Mapping metabolic changes associated with early Radiation Induced Lung Injury post conformal radiotherapy using hyperpolarized ¹³C-pyruvate Magnetic Resonance Spectroscopic Imaging.

Purpose: Radiation Pneumonitis (RP) limits radiotherapy. Detection of early metabolic changes in the lungs associated with RP may provide an opportunity to adjust treatment before substantial toxicities occur. In this work, regional lactate-to-pyruvate signal ratio (lac/pyr) was quantified in rat lungs and heart following administration of hyperpolarized (13)C-pyruvate magnetic resonance imaging (MRI) at day 5, 10, 15 and 25-post conformal radiotherapy.

Genistein can mitigate the effect of radiation on rat lung tissue.

We investigated whether genistein could protect the lung from radiation-induced injury. We hypothesized that genistein would reduce the levels of inflammatory cytokines and ROS after irradiation and therefore lead to reduced DNA damage and functional deficits. Whole lungs of Sprague-Dawley rats were irradiated with 18 Gy at approximately 0.

The effects of field-of-view and patient size on CT numbers from cone-beam computed tomography.

Cone-beam computed tomography (CBCT) is used for patient alignment before treatment and is ideal for use in adaptive radiotherapy to account for tumor shrinkage, organ deformation and weight loss. However, CBCT images are prone to artifacts such as streaking and cupping effects, reducing image quality and CT number accuracy. Our goal was to determine the optimum combination of cone-beam imaging options to increase the accuracy of image CT numbers.

Variations of lung density and geometry on inhomogeneity correction algorithms: a Monte Carlo dosimetric evaluation.

This work contributed the following new information to the study of inhomogeneity correction algorithm: (1) Evaluation of lung dose calculation methods as a function of lung relative electron density (rhoe,lung) and treatment geometry and (2) comparison of doses calculated using the collapsed cone convolution (CCC) and adaptive convolution (AC) in lung using the Monte Carlo (MC) simulation with the EGSnrc-based code. The variations of rhoe,lung and geometry such as the position and dimension of the lung were studied with different photon beam energies and field sizes. Three groups of inhomogeneous lung phantoms, namely, "slab," "column," and "cube," with different positions, volumes, and shapes of lung in water as well as clinical computed tomography lung images were used.

Adaptive radiation therapy for localized mesothelioma with mediastinal metastasis using helical tomotherapy.

The purpose of this study was to compare 2 adaptive radiotherapy strategies with helical tomotherapy. A patient having mesothelioma with mediastinal nodes was treated using helical tomotherapy with pretreatment megavoltage CT (MVCT) imaging. Gross tumor volumes (GTVs) were outlined on every MVCT study.

Successful treatment of primary renal lymphoma using image guided helical tomotherapy.

Purpose: To describe a clinical pilot case of renal lymphoma successfully treated using helical tomotherapy, and to evaluate alternative hypofractionated treatment schedules and their potential applicability to future cases of renal cell carcinoma (RCC).

Patients And Methods: An 82-year-old female patient with a large right perinephric mass encircling the lower pole of the right kidney was treated on the Hi-ART unit (TomoTherapy Inc. Madison, WI, USA) with daily pretreatment megavoltage CT imaging.

Effects of genistein following fractionated lung irradiation in mice.

Background And Purpose: This study investigated protection of lung injury by genistein following fractionated doses of radiation and its effect on tumor response.

Material And Methods: C3H/HeJ mice were irradiated (100 kVp X-rays) with 9 fractions of 3.1 Gy over 30 days (approximately equivalent to 10 Gy single dose) and were maintained on a genistein diet ( approximately 10mg/kg).

A fully automated non-external marker 4D-CT sorting algorithm using a serial cine scanning protocol.

Current 4D-CT methods require external marker data to retrospectively sort image data and generate CT volumes. In this work we develop an automated 4D-CT sorting algorithm that performs without the aid of data collected from an external respiratory surrogate. The sorting algorithm requires an overlapping cine scan protocol.

The use of CT density changes at internal tissue interfaces to correlate internal organ motion with an external surrogate.

The purpose of this paper is to describe a non-invasive method to monitor the motion of internal organs affected by respiration without using external markers or spirometry, to test the correlation with external markers, and to calculate any time shift between the datasets. Ten lung cancer patients were CT scanned with a GE LightSpeed Plus 4-Slice CT scanner operating in a ciné mode. We retrospectively reconstructed the raw CT data to obtain consecutive 0.

Image registration of a moving target phantom with helical tomotherapy: effect of the CT acquisition technique and action level proposal.

This study aims to quantify the effects of target motion and resultant motion artifacts in planning and megavoltage CT (MVCT) studies on the automatic registration processes of helical tomotherapy. Clinical and experimental data were used to derive an action level for patient repositioning on helical tomotherapy. Planning CT studies of a respiratory motion phantom were acquired using conventional and four-dimensional CT (4D CT) techniques.

Experience-driven dose-volume histogram maps of NTCP risk as an aid for radiation treatment plan selection and optimization.

Commonly, the quality of treatment plans is judged by a dose-volume histogram (DVH) in regards to satisfying a series of dose-volume constraints. This paper presents a novel technique for mapping normal tissue complication probabilities (NTCP) onto regions of dose-volume space with statistical considerations of risk. Mapping is done for DVHs specific to one treatment technique for one disease site.

Adaptive radiotherapy planning on decreasing gross tumor volumes as seen on megavoltage computed tomography images.

Purpose: To evaluate gross tumor volume (GTV) changes for patients with non-small-cell lung cancer by using daily megavoltage (MV) computed tomography (CT) studies acquired before each treatment fraction on helical tomotherapy and to relate the potential benefit of adaptive image-guided radiotherapy to changes in GTV.

Methods And Materials: Seventeen patients were prescribed 30 fractions of radiotherapy on helical tomotherapy for non-small-cell lung cancer at London Regional Cancer Program from Dec 2005 to March 2007. The GTV was contoured on the daily MVCT studies of each patient.

Optimization of megavoltage CT scan registration settings for thoracic cases on helical tomotherapy.

This study aims to investigate the settings that provide optimum registration accuracy when registering megavoltage CT (MVCT) studies acquired on tomotherapy with planning kilovoltage CT (kVCT) studies of patients with lung cancer. For each experiment, the systematic difference between the actual and planned positions of the thorax phantom was determined by setting the phantom up at the planning isocenter, generating and registering an MVCT study. The phantom was translated by 5 or 10 mm, MVCT scanned, and registration was performed again.

Optimization of megavoltage CT scan registration settings for brain cancer treatments on tomotherapy.

This study aims to determine the settings that provide the optimal clinical accuracy and consistency for the registration of megavoltage CT (MVCT) with planning kilovoltage CT image sets on the Hi-ART tomotherapy system. The systematic offset between the MVCT and the planning kVCT was determined by registration of multiple MVCT scans of a head phantom aligned with the planning isocentre. Residual error vector lengths and components were used to quantify the alignment quality for the phantom shifted by 5 mm in different directions obtained by all 27 possible combinations of MVCT inter-slice spacing, registration techniques and resolution.

A prospective evaluation of helical tomotherapy.

Purpose: To report results from two clinical trials evaluating helical tomotherapy (HT).

Methods And Materials: Patients were enrolled in one of two prospective trials of HT (one for palliative and one for radical treatment). Both an HT plan and a companion three-dimensional conformal radiotherapy (3D-CRT) plan were generated.

Simultaneous infield boost with helical tomotherapy for patients with 1 to 3 brain metastases.

Objective: We sought to model the feasibility of a simultaneous in field boost (SIB) to individual brain metastases during a course of whole brain radiotherapy (WBXRT) using helical tomotherapy (HT) intensity-modulated radiation therapy.

Patients And Methods: Planning computed tomography data from 14 patients with 1 to 3 brain metastases were used to model an intralesional SIB delivery that yielded a total intralesional dose of 60 Gy with a surrounding whole brain dose of 30 Gy (designed to be isoeffective to WBXRT of 30 Gy with an 18 Gy in 1 fraction radiosurgery boost). Accuracy of treatment of a phantom on the HT unit was measured.

Dosimetric evaluation of daily rigid and nonrigid geometric correction strategies during on-line image-guided radiation therapy (IGRT) of prostate cancer.

The purpose of this study is to evaluate a geometric image guidance strategy that simultaneously correct for various inter-fractional rigid and nonrigid geometric uncertainties in an on-line environment, using field shape corrections (called the "MU-MLC" technique). The effectiveness of this strategy was compared with two other simpler on-line image guidance strategies that are more commonly used in the clinic. To this end, five prostate cancer patients, with at least 15 treatment CT studies each, were analyzed.

A treatment planning study comparing whole breast radiation therapy against conformal, IMRT and tomotherapy for accelerated partial breast irradiation.

Purpose And Background: Conventional early breast cancer treatment consists of a lumpectomy followed by whole breast radiation therapy. Accelerated partial breast irradiation (APBI) is an investigational approach to post-lumpectomy radiation for early breast cancer. The purpose of this study is to compare four external beam APBI techniques, including tomotherapy, with conventional whole breast irradiation for their radiation conformity index, dose homogeneity index, and dose to organs at risk.

Prostate contouring uncertainty in megavoltage computed tomography images acquired with a helical tomotherapy unit during image-guided radiation therapy.

Purpose: To evaluate the image-guidance capabilities of megavoltage computed tomography (MVCT), this article compares the interobserver and intraobserver contouring uncertainty in kilovoltage computed tomography (KVCT) used for radiotherapy planning with MVCT acquired with helical tomotherapy.

Methods And Materials: Five prostate-cancer patients were evaluated. Each patient underwent a KVCT and an MVCT study, a total of 10 CT studies.

Partial volume rat lung irradiation: the protective/mitigating effects of Eukarion-189, a superoxide dismutase-catalase mimetic.

Background And Purpose: The purpose of the current study was to elucidate the protective/mitigating effects of a SOD-catalase mimetic, Eukarion-189 (EUK-189), on DNA damage in rat lung following irradiation. The particular focus of these studies was the efficacy of EUK-189 when given after irradiation (mitigation).

Patients And Methods: We exposed whole or lower lungs of female Sprague-Dawley rats to doses ranging from 10 to 20.

Comparative planning evaluation of intensity-modulated radiotherapy techniques for complex lung cancer cases.

Background And Purpose: Lung cancer treatment can be one of the most challenging fields in radiotherapy. The aim of the present study was to compare different modalities of radiation delivery based on a balanced scoring scheme for target coverage and normal tissue avoidance.

Patients And Methods: Treatment plans were developed for 15 patients with stage III inoperable non-small cell lung cancer using 3D conformal technique and intensity-modulated radiotherapy (IMRT).

Evaluation of image-guided radiation therapy (IGRT) technologies and their impact on the outcomes of hypofractionated prostate cancer treatments: a radiobiologic analysis.

Purpose: To quantify the mitigation of geometric uncertainties achieved with the application of various patient setup techniques during the delivery of hypofractionated prostate cancer treatments, using tumor control probability (TCP) and normal tissue complication probability.

Methods And Materials: Five prostate cancer patients with approximately 16 treatment CT studies, taken during the course of their radiation therapy (77 total), were analyzed. All patients were planned twice with an 18 MV six-field conformal technique, with 10- and 5-mm margin sizes, with various hypofractionation schedules (5 to 35 fractions).

Image-guided adaptive radiation therapy (IGART): Radiobiological and dose escalation considerations for localized carcinoma of the prostate.

The goal of this work was to evaluate the efficacy of various image-guided adaptive radiation therapy (IGART) techniques to deliver and escalate dose to the prostate in the presence of geometric uncertainties. Five prostate patients with 15-16 treatment CT studies each were retrospectively analyzed. All patients were planned with an 18 MV, six-field conformal technique with a 10 mm margin size and an initial prescription of 70 Gy in 35 fractions.

Image-guided adaptive radiation therapy (IGART): Radiobiological and dose escalation considerations for localized carcinoma of the prostate.

The goal of this work was to evaluate the efficacy of various image-guided adaptive radiation therapy (IGART) techniques to deliver and escalate dose to the prostate in the presence of geometric uncertainties. Five prostate patients with 15-16 treatment CT studies each were retrospectively analyzed. All patients were planned with an 18 MV, six-field conformal technique with a 10 mm margin size and an initial prescription of 70 Gy in 35 fractions.