Preliminary investigations for the option to use fast uniform scanning with compensators on a gantry designed for IMPT.

Purpose: In this experimental study, the authors explored the possibility to deliver the dose for proton therapy with fast uniform scanning on a gantry primarily designed for the delivery of conformal beam scanning and IMPT. The uniform scanning submode has been realized without equipment modifications by using the same small pencil beam used for conformal scanning, resulting in reduced realization costs. Uniform scanning has recently been adopted in a few proton therapy centers, as a basic beam delivery solution, and as an alternative to the use of scattering foils.

Spatial resolution of proton tomography: Methods, initial phase space and object thickness.

Purpose: Proton radiography and tomography was investigated since the early 1970s because of its low radiation dose, high density resolution and ability to image directly proton stopping power. However, spatial resolution is still a limiting factor and as a consequence experimental methods and image reconstruction should be optimized to improve position resolution.

Methods: Spatial resolution of proton radiography and tomography is given by multiple Coloumb scattering (MCS) of the protons in the patient.

Special report: workshop on 4D-treatment planning in actively scanned particle therapy--recommendations, technical challenges, and future research directions.

This article reports on a 4D-treatment planning workshop (4DTPW), held on 7-8 December 2009 at the Paul Scherrer Institut (PSI) in Villigen, Switzerland. The participants were all members of institutions actively involved in particle therapy delivery and research. The purpose of the 4DTPW was to discuss current approaches, challenges, and future research directions in 4D-treatment planning in the context of actively scanned particle radiotherapy.

More than 10 years experience of beam monitoring with the Gantry 1 spot scanning proton therapy facility at PSI.

Purpose: The beam monitoring equipments developed for the first PSI spot scanning proton therapy facility, Gantry 1, have been successfully used for more than 10 years. The purpose of this article is to summarize the author's experience in the beam monitoring technique for dynamic proton scanning.

Methods: The spot dose delivery and verification use two independent beam monitoring and computer systems.

Proton spot scanning radiotherapy of spontaneous canine tumors.

Thirty dogs with spontaneous tumors were irradiated with proton therapy using a novel spot scanning technique to evaluate the safety and efficacy of the system, and to study the acute and late radiation reactions. Nasal tumors, soft tissue sarcomas, and miscellaneous tumors of the head were treated with a median total dose of 52.5 Gy given in 3.

Effectiveness and safety of spot scanning proton radiation therapy for chordomas and chondrosarcomas of the skull base: first long-term report.

Purpose: To evaluate effectiveness and safety of spot-scanning-based proton radiotherapy (PT) in skull-base chordomas and chondrosarcomas.

Methods And Materials: Between October 1998 and November 2005, 64 patients with skull-base chordomas (n = 42) and chondrosarcomas (n = 22) were treated at Paul Scherrer Institute with PT using spot-scanning technique. Median total dose for chordomas was 73.

Experiences at the Paul Scherrer Institute with a remote patient positioning procedure for high-throughput proton radiation therapy.

Purpose: To describe a remote positioning system for accurate and efficient proton radiotherapy treatments.

Methods And Materials: To minimize positioning time in the treatment room (and thereby maximize beam utility), we have adopted a method for remote patient positioning, with patients positioned and imaged outside the treatment room. Using a CT scanner, positioning is performed using orthogonal topograms with the measured differences to the reference images being used to define daily corrections to the patient table in the treatment room.

Postoperative spot-scanning proton radiation therapy for chordoma and chondrosarcoma in children and adolescents: initial experience at paul scherrer institute.

Purpose: To evaluate postoperative spot-scanning proton radiation therapy (PT) and intensity-modulated PT (IMPT) for chordoma and chondrosarcoma in pediatric patients.

Methods And Materials: Between 2000 and 2005, 10 patients (six male patients, four female patients; six chordomas, four chondrosarcomas), aged 10-20 years (median, 16 years), were treated at our institute. Tumor sites were in the brain (one case), skull base (five cases), cervical (three cases), and lumbar spine (one case).

Spot scanning proton therapy in the curative treatment of adult patients with sarcoma: the Paul Scherrer institute experience.

Purpose: To assess the safety and efficacy of spot scanning proton beam therapy (PT) in the curative treatment of soft-tissue sarcoma (STS) in adults patients.

Patients And Methods: We identified 13 STS patients treated with PT between July 1998 and May 2005 in our institutional database. Tumor histology varied with the most common histologic subtypes including liposarcoma and peripheral nerve sheet tumor.

Spot-scanning proton therapy for malignant soft tissue tumors in childhood: First experiences at the Paul Scherrer Institute.

Purpose: Radiotherapy plays a major role in the treatment strategy of childhood sarcomas. Consequences of treatment are likely to affect the survivor's quality of life significantly. We investigated the feasibility of spot-scanning proton therapy (PT) for soft tissue tumors in childhood.

Extracranial chordoma: Outcome in patients treated with function-preserving surgery followed by spot-scanning proton beam irradiation.

Purpose: To evaluate the use of postoperative proton therapy (PT) in extracranial chordoma.

Patients And Methods: Twenty-six patients were treated. Gross total resection was achieved in 18 patients.

Results of spot-scanning proton radiation therapy for chordoma and chondrosarcoma of the skull base: the Paul Scherrer Institut experience.

Purpose: To assess the clinical results of spot scanning proton beam radiation therapy (PT) in the treatment of skull base chordomas and low-grade chondrosarcomas (CS).

Methods And Materials: Between October 1998 and October 2003, 29 patients (median age, 39 years) with chordomas (n = 18) and CS (n = 11) were treated at the Paul Scherrer Institut (PSI) with protons using the main 510-MeV cyclotron. Tumor conformal application of proton beams was realized by spot scanning technology.

Relative biologic effectiveness determination in mouse intestine for scanning proton beam at Paul Scherrer Institute, Switzerland. Influence of motion.

Purpose: To determine the relative biologic effectiveness (RBE) of the Paul Scherrer Institute (PSI) scanning proton beam in reference conditions and to evaluate the influence of intestine motion on the proton dose homogeneity.

Methods And Materials: First, RBE was determined for crypt regeneration in mice after irradiation in a single fraction. Irradiation was performed at the middle of a 7-cm spread out Bragg peak (SOBP; reference position), as well as in the proximal part of the plateau and at the distal end of the SOBP.

Patient specific optimization of the relation between CT-hounsfield units and proton stopping power with proton radiography.

The purpose of this work is to show the feasibility of using in vivo proton radiography of a radiotherapy patient for the patient individual optimization of the calibration from CT-Hounsfield units to relative proton stopping power. Water equivalent tissue (WET) calibrated proton radiographs of a dog patient treated for a nasal tumor were used as baseline in comparison with integrated proton stopping power through the calibrated CT of the dog. In an optimization procedure starting with a stoichiometric calibration curve, the calibration was modified randomly.

Treatment planning and verification of proton therapy using spot scanning: initial experiences.

Since the end of 1996, we have treated more than 160 patients at PSI using spot-scanned protons. The range of indications treated has been quite wide and includes, in the head region, base-of-skull sarcomas, low-grade gliomas, meningiomas, and para-nasal sinus tumors. In addition, we have treated bone sarcomas in the neck and trunk--mainly in the sacral area--as well as prostate cases and some soft tissue sarcomas.

Development of an inorganic scintillating mixture for proton beam verification dosimetry.

The availability at the Paul Scherrer Institute (PSI) of a spot-scanning technique with an isocentric beam delivery system (gantry) allows the realization of intensity-modulated proton therapy (IMPT). The development of 3D dosimetry is an important tool for the verification of IMPT therapy plans based on inhomogeneous 3D conformal dose distributions. For that purpose new dosimeters are being developed.

The clinical potential of intensity modulated proton therapy.

Intensity Modulated Proton Therapy (IMPT) differs from conventional proton therapy in its ability to deliver depth-shifted, arbitrarily complex proton fluence maps from each incident field direction. As the individual Bragg peaks delivered from any field can be distributed in three-dimensions throughout the target volume, IMPT provides many more degrees of freedom for designing dose distributions than IMRT or conventional proton therapy techniques. So how can the flexibility of IMPT best be exploited? Here we argue that IMPT has two main advantages over photon IMRT and conventional proton therapy: the ability to better 'sculpt' the dose to the target and around neighbouring critical structures, and the ability to find clinically acceptable solutions whilst simultaneously reducing the sensitivity of the treatments to potential delivery errors.

First proton radiography of an animal patient.

The purpose of this work is to show the feasibility of proton radiography in terms of radiation dose, imaging speed, image quality (density and spatial resolution), and image content under clinical conditions. Protons with 214 MeV energy can penetrate through most patients and were used for imaging. The measured residual range (or energy) of the protons behind the patient was subtracted from the range without an object in the beam path and used to create a projected image.

Spot-scanning proton radiation therapy for recurrent, residual or untreated intracranial meningiomas.

Background And Purpose: To assess the safety and efficacy of spot scanning proton beam radiation therapy (PRT) in the treatment of intracranial meningiomas.

Patients And Methods: Sixteen patients with intracranial meningioma (histopathologically proven in 13/16 cases) were treated with PRT between July 1997 and July 2002. Eight patients had skull base lesions.

The PSI Gantry 2: a second generation proton scanning gantry.

PSI is still the only location in which proton therapy is applied using a dynamic beam scanning technique on a very compact gantry. Recently, this system is also being used for the application of intensity-modulated proton therapy (IMPT). This novel technical development and the success of the proton therapy project altogether have led PSI in Year 2000 to further expand the activities in this field by launching the project PROSCAN.

The water equivalence of solid materials used for dosimetry with small proton beams.

Various solid materials are used instead of water for absolute dosimetry with small proton beams. This may result in a dose measurement different to that in water, even when the range of protons in the phantom material is considered correctly. This dose difference is caused by the diverse cross sections for inelastic nuclear scattering in water and in the phantom materials respectively.

Secondary neutron dose during proton therapy using spot scanning.

Purpose: During proton radiotherapy, secondary neutrons are produced by nuclear interactions in the material in the beam line before and after entering the patient. The dose equivalent deposited by these neutrons is usually not considered in routine treatment planning. In this study, we estimated the neutron dose in patients from a spot scanning beam line by performing measurements and Monte Carlo simulations.