A commissioning protocol for portal imaging-based radiotherapy in vivo dosimetry systems.

Background And Purpose: With the availability of commercial electronic portal imaging detector-based in vivo dosimetry (EPID-based IVD) solutions, many radiotherapy departments are adopting this technology. However, comprehensive commissioning guidance is lacking. This study aims to provide a protocol for testing the accuracy and sensitivity of EPID-based IVD systems.

Protocol compliance in a multicentric phase III trial investigating scheduled adaptive radiotherapy and dose painting in head and neck cancer.

Purpose: To report on quality assurance (QA) and protocol adherence (PA) in a multicentre phase III trial for head and neck cancer, evaluate patterns of protocol deviations and investigate the effect of PA on study outcomes.

Methods: All 221 patients from the ARTFORCE trial (NCT01504815) were included in this study. Pre- and per-treatment QA measures included protocol guidelines, a dummy run, early case reviews and trial meetings.

The Safe Use of I-Seeds as a Localization Technique in Breast Cancer during Pregnancy.

Introduction: Some aspects of the treatment protocol for breast cancer during pregnancy (PrBC) have not been thoroughly studied. This study provides clarity regarding the safety of the use of I-seeds as a localization technique for breast-conserving surgery in patients with PrBC.

Methods: To calculate the exposure to the fetus of one I-seed implanted in a breast tumor, we developed a model accounting for the decaying I-source, time to surgery, and the declining distance between the I-seed and the fetus.

Dose response modelling of secretory cell loss in salivary glands using PSMA PET.

Background And Purpose: Xerostomia remains a common side effect of radiotherapy (RT) for patients with head and neck (H&N) cancer despite advancements in treatment planning and delivery. Secretory salivary gland cells express the prostate-specific membrane antigen (PSMA), and show significant uptake on PET scans using Ga/F-PSMA-ligands. We aimed to objectively quantify the dose-response of salivary glands to RT using PSMA PET.

National Protocol for Model-Based Selection for Proton Therapy in Head and Neck Cancer.

In the Netherlands, the model-based approach is used to identify patients with head and neck cancer who may benefit most from proton therapy in terms of prevention of late radiation-induced side effects in comparison with photon therapy. To this purpose, a National Indication Protocol Proton therapy for Head and Neck Cancer patients (NIPP-HNC) was developed, which has been approved by the health care authorities. When patients qualify according to the guidelines of the NIPP-HNC, proton therapy is fully reimbursed.

The dynamics and prognostic value of FDG PET-metrics in weekly monitoring of (chemo)radiotherapy for NSCLC.

Purpose: To test if the relative change in FDG-PET SUV over the course of treatment was associated with disease progression and overall survival. Additionally, the prognostic values of other first-order PET-metric changes were investigated.

Methods: The study included 38 patients with stage II-III NSCLC, who underwent concurrent chemoradiotherapy.

Motion-compensated FDG PET/CT for oesophageal cancer.

Purpose: Respiratory-induced motion of oesophageal tumours and lymph nodes can influence positron-emission tomography/computed tomography (PET/CT). The aim was to compare standard three-dimensional (3D) and motion-compensated PET/CT regarding standardized uptake value (SUV), metabolic tumour volume (MTV) and detection of lymph node metastases.

Methods: This prospective observational study (NCT02424864) included 37 newly diagnosed oesophageal cancer patients.

Radiotherapy treatment scheduling: Implementing operations research into clinical practice.

Background: Every week, radiotherapy centers face the complex task of scheduling hundreds of treatment sessions amongst the available linear accelerators. With the increase in cancer patient numbers, manually creating a feasible and efficient schedule has shown to be a difficult, time-consuming task. Although operations research models have been increasingly reported upon to optimize patient care logistics, there is almost no scientific evidence of implementation in practice.

Radiotherapy treatment scheduling considering time window preferences.

External-beam radiotherapy treatments are delivered by a linear accelerator (linac) in a series of high-energy radiation sessions over multiple days. With the increase in the incidence of cancer and the use of radiotherapy (RT), the problem of automatically scheduling RT sessions while satisfying patient preferences regarding the time of their appointments becomes increasingly relevant. While most literature focuses on timeliness of treatments, several Dutch RT centers have expressed their need to include patient preferences when scheduling appointments for irradiation sessions.

Single-Center Prospective Trial Investigating the Feasibility of Serial FDG-PET Guided Adaptive Radiation Therapy for Head and Neck Cancer.

Purpose: We investigated in a single-center prospective trial (NCT03376386) the use of serial fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET)/computed tomography (CT) to determine the boost dose and to guide boost segmentation in head and neck cancer.

Methods And Materials: Patients were eligible when treated with curative radiation therapy with or without systemic treatment for T2-4 squamous cell carcinoma of the hypopharynx, larynx, or oropharynx (20 patients in total). FDG-PET/CT scans were made at baseline and for redelineation and replanning at the end of weeks 2 and 4 of radiation therapy.

Robust, independent and relevant prognostic 18F-fluorodeoxyglucose positron emission tomography radiomics features in non-small cell lung cancer: Are there any?

In locally advanced lung cancer, established baseline clinical variables show limited prognostic accuracy and 18F-fluorodeoxyglucose positron emission tomography (FDG PET) radiomics features may increase accuracy for optimal treatment selection. Their robustness and added value relative to current clinical factors are unknown. Hence, we identify robust and independent PET radiomics features that may have complementary value in predicting survival endpoints.

Protocolised way to cope with anatomical changes in head & neck cancer during the course of radiotherapy.

Introduction: During a course of radiotherapy for head-and-neck-cancer (HNC), non-rigid anatomical changes can be observed on daily Cone Beam CT (CBCT). To objectify responses to these changes, we use a decision support system (traffic light protocol). Action levels orange and red may lead to re-planning.

Targeted Intervention to Improve the Quality of Head and Neck Radiation Therapy Treatment Planning in the Netherlands: Short and Long-Term Impact.

Purpose: To benchmark and improve, through means of a targeted intervention, the quality of intensity modulated radiation therapy treatment planning for locally advanced head and neck cancer (HNC) in the Netherlands. The short and long-term impact of this intervention was assessed.

Methods And Materials: A delineated computed tomography-scan of an oropharynx HNC case was sent to all 15 Dutch radiation therapy centers treating HNC.

The Prognostic Value of Baseline 18F-FDG PET/CT in Human Papillomavirus-Positive Versus Human Papillomavirus-Negative Patients With Oropharyngeal Cancer.

Purpose: Oropharynx cancer (OPC) is heterogeneous; human papillomavirus (HPV)-positive and HPV tumors represent 2 disease entities with a different prognosis. Earlier studies investigating the prognostic value of pretreatment F-FDG PET in OPC are small or included patients with unknown HPV status. This study assessed the prognostic value of PET variables, in a large cohort with balanced HPV status.

Prostate-specific membrane antigen positron emission tomography/computed tomography as a potential tool to assess and guide salivary gland irradiation.

Evaluation of salivary gland damage after head and neck radiotherapy (RT) is difficult with current tools, such as subjective patient-reported outcome measures. We demonstrate the use of prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) as an objective non-invasive tool to visualize damage to salivary glands resulting from RT. In three clinical cases, the PSMA-ligand distribution correlates to the RT dose distribution including intra-gland dose gradients and matches patient-reported toxicity, suggesting a dose-response relation.

The developing role of FDG PET imaging for prognostication and radiotherapy target volume delineation in non-small cell lung cancer.

Advancements in functional imaging technology have allowed new possibilities in contouring of target volumes, monitoring therapy, and predicting treatment outcome in non-small cell lung cancer (NSCLC). Consequently, the role of F-fluorodeoxyglucose positron emission tomography (FDG PET) has expanded in the last decades from a stand-alone diagnostic tool to a versatile instrument integrated with computed tomography (CT), with a prominent role in lung cancer radiotherapy. This review outlines the most recent literature on developments in FDG PET imaging for prognostication and radiotherapy target volume delineation (TVD) in NSCLC.

An on-site dosimetry audit for high-energy electron beams.

Background And Purpose: External dosimetry audits are powerful quality assurance instruments for radiotherapy. The aim of this study was to implement an electron dosimetry audit based on a contemporary code of practice within the requirements for calibration laboratories performing proficiency tests. This involved the determination of suitable acceptance criteria based on thorough uncertainty analyses.

Auditing local methods for quality assurance in radiotherapy using the same set of predefined treatment plans.

Background And Purpose: Local implementation of plan-specific quality assurance (QA) methods for intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) treatment plans may vary because of dissimilarities in procedures, equipment and software. The purpose of this work is detecting possible differences between local QA findings and those of an audit, using the same set of treatment plans.

Methods: A pre-defined set of clinical plans was devised and imported in the participating institute's treatment planning system for dose computation.

Operations research for resource planning and -use in radiotherapy: a literature review.

Background: The delivery of radiotherapy (RT) involves the use of rather expensive resources and multi-disciplinary staff. As the number of cancer patients receiving RT increases, timely delivery becomes increasingly difficult due to the complexities related to, among others, variable patient inflow, complex patient routing, and the joint planning of multiple resources. Operations research (OR) methods have been successfully applied to solve many logistics problems through the development of advanced analytical models for improved decision making.

The NCS code of practice for the quality assurance and control for volumetric modulated arc therapy.

In 2010, the NCS (Netherlands Commission on Radiation Dosimetry) installed a subcommittee to develop guidelines for quality assurance and control for volumetric modulated arc therapy (VMAT) treatments. The report (published in 2015) has been written by Dutch medical physicists and has therefore, inevitably, a Dutch focus. This paper is a condensed version of these guidelines, the full report in English is freely available from the NCS website www.

Clinical evaluation of respiration-induced attenuation uncertainties in pulmonary 3D PET/CT.

Background: In contemporary positron emission tomography (PET)/computed tomography (CT) scanners, PET attenuation correction is performed by means of a CT-based attenuation map. Respiratory motion can however induce offsets between the PET and CT data. Studies have demonstrated that these offsets can cause errors in quantitative PET measures.

4D CT amplitude binning for the generation of a time-averaged 3D mid-position CT scan.

The purpose of this study was to develop a method to use amplitude binned 4D-CT (A-4D-CT) data for the construction of mid-position CT data and to compare the results with data created from phase-binned 4D-CT (P-4D-CT) data. For the latter purpose we have developed two measures which describe the regularity of the 4D data and we have tried to correlate these measures with the regularity of the external respiration signal. 4D-CT data was acquired for 27 patients on a combined PET-CT scanner.