Validation of Microionization Chambers in Small-field Dosimetry.

Aim: This study aims to validate the Razor Nano Chamber (RNC) and Razor Chamber (RC) dosimetric characteristics in a small field. The dosimetric parameters of the two chambers were compared.

Materials And Methods: The chamber characteristics of leakage (pre and post), stability, energy dependency, dose linearity, dose rate effect, stem effect, angular dependency, ion recombination effect, and polarity effect were studied.

Effect of Detector Orientation and Influence of Jaw Position in the Determination of Small-field Output Factor with Various Detectors for High-energy Photon Beams.

Background: Accurate dose measurements are difficult in small fields due to charge particle disequilibrium, partial source occlusion, steep dose gradient, and the finite size of the detector.

Aim: The study aims to determine the output factor using various detectors oriented in parallel and perpendicular orientations for three different tertiary collimating systems using 15 MV photon beams. In addition, this study analyzes how the output factor could be affected by different configurations of X and Y jaws above the tertiary collimators.

Characteristics Performance of Newly Developed Parallel Plate Chamber in Electron Beams.

Background: To investigate the dosimetric performance of newly developed parallel plate chamber in electron beams.

Materials And Methods: Rosalina Instruments India Private Limited (Mumbai, Maharashtra, India) has designed and fabricated PRATT2 parallel plate chamber. The various dosimetric characteristics, including pre- and post-irradiation leakage, stability, polarity effect, chamber response with bias voltage, dose linearity, dose rate effect, and chamber absorbed dose calibration, were performed for the developed chamber.

Evaluation of International Atomic Energy Agency Technical Report Series-483 Detector-specific Output Correction Factor for Various Collimator Systems.

Aim: In this study, a 6MV flattening filter (FF) and 6MV FF Free (FFF) photon beam small-field output factors (OF) were measured with various collimators using different detectors. The corrected OFs were compared with the treatment planning system (TPS) calculated OFs.

Materials And Methods: OF measurements were performed with four different types of collimators: Varian Millennium multi-leaf collimator (MLC), Elekta Agility MLC, Apex micro-MLC (mMLC) and a stereotactic cone.

Determination of small-field output factors for beam-matched linear accelerators using various detectors and comparison of detector-specific output correction factors using IAEA Technical Report Series 483 protocol.

Background: Beam matching is widely used to ensure that linear accelerators used in radiotherapy have equal dosimetry characteristics. Small-field output factors (OF) were measured using different detectors infour beam-matched linear accelerators and the measured OFs were compared with existing treatment planning system (TPS) Monte Carlo algorithm calculated OFs.

Materials And Methods: Three Elekta Versa HD and one Elekta Infinitylinear accelerators with photon energies of 6 MV flattening filter (FF), 10 MVFF, 6 MV flattening filter free (FFF) and 10 MVFFF were used in this study.

Validation of American Association of Physicists in Medicine TG 43 Dosimetry Data in Commercial Treatment Planning System.

Aims: This study aimed to validate the dosimetric data of low-energy photon-emitting low-dose rate (LE-LDR) brachytherapy seed sources in commercial treatment planning system (TPS).

Materials And Methods: The LE-LDR seed sources dosimetric data were published in the American Association of Physicists in Medicine (AAPM) Task Group reports TG-43 (1995), TG-43U1 (2004), TG-43U1S1 (2007), and TG-43U1S2. The Bhabha Atomic Research centre (BARC) I Ocu-Prosta seed dosimetry data are also available in the literature.

Prostate permanent implant brachytherapy with BARC I-125 Ocu-Prosta seeds.

Aim: The aim of this study is implementation and establishment of standard operating procedure for permanent prostate implant brachytherapy technique using BARC I-125 Ocu-Prosta seeds.

Materials And Methods: The transrectal ultrasound (US)-guided procedure was used for permanent implant procedure. The Best Sonalis™ US Imaging System and Best NOMOS™ Treatment Planning system was used for volume study and implant procedure.

Magnetic resonance image-based 3D volume interstitial brachytherapy using polyether ether ketone catheters in advanced cervical cancer - a feasibility study.

Purpose: A feasibility study of 3D volume-based interstitial brachytherapy using thermoplastic polyether ether ketone (PEEK) catheters in advanced cervical cancer MR-based brachytherapy, when MR-compatible applicators are not available.

Material And Methods: Five cervical cancer patients received EBRT dose of 50 Gy in 25 fractions to whole pelvis using 3D conformal radiotherapy after standard pre-treatment evaluation. In our institute, interstitial brachytherapy (ISBT) is planned in BrachyVision TPS and routinely performed using stainless steel needles with Syed-Neblett template.

Evaluation of optically stimulated luminescence dosimeter for exit dose dosimetry in radiation therapy.

Aim: The aim of this study was to assess and analyze the exit dose in radiotherapy using optically stimulated luminescence dosimeter (OSLD) with therapeutic photon beams.

Materials And Methods: Measurements were carried out with OSLD to estimate the exit dose in phantom for different field sizes, various phantom thicknesses, and with added backscatter material. The data obtained were validated with ionization chamber data where applicable.

Dosimetric characterization of optically stimulated luminescence dosimeter with therapeutic photon beams for use in clinical radiotherapy measurements.

Aim: The modern radiotherapy techniques impose new challenges for dosimetry systems with high precision and accuracy in in vivo and in phantom dosimetric measurements. The knowledge of the basic characterization of a dosimetric system before patient dose verification is crucial. This incites the investigation of the potential use of nanoDot optically stimulated luminescence dosimeter (OSLD) for application in radiotherapy with therapeutic photon beams.

Dosimetric evaluation of newly developed well-type ionization chamber for use in the calibration of brachytherapy sources.

The well-type ionization chamber has been designed for convenient use in brachytherapy source strength calibration. The chamber has a volume of 240 cm, weight of 2.5 kg, and is open to atmospheric conditions.

The effect of influence quantities and detector orientation on small-field patient-specific IMRT QA: comparison of measurements with various ionization chambers.

Intensity-modulated radiation therapy (IMRT) requires a patient-specific quality assurance (QA) program to validate the treatment plan and a high level of dosimetric accuracy in the treatment delivery. Dosimetric verification generally consists of both absolute- and relative-dose measurements in a phantom using ionization chambers. Measurements were carried out with three different ionization chambers (Scanditronix FC 65G, Exradin A18, and PTW PinPoint 31014) to assess the effects of influence quantities such as the stability, pre- and post-irradiation leakage, stem effect, polarity, and ion recombination on the IMRT point-dose verification with two different orientations.

Dosimetric Performance of Newly Developed Farmer-Type Ionization Chamber in Radiotherapy Practice.

Dose measurement with ionization chamber is essential to deliver accurate dose to the tumor in radiotherapy. The cylindrical Farmer-type ionization chamber is recommended by various dosimetry protocols for dose measurement of radiotherapy beams. The air-equivalent graphite wall Farmer-type ionization chamber (FAR 65 GB) of active volume 0.

Comparison of individual and composite field analysis using array detector for Intensity Modulated Radiotherapy dose verification.

Aim: To compare the measured and calculated individual and composite field planar dose distribution of Intensity Modulated Radiotherapy plans.

Materials And Methods: The measurements were performed in Clinac DHX linear accelerator with 6 MV photons using Matrixx device and a solid water phantom. The 20 brain tumor patients were selected for this study.

Dosimetric evaluation of two treatment planning systems for high dose rate brachytherapy applications.

Various treatment planning systems are used to design plans for the treatment of cervical cancer using high-dose-rate brachytherapy. The purpose of this study was to make a dosimetric comparison of the 2 treatment planning systems from Varian medical systems, namely ABACUS and BrachyVision. The dose distribution of Ir-192 source generated with a single dwell position was compared using ABACUS (version 3.

Plan evaluation and dosimetric comparison of IMRT using AAPM TG119 test suites and recommendations.

In order to verify intensity modulated radiotherapy quality assurance procedure and to establish the practical base line commissioning, American Association of Physicists in Medicine-Task Group 119 test suite DICOM-RT images and structure were downloaded for planning and dosimetric comparison. The square slab phantom of water equivalent plastic was used for the measurement. This phantom can permit point dose measurement with ionization chamber by placing the chamber at 7.

Comparison of dosimetric characteristics of physical and enhanced dynamic wedges.

Background: Wedge filters can be used as missing tissue compensators or wedge pairs to alter the shape of isodose curves so that two beams can be angled with a small hinge angle at a target volume without creating a hotspot.

Aim: In this study the dosimetric properties of Varian Enhanced Dynamic Wedge (EDW) and physical wedges (PW) were analyzed and compared.

Materials And Methods: Ionometric measurements of open field output factor, physical wedge output factor, physical wedge factor and EDW factor for photon beams were carried out.

Dosimetric study of 2D ion chamber array matrix for the modern radiotherapy treatment verification.

Intensity-modulated radiotherapy treatment demands stringent quality assurance and accurate dose determination for delivery of highly conformal dose to the patients. Generally 3D dose distributions obtained from a treatment planning system have to be verified by dosimetric methods. Mainly, a comparison of two-dimensional calculated and measured data in several coplanar planes is performed.

Backscattered dose perturbation effects at metallic interfaces irradiated by high-energy X- and gamma-ray therapeutic beams.

Purpose: To analyze backscattered dose enhancements near different metallic interfaces for cobalt-60 ((60)Co) gamma rays and 6- and 18-MV photon beams.

Material And Methods: Measurements were carried out with a PTW thin-window, parallel-plate ionization chamber and an RDM-1F electrometer. Thin sheets of aluminum, mild steel, copper, cadmium and lead were used as inhomogeneities.