXA, US) are applied for bone densitometry. The paper presents a protocol for quality assurance especially of DXA-bone densitometers including quality control made in compliance with international standards (ISCD, IOF). The methodology has been tested in practice by measurements on site-functional assessment, entrance dose, radiation protection, calibration, in-vitro precision. It is expected to raise the quality of the diagnostic process in concert with the EU Medical Directive 97/43 particularly for population screening and sensitive groups. The protocol is an essential part of the National Program for constraining osteoporosis which has been elaborated at the Ministry of Health and at present under implementation throughout the country. It aims at reducing the risk, factors spreading, at diminishing the fracture risk the morbidity and the mortality from osteoporosis. An integral multidisciplinary approach to the problem solving is applied as well as training on three levels — doctors, patients, population, which effectively will contribute for obtaining real results in preventing osteoporosis.

Open access

Sanjay Supe, B. Shwetha, T. Bijina, C. Varatharaj, S. Sathiyan, K. Ganesh, T. Arunkumar and M. Ravikumar

Measurement of Transit Time of a Gammamed-Plus Remote Afterloading High Dose Rate Brachytherapy Source

Accurate measurement of transit time of the HDR brachytherapy source of a remote after-loading unit is necessary to calculate the total radiation dose given to the treatment volume. Presently, most of the HDR brachytherapy treatment planning systems neglect the transit time in the computation of dose. The aim of this investigation is to use a well type ionization chamber to measure the transit time during the source movement between two dwell positions. As well type ionization chamber and a precision electrometer (manufacturer CD instruments, Bangalore) were used to measure the charge generated during the movement of the Ir-192 source of a Gammamed HDR brachytherapy unit with an interstitial needle. Effective transit time and effective speed were determined on the basis of methodology described by Sahoo [2]. Corrections were done on the basis of relative sensitivity values for varaious dwell position in the ionization chamber. In the present study the variation of effective speed with interdwell distance was minimal as compared with that of Sahoo [2]. The effective transit times were 0.129, 0.182, 0.301, 0.402, 0.701, and 0.993 seconds for 1, 2, 4, 6, 8 and 10 cm interdwell separations respectively. The effective transit times in the present study were higher than those of Sahoo [2]. Software modification accounting for the dynamic dose should be incorporated into all HDR planning systems. Such an improvement would enhance the safety and accuracy of HDR brachytherapy.

Open access

Agata Jodda, Bartosz Urbański, Tomasz Piotrowski and Julian Malicki

Abstract

Background: The paper shows the methodology of an in-phantom study of the protection level of the bone marrow in patients with cervical or endometrial cancer for three radiotherapy techniques: three-dimensional conformal radiotherapy, intensity modulated radiotherapy, and volumetric modulated arc therapy, preceded by the procedures of image guidance.

Methods/Design: The dosimetric evaluation of the doses will be performed in an in-house multi-element anthropomorphic phantom of the female pelvic area created by three-dimensional printing technology. The volume and position of the structures will be regulated according to the guidelines from the Bayesian network. The input data for the learning procedure of the model will be obtained from the retrospective analysis of imaging data obtained for 96 patients with endometrial cancer or cervical cancer treated with radiotherapy in our centre in 2008-2013. Three anatomical representations of the phantom simulating three independent clinical cases will be chosen. Five alternative treatment plans (1 × three-dimensional conformal radiotherapy, 2 × intensity modulated radiotherapy and 2 × volumetric modulated arc therapy) will be created for each representation. To simulate image-guided radiotherapy, ten specific recombinations will be designated, for each anatomical representation separately, reflecting possible changes in the volume and position of the phantom components.

Discussion: The comparative analysis of planned measurements will identify discrepancies between calculated doses and doses that were measured in the phantom. Finally, differences between the doses cumulated in the hip plates performed by different techniques simulating the gynaecological patients' irradiation of dose delivery will be established. The results of this study will form the basis of the prospective clinical trial that will be designed for the assessment of hematologic toxicity and its correlation with the doses cumulated in the hip plates, for gynaecologic patients undergoing radiation therapy.

Open access

Ciszewska Katarzyna, Dymecka Malgorzata, Pliszczynski Tomasz and Osko Jakub

References Filipiak B, Haratym Z, Pliszczynski T, Snopek B, at al. Estimation of radiological protection at Institute of Atomic Energy on the territory of Nuclear Centre Swierk and its vicinity and National Radioactive Waste Repository Rozan. IEA Annual Report B-16/2010. Mingote RM, Barbeira PJS, Rocha Z. Methodology for rapid tritium determination in urine. J Radioanal Nucl Chem. 2006;269(2):475-479. Mosqueda F, Villa M, Vaca F, Bolivar JP. Colour quenching corrections on the

Open access

Elzbieta Olejarczyk, Maciej Kaminski, Radoslaw Marciniak, Tomasz Byrczek, Michal Stasiowski, Przemyslaw Jalowiecki, Aleksander Sobieszek and Wojciech Zmyslowski

sleep and wakefulness. Electroenceph Clin Neurophysiol. 1997;102:216-227. Olejarczyk E, Sobieszek A, Rudner R, Marciniak R, Wartak M, Stasiowski M, Jalowiecki P. Evaluation of the EEGsignal during volatile anaesthesia: methodological approach. Biocybern Biomed Eng. 2009;29(1):3-28. Olejarczyk E, Sobieszek A, Rudner R, Marciniak R, Wartak M, Stasiowski M, Jalowiecki P. Spectral analysis of the EEGsignal registered during anaesthesia induced by propofol and maintained by fluorinated inhalation anaesthetics. Biocybern

Open access

Donia Ben Hassen, Sihem Ben Zakour and Hassen Taleb

representation and recognition. Neural Networks. 2005;18(5):585-594. [18] Metz CE. ROC methodology in radiologic imaging. Invest Radiol. 1986;21(9):720-733.