Correlations between the shifts in prompt gamma emission profiles and the changes in daily target coverage during simulated pencil beam scanning proton therapy.

The aim of this study was to investigate the feasibility of using prompt gamma (PG) ray emission profiles to monitor changes in dose to the planning target volume (PTV) during pencil beam scanning (PBS) proton therapy as a result of day-to-day variation in patient anatomy. For 11 prostate patients, we simulated treatment plan delivery using the patients' daily anatomy as observed in the planning CT and 7-9 control CT scans, including the detected PG profiles resulting from the 5%, 10%, and 20% most intense proton pencil beams. For each patient, we determined the changes in dosimetric parameters for the high- and low-dose PTVs between the simulations performed using the planning CT scan and the different control CT scans and correlated these to changes in the PG emission profiles.

Quality assurance of the PREOPANC trial (2012-003181-40) for preoperative radiochemotherapy in pancreatic cancer : The dummy run.

Background: The Dutch Pancreatic Cancer Group initiated the national, multicentre, controlled PREOPANC trial, randomising between preoperative radiochemotherapy and direct explorative laparotomy for patients with (borderline) resectable pancreatic cancer. The aim of this dummy run is to evaluate compliance with the radiotherapy protocol of this trial, and the quality of delineation and radiation plans.

Methods: Eleven radiation oncology departments open for accrual of patients in the PREOPANC trial were provided with all necessary information of a selected 'dummy' patient.

Addition of MRI for CT-based pancreatic tumor delineation: a feasibility study.

Purpose: To assess the effect of additional magnetic resonance imaging (MRI) alongside the planning computed tomography (CT) scan on target volume delineation in pancreatic cancer patients.

Material And Methods: Eight observers (radiation oncologists) from six institutions delineated the gross tumor volume (GTV) on 3DCT, and internal GTV (iGTV) on 4DCT of four pancreatic cancer patients, while MRI was available in a second window (CT + MRI). Variations in volume, generalized conformity index (CI), and overall observer variation, expressed as standard deviation (SD) of the distances between delineated surfaces, were analyzed.

Considerable interobserver variation in delineation of pancreatic cancer on 3DCT and 4DCT: a multi-institutional study.

Background: The delineation of pancreatic tumors on CT is challenging. In this study, we quantified the interobserver variation for pancreatic tumor delineation on 3DCT as well as on 4DCT.

Methods: Eight observers (radiation oncologists) from six institutions delineated pancreatic tumors of four patients with (borderline) resectable pancreatic cancer.

Probabilistic treatment planning for pancreatic cancer treatment: prospective incorporation of respiratory motion shows only limited dosimetric benefit.

Background: We introduced a probabilistic treatment planning approach that prospectively incorporates respiratory-induced motion in the treatment plan optimization. The aim of this study was to determine the potential dosimetric benefit by comparing this approach to the use of an internal target volume (ITV).

Material And Method: We retrospectively compared the probabilistic respiratory motion-incorporated (RMI) approach to the ITV approach for 18 pancreatic cancer patients, for seven simulated respiratory amplitudes from 5 to 50 mm in the superior-inferior (SI) direction.

Quantitative assessment of biliary stent artifacts on MR images: Potential implications for target delineation in radiotherapy.

Purpose: Biliary stents may cause susceptibility artifacts, gradient-induced artifacts, and radio frequency (RF) induced artifacts on magnetic resonance images, which can hinder accurate target volume delineation in radiotherapy. In this study, the authors investigated and quantified the magnitude of these artifacts for stents of different materials.

Methods: Eight biliary stents made of nitinol, platinum-cored nitinol, stainless steel, or polyethylene from seven vendors, with different lengths (57-98 mm) and diameters (3.

Abdominal organ motion during inhalation and exhalation breath-holds: pancreatic motion at different lung volumes compared.

Purpose: Contrary to what is commonly assumed, organs continue to move during breath-holding. We investigated the influence of lung volume on motion magnitude during breath-holding and changes in velocity over the duration of breath-holding.

Materials And Methods: Sixteen healthy subjects performed 60-second inhalation breath-holds in room-air, with lung volumes of ∼100% and ∼70% of the inspiratory capacity, and exhalation breath-holds, with lung volumes of ∼30% and ∼0% of the inspiratory capacity.

Considerable pancreatic tumor motion during breath-holding.

Background: Breath-holding (BH) is often used to reduce abdominal organ motion during radiotherapy. However, for inhale BH, abdominal tumor motion during BH has not yet been investigated. The aim of this study was to quantify tumor motion during inhale BH and tumor position variations between consecutive inhale BHs in pancreatic cancer patients.

Visibility and artifacts of gold fiducial markers used for image guided radiation therapy of pancreatic cancer on MRI.

Purpose: In radiation therapy of pancreatic cancer, tumor alignment prior to each treatment fraction is improved when intratumoral gold fiducial markers (from here onwards: markers), which are visible on computed tomography (CT) and cone beam CT, are used. Visibility of these markers on magnetic resonance imaging (MRI) might improve image registration between CT and magnetic resonance (MR) images for tumor delineation purposes. However, concomitant image artifacts induced by markers are undesirable.

Dosimetric Advantages of Midventilation Compared With Internal Target Volume for Radiation Therapy of Pancreatic Cancer.

Purpose: The midventilation (midV) approach can be used to take respiratory-induced pancreatic tumor motion into account during radiation therapy. In this study, the dosimetric consequences for organs at risk and tumor coverage of using a midV approach compared with using an internal target volume (ITV) were investigated.

Methods And Materials: For each of the 18 patients, 2 treatment plans (25 × 2.

Limited role for biliary stent as surrogate fiducial marker in pancreatic cancer: stent and intratumoral fiducials compared.

Purpose: Because of low soft-tissue contrast of cone beam computed tomography (CBCT), fiducial markers are often used for radiation therapy patient setup verification. For pancreatic cancer patients, biliary stents have been suggested as surrogate fiducials. Using intratumoral fiducials as standard for tumor position, this study aims to quantify the suitability of biliary stents for measuring interfractional and respiratory-induced position variations of pancreatic tumors.

Differences in respiratory-induced pancreatic tumor motion between 4D treatment planning CT and daily cone beam CT, measured using intratumoral fiducials.

Background: In radiotherapy, the magnitude of respiratory-induced tumor motion is often measured using a single four-dimensional computed tomography (4DCT). This magnitude is required to determine the internal target volume. The aim of this study was to compare the magnitude of respiratory-induced motion of pancreatic tumors on a single 4DCT with the motion on daily cone beam CT (CBCT) scans during a 3-5-week fractionated radiotherapy scheme.