A comparison of several modulated radiotherapy techniques for head and neck cancer and dosimetric validation of VMAT.

Purpose: Volumetric modulated arc therapy (VMAT) has the potential to shorten treatment times for fluence modulated radiotherapy. We compared dose distributions of VMAT, step-and-shoot IMRT and serial tomotherapy for typical head and neck (H&N) planning target volumes (PTV) with sparing of one parotid, a complex paradigm and a situation often encountered in H&N radiotherapy. Finally, we validated the dosimetric accuracy of VMAT delivery.

Reirradiation of spinal column metastases: comparison of several treatment techniques and dosimetric validation for the use of VMAT.

Background: For reirradiation of spinal column metastases, intensity-modulated radiation therapy (IMRT) reduces the dose to the spinal cord, while allowing longer treatment times. We analyzed the potential of volumetric modulated arc therapy (VMAT) to reduce treatment time and number of monitor units (MU).

Patients And Methods: In CT datasets of 9 patients with spinal column metastases, the planned target volume (PTV) encompassed the macroscopic tumor including the spinal cord or medullary cone, respectively.

Clinical implementation of volumetric intensity-modulated arc therapy (VMAT) with ERGO++.

Background And Purpose: Volumetric modulated arc therapy (VMAT) has the potential to deliver dose distributions comparable to the established intensity-modulated radiotherapy techniques for a multitude of target paradigms. Prior to implementing VMAT into their clinical routine in December 2008, the authors evaluated the dose calculation/delivery accuracy of 24 sample VMAT plans (prostate and anal cancer target paradigms) with film and ionization dosimetry. After the start of the clinical program, in vivo measurements with a rectal probe were performed.

A new strategy for online adaptive prostate radiotherapy based on cone-beam CT.

Purpose: Interfractional organ motion and patient positioning errors during prostate radiotherapy can have deleterious clinical consequences. It has become clinical practice to re-position the patient with image-guided translational position correction before each treatment to compensate for those errors. However, tilt errors can only be corrected with table corrections in six degrees of freedom or "full" adaptive treatment planning strategies.

A fast radiotherapy paradigm for anal cancer with volumetric modulated arc therapy (VMAT).

Background/purpose: Radiotherapy (RT) volumes for anal cancer are large and of moderate complexity when organs at risk (OAR) such as testis, small bowel and bladder are at least partially to be shielded. Volumetric intensity modulated arc therapy (VMAT) might provide OAR-shielding comparable to step-and-shoot intensity modulated radiotherapy (IMRT) for this tumor entity with better treatment efficiency.

Materials And Methods: Based on treatment planning CTs of 8 patients, we compared dose distributions, comformality index (CI), homogeneity index (HI), number of monitor units (MU) and treatment time (TTT) for plans generated for VMAT, 3D-CRT and step-and-shoot-IMRT (optimized based on Pencil Beam (PB) or Monte Carlo (MC) dose calculation) for typical anal cancer planning target volumes (PTV) including inguinal lymph nodes as usually treated during the first phase (0-36 Gy) of a shrinking field regimen.

Volumetric modulated arc therapy (VMAT) vs. serial tomotherapy, step-and-shoot IMRT and 3D-conformal RT for treatment of prostate cancer.

Introduction: Volumetric modulated arc therapy (VMAT), a complex treatment strategy for intensity-modulated radiation therapy, may increase treatment efficiency and has recently been established clinically. This analysis compares VMAT against established IMRT and 3D-conformal radiation therapy (3D-CRT) delivery techniques.

Methods: Based on CT datasets of 9 patients treated for prostate cancer step-and-shoot IMRT, serial tomotherapy (MIMiC), 3D-CRT and VMAT were compared with regard to plan quality and treatment efficiency.

[Serial tomotherapy vs. MLC-IMRT (multileaf collimator intensity modulated radiotherapy) for simultaneous boost treatment large intracerebral lesions].

Introduction: Recent data suggest that a radiosurgery boost treatment for up to three brain metastases in addition to whole brain radiotherapy (WBRT) is beneficial. Sequential treatment of multiple metastatic lesions is time-consuming and optimal normal tissue sparing is not trivial for larger metastases when separate plans are created and are only superimposed afterwards. Sequential Tomotherapy (see image I) with noncoplanar arcs and Multi-field IMRT may streamline the process and enable easy simultaneous treatment.

Optimization of the gafchromic EBT protocol for IMRT QA.

Quality assurance of external beam (radio)therapy (EBT) requires tools with specific characteristics. A radiochromic film dubbed "Gafchromic EBT" (G-EBT) that is particularly suited for external beam therapy because of its features was introduced in 2004. Its characteristics, especially the high spatial resolution, make it suitable for measurement of dose distributions in radiotherapy, especially intensity-modulated radiation therapy (IMRT).

Phantom measurements to quantify the accuracy of a commercially available cone-beam CT gray-value matching algorithm using multiple Fiducials.

Purpose: : To assess the accuracy of the gray-value matching algorithm (XVI, Elekta) when multiple iodine-125 ((125)I) seeds are used as fiducials.

Material And Methods: : A phantom, consisting of a plastic box filled with water-dense material containing about 50 dummy seeds, developed primarily as a manual-skill trainer for (125)I seed implantation was used (Figure 1). The phantom was scanned first with a planning CT (PCT) at a slice thickness of 1 mm, 3 mm and 5 mm and with cone-beam CT (CBCT) to be associated with each reference PCT.

Accuracy of ultrasound-based (BAT) prostate-repositioning: a three-dimensional on-line fiducial-based assessment with cone-beam computed tomography.

Purpose: To assess the accuracy of ultrasound-based repositioning (BAT) before prostate radiation with fiducial-based three-dimensional matching with cone-beam computed tomography (CBCT).

Patients And Methods: Fifty-four positionings in 8 patients with 125I seeds/intraprostatic calcifications as fiducials were evaluated. Patients were initially positioned according to skin marks and after this according to bony structures based on CBCT.

Evaluation of calculation algorithms implemented in different commercial planning systems on an anthropomorphic breast phantom using film dosimetry.

Purpose: To evaluate the accuracy of dose calculation algorithms of different planning systems for postoperative tangential radiotherapy in breast cancer.

Material And Methods: On a CT dataset of an anthropomorphic phantom, a structure set of the left lung, clinical target volume (CTV), planning target volume, heart, and external contour were delineated. The dataset was processed by six radiation oncology centers participating in this multicenter dosimetry project.

On the performances of different IMRT Treatment Planning Systems for selected paediatric cases.

Background: To evaluate the performance of seven different TPS (Treatment Planning Systems: Corvus, Eclipse, Hyperion, KonRad, Oncentra Masterplan, Pinnacle and PrecisePLAN) when intensity modulated (IMRT) plans are designed for paediatric tumours.

Methods: Datasets (CT images and volumes of interest) of four patients were used to design IMRT plans. The tumour types were: one extraosseous, intrathoracic Ewing Sarcoma; one mediastinal Rhabdomyosarcoma; one metastatic Rhabdomyosarcoma of the anus; one Wilm's tumour of the left kidney with multiple liver metastases.

Intensity-modulated radiation therapy (IMRT) with different combinations of treatment-planning systems and linacs: issues and how to detect them.

Purpose: To compare different combinations of intensity-modulated radiation therapy (IMRT) system components with regard to quality assurance (QA), especially robustness against malfunctions and dosimetry.

Material And Methods: Three different treatment-planning systems (TPS), two types of linacs and three multileaf collimator (MLC) types were compared: commissioning procedures were performed for the combination of the TPS Corvus 5.0 (Nomos) and KonRad v2.

Evaluation of possible prostate displacement induced by pressure applied during transabdominal ultrasound image acquisition.

Background And Purpose: For accurate positioning of the prostate in external radiotherapy, transabdominal ultrasound localization and positioning systems are available. Reports have stated that probe pressure applied during image acquisition causes clinically relevant prostate displacement. The aim of this study was to investigate the prostate displacement due to the pressure applied during transabdominal ultrasound image acquisition with the BAT ultrasound system.