Potential Therapeutic Improvements in Prostate Cancer Treatment Using Pencil Beam Scanning Proton Therapy with LET Optimization and Disease-Specific RBE Models.

Purpose: To demonstrate the feasibility of improving prostate cancer patient outcomes with PBS proton LET optimization.

Methods: SFO, IPT-SIB, and LET-optimized plans were created for 12 patients, and generalized-tissue and disease-specific LET-dependent RBE models were applied. The mean LET in several structures was determined and used to calculate mean RBEs.

Fast MCsquare-Based Independent Dose Verification Platform for Pencil Beam Scanning Proton Therapy.

Purpose: To commission MCsquare (a multi-cores CPU-based dose calculation engine) for pencil beam scanning (PBS) proton therapy, integrate it into RayStation treatment plan system (TPS) to create a dedicated platform for fast independent dose verification.

Method: A MCsquare-based independent dose verification platform (MC2InRS) was developed to realize automatic dose re-calculation for clinical use, including data preparation, dose calculation, 2D/3D gamma analysis. MCsquare was commissioned based on in-air lateral dose profiles, integrated depth dose, and the absolute dose of different beam energies for ProteusONE.

The root cause analysis on failed patient-specific measurements of pencil beam scanning protons using a 2D detection array with finite size ionization chambers.

The aim of this report is to present the root cause analysis on failed patient-specific quality assurance (QA) measurements of pencil beam scanning (PBS) protons; referred to as PBS-QA measurement. A criterion to fail a PBS-QA measurement is having a <95% passing rate in a 3.0%-3.

Evaluations of a flat-panel based compact daily quality assurance device for proton pencil beam scanning (PBS) system.

Purpose: To evaluate the flat-panel detector quenching effect and clinical usability of a flat-panel based compact QA device for PBS daily constancy measurements.

Materials & Method: The QA device, named Sphinx Compact, is composed of a 20x20 cm flat-panel imager mounted on a portable frame with removable plastic modules for constancy checks of proton energy (100 MeV, 150 MeV, 200 MeV), Spread-Out-Bragg-Peak (SOBP) profile, and machine output. The potential quenching effect of the flat-panel detector was evaluated.

Implementation of a double scattering nozzle for Monte Carlo recalculation of proton plans with variable relative biological effectiveness.

A constant relative biological effectiveness () of 1.1 is currently used in clinical proton therapy. However, thevaries with factors such as dose level, linear energy transfer () and tissue type.

Development of an isocentric rotating chair positioner to treat patients of head and neck cancer at upright seated position with multiple nonplanar fields in a fixed carbon-ion beamline.

Purpose: An isocentric rotating chair for a positioner was developed as a nongantry solution to provide multiple nonplanar radiation fields with a maximum tilt of 20 for treating head and neck cancer patients at an upright seated position in a fixed carbon-ion beamline.

Methods: The preclinical validation of the chair was present for this study funded by a grant through the Shanghai Proton and Heavy Ion Center (SPHIC) in Shanghai, China. The chair was installed in SPHIC.

Analysis of measurement deviations for the patient-specific quality assurance using intensity-modulated spot-scanning particle beams.

To analyze measurement deviations of patient-specific quality assurance (QA) using intensity-modulated spot-scanning particle beams, a commercial radiation dosimeter using 24 pinpoint ionization chambers was utilized. Before the clinical trial, validations of the radiation dosimeter and treatment planning system were conducted. During the clinical trial 165 measurements were performed on 36 enrolled patients.

Utilization of optical tracking to assess efficacy of intracranial immobilization techniques in proton therapy.

We present a quantitative methodology to measure head interfraction movements within intracranial masks of commercial immobilization devices used for proton radiotherapy. A three-points tracking (3PtTrack) method was developed to measure the mask location for each treatment field over an average of 10 fractions for seven patients. Five patients were treated in supine with the Qfix Base-of-Skull (BoS) headframe, and two patients were treated in prone with the CIVCO Uni-frame baseplate.

Utilization of optical tracking to validate a software-driven isocentric approach to robotic couch movements for proton radiotherapy.

Purpose: An optical tracking and positioning system (OTPS) was developed to validate the software-driven isocentric (SDI) approach to control the six-degrees-of-freedom movement of a robotic couch.

Methods: The SDI approach to movements rotating around a predefined isocenter, referred to as a GeoIso, instead of a mechanical pivot point was developed by the robot automation industry. With robotic couch-sag corrections for weight load in a traditional SDI approach, movements could be accurately executed for a GeoIso located within a 500 mm cubic volume on the couch for treatments.

Dosimetric study of uniform scanning proton therapy planning for prostate cancer patients with a metal hip prosthesis, and comparison with volumetric-modulated arc therapy.

The main purposes of this study were to 1) investigate the dosimetric quality of uniform scanning proton therapy planning (USPT) for prostate cancer patients with a metal hip prosthesis, and 2) compare the dosimetric results of USPT with that of volumetric-modulated arc therapy (VMAT). Proton plans for prostate cancer (four cases) were generated in XiO treatment planning system (TPS). The beam arrangement in each proton plan consisted of three fields (two oblique fields and one lateral or slightly angled field), and the proton beams passing through a metal hip prosthesis was avoided.

Image-guided method for TLD-based in vivo rectal dose verification with endorectal balloon in proton therapy for prostate cancer.

Purpose: To present a practical image-guided method to position an endorectal balloon that improves in vivo thermoluminiscent dosimeter (TLD) measurements of rectal doses in proton therapy for prostate cancer.

Methods: TLDs were combined with endorectal balloons to measure dose at the anterior rectal wall during daily proton treatment delivery. Radiopaque metallic markers were employed as surrogates for balloon position reproducibility in rotation and translation.

Proton-based chemoradiation for synchronous bilateral non-small-cell lung cancers: A case report.

In this case report, we present the history and treatment of a 70-year-old man with synchronous bilateral non-small-cell lung cancers with proton-beam radiation. Surgical treatment was not feasible and optimized photon intensity-modulated radiotherapy (IMRT) to the primary tumors would have resulted in unacceptably high normal-tissue exposures. Proton-beam radiation enabled radiation dose escalation and concurrent chemotherapy while maintaining normal-tissue tolerance.

A novel daily QA system for proton therapy.

We describe the design and use of a daily quality assurance (QA) system for proton therapy. The QA system is designed to check the overall readiness of proton therapy system consistently within certain reference tolerances by a home-made QA device (the QA device). The QA device is comprised of a commercially available QA device, rf-Daily QA 3, a home-made acrylic phantom, a set of acrylic compensators with various thicknesses, and a mechanical indexing jig.

Beam characteristics in two different proton uniform scanning systems: a side-by-side comparison.

Purpose: To compare clinically relevant dosimetric characteristics of proton therapy fields produced by two uniform scanning systems that have a number of similar hardware components but employ different techniques of beam spreading.

Methods: This work compares two technologically distinct systems implementing a method of uniform scanning and layer stacking that has been developed independently at Indiana University (IU) and by Ion Beam Applications, S. A.

The development of iron-free partially stabilized cement for use as dental root-end filling material.

Aim: To determine the effect of increasing the proportion of zinc on partially stabilized cement (PSC) produced using a one-step sol gel process.

Methodology: A one-step sol-gel process of Portland cement-based PSC with Zn was synthesized by replacing iron nitrate. The crystalline phases of the PSC-Zn powder were analysed by using X-ray diffraction (XRD).

Spatial correlation of proton irradiation-induced activity and dose in polymer gel phantoms for PET/CT delivery verification studies.

Purpose: This work demonstrates a novel application of BANG3-Pro2 polymer gel dosimeter as a dosimetric phantom able to accurately capture both dose and induced activity.

Methods: BANG3-Pro2 dosimeters were irradiated with a clinical proton beam using an unmodulated beam and a spread-out Bragg peak (SOBP) modulation, the latter with a Lucite compensator to introduce a range offset in one quadrant of the circular field. The dosimeters were imaged in a nearby positron emission tomography/computed tomography (PET/CT) unit starting within 5 min of beam-off.

Evaluation of proton beam radiation sensitivity of proliferating choroidal endothelial and retinal ganglion cells with clonogenic assay.

Context: Proton beam therapy offers the advantage of precise delivery with limited damage to the healthy tissue and is being tested in the management of exudative age-related macular degeneration (AMD). However, the dosages tested are empirical and not based on preclinical studies.

Objective: In this study we evaluated the effects of varying doses of proton beam radiation on choroidal endothelial cells (CECs) and retinal ganglion cells (RGCs) using clonogenic assay to determine differential sensitivity.

Commissioning of output factors for uniform scanning proton beams.

Purpose: Current commercial treatment planning systems are not able to accurately predict output factors and calculate monitor units for proton fields. Patient-specific field output factors are thus determined by either measurements or empirical modeling based on commissioning data. The objective of this study is to commission output factors for uniform scanning beams utilized at the ProCure proton therapy centers.

Dosimetric characterization of whole brain radiotherapy of pediatric patients using modulated proton beams.

This study was designed to investigate dosimetric variations between proton plans with (PPW) and without (PPWO), a compensator for whole brain radiotherapy (WBRT). The retrospective study on PPW and PPWO in Eclipse and XiO systems and photon plans (XP) using controlled segments in Pinnacle system was performed on nine pediatric patients for craniospinal irradiations. DVHs and derived metrics, such as the homogeneity index (HI), the doses to 2% (D(2%)) and 5% (D(5%)) volumes, and mean dose (D(mean)) of the whole brain (i.

Evaluation of choroidal endothelial cell proliferation after exposure to varying doses of proton beam radiation.

Purpose: Focal epiretinal radiation has emerged as a promising tool in the management of choroidal neovascularization associated with age-related macular degeneration. However, the dosages tested are not backed by cell culture studies used in the clinical setting empirically.

Methods: Choroidal endothelial cells (RF6A) were maintained in a log scale and exposed to a single fraction of 2, 4, 8, and 12 cobalt gray-equivalent of proton radiation with an internal control.

In vivo verification of proton beam path by using post-treatment PET/CT imaging.

Purpose: The purpose of this study is to establish the in vivo verification of proton beam path by using proton-activated positron emission distributions.

Methods: A total of 50 PET/CT imaging studies were performed on ten prostate cancer patients immediately after daily proton therapy treatment through a single lateral portal. The PET/CT and planning CT were registered by matching the pelvic bones, and the beam path of delivered protons was defined in vivo by the positron emission distribution seen only within the pelvic bones, referred to as the PET-defined beam path.

Cine-magnetic resonance imaging assessment of intrafraction motion for prostate cancer patients supine or prone with and without a rectal balloon.

Purpose: Determine prostate intrafraction motion with Cine-magnetic resonance imaging (MRI) and deformable registration.

Methods: A total of 68 cine-MRI studies were done in 17 different series with 4 scans per series in 7 patients. In without rectal balloon (WORB) scans, 100 mL of water was infused in the rectum.

Energy spectrum control for modulated proton beams.

In proton therapy delivered with range modulated beams, the energy spectrum of protons entering the delivery nozzle can affect the dose uniformity within the target region and the dose gradient around its periphery. For a cyclotron with a fixed extraction energy, a rangeshifter is used to change the energy but this produces increasing energy spreads for decreasing energies. This study investigated the magnitude of the effects of different energy spreads on dose uniformity and distal edge dose gradient and determined the limits for controlling the incident spectrum.

Range and modulation dependencies for proton beam dose per monitor unit calculations.

Calculations of dose per monitor unit (D/MU) are required in addition to measurements to increase patient safety in the clinical practice of proton radiotherapy. As in conventional photon and electron therapy, the D/MU depends on several factors. This study focused on obtaining range and modulation dependence factors used in D/MU calculations for the double scattered proton beam line at the Midwest Proton Radiotherapy Institute.

Dosimetric uncertainty in prostate cancer proton radiotherapy.

Purpose: The authors we evaluate the uncertainty in proton therapy dose distribution for prostate cancer due to organ displacement, varying penumbra width of proton beams, and the amount of rectal gas inside the rectum.

Methods And Materials: Proton beam treatment plans were generated for ten prostate patients with a minimum dose of 74.1 cobalt gray equivalent (CGE) to the planning target volume (PTV) while 95% of the PTV received 78 CGE.