The effect of linguistic background on rapid number naming: implications for native versus non-native English speakers on sideline-focused concussion assessments.

OBJECTIVE: To determine if native English speakers (NES) perform differently compared to non-native English speakers (NNES) on a sideline-focused rapid number naming task. A secondary aim was to characterize objective differences in eye movement behaviour between cohorts. BACKGROUND: The King-Devick (KD) test is a rapid number-naming task in which numbers are read from left-to-right. This performance measure adds vision-based assessment to sideline concussion testing. Reading strategies differ by language. Concussion may also impact language and attention. Both factors may affect test performance. METHODS: Twenty-seven healthy  NNES and healthy NES performed a computerized KD test under high-resolution video-oculography.  NNES also performed a Bilingual Dominance Scale (BDS) questionnaire to weight linguistic preferences (i.e., reliance on non-English language(s)). RESULTS: Inter-saccadic intervals were significantly longer in  NNES (346.3 ± 78.3 ms vs. 286.1 ± 49.7 ms, p = 0.001), as were KD test times (54.4 ± 15.1 s vs. 43.8 ± 8.6 s, p = 0.002). Higher BDS scores, reflecting higher native language dominance, were associated with longer inter-saccadic intervals in  NNES. CONCLUSION: These findings have direct implications for the assessment of athlete performance on vision-based and other verbal sideline concussion tests; these results are particularly important given the international scope of sport. Pre-season baseline scores are essential to evaluation in the event of concussion, and performance of sideline tests in the athlete's native language should be considered to optimize both baseline and post-injury test accuracy.

A semi-automated 2D/3D marker-based registration algorithm modelling prostate shrinkage during radiotherapy for prostate cancer.

BACKGROUND AND PURPOSE: Currently, most available patient alignment tools based on implanted markers use manual marker matching and rigid registration transformations to measure the needed translational shifts. To quantify the particular effect of prostate gland shrinkage, implanted gold markers were tracked during a course of radiotherapy including an isotropic scaling factor to model prostate shrinkage. MATERIALS AND METHODS: Eight patients with prostate cancer had gold markers implanted transrectally and seven were treated with (neo) adjuvant androgen deprivation therapy. After patient alignment to skin tattoos, orthogonal electronic portal images (EPIs) were taken. A semi-automated 2D/3D marker-based registration was performed to calculate the necessary couch shifts. The registration consists of a rigid transformation combined with an isotropic scaling to model prostate shrinkage. RESULTS: The inclusion of an isotropic shrinkage model in the registration algorithm cancelled the corresponding increase in registration error. The mean scaling factor was 0.89+/-0.09. For all but two patients, a decrease of the isotropic scaling factor during treatment was observed. However, there was almost no difference in the translation offset between the manual matching of the EPIs to the digitally reconstructed radiographs and the semi-automated 2D/3D registration. A decrease in the intermarker distance was found correlating with prostate shrinkage rather than with random marker migration. CONCLUSIONS: Inclusion of shrinkage in the registration process reduces registration errors during a course of radiotherapy. Nevertheless, this did not lead to a clinically significant change in the proposed table translations when compared to translations obtained with manual marker matching without a scaling correction.

The use of a multipurpose phantom for mailed dosimetry checks of therapeutic photon beams: 'OPERA' (operational phantom for external radiotherapy audit).

BACKGROUND AND PURPOSE: This study presents a technical description of the solid multipurpose phantom (MPP) 'OPERA' (operational phantom for external radiotherapy audit) for mailed dosimetry checks of photon beams in reference and non-reference conditions. The aim is to test the functionality of this phantom by comparing the results provided by the local treatment planning system (TPS) with the measurements by film and thermoluminescence dosimeters (TLDs) in a number of clinical conditions. MATERIAL AND METHODS: The polystyrene MPP is constructed to check the following five irradiation conditions: square fields, asymmetrical fields, wedged beams, oblique incidence and influence of inhomogeneities in the field. The absorbed dose on the central beam axis is measured with TLDs for the first three irradiation conditions and the relative dose distributions are verified with film. RESULTS: The 'OPERA' phantom and the corresponding instruction sheets were mailed to radiotherapy centres of 12 different countries, in order to verify its functionality. A good agreement between TPS and the film data is found: the mean deviations between relative dose profiles obtained from film and locally applied TPS data range between -1.2 and 0.4%, except for the short side of the asymmetrical field. The standard deviations (SDs) generally increase off-axis, with a large SD on the asymmetrical side. Considering the TLD results, a mean ratio of measured to stated dose of 0.995+/-0.014 (1 SD), 0.988+/-0.019 (1 SD) and 0.981+/-0.024 (1 SD) for set-up 1 (square field), 2 (asymmetrical field) and 3 (wedged field), respectively, has been found. CONCLUSION: The 'OPERA' phantom can be useful for on- and off-axis verification of the TPS, as well as for mailed dosimetrical checks of photon beams in reference and non-reference conditions.

Feasibility study of entrance in vivo dose measurements with mailed thermoluminescence detectors.

BACKGROUND AND PURPOSE: The aim of this work is to set-up mailed entrance in vivo dosimetry by means of thermoluminescence dosimeters (TLDs) in the form of LiF powder in order to assess the overall accuracy of patient treatment delivery by comparing the doses delivered to patients with the doses calculated by the treatment planning system (TPS) in different institutions. PATIENTS AND METHODS: Two millimeter thick copper (for 6 MV photon beams) and 1.3 mm thick aluminium (for (60)Co gamma beams) build-up caps are developed. The characteristics of these build-up caps are tested by phantom measurements: the response of the TLD inside the build-up cap is compared to the ionisation chamber (IC) signal in the same irradiation conditions. A pilot study using the copper build-up cap is performed on 8 patients, treated with a 6 MV photon beam at the radiotherapy department of the University Hospital of Leuven. Additionally, a first run of mailed entrance in vivo dosimetry is performed by 18 radiotherapy centres in Europe. RESULTS: For 80 different phantom set-ups using copper and aluminium build-up caps, the mean TLD dose compared to the IC dose is 0.993+/-0.015 (1SD). Regarding the patient measurements in the radiotherapy department of the University Hospital of Leuven, the mean ratio of the measured entrance dose (TLD) to the entrance dose calculated by the TPS, is equal to 0.986+/-0.017 (1SD) (N=8), after correction of an error detected in one of the patient treatments. For the 18 radiotherapy centres participating in the mailed in vivo TLD study, the mean measured versus stated entrance dose for patients treated in a (60)Co and 6 MV photon beam is 1.004+/-0.021 (1SD) (N=143). CONCLUSIONS: From the results, it can be deduced that the build-up caps and the proposed calibration methodology allow the use of TLD in the form of powder to be applied in large scale in vivo dose audits.

In search of the economic sustainability of Hadron therapy: the real cost of setting up and operating a Hadron facility.

PURPOSE: To determine the treatment cost and required reimbursement for a new hadron therapy facility, considering different technical solutions and financing methods. METHODS AND MATERIALS: The 3 technical solutions analyzed are a carbon only (COC), proton only (POC), and combined (CC) center, each operating 2 treatment rooms and assumed to function at full capacity. A business model defines the required reimbursement and analyzes the financial implications of setting up a facility over time; activity-based costing (ABC) calculates the treatment costs per type of patient for a center in a steady state of operation. Both models compare a private, full-cost approach with public sponsoring, only taking into account operational costs. RESULTS: Yearly operational costs range between €10.0M (M = million) for a publicly sponsored POC to €24.8M for a CC with private financing. Disregarding inflation, the average treatment cost calculated with ABC (COC: €29,450; POC: €46,342; CC: €46,443 for private financing; respectively €16,059, €28,296, and €23,956 for public sponsoring) is slightly lower than the required reimbursement based on the business model (between €51,200 in a privately funded POC and €18,400 in COC with public sponsoring). Reimbursement for privately financed centers is very sensitive to a delay in commissioning and to the interest rate. Higher throughput and hypofractionation have a positive impact on the treatment costs. CONCLUSIONS: Both calculation methods are valid and complementary. The financially most attractive option of a publicly sponsored COC should be balanced to the clinical necessities and the sociopolitical context.

Patient positioning based on a radioactive tracer implanted in patients with localized prostate cancer: a performance and safety evaluation.

PURPOSE: To evaluate the performance and safety of a radiation therapy positioning system (RealEye) based on tracking a radioactive marker (Tracer) implanted in patients with localized prostate cancer. METHODS AND MATERIALS: We performed a single-arm multi-institutional trial in 20 patients. The iridium-192 ((192)Ir)-containing Tracer was implanted in the patient together with 4 standard gold seed fiducials. Patient prostate-related symptoms were evaluated with the International Prostate Symptom Score (IPSS) questionnaire. Computed tomography (CT) was performed for treatment planning, during treatment, and after treatment to evaluate the migration stability of the Tracer. At 5 treatment sessions, cone beam CT was performed to test the positioning accuracy of the RealEye. RESULTS: The Tracer was successfully implanted in all patients. No device or procedure-related adverse events occurred. Changes in IPSS scores were limited. The difference between the mean change in Tracer-fiducial distance and the mean change in fiducial-fiducial distance was -0.39 mm (95% confidence interval [CI] upper boundary, -0.22 mm). The adjusted mean difference between Tracer position according to RealEye and the Tracer position on the CBCT for all patients was 1.34 mm (95% CI upper boundary, 1.41 mm). CONCLUSIONS: Implantation of the Tracer is feasible and safe. Migration stability of the Tracer is good. Prostate patients can be positioned and monitored accurately by using RealEye.

The cost of radiotherapy in a decade of technology evolution.

PURPOSE: To quantify changes in radiotherapy costs occurring in a decade of medical-technological evolution. MATERIALS AND METHODS: The activity-based costing (ABC) model of the University Hospitals Leuven (UHL) radiotherapy (RT) department was adapted to current RT standards. It allocated actual resource costs to the treatments based on the departmental work-flow and patient mix in 2009. A benchmark with the former model analyzed the cost increases related to changes in RT infrastructure and practice over 10 years. RESULTS: A considerable increase in total RT costs was observed, resulting from higher capital investments (96%) and personnel cost (103%), the latter dominating the total picture. Treatment delivery remains the most costly activity, boosted by the cost of improved quality assurance (QA), 23% of total product costs, coming along with more advanced RT techniques. Hence, cost increases at the product level are most obvious for complex treatments, such as intensity-modulated radiotherapy (IMRT), representing cost increases ranging between 38% and 88% compared to conformal approaches. CONCLUSIONS: The ABC model provides insight into the financial consequences of evolving technology and practice. Such data are a mandatory first step in our strive to prove RT cost-effectiveness and thus support optimal reimbursement and provision of radiotherapy departments.

Intrafractional prostate motion during online image guided intensity-modulated radiotherapy for prostate cancer.

INTRODUCTION: Intrafractional motion consists of two components: (1) the movement between the on-line repositioning procedure and the treatment start and (2) the movement during the treatment delivery. The goal of this study is to estimate this intrafractional movement of the prostate during prostate cancer radiotherapy. MATERIAL AND METHODS: Twenty-seven patients with prostate cancer and implanted fiducials underwent a marker match procedure before a five-field IMRT treatment. For all fields, in-treatment images were obtained and then processed to enable automatic marker detection. Combining the subsequent projection images, five positions of each marker were determined using the shortest path approach. The residual set-up error (RSE) after kV-MV based prostate localization, the prostate position as a function of time during a radiotherapy session and the required margins to account for intrafractional motion were determined. RESULTS: The mean RSE and standard deviation in the antero-posterior, cranio-caudal and left-right direction were 2.3±1.5 mm, 0.2±1.1 mm and -0.1±1.1 mm, respectively. Almost all motions occurred in the posterior direction before the first treatment beam as the percentage of excursions>5 mm was reduced significantly when the RSE was not accounted for. The required margins for intrafractional motion increased with prolongation of the treatment. Application of a repositioning protocol after every beam could decrease the 1cm margin from CTV to PTV by 2 mm. CONCLUSIONS: The RSE is the main contributor to intrafractional motion. This RSE after on-line prostate localization and patient repositioning in the posterior direction emphasizes the need to speed up the marker match procedure. Also, a prostate IMRT treatment should be administered as fast as possible, to ensure that the pre-treatment repositioning efforts are not erased by intrafractional prostate motion. This warrants an optimized workflow with the use of faster treatment techniques.

IMRT-based optimization approaches for volumetric modulated single arc radiotherapy planning.

This paper reports on an evaluation of 5 RapidArc optimization approaches vs IMRT. This study includes 11 patients with adenocarcinoma of the prostate. Rectal Normal Tissue Complication Probability is used as a constraint in a dose escalation. RapidArc rectal NTCP's are lower than those of IMRT (p = 0.007). This allows a mean dose escalation of 2.1 Gy([0.7 Gy,3.5 Gy]).

Time and motion study of radiotherapy delivery: Economic burden of increased quality assurance and IMRT.

Time measurements were performed on daily treatment delivery with the aim to quantify the impact of quality assurance (QA) using an electronic portal imaging device (EPID) on RT delivery time and to validate the time burden of intensity modulated radiation therapy (IMRT) as an example of advanced technology. Both increased QA and the delivery of IMRT were found to be significant parameters determining daily treatment time (TT), which in turn translates in increased treatment costs.

Hypofractionated intensity modulated irradiation for localized prostate cancer, results from a phase I/II feasibility study.

BACKGROUND: To assess acute (primary endpoint) and late toxicity, quality of life (QOL), biochemical or clinical failure (secondary endpoints) of a hypofractionated IMRT schedule for prostate cancer (PC). METHODS: 38 men with localized PC received 66 Gy (2.64 Gy) to prostate,2 Gy to seminal vesicles (50 Gy total) using IMRT.Acute toxicity was evaluated weekly during radiotherapy (RT), at 1-3 months afterwards using RTOG acute scoring system. Late side effects were scored at 6, 9, 12, 16, 20, 24 and 36 months after RT using RTOG/EORTC criteria.Quality of life was assessed by EORTC-C30 questionnaire and PR25 prostate module. Biochemical failure was defined using ASTRO consensus and nadir+2 definition, clinical failure as local, regional or distant relapse. RESULTS: None experienced grade III-IV toxicity. 10% had no acute genito-urinary (GU) toxicity, 63% grade I; 26% grade II. Maximum acute gastrointestinal (GI) scores 0, I, II were 37%, 47% and 16%. Maximal acute toxicity was reached weeks 4-5 and resolved within 4 weeks after RT in 82%.Grade II rectal bleeding needing coagulation had a peak incidence of 18% at 16 months after RT but is 0% at 24-36 months. One developed a urethral stricture at 2 years (grade II late GU toxicity) successfully dilated until now. QOL urinary symptom scores reached a peak incidence 1 month after RT but normalized 6 months later. Bowel symptom scores before, at 1-6 months showed similar values but rose slowly 2-3 years after RT. Nadir of sexual symptom scores was reached 1-6 months after RT but improved 2-3 years later as well as physical, cognitive and role functional scales.Emotional, social functional scales were lowest before RT when diagnosis was given but improved later. Two years after RT global health status normalized. CONCLUSION: This hypofractionated IMRT schedule for PC using 25 fractions of 2.64 Gy did not result in severe acute side effects. Until now late urethral, rectal toxicities seemed acceptable as well as failure rates. Detailed analysis of QOL questionnaires resulted in the same conclusion.