Multilayer intensity modulated contact interventional radiotherapy (brachytherapy): Stretching the therapeutic window in skin cancer.

Interventional radiotherapy (IRT, brachytherapy) is a highly effective treatment method for non-melanoma skin cancer (NMSC). Traditionally, the maximum depth of NMSC lesions considered eligible for contact IRT was 5 mm; however, following several national surveys and recent recommendations, such cut-off, lesions thicker than 5 mm may be treated by contact IRT. The use of image guidance in defining the actual depth in treating NMSC to correctly identify clinical target volume (CTV) and prevent unnecessary toxicity is of paramount importance.

Use of secondary air kerma from dose area product and fluoroscopy time for preventive effective dose estimation in interventional radiology procedures for staff.

Introduction: interventional radiology workers are potentially exposed to high levels of ionizing radiation, therefore preventive dose estimation is mandatory for the correct risk classification of staff. Effective dose (ED) is a radiation protection quantity strictly related to the secondary air kerma (), using appropriate multiplicative conversion factors (ICRP 106). The aim of this work is to evaluate the accuracy ofestimated from physically measurable quantities such as dose-area product (DAP) or fluoroscopy time (FT).

Ventricular tachycardia ablation through radiation therapy (VT-ART) consortium: Concept description of an observational multicentric trial matched pair analysis.

Introduction: Monomorphic ventricular tachycardia (VT) is a life-threatening condition often observed in patients with structural heart disease. Ventricular tachycardia ablation through radiation therapy (VT-ART) for sustained monomorphic ventricular tachycardia seems promising, effective, and safe. VT-ART delivers focused, high-dose radiation, usually in a single fraction of 25 Gy, allowing ablation of VT by inducing myocardial scars.

Evaluation of a generalized knowledge-based planning performance for VMAT irradiation of breast and locoregional lymph nodes-Internal mammary and/or supraclavicular regions.

Purpose: To evaluate the performance of eleven Knowledge-Based (KB) models for planning optimization (RapidPlantm (RP), Varian) of Volumetric Modulated Arc Therapy (VMAT) applied to whole breast comprehensive of nodal stations, internal mammary and/or supraclavicular regions.

Methods And Materials: Six RP models have been generated and trained based on 120 VMAT plans data set with different criteria. Two extra-structures were delineated: a PTV for the optimization and a ring structure.

A new standardized data collection system for brain stereotactic external radiotherapy: the PRE.M.I.S.E project.

Background: In recent years, novel radiation therapy techniques have moved clinical practice toward tailored medicine. An essential role is played by the decision support system, which requires a standardization of data collection. The Aim of the Prediction Models In Stereotactic External radiotherapy (PRE.

Evaluation of a simplified optimizer for MR-guided adaptive RT in case of pancreatic cancer.

Purpose: Magnetic resonance-guided adaptive radiotherapy (MRgART) is considered a promising resource for pancreatic cancer, as it allows to online modify the dose distribution according to daily anatomy. This study aims to compare the dosimetric performance of a simplified optimizer implemented on a MR-Linac treatment planning system (TPS) with those obtained using an advanced optimizer implemented on a conventional Linac.

Methods: Twenty patients affected by locally advanced pancreatic cancer (LAPC) were considered.

A new three-dimensional conformal radiotherapy (3DCRT) technique for large breast and/or high body mass index patients: evaluation of a novel fields assessment aimed to reduce extra-target-tissue irradiation.

Objective: To develop an alternative three-dimensional treatment plan with standardized fields class solution for whole-breast radiotherapy in patients with large/pendulous breast and/or high body mass index (BMI).

Methods: Two treatment plans [tangential fields and standardized five-fields technique (S5F)] for a total dose of 50 Gy/25 fractions were generated for patients with large breasts [planning target volume (PTV) >1000 cm(3) and/or BMI >25 kg m(-2)], supine positioned. S5F plans consist of two wedged tangential beams, anteroposterior: 20° for the right breast and 340° for the left breast, and posteroanterior: 181° for the right breast and 179° for the left breast.

Initial experience of ArcCHECK and 3DVH software for RapidArc treatment plan verification.

The purpose of this study was to perform delivery quality assurance with ArcCHECK and 3DVH system (Sun Nuclear, FL) and to evaluate the suitability of this system for volumetric-modulated arc therapy (VMAT) (RapidArc [RA]) verification. This software calculates the delivered dose distributions in patients by perturbing the calculated dose using errors detected in fluence or planar dose measurements. The device is tested to correlate the gamma passing rate (%GP) and the composite dose predicted by 3DVH software.

Whole-breast irradiation: a subgroup analysis of criteria to stratify for prone position treatment.

To select among breast cancer patients and according to breast volume size those who may benefit from 3D conformal radiotherapy after conservative surgery applied with prone-position technique. Thirty-eight patients with early-stage breast cancer were grouped according to the target volume (TV) measured in the supine position: small (≤400 mL), medium (400-700 mL), and large (≥700 ml). An ad-hoc designed and built device was used for prone set-up to displace the contralateral breast away from the tangential field borders.

Beams arrangement in non-small cell lung cancer (NSCLC) according to PTV and dosimetric parameters predictive of pneumonitis.

The aim of this study is to propose and validate an original new class of solutions for three-dimensional conformal radiation therapy (3DCRT) treatment planning for non-small cell lung cancer (NSCLC) according to the different patterns of disease presentation (on the basis of tumor location and volume) and to explore beams arrangement (planar or no-planar solutions) to respect dose constraints to the lung parenchyma. Benchmarks matched to validate the new approach are interuser reproducibility and saving on planning time. Tumor location was explored and specific categories created according to the tumor volume and location.

Adding ipsilateral V20 and V30 to conventional dosimetric constraints predicts radiation pneumonitis in stage IIIA-B NSCLC treated with combined-modality therapy.

Purpose: To determine lung dosimetric constraints that correlate with radiation pneumonitis in non-small-cell lung cancer patients treated with three-dimensional radiation therapy and concurrent chemotherapy.

Methods And Materials: Between June 2002 and December 2006, 97 patients with locally advanced non-small-cell lung cancer were treated with concomitant radiochemotherapy. All patients underwent complete three-dimensional treatment planning (including dose-volume histograms), and patients were treated only if the percentage of total lung volume exceeding 20 Gy (V(20)) and 30 Gy (V(30)), and mean lung dose (MLD) had not exceeded the constraints of 31%, 18%, and 20 Gy, respectively.

Integration between in vivo dosimetry and image guided radiotherapy for lung tumors.

The article reports a feasibility study about the potentiality of an in vivo dosimetry method for the adaptive radiotherapy of the lung tumors treated by 3D conformal radiotherapy techniques (3D CRTs). At the moment image guided radiotherapy (IGRT) has been used for this aim, but it requires taking many periodic radiological images during the treatment that increase workload and patient dose. In vivo dosimetry reported here can reduce the above efforts, alerting the medical staff for the commissioning of new radiological images for an eventual adaptive plan.

Molecularly targeted therapy and radiotherapy in the management of localized gastrointestinal stromal tumor (GIST) of the rectum: a case report.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. The main treatment for localized gastrointestinal stromal tumors is surgical resection. These tumors respond poorly to conventional cytotoxic chemotherapy agents and to radiotherapy.

In patient dose reconstruction using a cine acquisition for dynamic arc radiation therapy.

An amorphous silicon (a-Si) electronic portal imaging device (EPID) was implemented to perform transit in vivo dosimetry for dynamic conformal arc therapy (DCAT). A set of images was acquired for each arc irradiation using the EPID cine acquisition mode, that supplies a frame acquisition rate of one image every 1.66 s, with a monitor unit rate equal to 100 UM/min.

Dynamic conformal arc therapy: transmitted signal in vivo dosimetry.

A method for the determination of the in vivo isocenter dose, D(iso), has been applied to the dynamic conformal are therapy (DCAT) for thoracic tumors. The method makes use of the transmitted signal, S(t,alpha), measured at different gantry angles, a, by a small ion chamber positioned on the electronic portal imaging device. The in vivo method is implemented by a set of correlation functions obtained by the ratios between the transmitted signal and the midplane dose in a solid phantom, irradiated by static fields.

Application of a practical method for the isocenter point in vivo dosimetry by a transit signal.

This work reports the results of the application of a practical method to determine the in vivo dose at the isocenter point, D(iso), of brain thorax and pelvic treatments using a transit signal S(t). The use of a stable detector for the measurement of the signal S(t) (obtained by the x-ray beam transmitted through the patient) reduces many of the disadvantages associated with the use of solid-state detectors positioned on the patient as their periodic recalibration, and their positioning is time consuming. The method makes use of a set of correlation functions, obtained by the ratio between S(t) and the mid-plane dose value, D(m), in standard water-equivalent phantoms, both determined along the beam central axis.

Breast in vivo dosimetry by a portal ionization chamber.

This work reports a practical method for the determination of the in vivo breast middle dose value, D(m) on the beam central axis, using a signal S(t), obtained by a small thimble ion chamber positioned at the center of the electronic portal imaging device, and irradiated by the x-ray beam transmitted through the patient. The use of a stable ion chamber reduces many of the disadvantages associated with the use of diodes as their periodic recalibration and positioning is time consuming. The method makes use of a set of correlation functions obtained by the ratios S(t)/D(m), determined by irradiating cylindrical water phantoms with different diameters.

In vivo dosimetry by an aSi-based EPID.

A method for the in vivo determination of the isocenter dose, Diso, and mid-plane dose, Dm, using the transmitted signal St measured by 25 central pixels of an aSi-based EPID is here reported. The method has been applied to check the conformal radiotherapy of pelvic tumors and supplies accurate in vivo dosimetry avoiding many of the disadvantages associated with the use of two diode detectors (at the entrance and exit of the patient) as their periodic recalibration and their positioning. Irradiating water-equivalent phantoms of different thicknesses, a set of correlation functions F(w, l) were obtained by the ratio between St and Dm as a function of the phantom thickness, w, for a different field width, l.