Investigations of peripheral dose for helical tomotherapy.

Purpose: Whenever treating a patient with percutaneous radiotherapy, a certain amount of dose is inevitably delivered to healthy tissue. This is mainly due to beam's entry and exit in the region of the target volume. In regions distant from the target volume, dose is delivered by leakage from the MLC and head scatter from the accelerator head and phantom scatter from the target volume (peripheral dose).

Clinical evaluation of a laser surface scanning system in 120 patients for improving daily setup accuracy in fractionated radiation therapy.

Purpose: To evaluate the clinical suitability of a specific optical surface imaging system to detect setup errors in fractionated radiation therapy.

Methods And Materials: The setup correction accuracy of a 3-dimensional laser imaging system was analyzed for 6 different tumor locations with 20 patients each. For each patient, the setup corrections of the megavoltage computed tomography (MVCT) images of a TomoTherapy unit (TomoTherapy, Madison, WI) were compared with those of the laser system for the first 10 fractions.

CT-myelography for high-dose irradiation of spinal and paraspinal tumors with helical tomotherapy: revival of an old tool.

Background And Purpose: High-dose irradiation or reirradiation of spinal and paraspinal tumors is a challenge particularly in the presence of metal artifacts after surgery. Image-guided advanced intensity-modulated radiotherapy delivers high-dose radiation to the tumor sparing the spinal cord. Precise delineation of the spinal cord is necessary treating para- and intraspinal tumors with a sufficient dose.

Leakage of the Siemens 160 MLC multileaf collimator on a dual energy linear accelerator.

Multileaf collimators (MLCs) have been in clinical use for many years and meanwhile are commonly used to deliver intensity-modulated radiotherapy (IMRT) beams. For this purpose it is important to know their dosimetric properties precisely, one of them being inter- and intraleaf leakage. The Siemens 160 MLC features a single focus design with flat-sided and tilted leaves instead of tongue-and-groove.

Technical performance of a commercial laser surface scanning system for patient setup correction in radiotherapy.

In conformal radiotherapy, careful setup of the patient and setup verification prior to irradiation is essential. The technical performance of a commercial 3D-surface imaging system (Galaxy, LAP Laser, Lüneburg, Germany) for patient setup correction was evaluated. The system reconstructs a 3D-surface model by scanning the patient with a laser line while a camera records its reflections.

Dynamic jaws and dynamic couch in helical tomotherapy.

Purpose: To investigate the next generation of helical tomotherapy delivery with dynamic jaw and dynamic couch movements.

Methods And Materials: The new technique of dynamic jaw and dynamic couch movements is described, and a comparative planning study is performed. Ten nasopharyngeal cancer patients with skull base infiltration were chosen for this comparison of longitudinal dose profiles using regular tomotherapy delivery, running-start-stop treatment, and dynamic jaw and dynamic couch delivery.

Surface dose in the treatment of breast cancer with helical tomotherapy.

Purpose: Investigation of the effects of breathing motion- and misregistration-induced errors on the superficial dose in the treatment of breast cancer using helical tomotherapy (HT).

Material And Methods: Surface dose measurements were performed with thermoluminescence dosimetry (TLD). Two treatment plans with different planning target volume (PTV) definitions of the left breast were used: PTVskin had its ventral border exactly on skin level, while PTVair included also a 10-mm extension ventral to the PTVskin.

Megavoltage CT in helical tomotherapy - clinical advantages and limitations of special physical characteristics.

Helical tomotherapy is a form of image-guided intensity-modulated radiotherapy that introduces the ring gantry concept into radiation oncology. The system is a combination of a therapeutic linear accelerator and a megavoltage CT-scanner. This work describes the clinical experience with megavoltage CT with 456 patients in more than 11000 fractions.

Influence of intravenous contrast agent on dose calculation in 3-D treatment planning for radiosurgery of cerebral arteriovenous malformations.

Purpose: To investigate the influence of local density increase by i.v. contrast agent on dose calculation in linac-based radiosurgery (RS) of cerebral arteriovenous malformations (AVMs).

Dosimetric comparison of image guidance by megavoltage computed tomography versus bone alignment for prostate cancer radiotherapy.

Background And Purpose: Daily image guidance in irradiation of prostate cancer can be based on simple portal images or on soft-tissue imaging. This study compares daily bone alignment with daily pretreatment megavoltage computed tomography (MVCT).

Patients And Methods: Ten patients with a total of 356 fractions were analyzed.

Reirradiation of multiple brain metastases with helical tomotherapy. A multifocal simultaneous integrated boost for eight or more lesions.

Background And Purpose: : Recurrent brain metastases or new brain lesions after whole-brain radiotherapy represent a therapeutic challenge. While several treatment methods for single or few lesions have been described, options for multiple lesions are limited. This case report is intended to show an approach of whole-brain reirradiation with a simultaneous multifocal integrated boost using helical tomotherapy.

Evaluating target coverage and normal tissue sparing in the adjuvant radiotherapy of malignant pleural mesothelioma: helical tomotherapy compared with step-and-shoot IMRT.

Purpose: To evaluate the potential of helical tomotherapy in the adjuvant treatment of malignant pleural mesothelioma and compare target homogeneity, conformity and normal tissue dose with step-and-shoot intensity-modulated radiotherapy.

Methods And Materials: Ten patients with malignant pleural mesothelioma who had undergone neoadjuvant chemotherapy with cisplatin and permetrexed followed by extrapleural pneumonectomy (EPP) were treated in our department with 54 Gy to the hemithorax delivered by step-and-shoot IMRT. A planning comparison was performed by creating radiation plans for helical tomotherapy.

Helical tomotherapy. Experiences of the first 150 patients in Heidelberg.

Background And Purpose: Helical tomotherapy was introduced into clinical routine at the Department of Radiation Oncology, University Hospital of Heidelberg, Germany, in July 2006. This report is intended to describe the experience with the first 150 patients treated with helical tomotherapy. Patient selection, time effort, handling of daily image guidance with megavoltage (MV) CT, and quality of radiation plans shall be assessed.

Accuracy of a commercial optical 3D surface imaging system for realignment of patients for radiotherapy of the thorax.

Accurate and reproducible patient setup is a prerequisite to fractionated radiotherapy. To evaluate the applicability and technical performance of a commercial 3D surface imaging system for repositioning of breast cancer patients, measurements were performed in a rigid anthropomorphic phantom as well as in healthy volunteers. The camera system records a respiration-gated surface model of the imaged object, which may be registered to a previously recorded reference model.

Long-term results and predictive factors of three-dimensional conformal salvage radiotherapy for biochemical relapse after prostatectomy.

Purpose: Salvage radiotherapy (RT) is used to treat patients with biochemical failure after radical prostatectomy (RP). Although retrospective series have demonstrated that salvage RT will result in biochemical response in approximately 75% of patients, long-term response is much lower (20-40%). The purpose of this study was to determine prognostic factors related to the prostate-specific antigen (PSA) outcome after salvage RT.

Inversely planned intensity modulated radiotherapy of the breast including the internal mammary chain: a plan comparison study.

The aim of this paper is to evaluate the benefit of inversely planned intensity modulated radiotherapy (IMRT) in the adjuvant irradiation of breast cancer when internal mammary lymph nodes are included in the treatment volume. 20 patients treated with 3D-planned conventional radiotherapy (CRT) following breast conserving surgery were included in the study. We chose 10 patients with left-sided and 10 patients with right-sided tumors.

[Lung dose depending on exact patient positioning during total body irradiation (TBI). Isoeffectiveness considerations to assess the risk of interstitial pneumonia after TBI].

Purpose: In this case report, we studied the effect of patient's movements on total lung dose during total body irradiation (TBI). The dose-effect relationship regarding the development of interstitial pneumonitis and the problem of defining a threshold value are discussed. Based on considerations about the isoeffects we calculated the pneumonitis risk in dependence of increasing lung dose.