Low-dose-rate, high-dose-rate, and pulsed-dose-rate intra-cavitary brachytherapy for cervical cancer: The very first comparison study.

Purpose: For cervical cancer patients, intra-cavitary brachytherapy (ICBT) is utilized with various dose-rate systems, such as low-dose-rate (LDR), high-dose-rate (HDR), and pulsed-dose-rate (PDR). This retrospective analysis aimed to compare the therapeutic outcomes of cervical cancer patients treated with either LDR-, HDR-, or PDR-ICBT.

Material And Methods: A total of 613 patients were treated with pelvic external beam radiation therapy (EBRT), followed by either LDR- (271 patients), HDR- (259 patients), or PDR- (83 patients) ICBT.

Performance of a deformable image registration algorithm for CT and cone beam CT using physical multi-density geometric and digital anatomic phantoms.

Purpose: To study the accuracy of deformable registration algorithm for CT and cone beam CT (CBCT) using a combination of physical and digital phantoms.

Materials And Methods: The physical phantoms consisted of objects over a range of electron densities, shape and sizes. The system was tested for simple and complex scenarios including performance in the presence of metallic artefacts.

Auto-segmentation of head and neck organs at risk in radiotherapy and its dependence on anatomic similarity.

Purpose: The aim is to study the dependence of deformable based auto-segmentation of head and neck organs-at-risks (OAR) on anatomy matching for a single atlas based system and generate an acceptable set of contours.

Methods: A sample of ten patients in neutral neck position and three atlas sets consisting of ten patients each in different head and neck positions were utilized to generate three scenarios representing poor, average and perfect anatomy matching respectively and auto-segmentation was carried out for each scenario. Brainstem, larynx, mandible, cervical oesophagus, oral cavity, pharyngeal muscles, parotids, spinal cord, and trachea were the structures selected for the study.

Commissioning of portal dosimetry using a novel method for flattening filter-free photon beam in a nontrue beam linear accelerator.

Aim: The aim of this study is to commission and validate the portal dosimetry (PD) system using an indirect method for flattening filter free (FFF) photon beam of the upgraded c-series linear accelerator.

Background: Varian Medical System clinacs with amorphous-silicon portal imager panel (aSi-1000) do not have PD for FFF beams. Recently, our c-series linear accelerator was upgraded to deliver 6MV FFF (6MVFFF) photon beam with the highest dose rate of 1400 monitor unit (MU)/min.

Application of aSi-kVCBCT for Volume Assessment and Dose Estimation: An Offline Adaptive Study for Prostate Radiotherapy.

Objective: The purpose of this study is to develop a method to estimate the dose using amorphous silicon detector panel cone beam computed tomography (aSi-kVCBCT) for the OARs and targets in prostate radiotherapy and to compare with the actual planned dose. Methods: The aSi-kVCBCT is used widely in radiotherapy to verify the patient position before treatment. The advancement in aSi-kVCBCT combined with adaptive software allows us to verify the dose distribution in daily acquired CBCT images.

Multi-isocentric 4π volumetric-modulated arc therapy approach for head and neck cancer.

Objectives: To explore the feasibility of multi-isocentric 4π volumetric-modulated arc therapy (MI4π-VMAT) for the complex targets of head and neck cancers.

Methods: Twenty-five previously treated patients of HNC underwent re-planning to improve the dose distributions with either coplanar VMAT technique (CP-VMAT) or noncoplanar MI4π-VMAT plans. The latter, involving 3-6 noncoplanar arcs and 2-3 isocenters were re-optimized using the same priorities and objectives.

Dosimetric comparison of head and neck cancer patients planned with multivendor volumetric modulated arc therapy technology.

Aim: Purpose of this study is to dosimetrically compare head and neck (H and N) cancer patients planned with multivendor volumetric modulated arc therapy (VMAT) technology. VMAT treatment planning can be done using biological (treatment planning system [TPSB]: Monaco) or physical (TPSP: Eclipse)-based cost function optimization techniques. Planning and dosimetric comparisons were done in both techniques for H and N cases.

Feasibility of offline head & neck adaptive radiotherapy using deformed planning CT electron density mapping on weekly cone beam computed tomography.

Objective: The purpose of the study was to use deformable mapping of planning CT (pCT) electron density values on weekly cone-beam CT (CBCT) to quantify the anatomical changes and determine the dose-volume relationship in offline adaptive volumetric-modulated arc therapy.

Methods: 10 patients treated with RapidArc plans who had weekly CBCTs were selected retrospectively. The pCT was deformed to weekly CBCTs and the deformed contours were checked for any discrepancies.

Is 5 mm MMLC suitable for VMAT-based lung SBRT? A dosimetric comparison with 2.5 mm HDMLC using RTOG-0813 treatment planning criteria for both conventional and high-dose flattening filter-free photon beams.

The aim of this study is to assess the suitability of 5 mm millennium multileaf collimator (MMLC) for volumetric-modulated arc therapy (VMAT)-based lung stereotactic body radiotherapy (SBRT). Thirty lung SBRT patient treatment plans along with their planning target volumes (ranging from 2.01 cc to 150.

Comparative evaluation of two-dimensional radiography and three dimensional computed tomography based dose-volume parameters for high-dose-rate intracavitary brachytherapy of cervical cancer: a prospective study.

Background: Dosimetric comparison of two dimensional (2D) radiography and three-dimensional computed tomography (3D-CT) based dose distributions with high-dose-rate (HDR) intracavitry radiotherapy (ICRT) for carcinoma cervix, in terms of target coverage and doses to bladder and rectum.

Materials And Methods: Sixty four sessions of HDR ICRT were performed in 22 patients. External beam radiotherapy to pelvis at a dose of 50 Gray in 27 fractions followed by HDR ICRT, 21 Grays to point A in 3 sessions, one week apart was planned .

Early clinical outcomes and toxicity of intensity modulated versus conventional pelvic radiation therapy for locally advanced cervix carcinoma: a prospective randomized study.

Purpose: To evaluate the toxicity and clinical outcome in patients with locally advanced cervical cancer (LACC) treated with whole pelvic conventional radiation therapy (WP-CRT) versus intensity modulated radiation therapy (WP-IMRT).

Methods And Materials: Between January 2010 and January 2012, 44 patients with International Federation of Gynecology and Obstetrics (FIGO 2009) stage IIB-IIIB squamous cell carcinoma of the cervix were randomized to receive 50.4 Gy in 28 fractions delivered via either WP-CRT or WP-IMRT with concurrent weekly cisplatin 40 mg/m(2).

Critical appraisal of the accuracy of Acuros-XB and Anisotropic Analytical Algorithm compared to measurement and calculations with the compass system in the delivery of RapidArc clinical plans.

Background: The accuracy of the two dose calculation engines available for RapidArc planning (both released for clinical use) is investigated in comparison to the COMPASS data.

Methods: Two dose calculation algorithms (Acuros-XB and Anisotropic Analytic Algorithm (AAA)) were used to calculate RA plans and compared to calculations with the Collapsed Cone Convolution algorithm (CC) from the COMPASS system (IBA Dosimetry). CC calculations, performed on patient data, are based on experimental fluence measurements with a 2D array of ion chambers mounted on the linac head.

MAGAT gel and EBT2 film-based dosimetry for evaluating source plugging-based treatment plan in Gamma Knife stereotactic radiosurgery.

This work illustrates a procedure to assess the overall accuracy associated with Gamma Knife treatment planning using plugging. The main role of source plugging or blocking is to create dose falloff in the junction between a target and a critical structure. We report the use of MAGAT gel dosimeter for verification of an experimental treatment plan based on plugging.

High-dose rate interstitial brachytherapy using two weekly sessions of 10 Gy each for patients with locally advanced cervical carcinoma.

Purpose: To evaluate the feasibility of high-dose rate interstitial brachytherapy (HDR-IBT) using two weekly sessions of 10 Gy in combination to pelvic external beam radiation therapy (EBRT) for patients with locally advanced cervical carcinoma.

Methods And Materials: Between the year 2005 and 2007, 42 patients with locally advanced cervical carcinoma (International Federation of Gynecology and Obstetrics Stage IIB-IVA), not suitable for intracavitary radiotherapy after completing EBRT, were enrolled in this prospective study. Two weekly sessions of HDR-IBT with 10 Gy each were delivered 1 week after pelvic EBRT.

Use of transrectal ultrasound for high dose rate interstitial brachytherapy for patients of carcinoma of uterine cervix.

Objective: Transrectal ultrasound (TRUS) has been widely used for guiding prostate implants, but not much for interstitial brachytherapy (IBT) of cervix cancer. The aim of our study is to report our experience with TRUS guided high dose rate (HDR) IBT in patients with carcinoma of uterine cervix.

Methods: During the year 2005-2006, 25 patients of cervical cancer not suitable for intracavitary radiotherapy (ICRT), were enrolled in this prospective study.

Pulsed-dose-rate intracavitary brachytherapy for cervical carcinoma: the AIIMS experience.

Objective: The aim of present study was to analyze the results of pulsed-dose-rate (PDR) brachytherapy in patients with cervical carcinoma treated at our center.

Methods: From September 2003 to September 2005, 48 patients with histopathologically proved cervical carcinoma, stages IB to IVA, were treated with PDR intracavitary radiotherapy (ICRT) and pelvic irradiation at our center. Radiotherapy consisted of whole pelvis external beam radiation therapy (EBRT) with a dose of 40 Gy in 22 fractions over 4.

Characterization of responses and comparison of calibration factor for commercial MOSFET detectors.

A commercial metal oxide silicon field effect transistor (MOSFET) dosimeter of model TN502-RD has been characterized for its linearity, reproducibility, field size dependency, dose rate dependency, and angular dependency for Cobalt-60 (60Co), 6-MV, and 15-MV beam energies. The performance of the MOSFET clearly shows that it is highly reproducible, independent of field size and dose rate. Furthermore, MOSFET has a very high degree of linearity, with r-value>0.