A service evaluation of on-line image-guided radiotherapy to lower extremity sarcoma: Investigating the workload implications of a 3 mm action level for image assessment and correction prior to delivery.

INTRODUCTION: Although all systematic and random positional setup errors can be corrected for in entirety during on-line image-guided radiotherapy, the use of a specified action level, below which no correction occurs, is also an option. The following service evaluation aimed to investigate the use of this 3 mm action level for on-line image assessment and correction (online, systematic set-up error and weekly evaluation) for lower extremity sarcoma, and understand the impact on imaging frequency and patient positioning error within one cancer centre. METHODS: All patients were immobilised using a thermoplastic shell attached to a plastic base and an individual moulded footrest. A retrospective analysis of 30 patients was performed. Patient setup and correctional data derived from cone beam CT analysis was retrieved. The timing, frequency and magnitude of corrections were evaluated. The population systematic and random error was derived. RESULTS: 20% of patients had no systematic corrections over the duration of treatment, and 47% had one. The maximum number of systematic corrections per course of radiotherapy was 4, which occurred for 2 patients. 34% of episodes occurred within the first 5 fractions. All patients had at least one observed translational error during their treatment greater than 0.3 cm, and 80% of patients had at least one observed translational error during their treatment greater than 0.5 cm. The population systematic error was 0.14 cm, 0.10 cm, 0.14 cm and random error was 0.27 cm, 0.22 cm, 0.23 cm in the lateral, caudocranial and anteroposterial directions. The required Planning Target Volume margin for the study population was 0.55 cm, 0.41 cm and 0.50 cm in the lateral, caudocranial and anteroposterial directions. CONCLUSION: The 3 mm action level for image assessment and correction prior to delivery reduced the imaging burden and focussed intervention on patients that exhibited greater positional variability. This strategy could be an efficient deployment of departmental resources if full daily correction of positional setup error is not possible.

5-HT3A -driven green fluorescent protein delineates gustatory fibers innervating sour-responsive taste cells: A labeled line for sour taste?

Taste buds contain multiple cell types with each type expressing receptors and transduction components for a subset of taste qualities. The sour sensing cells, Type III cells, release serotonin (5-HT) in response to the presence of sour (acidic) tastants and this released 5-HT activates 5-HT3 receptors on the gustatory nerves. We show here, using 5-HT3A GFP mice, that 5-HT3 -expressing nerve fibers preferentially contact and receive synaptic contact from Type III taste cells. Further, these 5-HT3 -expressing nerve fibers terminate in a restricted central-lateral portion of the nucleus of the solitary tract (nTS)-the same area that shows increased c-Fos expression upon presentation of a sour tastant (30 mM citric acid). This acid stimulation also evokes c-Fos in the laterally adjacent mediodorsal spinal trigeminal nucleus (DMSp5), but this trigeminal activation is not associated with the presence of 5-HT3 -expressing nerve fibers as it is in the nTS. Rather, the neuronal activation in the trigeminal complex likely is attributable to direct depolarization of acid-sensitive trigeminal nerve fibers, for example, polymodal nociceptors, rather than through taste buds. Taken together, these findings suggest that transmission of sour taste information involves communication between Type III taste cells and 5-HT3 -expressing afferent nerve fibers that project to a restricted portion of the nTS consistent with a crude mapping of taste quality information in the primary gustatory nucleus.

Differences in bingeing behavior and cocaine reward following intermittent access to sucrose, glucose or fructose solutions.

Daily intermittent access to sugar solutions results in intense bouts of sugar intake (i.e. bingeing) in rats. Bingeing on sucrose, a disaccharide of glucose and fructose, has been associated with a "primed" mesolimbic dopamine (DA) pathway. Recent studies suggest glucose and fructose engage brain reward and energy-sensing mechanisms in opposing ways and may drive sucrose intake through unique neuronal circuits. Here, we examined in male Sprague-Dawley rats whether or not (1) intermittent access to isocaloric solutions of sucrose, glucose or fructose results in distinctive sugar-bingeing profiles and (2) previous sugar bingeing alters cocaine locomotor activation and/or reward, as determined by conditioned place preference (CPP). To encourage bingeing, rats were given 24-h access to water and 12-h-intermittent access to chow plus an intermittent bottle that contained water (control) or 8% solutions of sucrose, glucose or fructose for 9days, followed by ad libitum chow diet and a 10-day cocaine (15mg/kg; i.p.) CPP paradigm. By day 4 of the sugar-bingeing diet, sugar bingeing in the fructose group surpassed the glucose group, with the sucrose group being intermediate. All three sugar groups had similar chow and water intake throughout the diet. In contrast, controls exhibited chow bingeing by day 5 without altering water intake. Similar magnitudes of cocaine CPP were observed in rats with a history of sucrose, fructose or chow (control) bingeing. Notably, the glucose-bingeing rats did not demonstrate a significant cocaine CPP despite showing similar cocaine-induced locomotor activity as the other diet groups. Overall, these results show that fructose and glucose, the monosaccharide components of sucrose, produce divergent degrees of bingeing and cocaine reward.

Comparison of adaptive radiotherapy techniques for the treatment of bladder cancer.

OBJECTIVE: Day-to-day anatomical variations complicate bladder cancer radiotherapy treatment. This work quantifies the impact on target coverage and irradiated normal tissue volume for different adaptive strategies. METHODS: 20 patients were retrospectively planned using different three-dimensional conformal radiotherapy treatment strategies for whole-bladder carcinoma: (i) "conventional" treatment used isotropic expansion of the clinical target volume (CTV) by 15 mm to the planning target volume (PTV) for daily treatment; (ii) "plan of the day" used daily volumetric on-treatment imaging [cone beam CT (CBCT)] to select from four available plans with varying superior PTV margins; (iii) "composite" strategies used on-treatment CBCTs from Fractions 1-3 to inform a composite CTV and adapted PTV (5- and 10-mm margins for composite 1 and composite 2, respectively) for subsequent treatment. Target coverage was evaluated from available CBCTs (the first three fractions then the minimum weekly thereafter), and the reduction in the irradiated volume (i.e. within the 95% isodose) was quantified. RESULTS: Plan of the day improved target coverage (i.e. all of the bladder within the 95% isodose throughout the treatment) relative to conventional treatment (p=0.10), while no such benefit was observed with composite 2. Target coverage was reduced with composite 1 relative to conventional treatment. The mean irradiated volume was reduced by 17.2%, 35.0% and 14.6% relative to conventional treatment, for plan of the day, composite 1 and composite 2, respectively (p<0.01 in all cases). No parameters predictive of large changes in bladder volume later in the treatment were identified. CONCLUSIONS: Adaptive techniques can maintain or improve target coverage while allowing for reduced irradiated volume and possibly reduced toxicity. The plan-of-the-day technique appeared to provide the optimal balance between target coverage and normal tissue sparing. ADVANCES IN KNOWLEDGE: This study suggests that plan-of-the-day techniques will provide optimal outcomes for adaptive bladder radiotherapy.

A megavoltage scatter correction technique for cone-beam CT images acquired during VMAT delivery.

Kilovoltage cone-beam CT (kV CBCT) can be acquired during the delivery of volumetric modulated arc therapy (VMAT), in order to obtain an image of the patient during treatment. However, the quality of such CBCTs is degraded by megavoltage (MV) scatter from the treatment beam onto the imaging panel. The objective of this paper is to introduce a novel MV scatter correction method for simultaneous CBCT during VMAT, and to investigate its effectiveness when compared to other techniques. The correction requires the acquisition of a separate set of images taken during VMAT delivery, while the kV beam is off. These images--which contain only the MV scatter contribution on the imaging panel--are then used to correct the corresponding kV/MV projections. To test this method, CBCTs were taken of an image quality phantom during VMAT delivery and measurements of contrast to noise ratio were made. Additionally, the correction was applied to the datasets of three VMAT prostate patients, who also received simultaneous CBCTs. The clinical image quality was assessed using a validated scoring system, comparing standard CBCTs to the uncorrected simultaneous CBCTs and a variety of correction methods. Results show that the correction is able to recover some of the low and high-contrast signal to noise ratio lost due to MV scatter. From the patient study, the corrected CBCT scored significantly higher than the uncorrected images in terms of the ability to identify the boundary between the prostate and surrounding soft tissue. In summary, a simple MV scatter correction method has been developed and, using both phantom and patient data, is shown to improve the image quality of simultaneous CBCTs taken during VMAT delivery.

Anatomical failure following laparoscopic antireflux surgery (LARS): does it really matter?

INTRODUCTION: Failure rates of laparoscopic antireflux surgery (LARS) vary from 2-30%. A degree of anatomical failure is common, and the most common failure is intrathoracic wrap herniation. We have assessed anatomical integrity of the crural repair and wrap using marking Liga clips placed at the time of surgery and compared this with symptomatic outcome. PATIENTS AND METHODS: A prospective study was undertaken on 50 patients who underwent LARS in a single centre over a 3-year period. Each had an X-ray on the first postoperative day and a barium swallow at 6 months at which the distance was measured between the marking Liga clips. An increase in interclip distance of > 25-49% was deemed 'mild separation', and an increase of > 50% 'moderate separation'. Patients completed a standardised symptom questionnaire at 6 months. RESULTS: At 6 months' postoperatively, 22% had mild separation of the crural repair with a mean Visick score of 1.18, and 54% had moderate separation with a mean Visick score of 1.26. Mild separation of the wrap occurred in 28% with a mean Visick score of 1.21 and 22% moderate separation with a mean Visick score of 1.18. Three percent had mild separation of both the crural repair and wrap with a mean Visick score of 1.0, and 16% moderate separation with a mean Visick score of 1.13. Of patients, 14% had evidence of some degree of failure on barium swallow but only one of these was significant intrathoracic migration of the wrap which was symptomatic and required re-do surgery. CONCLUSIONS: The prevalence of some form of anatomical failure, as determined by an increase in the interclip distance, is high at 6 months' postoperatively following LARS. However, this does not seem to correlate with a subjective recurrence of symptoms.

Ultrasound imaging to assess inter- and intra-fraction motion during bladder radiotherapy and its potential as a verification tool.

AIMS: Organ motion is the principle source of error in bladder cancer radiotherapy. The aim of this study was to evaluate ultrasound bladder volume measurement as a surrogate measure of organ motion during radiotherapy: (1) to assess inter- and intra-fraction bladder variation and (2) as a potential treatment verification tool. MATERIALS AND METHODS: Twenty patients receiving radical radiotherapy for bladder cancer underwent post-void ultrasound bladder volume measurement at the time of radiotherapy treatment planning (RTP), and immediately before (post-void) and after receiving daily fractions. RESULTS: Ultrasound bladder volume measurement was found to be a simple and acceptable method to estimate relative bladder volume changes. Six patients showed significant changes to post-void bladder volume over the treatment course (P<0.05). The mean inter-fraction post-void bladder volume of five patients exceeded their RTP ultrasound bladder volume by more than 50%. Intra-fraction bladder volume increased on 275/308 (89%) assessed fractions, with the mean intra-fraction volume increases of seven patients exceeding their RTP ultrasound bladder volume by more than 50%. CONCLUSIONS: Both day-to-day bladder volume variation and bladder filling during treatment should be considered in RTP and delivery. Ultrasound may provide a practical daily verification tool by: supporting volume limitation as a method of treatment margin reduction; allowing detection of patients who may require interventions to promote bladder reproducibility; and identifying patients with prominent volume changes for the selective application of more advanced adaptive/image-guided radiotherapy techniques.

Randomized clinical trial of laparoscopic total (Nissen) versus posterior partial (Toupet) fundoplication for gastro-oesophageal reflux disease based on preoperative oesophageal manometry.

BACKGROUND: Laparoscopic fundoplication is an accepted treatment for symptomatic gastro-oesophageal reflux disease. The aim of this study was to clarify whether total (Nissen) or partial (Toupet) fundoplication is preferable, and whether preoperative oesophageal manometry should be used to determine the degree of fundoplication performed. METHODS: Preoperative oesophageal manometry was used to stratify 127 patients with established gastro-oesophageal reflux disease into effective (75) and ineffective (52) oesophageal motility groups. Patients in each group were randomized to Nissen (64) or Toupet (63) fundoplication. RESULTS: No significant differences between the operative groups were seen in heartburn, regurgitation or other reflux-related symptoms up to 1 year after surgery. Dysphagia of any degree (27 versus 9 per cent; P = 0.018) and chest pain on eating (22 versus 5 per cent; P = 0.018) were more prevalent at 1 year in the Nissen group. There were no differences in postoperative symptoms between the effective and ineffective motility groups. Surgery failed in eight patients on postoperative pH criteria, three in the Nissen group and five in the Toupet group. CONCLUSION: Any differences in the symptomatic outcome of laparoscopic Nissen and Toupet fundoplication appear minimal. There is no reason to tailor the degree of fundoplication to preoperative oesophageal manometry.

The extended learning curve for laparoscopic fundoplication: a cohort analysis of 400 consecutive cases.

Many studies have looked at the learning curve associated with laparoscopic Nissen fundoplication (LNF) in a given institution. This study looks at the learning curve of a single surgeon with a large cohort of patients over a 10-year period. Prospective data were collected on 400 patients undergoing laparoscopic fundoplication for over 10 years. The patients were grouped consecutively into cohorts of 50 patients. The operating time, the length of postoperative hospital stay, the conversion rate to open operation, the postoperative dilatation rate, and the reoperation rate were analyzed. Results showed that the mean length of operative time decreased from 143 min in the first 50 patients to 86 min in the last 50 patients. The mean postoperative length of hospital stay decreased from 3.7 days initially to 1.2 days latterly. There was a 14% conversion to open operation rate in the first cohort compared with a 2% rate in the last cohort. Fourteen percent of patients required reoperation in the first cohort and 6% in the last cohort. Sixteen percent required postoperative dilatation in the first cohort. None of the last 150 patients required dilatation. In conclusion, laparoscopic fundoplication is a safe and effective operation for patients with gastroesophageal reflux disease. New techniques and better instrumentation were introduced in the early era of LNF. The learning curve, however, continues well beyond the first 20 patients.

Developments in and experience of kilovoltage X-ray cone beam image-guided radiotherapy.

This paper offers a realistic review of kilovoltage X-ray cone beam tomography integrated with the treatment machine for image-guided radiotherapy in the light of experience taking a commercial system from prototype development into clinical use. It shows that key practicalities cannot be ignored, in particular the regular characterization of mechanical flex during gantry rotation, the mapping of defects in flat panel image transducers and their response to X-ray exposure. The number of X-ray projections and the doses required for clinically useful cone beam reconstruction at different therapy sites are considered in the context of imaging that is fit for purpose. Three roles for cone beam tomography in radiotherapy are identified: patient setup in three dimensions (3D), where even low dose cone beam tissue detail is superior to megavoltage imaging; disease targeting where, despite wide field scatter and slow scanning, it is possible to generate images that are suitable for tumour delineation even at challenging sites; adaptive treatment planning, where calibrated cone beam images have been shown to provide sufficient target detail to support "plan of the day" selection and have the potential for planning with bulk corrections. With frequent use in mind, the need to limit patient dose during setup, yet maximize much needed image quality in the target zone, is considered. Finally, it is noted that the development of cone beam tomography for radiotherapy is far from complete, with X-ray source, image transducer, reconstruction algorithms and techniques for image profile collection still being researched.

Radiotherapy treatment verification in the UK: an audit of practice in 2004.

AIMS: To audit current practice related to treatment verification undertaken in radiotherapy departments throughout the UK. MATERIALS AND METHODS: A questionnaire was circulated to the radiotherapy service managers of 62 radiotherapy centres in the UK. This looked in detail at the department demographics, imaging equipment, site-specific verification protocols, and training and competency assessment of staff responsible for verification. RESULTS: The response rate was 48% (30/62). All departments were using megavoltage imaging equipment in routine clinical practice. Twenty-four out of 29 (83%) departments that had electronic portal imaging capability were using image analysis software for verification. Twenty-nine out of 30 (97%) departments had site-specific written verification protocols. Twenty out of 30 (67%) treatment centres audited set-up errors within their department. Forty-three per cent of centres were using simulator image as the reference image of choice across all sites. Electronic portal imaging, alone or in combination with portal film, was being used for verification in 75% of the centres. Fifty-three per cent of centres used off-line correction strategies for measuring set-up errors across all sites. Radiographer-led interventions were primarily in the pelvis. CONCLUSION: Presently in the UK, verification strategies vary widely at individual treatment sites and between departments. Dedicated departmental verification teams, with input from radiographers, physicists and clinicians, may assist in the effective implementation of evidence-based verification. The inclusion of comprehensive verification protocols within multicentre radiotherapy trials encourages standardisation across treatment centres.

A poor response to proton pump inhibition is not a contraindication for laparoscopic antireflux surgery for gastro esophageal reflux disease.

BACKGROUND: We aimed to determine if a poor response to proton pump inhibitors (PPIs) can predict a poor outcome following laparoscopic antireflux surgery (LARS) in our surgically treated population. METHODS: A total of 324 patients undergoing LARS were included in this study. Following standardized assessment, patients recorded the efficacy of their medication on visual analogue scales. Pre- and postoperative symptom scores were recorded, with outcomes measured by modified Visick scores. RESULTS: There were 233 good responders (>50% relief) and 91 poor responders (<49% relief). Both groups demonstrated a significant decline in postoperative symptom scores. Ninety-four percent of good responders had an excellent or good outcome, compared to 87% of poor responders. Twenty-seven patients reported a fair or poor outcome, despite improved postoperative symptom scores. Fifteen of these patients reported continuing heartburn; five had positive pH tests. CONCLUSION: Our results do not support the assumption that a poor response to PPIs equates to a poor outcome after LARS.

An assessment of clinically optimal gold marker length and diameter for pelvic radiotherapy verification using an amorphous silicon flat panel electronic portal imaging device.

Verification of target organ position is essential for the accurate delivery of conformal radiotherapy. Megavoltage electronic portal imaging with flat panel amorphous silicon detectors delivers high quality images that can be used for verification of bony landmark position. Gold markers implanted into the target organ can be visualized and used as a surrogate of actual organ position. On-line compensation for marker displacement, by adjusting patient position, can reduce geometric errors associated with radiation delivery. This study assesses the optimal marker length and diameter to be used with an amorphous silicon (a-Si) flat panel detector and electronic portal images (EPIs), prior to implementation of a clinical programme of gold marker insertion in prostate cancer patients. Seven marker sizes varying from 3 mm to 8 mm in length and 0.8 mm to 1.1 mm in diameter were investigated in a group of patients undergoing pelvic radiotherapy using an 8 MV Elekta SL20 linear accelerator. Markers were placed on the skin entry and exit sites of the treatment beam and EPIs in both lateral and anterior pelvic views were acquired. Three observers independently assessed visibility success and failure using a subjective scoring system. Markers less than 5 mm in length or 0.9 mm in diameter were poorly visualized (<70% visualization success in lateral EPIs). The marker measuring 0.9 mm x 5 mm appears to be clinically optimal in pelvic radiotherapy patients (80% visualization success in lateral EPIs) and will be used for actual organ implantation.

Laparoscopic fundoplication in mentally normal children with gastroesophageal reflux disease.

Laparoscopic antireflux surgery has been performed in neurologically impaired and scoliotic children. We aimed to assess the effectiveness of laparoscopic fundoplication in mentally normal children with gastroesophageal reflux disease that failed to respond to medical therapy. Data were prospectively collected (symptoms, medical therapy, endoscopies' findings) on 12 children (nine boys, three girls) aged 9-15 years with gastroesophageal reflux disease. Pre- and postoperative ambulatory 24-h pH and DeMeester and Johnson scores were also recorded. Effectiveness of surgery was assessed by comparison of pre- and postoperative total acid exposure time, Visick grade, need for antireflux medication and symptom scores. In total, 11 children underwent a laparoscopic Nissen fundoplication and one underwent a Toupet procedure. Median length of stay was 2 (2-3) nights. The median preoperative pH acid exposure time (AET) was 4.7 (0.8-16.4) percent compared with postoperative AET of 0.4 (0-3) percent. Early postoperative dysphagia occurred in four out of 12 patients, requiring a total of six dilatations. Postoperative Visick scores were: grade I=7 and grade II=5. Laparoscopic fundoplication can be safely performed and is effective in children with GERD who have failed to respond to medical therapy.

Preoperative esophageal body motility does not influence the outcome of laparoscopic Nissen fundoplication for gastroesophageal reflux disease.

We evaluated a policy of performing laparoscopic antireflux surgery without tailoring the procedure to the results of preoperative esophageal motility tests. A total of 117 patients (82 with normal esophageal motility; 35 with ineffective motility, IEM) underwent laparoscopic Nissen fundoplication for symptomatic gastroesophageal reflux. There were no significant differences in preoperative symptom length, dysphagia, DeMeester symptom scores, acid exposure times or lower esophageal sphincter pressures between the two groups. Both groups showed postoperative improvements in DeMeester symptom scores, dysphagia and acid exposure, with no differences between groups. At 1 year after surgery, 95% of the normal motility group and 91% of the IEM group had a good/excellent outcome from surgery. None of the IEM group required postoperative dilatation or reoperation. Patients with IEM fare equally well from laparoscopic Nissen fundoplication as those with normal esophageal motility. There is no merit in tailoring antireflux surgery to the results of preoperative motility tests.

Changes to the TEF schemes can have significant impacts on regulation and management of PCDD/F and PCB.

The changes recommended by the World Health Organisation (WHO) to the toxic equivalency factors (TEFs) for polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) and the recommendation to extend both the TEF scheme and the tolerable daily intake (TDI) to include "dioxin-like" PCB congeners have significant implications for regulators who have relied heavily on the International TEF (I-TEF) scheme in setting and monitoring limits and exposure to these compounds. This paper examines example data sets of sources, environmental concentrations, food and exposure to indicate likely changes in calculated toxic equivalent (TEQ) due to the recommended changes to TEFs. Many published data sets available do not provide congener specific data for PCDD/F which limits the ability to recalculate TEQs. There are even fewer congener specific data published to enable calculation of TEQs for the dioxin-like PCBs. In general TEQs calculated using the WHO scheme for emissions to air were found to show small increases (in the order of 1-10%) in comparison to the I-TEQ (for PCDD/F), some sludge samples showed substantial decreases (up to 70%). Levels in food and calculations of exposure showed that the change to TEFs for PCDD/F increased calculated exposure by 10-20% while the change to PCB TEFs decreased calculated TEQ attributable to PCB by 0-10%. The effects of including PCB in the overall TEQ and the changes to TEFs for PCDD/F substantially increase calculated TEQ exposure. Congener specific data should be presented to allow calculation of desired TEQ and the impact of the changes on emission limits, regulations on sludge use and environmental quality standards should all be carefully considered. The absence of data on emissions of dioxin-like PCB means that it is not possible to estimate with any certainty the impact on overall TEQ emissions of including the nominated PCB. Given the potential for confusion with the proliferation of TEFs and the extension to include both PCDD/F and PCB in the calculation of TEQs it is important that great care is taken to clearly express which compounds are included and which TEF scheme has been applied in each case.

Results of laparoscopic Nissen fundoplication at 2-8 years after surgery.

BACKGROUND: Although the long-term results of open fundoplication for gastro-oesophageal reflux disease are well documented, there have been few reports of the long-term results of laparoscopic fundoplication. METHODS: Between January 1993 and July 1999, 179 consecutive patients underwent laparoscopic floppy Nissen fundoplication. Of these, 175 were available for long-term follow-up. Structured symptom questionnaires were completed by 140 patients (80 per cent) at 2-5 years (n = 92) or 5-8 years (n = 48) after operation. RESULTS: Patient satisfaction with surgery was 91 per cent at a median follow-up of 48 (range 24-99) months. Visick scores of I or II were recorded by 84 per cent. Ninety per cent of patients remained free from significant reflux symptoms. Side-effects were common (22 per cent) but rarely affected patient satisfaction. Of the 19 patients (14 per cent) taking regular antireflux medication, eight used it for non-reflux symptoms and 12 had normal postoperative pH tests. CONCLUSION: Laparoscopic floppy Nissen fundoplication is an effective and durable treatment for gastro-oesophageal reflux disease. Longer-term follow-up of patients operated on beyond the learning curve can be expected to show further improvements in surgical outcome.

Patient self-assessment of test-day symptoms in 24-h pH-metry for suspected gastroesophageal reflux disease.

BACKGROUND: Marked daily fluctuations may occur in the pattern and degree of gastroesophageal reflux (GOR) and in patients' symptoms. The aim of this study was to observe how patients' self-assessment of their symptoms on the day of a 24-h pH test correlates with the likely outcome of the test and the potential value in repeating it. METHODS: 367 patients with symptoms suggestive of GOR underwent 24-h pH tests. Fifty-eight patients had repeat studies. Patients assessed the severity of their test-day symptoms as 'better than typical', 'typical' or 'worse than typical'. RESULTS: A 'typical' or 'worse than typical' day was more likely to produce an abnormal test result (P < 0.0001). A normal first test on a 'better than typical' day was more likely to be followed by an abnormal second test than a normal first test on a 'typical' or 'worse than typical' day (55% versus 22%; P = 0.025). The symptom index score, the total acid exposure time on the first test and the presence of oesophagitis were not associated with an abnormal second test (P not significant). CONCLUSIONS: Patients' self-assessment of the severity of their test-day symptoms should be included in the interpretation of 24-h pH tests for suspected GOR. Patients with a normal pH test on a 'better than typical day warrant a repeat test.