Errors In Patient Positioning Research Articles

Cardiac motion in patients with ventricular tachycardia: potential implications for the treatment of patients candidates to stereotactic arrhythmia radio-ablation (STAR)

Abstract Background Stereotactic arrhythmia radio-ablation (STAR) has proven to be a valid alternative treatment for refractory ventricular tachycardia (VT) in patients who are unsuitable to undergo standard catheter ablation (CA). It consists in the application of external beam radiotherapy in a single dose of 25 Gy to the target areas. There is increased research activity on better understanding the complex and fast motion of the heart and on reducing radiation toxicity. Purpose In the context of an in silico study to evaluate the feasibility of STAR with protons in patients with VT, the initial findings related to cardiac motion on the first 10 patients are here presented. Methods Prior to CA, each patient underwent ECG gated CT scans in expiratory breath-hold, with and without contrast and reconstructed at 30% (systole) and 80% (diastole) of the cardiac R-R cycle. Contouring of the ablation target as a clinical target volume (CTV) for proton treatment planning was performed based on a standard electrophysiological study with 3D eletroanatomical mapping. Two different treatment plans were created: the first with only the diastolic CTV as target (gated treatment), the second including both diastolic and systolic CTVs to create an Internal Target Volume (ITV) in the hypothesis of non-gated treatment. Robust optimization was used to create the Planning Target Volume (PTV). Results The target volumes used for treatment planning are given in Table 1. The median CTV was 10.90 (2.93-36.94) cm3 for diastole and 14.26 (1.73-36.31) cm3 for systole. These volumes are somewhat smaller than those reported in patients treated previously with STAR: this difference may be due to the fact that no respiratory motion was included in the target contour and that the study population includes many patients referred for ventricular ectopic beats without structural heart disease, where the ablation target is expected to be smaller as compared to patients with VT in structural heart disease. Despite a small median difference between the diastolic and systolic CTV of 0.53 (0.03-9.61) cm3, the ITV approach resulted in a median increase in volume compared to the largest of the two CTVs of 29 % (1%-44%). When considering the proton range uncertainty and potential errors in patient positioning (PTV), the target is this time enlarged by a factor 2.9 (1.9-3.9). This data indicates that both cardiac motion and uncertainties in patient positioning before treatment will have a large impact on the treatment volume thus affecting the amount of surrounding tissue exposed to radiation. Conclusion The ablation target contour at systole and diastole are of similar magnitude but their non-overlap results in a large increase in treated volume when radiation delivery is not gated for cardiac motion. Further analysis shall investigate on a case-by-case basis the potential reduction in risk of healthy tissue toxicity with cardiac-gated proton delivery.Table 1

Assessment of Panoramic Radiograph Errors: An Evaluation of Patient Preparation and Positioning Quality at Soelastri Dental and Oral Hospital

Background: Dental radiography is an important component of comprehensive patient care. One of the most frequently used extraoral radiographic techniques is panoramic radiography. Panoramic radiographs lose value when the quality of the diagnostic radiographs is poor. In their application, there are still many errors that occur in panoramic radiographs. Objective: This study aimed to determine the quality and frequency of panoramic radiograph errors due to patient preparation and positioning errors at the Soelastri Dental and Oral Hospital, Universitas Muhammadiyah Surakarta (RSGM Soelastri UMS), Indonesia. Methods: This type of research is descriptive, quantitative, observational, and takes a retrospective approach. A total of 312 panoramic radiographs of patients at RSGM Soelastri UMS from January to December 2021 who met the inclusion and exclusion criteria were taken at random stages and evaluated. Radiographs were compared with ideal quality, given a National Radiological Protection Board (NRPB) rating, and the frequency of errors that occurred was evaluated. Results: The most common rating obtained on panoramic radiographs in this study was 2 of 173 (55.45%). The frequency of preparation errors was 1.22%, while the frequency of patient position errors was 98.78%. The highest patient position error was not placing the tongue on the palate, which was 49.68%. Conclusion: The quality of panoramic radiographs at RSGM Soelastri UMS in the period from January–December 2021 generally has a rating of 2, according to the NRPB, and there are still errors in patient preparation and positioning.

Nerve lesions during arthroscopic procedure: a literature overview.

Arthroscopy is more and more popular. Although minimally-invasive, it's not completely free of complications as nerves lesions which can be invalidating for the patient and frustrating for the surgeon with significant economic, psychological and medico-legal implications. The purpose was to review the literature about nerve injuries related to arthroscopy. A scientific literature review was performed in PubMed/Medline, including articles dealing with cases of iatrogen lesions of the peripheral nerves occurred during arthroscopic procedures. These lesions are mainly due to direct damage by nerve section while cutting for making the portals or during surgical maneuvers, or indirect damage due to traction or pressure mechanisms especially for errors in patient positioning. Also the tourniquet can lead to compression and ischemic nerve injury. Arthroscopy can cause both transient and permanent neurological lesions manifested with dysesthesia up to paralysis according to Seddon's classification in neuroapraxia, axonotmesis and neurotmesis. Incidence of complications in general and of nerve injuries during arthroscopy are reported by joint. A rigorous respect for surgical technique and all perioperative precautions, particularly in relation to the positioning of the patient, greatly reduce the risk of nerve injury. The suggested waiting time before surgical nerve revision is 6 months. In the meanwhile the patient should perform physiotherapy constantly and improvements should be evaluated with clinical examination and electromyography 15-20 days after the lesion, and thereafter at 3 and 6 months.

Perioperative Peripheral Nerve Injury After General Anesthesia: A Qualitative Systematic Review.

Perioperative peripheral nerve injury (PNI) is a well-recognized complication of general anesthesia that continues to result in patient disability and malpractice claims. However, the multifactorial etiology of PNI is often not appreciated in malpractice claims given that most PNI is alleged to be due to errors in patient positioning. New advances in monitoring may aid anesthesiologists in the early detection of PNI. This article reviews recent studies of perioperative PNI after general anesthesia and discusses the epidemiology and potential mechanisms of injury and preventive measures. We performed a systematic literature search, reviewed the available evidence, and identified areas for further investigation. We also reviewed perioperative PNI in the Anesthesia Closed Claims Project database for adverse events from 1990 to 2013. The incidence of perioperative PNI after general anesthesia varies considerably depending on the type of surgical procedure, the age and risk factors of the patient population, and whether the detection was made retrospectively or prospectively. Taken together, studies suggest that the incidence in a general population of surgical patients undergoing all types of procedures is <1%, with higher incidence in cardiac, neurosurgery, and some orthopedic procedures. PNI represent 12% of general anesthesia malpractice claims since 1990, with injuries to the brachial plexus and ulnar nerves representing two-thirds of PNI claims. The causes of perioperative PNI after general anesthesia are likely multifactorial, resulting in a "difficult to predict and prevent" phenomenon. Nearly half of the PNI closed claims did not have an obvious etiology, and most (91%) were associated with appropriate anesthetic care. Future studies should focus on the interaction between different mechanisms of insult, severity and duration of injury, and underlying neuronal reserves. Recent automated detection technology in neuromonitoring with somatosensory evoked potentials may increase the ability to identify at-risk patients and individualize patient management.

Errors in Patient Positioning for Bone Mineral Density Assessment by Dual X-Ray Absorptiometry: Effect of Technologist Retraining

Improper positioning is one of the factors that can lead to incorrect bone mineral density (BMD) results. This study aimed to assess the frequencies of erroneous positioning during three periods: before retraining of the technologists (BR), after retraining (AR), and at the current timepoint 8 years after retraining (C). The BMD images of the first 150 consecutive patients who underwent DXA of the lumbar spine and hip during each of the three periods were retrospectively reviewed. Patients were excluded if they had severe scoliosis, rendering proper positioning impossible. Each BMD image was assessed by an International Society of Clinical Densitometry certified clinical densitometrist who was blinded to the date of the initial examination. For the lumbar spine in the BR group, the criteria frequently not met were inclusion of both iliac crests (33.8%), straightness (30.3%), and midline positioning (20.4%); the respective frequencies were significantly reduced to 0.8%−5.6%, 2.1%−3.0%, and 0%−2.8% in the AR and C groups (p < 0.05). For the hip in the BR group, the criteria frequently not met were straightness (52.8%) and internal rotation (21.8%); the respective frequencies were significantly reduced to 0%−4.2% and 8.3%−8.4% in the AR and C groups (p < 0.05). Overall improper positioning in the BR group was 49.3% and 57.3% at the lumbar spine and the hip, respectively; the respective frequencies were reduced to 9.3% and 12.7% in the AR group, and to 2.7% and 7.3% in the C group. The least significant change values for the lumbar spine, femoral neck, and total hip also became smaller after retraining. Retraining the technologists improved patient positioning, as evidenced by the decreased frequencies of erroneous positioning and the improved least significant change values after the retraining.

Bone Loss or a Case of Mistaken Identity?

The diagnosis of osteoporosis and monitoring of treatment is a challenge due to the use of different technologies for measuring bone mineral density (BMD), with many instrument manufacturers, instrument models, and software versions. Interpreters of bone density tests must be aware of these complexities when evaluating the results, with care to examine the images as well as the numerical data. Dual-energy X-ray absorptiometry (DXA) is the goldstandard technology for the diagnosis of osteoporosis and monitoring the skeletal effects of treatment. However, BMD results can sometimes be misleading due to lack of technologist training leading to errors in patient positioning, incorrect analysis, or invalid data. This is a case presentation that illustrates an easily avoidable BMD testing error that could lead to inappropriate treatment decisions, highlighting the importance of quality BMD testing and reporting.

Bone Loss or a Case of Mistaken Gender?

Osteoporosis can occur in men and women of any age or ethnicity. Osteoporotic fractures are associated with increased mortality, even in younger patients. Hip fractures and vertebral fractures are public health concerns due to long-term disability and high Cost. The lifetime risk of an osteoporotic fracture in men over the age of 50 years is about 1 in 4, with the chances of a new fracture higher than the lifetime risk of developing prostate cancer. The mortality associated with hip fractures is higher in men that in women. By 2025, the estimated number of hip fractures occurring worldwide in men will be close to that seen in women in 1990. Dualenergy X-ray absorptiometry (DXA) is the gold-standard technology for the diagnosis of osteoporosis and monitoring the skeletal effects of treatment. However, DXA results can sometimes be misleading due to errors in patient positioning, incorrect analysis, invalid data, or poor interpretation. This case presentation illustrates an easily avoidable testing error that could lead to inappropriate treatment decisions, highlighting the importance of quality DXA testing and reporting.

Placement of the acetabular component.

Ideal placement of the acetabular component remains elusive both in terms of defining and achieving a target. Our aim is to help restore original anatomy by using the transverse acetabular ligament (TAL) to control the height, depth and version of the component. In the normal hip the TAL and labrum extend beyond the equator of the femoral head and therefore, if the definitive acetabular component is positioned such that it is cradled by and just deep to the plane of the TAL and labrum and is no more than 4mm larger than the original femoral head, the centre of the hip should be restored. If the face of the component is positioned parallel to the TAL and psoas groove the patient specific version should be restored. We still use the TAL for controlling version in the dysplastic hip because we believe that the TAL and labrum compensate for any underlying bony abnormality. The TAL should not be used as an aid to inclination. Worldwide, > 75% of surgeons operate with the patient in the lateral decubitus position and we have shown that errors in post-operative radiographic inclination (RI) of > 50° are generally caused by errors in patient positioning. Consequently, great care needs to be taken when positioning the patient. We also recommend 35° of apparent operative inclination (AOI) during surgery, as opposed to the traditional 45°.

A planning target volume margin formula for hypofractionated intracranial stereotactic radiotherapy under cone beam CT image guidance with a six-degrees-of-freedom robotic couch and a mouthpiece-assisted mask system: a preliminary study.

A planning target volume (PTV) margin formula for hypofractionated intracranial stereotactic radiotherapy (SRT) has been proposed under cone beam CT (CBCT) image guidance with a six-degrees-of-freedom (6-DOF) robotic couch. CBCT-based registration using a 6-DOF couch reportedly led to negligibly small systematic positioning errors, suggesting that each in-treatment positioning error during the treatment courses for the patients employing this combination was predominantly caused by a random gaussian process. Under this assumption, an anisotropic PTV margin for each axis was formulated based on a gaussian distribution model. 19 patients with intracranial lesions who underwent additional post-treatment CBCT were consecutively selected, to whom stereotactic hypofractionated radiotherapy was delivered by a linear accelerator equipped with a CBCT imager, a 6-DOF couch and a mouthpiece-assisted mask system. Time-averaged patient-positioning errors during treatment were estimated by comparing the post-treatment CBCT with the reference planning CT images. It was suggested that each histogram of the in-treatment positioning error in each axis would approach each single gaussian distribution with a mean of zero. The calculated PTV margins in the x, y and z directions were 0.97, 1.30 and 0.88 mm, respectively. The empirical isotropic PTV margin of 2 mm used in our facility for intracranial SRT was consistent with the margin calculated by the proposed gaussian model. We have proposed a PTV margin formula for hypofractionated intracranial SRT under CBCT image guidance with a 6-DOF robotic couch.

Inter- and intrafractional localisation errors in cone-beam CT guided stereotactic radiation therapy of tumours in the liver and lung

Background. Localisation errors in cone-beam CT (CBCT) guided stereotactic body radiation therapy (SBRT) were evaluated and compared to positioning using the external coordinates of a stereotactic body frame (SBF) alone. Possible correlations to patient- or treatment-specific factors such as body mass index (BMI), planning time, treatment delivery time, and distance between tumour and spinal cord were explored to determine whether they influenced on the benefit of image-guidance. Material and methods. A total of 34 patients received SBRT (3 fractions) for tumours in the liver (15 patients) or the lung (19 patients). Immobilisation and positioning was obtained with a SBF. Pre- and post-treatment CBCT scans were registered with the bony anatomy of the planning CT to find inter- and intrafractional patient positioning errors (PPE). For lung tumour patients, matching was also performed on the tumours to find the tumour positioning errors (TPE) and baseline shifts relative to bony anatomy. Results. The mean inter- and intrafractional 3D vector PPE was 4.5 ± 2.7 mm (average ± SD) and 1.5 ± 0.6 mm, respectively, for the combined group of patients. For lung tumours, the interfractional misalignment was 5.6 ± 1.8 mm. The baseline shift was 3.9 ± 2.0 mm. Intrafractional TPE and baseline shifts were 2.1 ± 0.7 mm and 1.9 ± 0.6 mm, respectively. The magnitude of interfractional baseline shift was closely correlated with the distance between the tumour and the spinal cord. Intrafractional errors were independent of patient BMI, age or gender. Conclusion. Image-guidance reduced setup errors considerably. The study demonstrated the benefit of CBCT-guidance regardless of patient specific factors such as BMI, age or gender. Protection of the spinal cord was facilitated by the correlation between the tumour position relative to the spinal cord and the magnitude of baseline shift.

Dosimetric consequences of uncorrected setup errors in helical Tomotherapy treatments of breast-cancer patients

Background and purpose The Tomotherapy Hi-Art II system allows acquisition of pre-treatment MVCT images to correct patient position. This work evaluates the dosimetric impact of uncorrected setup errors in breast-cancer radiation therapy. Materials and methods Breast-cancer patient-positioning errors were simulated by shifting the patient computed-tomography (CT) dataset relative to the planned photon fluence and re-computing the dose distributions. To properly evaluate the superficial region, film measurements were compared against the Tomotherapy treatment planning system (TPS) calculations. A simulation of the integrated dose distribution was performed to evaluate the setup error impact over the course of treatment. Results Significant dose differences were observed for 11-mm shifts in the anterolateral and 3-mm shifts in the posteromedial directions. The results of film measurements in the superficial region showed that the TPS overestimated the dose by 14% at a 1-mm depth, improving to 3% at depths ⩾5 mm. Significant dose reductions in PTV were observed in the dose distributions simulated over the course of treatment. Conclusions Tomotherapy’s rotational delivery provides sufficient photon fluence extending beyond the skin surface to allow an up to 7-mm uncorrected setup error in the anterolateral direction. However, the steep dose falloff that conforms to the lung surface leads to compromised dose distributions with uncorrected posteromedial shifts. Therefore, daily image guidance and consequent patient repositioning is warranted for breast-cancer patients.

Rotation of the Sacrum During Bellyboard Pelvic Radiotherapy

Patients with cervical, uterine, and rectal carcinomas are usually treated in the prone position using the bellyboard positioning device. Specific and uncomfortable prone position gives rise to uncertainties in the daily set-up of patients during the treatment. During investigation of translational movements, rotational movements of the pelvis are observed and investigated. The film portal imaging is used to discover patient positioning errors during treatment. We defined the rotational set-up errors by angle deviations of the sacrum. Thirty-six patients were included in the study; 15 patients were followed during the whole treatment and 21 during the first 5 consecutive treatment days. The image acquisitions were completed in 84%. Systematic and random positioning errors were analyzed in 725 images. Approximately half of the patients had adjusted to the bellyboard in the first few fractions, with sacrum angles remaining the same for the rest of the treatment. The other half had drifts of the sacrum angle during the whole treatment. The rotation of the sacrum during treatment ranged up to 14°, causing the usual set-up verification and correction procedure to result in errors up to 15 mm. Rotational movements of the patient pelvis during bellyboard pelvis radiotherapy can introduce considerable patient position error.

A dynamic compensation strategy to correct patient-positioning errors in conformal prostate radiotherapy

Traditionally, pretreatment detected patient-positioning errors have been corrected by repositioning the couch to align the patient to the treatment beam. We investigated an alternative strategy: aligning the beam to the patient by repositioning the dynamic multileaf collimator and adjusting the beam weights, termed dynamic compensation. The purpose of this study was to determine the geometric range of positioning errors for which the dynamic compensation method is valid in prostate cancer patients treated with three-dimensional conformal radiotherapy. Twenty-five previously treated prostate cancer patients were replanned using a four-field technique to deliver 72 Gy to 95% of the planning target volume (PTV). Patient-positioning errors were introduced by shifting the patient reference frame with respect to the treatment isocenter. Thirty-six randomly selected isotropic displacements with magnitudes of 1.0, 2.0, 4.0, 6.0, 8.0, and 10.0 cm were sampled for each patient, for a total of 5400 errors. Dynamic compensation was used to correct each of these errors by conforming the beam apertures to the new target position and adjusting the monitor units using inverse-square and off-axis factor corrections. The dynamic compensation plans were then compared with the original treatment plans via dose-volume histogram (DVH) analysis. Changes of more than 5% of the prescription dose, 3.6 Gy, were deemed significant. Compared with the original treatment plans, dynamic compensation produced small discrepancies in isodose distributions and DVH analyses. These differences increased with the magnitudes of the initial patient-positioning errors. Coverage of the PTV was excellent: D95 and Dmean were not increased or decreased by more than 5% of the prescription dose, and D5 was not decreased by more than 5% of the prescription dose for any of the 5400 simulated positioning errors. D5 was increased by more than 5% of the prescription dose in only three of the 5400 positioning errors, all three occurring with a positioning error of 10.0 cm. Dose increases for adjacent organs at risk were more common. D33 of the rectum and the periprostatic rectum was increased by more than 5% of the prescription dose in 235 (4.4%) and 212 (3.9%) of the 5400 positioning errors, respectively. D10 of the right femoral head increased by more than 5% of the prescription dose in 444 (8.2%) positioning errors, and the degree of change was highly related to individual patient anatomy and simulation position. For the bladder D20, there were three increases of more than 5% of the prescription dose. These data demonstrate the robustness of dynamic compensation for correction of patient-positioning errors in four-field conformal prostate radiotherapy, with minimal deviation from the original treatment plans even for errors greatly exceeding those commonly encountered in the clinic. Dynamic compensation can be performed remotely, thus eliminating errors that may result from unnecessary increases in treatment time or from secondary patient motion induced by couch motion during the repositioning process. Further, the ability of dynamic compensation to correct large positioning errors has implications for the accuracy necessary during the initial patient setup and, hence, patient throughput for prostate radiotherapy.

Immobilization improves the reproducibility of patient positioning during six-field conformal radiation therapy for prostate carcinoma

Purpose : To determine the magnitude of patient positioning errors associated with six field conformal therapy for carcinoma of the prostate, and to assess the impact of alpha-cradle immobilization on these errors. Methods and Materials : The records of 22 patients, treated at two of the treatment facilities within our department, using computed tomography-planned conformal six field therapy for carcinoma of the prostate, were reviewed. At one facility (UCD), patients were routinely treated with immobilization, while at the other (UCSF) no rigid immobilization was used. Portal films of patients treated at both facilities were subsequently reviewed, and the deviation of each portal from the simulation film was determined (simulation-to-treatment variability). In addition, for each patient, the average deviation of each portal film from the average portal film (treatment-to-treatment variability) was determined. Results : The mean and median simulation-to-treatment variability was 0.4 cm for those patients treated with immobilization, versus 0.6 cm for those treated without immobilization. The 90th percentile of simulation-to-treatment variability was 0.7 cm for those patients treated with immobilization, versus 1.1 cm for those not immobilized. There was a significant reduction in the number of portals observed with errors of ≥0.50 cm ( 132 201 vs. 37 87 , 66% vs. 43%; p < 0.001), 0.75 cm ( 184 201 vs. 59 87 , 92% vs. 68%; p < 0.001), and 1.0 cm ( 196 201 vs. 74 87 , 98% vs. 85%; p < 0.001) for patients treated with immobilization. There was also a significant reduction in the number of patients with treatment-to-treatment variability ≥0.5 cm 1 10 vs. 8 12 ; p = 0.01) for patients treated with immobilization. Conclusion : The use of immobilization devices significantly reduces errors in patient positioning, potentially permitting the use of smaller treatment volumes. Immobilization should be a component of conformal radiation therapy programs for prostate carcinoma.

A review of panoramic radiography and its potential use in implant dentistry.

Radiographic follow-up of dental implants is one of the most important clinical parameters a practitioner can assess. Recent advances in the design of panoramic radiograph machines have increased their potential use in the longitudinal clinical evaluation of dental implants. Changes from the earliest designs allow for a projection geometry that more closely approximates the shape of the human jaw. The fundamentals of panoramic radiography are reviewed including common errors in patient positioning, their effect on the radiographic image, and how to correct the errors. Comparative advantages and disadvantages of intraoral periapical and bitewing films as compared with panoramic radiographs are discussed, specifically focusing on the amount of radiation exposure, ability to detect bone loss/bone defects, and inherent problems with both systems.

Technological features and clinical feasibility of megavoltage CT scanning

Megavoltage CT scanning using 4-MV and 6-MV radiotherapy beams has been developed and applied to verify errors in patient positioning. A detect or system composed of 120 pairs of cadmium tungstate scintillators with photodiodes is mounted to the treatment unit at a distance of 160 cm from the beam source. Image reconstruction is performed with a standard filtered back-projection algorithm. Scanning time and reconstruction time for a slice is approximately 35 s and 60 s respectively. Although spatial resolution is as large as 4 mm, it has sufficient image quality to be applied for treatment planning and verification. The delivered dose with 4 MV and 6 MV is about 1.4 cGy and 28. cGY respectively. When a megavoltage CT image is taken in treatment position, the positioning errors are easily detected by comparing it with diagnostic CT sections for treatment planning. Several clinical examples are presented.

An Assessment of a Film Enhancement System for Use in a Radiation Therapy Department

The clinical uses of a radiotherapy film enhancement system are explored. The primary functions of the system are to improve the quality of poorly exposed simulator and portal films, and to perform comparisons between the two films to determine whether patient or block positioning errors are present. Other features include: the production of inexpensive, high quality hardcopy images of simulation films and initial portal films for chart documentation, the capacity to overlay lateral simulation films with sagittal MRI films to aid in field design, and a mode to zoom in on individual CT or MRI images and enlarge them for video display during chart rounds or instructional sessions. This commercially available system is comprised of a microcomputer, frame grabber, CCD camera with zoom lens, and a high-resolution thermal printer. The user-friendly software is menu driven and utilizes both keyboard and track ball to perform its functions. At the heart of the software is a very fast Adaptive Histogram Equalization (AHE) routine, which enhances and improves the readability of most portal films. The system has been evaluated for several disease sites, and its advantages and limitations will be presented.

Evaluation of panoramic dental radiographs taken in private practice

Five hundred panoramic radiographs submitted to Delta Dental Plan of Michigan for preauthorization or claim processing were evaluated for frequency of occurrence of 15 categories of technical errors in patient positioning, film processing, and general film handling. Only one radiograph showed no errors. The average radiograph contained 2.2 positioning errors, 1.0 processing errors, and 1.5 miscellaneous errors, for a total of 4.7 errors. Of the 500 radiographs, 467 had positioning errors, 441 had processing errors, and 424 had miscellaneous errors. Diagnostic quality was judged to be adequate in 365 radiographs, inadequate in 91 radiographs and marginal in 44 radiographs. The severity of error was of more importance than the number of errors in the determination of diagnostic adequacy.