Coverage with dosimetric concordance index (CDCI): a tool for evaluating dosimetric impact of inter-observer target variability in brachytherapy.

Purpose: The aim of this study was to propose an index for evaluating dosimetric impact of inter-observer target delineation variability in brachytherapy.

Material And Methods: The coverage with dosimetric concordance index (CDCI) is expressed as CDCI and CDCI. The CDCI is the mean coverage of target volume with common volume irradiated by prescription dose among all observers and represents the condition of worst target coverage.

Impact of inter-observer variations in target volume delineation on dose volume indices for accelerated partial breast irradiation with multi-catheter interstitial brachytherapy.

Purpose: To investigate dosimetric impact of inter-observer variation in clinical target volume(CTV) delineation for patients undergoing interstitial partial breast brachytherapy.

Methods: Five radiation oncologists delineated CTV in twenty patients who underwent multi-catheter partial breast brachytherapy. Five treatment plans for each patient were graphically optimized for CTV of all observers and evaluated using coverage index(CI), external volume index(EI), overdose volume index(OI) and conformal index(COIN).

Change of target volume and its dosimetric impact during the course of accelerated partial breast irradiation using intraoperative multicatheter interstitial brachytherapy after open cavity surgery.

Purpose: To investigate the change of clinical target volume (CTV) and its dosimetric impact during the course of accelerated partial breast irradiation (APBI) using intraoperative multicatheter interstitial brachytherapy after open cavity surgery.

Methods And Materials: Twenty-two patients of APBI with intraoperative placement of catheters underwent computed tomography scans for the treatment planning before the first (CT1) and the last (CT2) treatment fraction. Delineation of lumpectomy cavity and CTV was done consistently on both CT data sets by one of the coauthors.

Interobserver variations of target volume delineation and its impact on irradiated volume in accelerated partial breast irradiation with intraoperative interstitial breast implant.

Purpose: To investigate the interobserver variations in delineation of lumpectomy cavity (LC) and clinical target volume (CTV), and its impact on irradiated volume in accelerated partial breast irradiation using intraoperative multicatheter brachytherapy.

Material And Methods: Delineation of LC and CTV was done by five radiation oncologists on planning computed tomography (CT) scans of 20 patients with intraoperative interstitial breast implant. Cavity visualization index (CVI), four-point index ranging from (0 = poor) to (3 = excellent) was created and assigned by observers for each patient.

Measurement of Total Scatter Factor for Stereotactic Cones with Plastic Scintillation Detector.

Advanced radiotherapy modalities such as stereotactic radiosurgery (SRS) and image-guided radiotherapy may employ very small beam apertures for accurate localized high dose to target. Accurate measurement of small radiation fields is a well-known challenge for many dosimeters. The purpose of this study was to measure total scatter factors for stereotactic cones with plastic scintillation detector and its comparison against diode detector and theoretical estimates.

Dosimetric response of variable-size cavities in photon-irradiated media and the behaviour of the Spencer-Attix cavity integral with increasing Δ.

Cavity theory is fundamental to understanding and predicting dosimeter response. Conventional cavity theories have been shown to be consistent with one another by deriving the electron (+positron) and photon fluence spectra with the FLURZnrc user-code (EGSnrc Monte-Carlo system) in large volumes under quasi-CPE for photon beams of 1 MeV and 10 MeV in three materials (water, aluminium and copper) and then using these fluence spectra to evaluate and then inter-compare the Bragg-Gray, Spencer-Attix and 'large photon' 'cavity integrals'. The behaviour of the 'Spencer-Attix dose' (aka restricted cema), D S-A(▵), in a 1-MeV photon field in water has been investigated for a wide range of values of the cavity-size parameter ▵: D S-A(▵) decreases far below the Monte-Carlo dose (D MC) for ▵ greater than  ≈  30 keV due to secondary electrons with starting energies below ▵ not being 'counted'.

Setup error analysis in helical tomotherapy based image-guided radiation therapy treatments.

The adequacy of setup margins for various sites in patients treated with helical tomotherapy was investigated. A total of 102 patients were investigated. The breakdown of the patients were as follows: Twenty-five patients each in brain, head and neck (H and N), and pelvis, while 12 patients in lung and 15 in craniospinal irradiation (CSI).

Dosimetric comparison of three-dimensional conformal radiotherapy, intensity modulated radiotherapy, and helical tomotherapy for lung stereotactic body radiotherapy.

To compare the treatment plans generated with three-dimensional conformal radiation therapy (3DCRT), intensity modulated radiotherapy (IMRT), and helical tomotherapy (HT) for stereotactic body radiotherapy of lung, twenty patients with medically inoperable (early nonsmall cell lung cancer) were retrospectively reviewed for dosimetric evaluation of treatment delivery techniques (3DCRT, IMRT, and HT). A dose of 6 Gy per fraction in 8 fractions was prescribed to deliver 95% of the prescription dose to 95% volume of planning target volume (PTV). Plan quality was assessed using conformity index (CI) and homogeneity index (HI).

Uncertainties of deformable image registration for dose accumulation of high-dose regions in bladder and rectum in locally advanced cervical cancer.

Purpose: To compare the dose accumulation for bladder and rectum by deformable image registration (DIR) and direct addition (DA) of dose volume histogram parameters in magnetic resonance image-guided adaptive brachytherapy (IGABT). Two DIR algorithms, contour- and intensity-based, also have been analyzed.

Methods And Materials: Patients (n = 21) treated with IGABT for carcinoma cervix under the IntErnational study on MRI-guided BRachytherapy in locally Advanced CErvical cancer protocol were analyzed.

Characterization of commercial MOSFET detectors and their feasibility for in-vivo HDR brachytherapy.

Aim: The present study was to investigate the use of MOSFET as an vivo dosimeter for the application of Ir-192 HDR brachytherapy treatments.

Material And Methods: MOSFET was characterized for dose linearity in the range of 50-1000 cGy, depth dose dependence from 2 to 7 cm, angular dependence. Signal fading was checked for two weeks.

Breakdown of Bragg-Gray behaviour for low-density detectors under electronic disequilibrium conditions in small megavoltage photon fields.

In small photon fields ionisation chambers can exhibit large deviations from Bragg-Gray behaviour; the EGSnrc Monte Carlo (MC) code system has been employed to investigate this 'Bragg-Gray breakdown'. The total electron (+positron) fluence in small water and air cavities in a water phantom has been computed for a full linac beam model as well as for a point source spectrum for 6 MV and 15 MV qualities for field sizes from 0.25  ×  0.

Monte-Carlo-derived insights into dose-kerma-collision kerma inter-relationships for 50 keV-25 MeV photon beams in water, aluminum and copper.

The relationships between D, K and Kcol are of fundamental importance in radiation dosimetry. These relationships are critically influenced by secondary electron transport, which makes Monte-Carlo (MC) simulation indispensable; we have used MC codes DOSRZnrc and FLURZnrc. Computations of the ratios D/K and D/Kcol in three materials (water, aluminum and copper) for large field sizes with energies from 50 keV to 25 MeV (including 6-15 MV) are presented.

Radiation exposure among medical professionals working in the Intensive Care Unit.

Background And Aims: With the expanding use of diagnostic and therapeutic radiological modalities in critically ill patients, doctors working in Intensive Care Units (ICUs) are increasingly exposed to ionizing radiation. This risk of radiation exposure occurs not only during bedside radiologic procedures, but also when ICU physicians accompany patients to radiology suites. The aim of this study was to quantify levels of radiation exposure among medical professionals working in the ICU.

Estimation of dose enhancement to soft tissue due to backscatter radiation near metal interfaces during head and neck radiothearpy - A phantom dosimetric study with radiochromic film.

The objective of this study was to investigate the dose enhancement to soft tissue due to backscatter radiation near metal interfaces during head and neck radiotherapy. The influence of titanium-mandibular plate with the screws on radiation dose was tested on four real bones from mandible with the metal and screws fixed. Radiochromic films were used for dosimetry.

Inter-application variation of dose and spatial location of D(2cm(3)) volumes of OARs during MR image based cervix brachytherapy.

Purpose: Evaluation of Inter-application variation of doses and spatial location of D(2cm(3)) volumes of OARs during MR-image based cervix brachytherapy.

Materials And Methods: Twenty-seven patients treated with EMBRACE protocol were analyzed. Every patient had two applications, one week apart.

Trans-abdominal ultrasound (US) and magnetic resonance imaging (MRI) correlation for conformal intracavitary brachytherapy in carcinoma of the uterine cervix.

Purpose: Trans-abdominal ultrasonography (US) is capable of determining size, shape, thickness, and diameter of uterus, cervix and disease at cervix or parametria. To assess the potential value of US for image-guided cervical cancer brachytherapy, we compared US-findings relevant for brachytherapy to the corresponding findings obtained from MR imaging.

Materials And Methods: Twenty patients with biopsy proven cervical cancer undergoing definitive radiotherapy with/without concomitant Cisplatin chemotherapy and suitable for brachytherapy were invited to participate in this study.

Reporting and validation of gynaecological Groupe Euopeen de Curietherapie European Society for Therapeutic Radiology and Oncology (ESTRO) brachytherapy recommendations for MR image-based dose volume parameters and clinical outcome with high dose-rate brachytherapy in cervical cancers: a single-institution initial experience.

Objective: The objectives are to report the dosimetric analysis, preliminary clinical outcome, and comparison with published data of 3-dimensional magnetic resonance-based high dose rate brachytherapy (BT) in cervical cancer.

Materials And Methods: The data set of 24 patients with cervical cancer treated with high dose-rate brachytherapy applications was analyzed. All patients received radiation with or without chemotherapy (10 patients received concomitant chemoradiation).

Comparison of IPSA with dose-point optimization and manual optimization for interstitial template brachytherapy for gynecologic cancers.

Purpose: To compare inverse planning simulated annealing (IPSA) algorithm with the dose-point optimized (DPO) plan and manual/graphically optimized (GrO) plan for interstitial template brachytherapy for gynecologic cancers.

Methods And Materials: The data set of 10 consecutive patients was selected for this dosimetric study. For each patient, three plans were calculated: DPO, GrO, and IPSA.

Comparison of DVH parameters and loading patterns of standard loading, manual and inverse optimization for intracavitary brachytherapy on a subset of tandem/ovoid cases.

Purpose: Comparison of inverse planning with the standard clinical plan and with the manually optimized plan based on dose-volume parameters and loading patterns.

Materials And Methods: Twenty-eight patients who underwent MRI based HDR brachytherapy for cervix cancer were selected for this study. Three plans were calculated for each patient: (1) standard loading, (2) manual optimized, and (3) inverse optimized.

Characterization of metal oxide field-effect transistors for first helical tomotherapy Hi-Art II unit in India.

Purpose: To characterize metal oxide semiconductor field-effect transistors (MOSFETs) for a 6-MV photon beam with a first helical tomotherapy Hi-Art II unit in India.

Materials And Methods: Standard sensitivity MOSFETs were first calibrated and then characterized for reproducibility, field size dependence, angular dependence, fade effects, and temperature dependence. The detector sensitivity was estimated for static as well as rotational modes for three jaw settings (1.

Dose optimization of intra-operative high dose rate interstitial brachytherapy implants for soft tissue sarcoma.

Objective: A three dimensional (3D) image-based dosimetric study to quantitatively compare geometric vs. dose-point optimization in combination with graphical optimization for interstitial brachytherapy of soft tissue sarcoma (STS).

Materials And Methods: Fifteen consecutive STS patients, treated with intra-operative, interstitial Brachytherapy, were enrolled in this dosimetric study.

Dosimetric validation of first helical tomotherapy Hi-Art II machine in India.

A Helical Tomotherapy (HT) Hi-Art II machine, Hi ART (TomoTherapy, Inc., Madison, WI, USA) was installed at our center in July 2007, and was the first machine in India. Image-guided HT is a new modality for delivering intensity modulated radiotherapy (IMRT).

Initial dosimetric experience with mega voltage computed tomography detectors and estimation of pre and post-repair dosimetric parameters of a first Helical Hi-Art II tomotherapy machine in India.

A Helical Tomotherapy (HT) Hi-Art II (TomoTherapy, Inc., Madison, WI, USA) has been one of the important innovations to help deliver IMRT with image guidance. On-board, mega voltage computed tomography (MVCT) detectors are used for imaging and dosimetric purpose.

Treatment planning of epithelial ovarian cancers using helical tomotherapy.

Whole Abdomen Radiotherapy (WAR) for epithelial ovarian cancer though effective has been used sparingly due to inadequate target coverage and poor sparing of Organ At Risk (OAR) leading to significantly higher toxicities. Newer radiation techniques have shown potential for significant improvement in the therapeutic ratio. The purpose of this study was to evaluate Helical Tomotherapy(HT) for WAR.