Valuing EQ-5D-Y: the current state of play

BACKGROUND

For nearly a decade, value sets for the EQ-5D-Y were not available, reflecting challenges in valuing child HRQoL. A methodological research programme led to publication of a valuation protocol in 2020, which was rapidly taken up by local study teams. By the end of 2022, between 11 and 17 EQ-5D-Y value sets will be available, more than for any other child HRQoL measure. It is timely to review the experience of those using the protocol to identify early learnings and remaining issues where more research is needed.

METHODS

In June 2021, the EuroQol Group organised a three-day workshop, bringing together all those involved in EQ-5D-Y value set studies and related methodological research concerning EQ-5D-Y and valuation. Workshop discussions were captured by note taking and recording all sessions and online chat. A narrative summary of all sessions was produced and synthesised to identify points of agreement and aspects of methods where uncertainty remains.

RESULTS

There was broad agreement that DCE is working well as the principal valuation method. However, the most appropriate means of anchoring the latent scale values produced by DCE remains unclear. Some studies have deviated from the protocol by extending the number of states included in TTO tasks, to better support modelling of DCE and TTO. There is ongoing discussion about the relative merits of alternative variants of TTO and other methods for anchoring. Very few studies have consulted with local end-users to gauge the acceptability of methods used to value EQ-5D-Y.

CONCLUSIONS

Priority areas for research include testing alternative methods for anchoring DCE data; exploring the preferences of adolescents; and scale differences in values for EQ-5D-Y and adult EQ-5D states, and implications of such differences for the use of EQ-5D-Y values in HTA. Given the normative elements of the protocol, engaging with HTA bodies and other local users should be the first step for all future value set studies. Value sets undertaken to date are for the three-level EQ-5D-Y. However, the issues discussed in this paper are equally relevant to valuation of the five-level version of EQ-5D-Y; indeed, similar challenges are encountered valuing any measure of child HRQoL.

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.

Tortuosity and mass transfer limitations in industrial hydrotreating catalysts: effect of particle shape and size distribution

Comparison of the tortuosity factor of γ-alumina supports and hydrotreating catalysts evaluated with PFG-NMR, inverse liquid chromatography and catalytic experiments.

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.

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.

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.

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.

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.

Pre-treatment dosimetric verification by means of a liquid-filled electronic portal imaging device during dynamic delivery of intensity modulated treatment fields

BACKGROUND AND PURPOSE

Although intensity modulated radiation therapy is characterized by three-dimensional dose distributions which are often superior to those obtained with conventional treatment plans, its routine clinical implementation is partially held back by the complexity of the beam verification. This is even more so when a dynamic multileaf collimator (dMLC) is used instead of a segmented beam delivery. We have therefore investigated the possibility of using a commercially available, liquid-filled electronic portal imaging device (EPID) for the pre-treatment quality assurance of dynamically delivered dose distributions.

METHODS AND MATERIALS

A special acquisition mode was developed to optimize the image acquisition speed for dosimetry with the liquid-filled EPID. We investigated the accuracy of this mode for 6 and 18 MV photon beams through comparison with film and ion chamber measurements. The impact of leaf speed and pulse rate fluctuations was quantified by means of dMLC plans especially designed for this purpose. Other factors influencing the accuracy of the dosimetry (e.g. the need for build-up, remanence of the ion concentration in the liquid and bulging of the liquid at non-zero gantry angles) were studied as well. We finally compared dosimetric EPID images with the corresponding image prediction delivered without a patient in the beam.

RESULTS

The dosimetric accuracy of the measured dose distribution is approximately 2% with respect to film and ion chamber measurements. The accuracy declines when leaf speed is increased beyond 2 cm/s, but is fairly insensitive to accelerator pulse rate fluctuations. The memory effect is found to be of no clinical relevance. When comparing the acquired and expected distributions, an overall agreement of 3% can be obtained, except at areas of steep dose gradients where slight positional shifts are translated into large errors.

CONCLUSIONS

Accurate dosimetric images of intensity modulated beam profiles delivered with a dMLC can be obtained with a commercially available, liquid-filled EPID. The developed acquisition mode is especially suited for fast and accurate pre-treatment verification of the intensity modulated fields.

External audits of electron beams using mailed TLD dosimetry: preliminary results

AIM

A feasibility study has been performed to investigate the possibility of using mailed thermoluminescence dosimetry (TLD) for external audits of clinical electron beams in Europe.

METHODS

In the frame of the EC Network Project for Quality Assurance in Radiotherapy, instruction sheets and mailing procedures have been defined for mailed TLD dosimetry using the dedicated holder developed by a panel of experts of the International Atomic Energy Agency (IAEA). Three hundred and thirty electron beam set-ups have been checked in the reference centres and some local centres of the EC Network Project and in addition through the centres participating to the EORTC Radiotherapy Group trial 22922.

RESULTS

The mean ratio of measured dose to stated dose is 0.2% and the standard deviation of measured dose to stated dose is 3.2%. In seven beam set-ups, deviations greater than 10% were observed (max. 66%), showing the usefulness of these checks.

CONCLUSION

The results of this feasibility study (instruction sheets, mailing procedures, holder) are presently endorsed by the EQUAL-ESTRO structure in order to offer in the future to all ESTRO members the possibility to request external audits of clinical electron beams.

[Dental medicine in the service of the mentally handicapped: personal experiences]

The article is the reflection of twenty years of experience in dental care for the handicapped. The first part of the article gives you general advises called 'golden rules' and a planning method. In the second part you can find advises how to deal with the different disciplines of dental care as prosthesis, extraction, etc. A lot of examples illustrate the theory.

Quality assessment of medical decision making in radiation oncology: variability in target volume delineation for brain tumours

The enormous developments in radiation technology open new horizons for improvements in local tumour control. However, the evolution from conventional external beam radiotherapy planning to conformal therapy might be hampered by the potential risk of over-reliance on the physician's capability of estimating the tumour extent from imaging modalities. The variability between 12 volunteering physicians in the delineation of tumour and target volume on the lateral orthogonal localisation radiograph from CT was assessed for 5 brain tumours. The estimated tumour and target sizes varied, respectively with a factor of 1.3-2.6 and with a factor of 1.3-2.1. The anatomical location of the volumes showed maximum variations from 11 to 27 mm in the cranio-caudal direction and from 14 to 21 mm in the fronto-occipital direction. For the 5 test cases, the tumour area on which all radiation oncologists agreed, represented only 25-73% of the corresponding mean tumour area. Although the introduction of computed tomography in radiation treatment planning was proved to be a major step forwards for treatment planning in many tumour sites, the results of the present study on brain tumours demonstrate that the subjective interpretation of the tumour extent based on CT images might be one of the largest factors contributing to the overall uncertainty in radiation treatment planning. Moreover, this study endorses the need for uncertainty analysis of the medical decision-making process. It may be that the process of making uncertainties explicit can contribute to the improvement of our present concept of radiation treatment planning.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of sustained phonation at high and low pitch on vocal jitter and shimmer

Looking for possible signs of vocal fatigue, acoustic waveform perturbation was measured in normal female subjects during sustained phonation at various fundamental frequencies (Fo). At none of the pitch levels a rise of the jitter or the shimmer was found after 25 min of vocalization. On the other hand, an effect of Fo was seen from the start: above the habitual speaking Fo of our subjects' voices there was a tendency for the jitter to be higher and for the shimmer to be lower.

Assessment of dose inhomogeneity at target level by in vivo dosimetry: can the recommended 5% accuracy in the dose delivered to the target volume be fulfilled in daily practice?

The inhomogeneity of the dose delivered to the target volume due to irregular body surface and tissue densities remains in many cases unknown, since the dose distribution is calculated for most radiation treatments in only one transverse section and assuming the patient to be water equivalent. In the present study, the transmission and the target absorbed dose homogeneity is assessed for 11 head-and-neck cancer treatments by in vivo measurements with silicon diodes. Besides the dose to the specification point, the dose delivered to 2-4 off-axis points in the midline sagittal plane is estimated from entrance and exit dose measurements. Simultaneously made portal films allow to identify the anatomical structures passed by the beam before reaching the exit diode. The mean deviation from the expected transmission is -6.8% for bone, +6% for air cavities and -2.5% for soft tissue. At the midplane, the mean deviations from the expected target dose are respectively -3.5%, +2.3% and -1.9%. The deviations from the prescribed dose are larger than 5% in 12 out of the 39 target points. The accuracy requirement in target dose delivery of plus or minus 5%, as proposed by ICRU, cannot be fulfilled in 7 out of the 11 patients and is mostly due to irregular body contour and tissue densities. As only a limited number of points are considered, the inhomogeneity in the dose delivered throughout the whole irradiated volume is underestimated as is illustrated from the exit dose profiles obtained from the portal image.(ABSTRACT TRUNCATED AT 250 WORDS)

Human errors in data transfer during the preparation and delivery of radiation treatment affecting the final result: "garbage in, garbage out"

Due to the large number of steps and the number of persons involved in the preparation of a radiation treatment, the transfer of information from one step to the next is a very critical point. Errors due to inadequate transfer of information will be reflected in every next step and can seriously affect the final result of the treatment. We studied the frequency and the sources of the transfer errors. A total number of 464 new treatments has been checked over a period of 9 months (January to October 1990). Erroneous data transfer has been detected in 139/24,128 (less than 1%) of the transferred parameters; they affected 26% (119/464) of the checked treatments. Twenty-five of these deviations could have led to large geographical miss or important over- or underdosage (much more than 5%) of the organs in the irradiated volume, thus increasing the complications or decreasing the tumour control probability, if not corrected. Such major deviations, only occurring in 0.1% of the transferred parameters, affected 5% (25/464) of the new treatments. The sources of these large deviations were nearly always human mistakes, whereas a considerable number of the smaller deviations were, in fact, consciously taken decisions to deviate from the intended treatment. Nearly half of the major deviations were introduced during input of the data in the check-and-confirm system, demonstrating that a system aimed to prevent accidental errors, can lead to a considerable number of systematic errors if used as an uncontrolled set-up system. The results of this study show that human mistakes can seriously affect the outcome of patient treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo dosimetry for tangential breast irradiation: role of the equipment in the accuracy of dose delivery

Entrance dose measurements (920) have been performed on both tangential treatment fields for 105 breast cancer patients. About half of them (52) were treated on a modern unit (Mevatron, Siemens), supplied with an automatic verification system, the other half (53) were treated on an old therapy unit (cobalt-60). A team of three radiographers worked on the modern unit, while on the old unit only one radiographer was responsible for the treatment set-up. A small systematic error (+ 1.4%) has been detected on the old unit: a small discrepancy existed in the region of the maximum dose between the measured and the published percentage depth-dose values (Br. J. Radiol., Suppl. 17), the latter being used for dose calculation. A striking difference has been observed for the rate of large deviations (deviations of 5% and more from the mean dose): 2.3% (10/430) for the modern unit versus 15% (75/490) for the old one. This shows clearly that the precision in dose delivery is strongly dependent on the characteristics and staffing of the therapy unit, the modern unit being supplied with a check-and-confirm system and with the beam accessory devices in a fixed position in the beam and a team of radiographers being responsible for the set-up.

Is it necessary to repeat quality control procedures for head and neck patients?

Using serial verification films for detection of localization errors and in vivo measurements of the delivered dose, a comparison was made of the information obtained from a single check on the first treatment session or from repeated checks in subsequent irradiations, leading to an assessment of the predictive value of a single check. A total number of 215 films and 261 entrance dose measurements have been performed on 34 fields for 10 head and neck patients. The patients are immobilized with individual plastic masks fixed on the couch and treated on a 6 MV linac, supplied with an automatic verification system excluding the couch parameters. The global results show Gaussian frequency distributions with standard deviations of 4 mm for port film measurements and 3.4% for the dose measurements. Large errors (greater than 5 mm displacement and greater than 4% deviation from the expected dose) have been detected in 16% in the cranio-caudal direction and 24% in the antero-posterior direction with port films and in 15% of the in vivo measurements. In order to identify the nature of the errors, which can be random or systematic, the first measurement is taken as the reference value and shows that consecutive measurements on the same field were reproducible with standard deviations of respectively 2.5 mm and 1.8%. This means that a large part of the spread of the global results can be explained by systematic errors in the treatment preparation chain. With the first check, 6 out of 10 systematic localization errors and 7 out of 7 systematic errors leading to erroneous dose delivery have been detected. Therefore, most of the systematic errors, which affect the overall quality of the treatment, can be identified with the first check. The four systematic localization errors, missed with the first film, were of rather limited size: only one of them showed a mean displacement larger than 7 mm. Because the first measurement is an acceptable indication of the overall quality of the treatment delivery, the authors propose a code of practice for checking the treatment quality at the patient level.

[Polychlorodibenzo-p-dioxins (author's transl)]

Polychlorodibenzo-p-dioxins (chlorodioxins) appear most frequently by heating of chlorophenols in alkaline solution specially when producing organic derivatives. Consequently chlorodioxins may contaminate several industrial chemical products largely used, for instance, as pesticides. Occasionally, chlorodioxins are also synthesized from chlorophenols or their derivatives in situ during industrial processes. Chlorodioxins are the cause of chloracne and chick edema which killed thousands of broiler chickens in the U.S.A. Furthermore chlorodioxins seem to be foetotoxic possible even for man. The present paper is the first part of our work. It is a review of the chemical and toxicological properties of chlorodioxins. We hope to publish later a review of analytical methods and the results of our analyses.