Set-up verification using portal imaging; review of current clinical practice

In this review of current clinical practice of set-up error verification by means of portal imaging, we firstly define the various types of set-up errors using a consistent nomenclature. The different causes of set-up errors are then summarized. Next, the results of a large number of studies regarding patient set-up verification are presented for treatments of patients with head and neck, prostate, pelvis, lung and breast cancer, as well as for mantle field/total body treatments. This review focuses on the more recent studies in order to assess the criteria for good clinical practice in patient positioning. The reported set-up accuracy varies widely, depending on the treatment site, method of immobilization and institution. The standard deviation (1 SD, mm) of the systematic and random errors for currently applied treatment techniques, separately measured along the three principle axes, ranges from 1.6-4.6 and 1.1-2.5 (head and neck), 1.0-3.8 and 1.2-3.5 (prostate), 1.1-4.7 and 1.1-4.9 (pelvis), 1.8-5.1 and 2.2-5.4 (lung), and 1.0-4.7 and 1.7-14.4 (breast), respectively. Recommendations for procedures to quantify, report and reduce patient set-up errors are given based on the studies described in this review. Using these recommendations, the systematic and random set-up errors that can be achieved in routine clinical practice can be less than 2.0 mm (1 SD) for head and neck, 2.5 mm (1 SD) for prostate, 3.0 mm (1 SD) for general pelvic and 3.5 mm (1 SD) for lung cancer treatment techniques.

Risk of pelvic fractures in older women following pelvic irradiation

CONTEXT

Pelvic fractures, including hip fractures, are a major source of morbidity and mortality in older women. Although therapeutic pelvic irradiation could increase the risk of such fractures, this effect has not been studied.

OBJECTIVE

To determine if women who undergo pelvic irradiation for pelvic malignancies (anal, cervical, or rectal cancers) have a higher rate of pelvic fracture than women with pelvic malignancies who do not undergo irradiation.

DESIGN, SETTING, AND PARTICIPANTS

We conducted a retrospective cohort study using Surveillance, Epidemiology, and End Results (SEER) cancer registry data linked to Medicare claims data. A total of 6428 women aged 65 years and older diagnosed with pelvic malignancies from 1986 through 1999 were included. We compared results for women who did (n = 2855) vs did not (n = 3573) undergo radiation therapy. To assess the influence of selection bias, we also evaluated the effect of irradiation on osteoporotic fractures in nonirradiated sites (arm and spine).

MAIN OUTCOME MEASURE

We evaluated the effect of irradiation on the incidence of pelvic fractures over time, and adjusted for potential confounders using a proportional hazards model.

RESULTS

Women who underwent radiation therapy were more likely to have a pelvic fracture than women who did not undergo radiation therapy (cumulative 5-year fracture rate, 14.0% vs 7.5% in women with anal cancer, 8.2% vs 5.9% in women with cervical cancer, and 11.2% vs 8.7% in women with rectal cancer); the difference was statistically significant and most fractures (90%) were hip fractures. We controlled for potential confounders including age, race, cancer stage, and geographic location. The impact of irradiation varied by cancer site: treatment for anal cancer was associated with a higher risk of pelvic fractures (hazard ratio, 3.16; 95% confidence interval, 1.48-6.73); than for cervical cancer (hazard ratio, 1.66; 95% confidence interval, 1.06-2.59); or rectal cancer (hazard ratio, 1.65; 95% confidence interval, 1.33-2.05). No statistically significant difference was found in the rate of arm or spine fractures between the irradiated and nonirradiated groups (hazard ratio, 1.15; 95% confidence interval, 0.89-1.48).

CONCLUSIONS

Pelvic irradiation substantially increases the risk of pelvic fractures in older women. Given the high baseline risk of pelvic fracture, this finding is of particular concern.

Dosimetric considerations for patients with HIP prostheses undergoing pelvic irradiation. Report of the AAPM Radiation Therapy Committee Task Group 63

This document is the report of a task group of the Radiation Therapy Committee of the AAPM and has been prepared primarily to advise hospital physicists involved in external beam treatment of patients with pelvic malignancies who have high atomic number (Z) hip prostheses. The purpose of the report is to make the radiation oncology community aware of the problems arising from the presence of these devices in the radiation beam, to quantify the dose perturbations they cause, and, finally, to provide recommendations for treatment planning and delivery. Some of the data and recommendations are also applicable to patients having implanted high-Z prosthetic devices such as pins, humeral head replacements. The scientific understanding and methodology of clinical dosimetry for these situations is still incomplete. This report is intended to reflect the current state of scientific understanding and technical methodology in clinical dosimetry for radiation oncology patients with high-Z hip prostheses.

Adaptive modification of treatment planning to minimize the deleterious effects of treatment setup errors

PURPOSE

Using daily setup variation measured from an electronic portal imaging device (EPID), radiation treatment of the individual patient can be adaptively reoptimized during the course of therapy. In this study, daily portal images were retrospectively examined to: (a) determine the number of initial days of portal imaging required to give adequate prediction of the systematic and random setup errors; and (b) explore the potential of using the prediction as feedback to reoptimize the individual treatment part-way through the treatment course.

METHODS AND MATERIALS

Daily portal images of 64 cancer patients, whose treatment position was not adjusted during the course of treatment, were obtained from two independent clinics with similar setup procedures. Systematic and random setup errors for each patient were predicted using different numbers of initial portal measurements. The statistical confidence of the predictions was tested to determine the number of daily portal measurements needed to give reasonable predictions. Two treatment processes were simulated to examine the potential opportunity for setup margin reduction and dose escalation. The first process mimicked a conventional treatment. A constant margin was assigned to each treatment field to compensate for the average setup error of the patient population. A treatment dose was then prescribed with reference to a fixed normal tissue tolerance, and then fixed in the entire course of treatment. In the second process, the same treatment fields and prescribed dose were used only for the initial plan and treatment. After several initial days of treatments, the treatment field shape and position were assumed to be adaptively modified using a computer-controlled multileaf collimator (MLC) in light of the predicted systematic and random setup errors. The prescribed dose was then escalated until the same normal tissue tolerance, as determined in the first treatment process, was reached.

RESULTS

The systematic setup error and the random setup error were predicted to be within +/-1 mm for the former and +/-0.5 mm for the latter at a > or = 95% confidence level using < or = 9 initial daily portal measurements. In the study, a large number of patients could be treated using a smaller field margin if the adaptive modification process were used. Simulation of the adaptive modification process for prostate treatment demonstrates that additional treatment dose could be safely applied to 64% of patients.

CONCLUSION

The adaptive modification process represents a different approach for use of on-line portal images. The portal imaging information from the initial treatments is used as feedback for reoptimization of the treatment plan, rather than adjustment of the treatment setup. Results from the retrospective study show that the treatment of individual patient can be improved with the adaptive modification process.

Gastrointestinal complications of pelvic radiotherapy: are they of any importance?

Radiation induced bowel damage affects 6000 individuals annually in the UK, with a negative impact on quality of life. Our understanding of how to treat these patients is dismally lacking an evidence base. Fibrosis seems to be the unifying underlying cause for most symptoms. Progress in understanding the development and treatment of fibrosis in these patients might have important consequences for patients with other causes of fibrosis in the gastrointestinal tract.

Stage C adenocarcinoma of the prostate. An analysis of 551 patients treated with external beam radiation

We retrospectively reviewed records of 551 patients with clinical Stage C prostatic adenocarcinoma treated with 60 to 70 Gy external beam radiation. Elective pelvic node irradiation was given to 247 patients (45%). Follow-up for all surviving patients ranged from 16 to 201 months (median, 6.5 years; mean, 7 years). The 5-, 10-, and 15-year uncorrected actuarial survival rates were 72%, 47%, and 27%, respectively. Disease-free survival rates were 59%, 46%, and 40% at the corresponding times. Actuarial local control rates were 88%, 81%, and 75% at 5, 10, and 15 years, respectively. Disease-free survival was adversely affected by high pathologic grade, disease fixed to the pelvic sidewall, invasion of the bladder, prior transurethral resection, hydronephrosis, and elevated serum levels of prostatic acid phosphatase and creatinine. Elective pelvic node irradiation did not improve the outcome. Complications of treatment were acceptable: minor anorectal and/or urinary symptoms, 11%; mild to moderate complications, 19%; serious problems requiring surgery, 3%. It is concluded that localized, high-energy external beam irradiation provides excellent local control of disease, low morbidity, and 5-, 10-, and 15-year survival rates that have not been rivaled by other treatment.

Gut microbial dysbiosis may predict diarrhea and fatigue in patients undergoing pelvic cancer radiotherapy: a pilot study

Fatigue and diarrhea are the most frequent adverse effects of pelvic radiotherapy, while their etiologies are largely unknown. The aim of this study is to investigate the correlations between fatigue, diarrhea, and alterations in gut microbiota induced by pelvic radiotherapy. During the 5-week treatment of pelvic radiotherapy in 11 cancer patients, the general fatigue score significantly increased and was more prominent in the patients with diarrhea. The fatigue score was closely correlated with the decrease of serum citrulline (an indicator of the functional enterocyte mass) and the increases of systemic inflammatory proteins, including haptoglobin, orosomuoid, α1-antitrypsin and TNF-α. Serum level of lipopolysaccharide (LPS) was also elevated, especially in the patients with diarrhea indicating epithelial barrier breach and endotoxemia. Pyrosequencing analysis of 16S rRNA gene revealed that microbial diversity, richness, and the Firmicutes/Bacteroidetes ratio were significantly altered prior to radiotherapy in patients who later developed diarrhea. Pelvic radiotherapy induced further changes in fecal microbial ecology, some of which were specific to the patients with or without diarrhea. Our results indicate that gut microbial dysbiosis prior to radiation therapy may be exploited to predict development of diarrhea and to guide preventive treatment options. Radiation-induced dysbiosis may contribute to pelvic radiation disease, including mucositis, diarrhea, systemic inflammatory response, and pelvic radiotherapy-associated fatigue in cancer patients.

Magnitude and clinical relevance of translational and rotational patient setup errors: A cone-beam CT study

PURPOSE

To establish volume imaging using an on-board cone-beam CT (CB-CT) scanner for evaluation of three-dimensional patient setup errors.

METHODS AND MATERIALS

The data from 24 patients were included in this study, and the setup errors using 209 CB-CT studies and 148 electronic portal images were analyzed and compared. The effect of rotational errors alone, translational errors alone, and combined rotational and translational errors on target coverage and sparing of organs at risk was investigated.

RESULTS

Translational setup errors using the CB-CT scanner and an electronic portal imaging device differed <1 mm in 70.7% and <2 mm in 93.2% of the measurements. Rotational errors >2 degrees were recorded in 3.7% of pelvic tumors, 26.4% of thoracic tumors, and 12.4% of head-and-neck tumors; the corresponding maximal rotational errors were 5 degrees , 8 degrees , and 6 degrees . No correlation between the magnitude of translational and rotational setup errors was observed. For patients with elongated target volumes and sharp dose gradients to adjacent organs at risk, both translational and rotational errors resulted in considerably decreased target coverage and highly increased doses to the organs at risk compared with the initial treatment plan.

CONCLUSIONS

The CB-CT scanner has been successfully established for the evaluation of patient setup errors, and its feasibility in day-to-day clinical practice has been demonstrated. Our results have indicated that rotational errors are of clinical significance for selected patients receiving high-precision radiotherapy.

Alterations of nutritional status: impact of chemotherapy and radiation therapy

The nutritional status of a cancer patient may be affected by the tumor, the chemotherapy and/or radiation therapy directed against the tumor, and by complications associated with that therapy. Chemotherapy-radiotherapy is not confined exclusively to malignant cell populations; thus, normal tissues may also be affected by the therapy and may contribute to specific nutritional problems. Impaired nutrition due to anorexia, mucositis, nausea, vomiting, and diarrhea may be dependent upon the specific chemotherapeutic agent, dose, or schedule utilized. Similar side effects from radiation therapy depend upon the dose, fractionation, and volume irradiated. When combined modality treatment is given the nutritional consequences may be magnified. Prospective, randomized clinical trials are underway to investigate the efficacy of nutritional support during chemotherapy-radiotherapy on tolerance to treatment, complications from treatment, and response rates to treatment. Preliminary results demonstrate that the administration of total parenteral nutrition is successful in maintaining weight during radiation therapy and chemotherapy, but that weight loss occurs after discontinuation of nutritional support. Thus, long-term evaluation is mandatory to learn the impact of nutritional support on survival, disease-free survival, and complication rates, as well as on the possible prevention of morbidity associated with aggressive chemotherapy-radiation therapy.

Comparison of onboard low-field magnetic resonance imaging versus onboard computed tomography for anatomy visualization in radiotherapy

BACKGROUND

Onboard magnetic resonance imaging (OB-MRI) for daily localization and adaptive radiotherapy has been under development by several groups. However, no clinical studies have evaluated whether OB-MRI improves visualization of the target and organs at risk (OARs) compared to standard onboard computed tomography (OB-CT). This study compared visualization of patient anatomy on images acquired on the MRI-(60)Co ViewRay system to those acquired with OB-CT.

MATERIAL AND METHODS

Fourteen patients enrolled on a protocol approved by the Institutional Review Board (IRB) and undergoing image-guided radiotherapy for cancer in the thorax (n = 2), pelvis (n = 6), abdomen (n = 3) or head and neck (n = 3) were imaged with OB-MRI and OB-CT. For each of the 14 patients, the OB-MRI and OB-CT datasets were displayed side-by-side and independently reviewed by three radiation oncologists. Each physician was asked to evaluate which dataset offered better visualization of the target and OARs. A quantitative contouring study was performed on two abdominal patients to assess if OB-MRI could offer improved inter-observer segmentation agreement for adaptive planning.

RESULTS

In total 221 OARs and 10 targets were compared for visualization on OB-MRI and OB-CT by each of the three physicians. The majority of physicians (two or more) evaluated visualization on MRI as better for 71% of structures, worse for 10% of structures, and equivalent for 14% of structures. 5% of structures were not visible on either. Physicians agreed unanimously for 74% and in majority for > 99% of structures. Targets were better visualized on MRI in 4/10 cases, and never on OB-CT.

CONCLUSION

Low-field MR provides better anatomic visualization of many radiotherapy targets and most OARs as compared to OB-CT. Further studies with OB-MRI should be pursued.

How patients manage gastrointestinal symptoms after pelvic radiotherapy

BACKGROUND

Approximately 13,000 patients undergo pelvic radiotherapy annually in the UK. It is not clear how frequently patients develop a permanent change in bowel habit after pelvic radiotherapy that affects their quality of life because the measures of gastrointestinal toxicity used in trials in the past have generally been inadequate. It has been suggested that patients who are symptomatic are only rarely referred to a gastroenterologist and it is not known how patients manage their symptoms.

METHODS

Patients who had completed radiotherapy for pelvic cancer at least 1 year previously were invited to answer 30 structured questions in a face-to-face interview to determine the frequency of gastrointestinal symptoms and what orthodox, dietary and complementary therapies they used to deal with them. They were also asked to score the effectiveness of the measures they had taken.

RESULTS

One hundred and seven patients were recruited [35 males; median age, 65 years (range, 35-80 years); 72 females; median age, 67.5 years (range, 31-87 years)]. Eight had been treated for a gastrointestinal primary tumour, 34 for a urological tumour and 65 for gynaecological tumours. Eighty-seven patients (81%) described new-onset gastrointestinal problems starting after radiotherapy. These symptoms affected the quality of life in 56 patients (52%). Significant effects on the quality of life were caused by diarrhoea or constipation (n = 53), faecal leakage (n = 19), abdominal, rectal or perineal pain (n = 14) and rectal bleeding (n = 6). Fifty-nine patients had seen a doctor for their symptoms (86% found this helpful), 12 had seen a dietician or nurse (50% found this helpful) and 14 had seen alternative practitioners (88% found this helpful). Dietary manipulation generally did not improve symptoms, except in a small group of patients (14/15) who avoided raw vegetables to great benefit.

CONCLUSIONS

At least 1 year after pelvic radiotherapy, gastrointestinal symptoms which have an adverse effect on the quality of life may be more common than generally reported. Patients found that advice from doctors and alternative practitioners was equally valuable. Dietary manipulation was generally unhelpful for gastrointestinal symptoms after pelvic radiotherapy, although the role of eliminating raw vegetables may benefit from further evaluation.

Acute radiation proctitis: a sequential clinicopathologic study during pelvic radiotherapy

PURPOSE

Rectal toxicity is often dose limiting during pelvic radiation therapy. This prospective study examined the sequential development and associations of clinical, endoscopic, and histopathologic rectal toxicity during ongoing radiation therapy.

METHODS AND MATERIALS

Thirty-three patients with nongastrointestinal pelvic carcinomas underwent proctoscopy with biopsy before radiation therapy, after 2 weeks treatment, and toward the end of the treatment course (6 weeks). Symptoms of acute toxicity were recorded, and endoscopic changes were graded. Histologic changes in the surface epithelium, glandular layer, and lamina propria were assessed using an ad hoc scoring system. Macrophage accumulation was evaluated in anti-CD68 stained sections.

RESULTS

Pretreatment endoscopy and biopsies were unremarkable. Clinical symptoms progressed toward the end of the treatment course. In contrast, endoscopic pathology was maximal at 2 weeks. Biopsies obtained during treatment exhibited atrophy of the surface epithelium, acute cryptitis, crypt abscesses, crypt distortion and atrophy, and stromal inflammation. Histologic changes, particularly those in the surface epithelium, were consistently more pronounced at 2 weeks than they were at 6 weeks.

CONCLUSION

In contrast to clinical symptoms, endoscopic changes stabilize and histologic changes regress from the 2nd to the 6th week of treatment. These results may have implications for the design and timing of prophylactic and therapeutic interventions to reduce radiation proctitis.

Systematic review for non-surgical interventions for the management of late radiation proctitis

Chronic radiation proctitis produces a range of clinical symptoms for which there is currently no recommended standard management. The aim of this review was to identify the various non-surgical treatment options for the management of late chronic radiation proctitis and evaluate the evidence for their efficacy. Synonyms for radiation therapy and for the spectrum of lower gastrointestinal radiation toxicity were combined in an extensive search strategy and applied to a range of databases. The included studies were those that involved interventions for the non-surgical management of late radiation proctitis. Sixty-three studies were identified that met the inclusion criteria, including six randomised controlled trials that described the effects of anti-inflammatory agents in combination, rectal steroids alone, rectal sucralfate, short chain fatty acid enemas and different types of thermal therapy. However, these studies could not be compared. If the management of late radiation proctitis is to become evidence based, then, in view of its episodic and variable nature, placebo controlled studies need to be conducted to clarify which therapeutic options should be recommended. From the current data, although certain interventions look promising and may be effective, one small or modest sized study, even if well-conducted, is insufficient to implement changes in practice. In order to increase recruitment to trials, a national register of cases with established late radiation toxicity would facilitate multi-centre trials with specific entry criteria, formal baseline and therapeutic assessments providing standardised outcome data.

Precision of Image-Guided Radiotherapy (IGRT) in Six Degrees of Freedom and Limitations in Clinical Practice

PURPOSE

To evaluate the precision of image-guided radiotherapy (IGRT) using cone-beam computed tomography (CB-CT) for volume imaging and a robotic couch for correcting setup errors in six degrees of freedom.

PATIENTS AND METHODS

47 consecutive patients with 372 fractions were classified according to whether a patient fixation device was used (pat(fix): n = 28) or not (pat(non-fix): n = 19). Prior to treatment a CB-CT was acquired and translational and rotational setup errors were corrected online without an action level using a robotic couch (HexaPOD). A second CB-CT was acquired after the correction process and after treatment in 134 and 238 fractions, respectively.

RESULTS

In 17 fractions (4.6%) rotational errors > 3 degrees exceeded the motion range of the HexaPOD. Errors (3D vector) after the correction process were significantly smaller for pat(fix) compared to pat(non-fix) (p < 0.001): 0.9 mm +/- 0.5 mm and 1.6 mm +/- 0.8 mm, respectively. For pat(non-fix) the correction of rotational errors resulted in displacements of the patients on the angled couch of 0.6 mm/1 degree. Intrafractional motion further decreased precision in pat(non-fix) but not in pat(fix).

CONCLUSION

Very high precision in cranial and extracranial treatment of immobilized patients was demonstrated. Without application of adequate immobilization the correction of rotational errors and intrafractional patient motion significantly decreased the accuracy of the online correction protocol.

Deformable image registration for contour propagation from CT to cone-beam CT scans in radiotherapy of prostate cancer

BACKGROUND AND PURPOSE

Daily organ motion occurring during the course of radiotherapy in the pelvic region leads to uncertainties in the doses delivered to the tumour and the organs at risk. Motion patterns include both volume and shape changes, calling for deformable image registration (DIR), in approaches involving dose accumulation and adaptation. In this study, we tested the performance of a DIR application for contour propagation from the treatment planning computed tomography (pCT) to repeat cone-beam CTs (CBCTs) for a set of prostate cancer patients.

MATERIAL AND METHODS

The prostate, rectum and bladder were delineated in the pCT and in six to eight repeat CBCTs for each of five patients. The pCT contours were propagated onto the corresponding CBCT using the Multi-modality Image Registration and Segmentation application, resulting in 36 registrations. Prior to the DIR, a rigid registration was performed. The algorithm used for the DIR was based on a 'demons' algorithm and the performance of it was examined quantitatively using the Dice similarity coefficient (DSC) and qualitatively as visual slice-by-slice scoring by a radiation oncologist grading the deviations in shape and/or distance relative to the anatomy.

RESULTS

The average DSC (range) for the DIR over all scans and patients was 0.80 (0.65-0.87) for prostate, 0.77 (0.63-0.87) for rectum and 0.73 (0.34-0.91) for bladder, while the corresponding DSCs for the rigid registrations were 0.77 (0.65-0.86), 0.71 (0.55-0.82) and 0.64 (0.33-0.87). The percentage of propagated contours of good/acceptable quality was 45% for prostate; 20% for rectum and 33% for bladder. For the bladder, there was an association between the average DSC and the different scores of the qualitative evaluation.

CONCLUSIONS

DIR improved the performance of pelvic organ contour propagation from the pCT to CBCTs as compared to rigid registration only. Still, a large fraction of the propagated rectum and bladder contours were unacceptable. The image quality of the CBCTs was sub-optimal and the usability of CBCTs for dose accumulation and adaptation purposes is therefore likely to benefit from improved image quality and improvements of the DIR algorithm.

Double-blind, randomized clinical study comparing hyaluronic acid cream to placebo in patients treated with radiotherapy

PURPOSE

The effect of hyaluronic acid (Ialugen cream) on acute skin reactions after radiotherapy, was assessed in a randomized, double-blind, placebo-controlled study.

MATERIAL AND METHODS

Out of the 152 patients presenting with head and neck, breast or pelvic carcinomas and registered in the study, 134 cases-70 in the Ialugen group (IA) and 64 in the placebo group (PBO)-completed their IA or PBO treatment. At the time of randomisation, these two groups were balanced for sex, age, weight and height. The mean total dose of radiation given during the study was 60.6 +/- 10.9 Gy in the IA group and 64.3 +/- 10.8 Gy in the PBO group (P = 0.47).

RESULTS

Acute radio-epithelitis scores were significantly higher in the PBO group than in the IA group, starting from the control at week 3 and throughout the 6 weeks of treatment (P < 0.01 from week 3 to week 7; P < 0.05 at weeks 8 and 10). Likewise, the global efficacy judgement expressed, at the end of treatment, by both the physician and the patient showed a significant difference in favour of Ialugen (P < 0.01 and P < 0.05, respectively). There was no significant difference of tolerance between the IA and PBO treatments (P = 0.18 according to the physician and P = 0.42 from the patient's viewpoint).

CONCLUSION

The prophylactic use of a cream with hyaluronic acid is shown to reduce the incidence of high grade radio-epithelitis, suggesting an interesting role of the hyaluronic acid cream as supportive treatment to improve compliance and quality of life in patients undergoing radiation therapy.

Aspects of MR image distortions in radiotherapy treatment planning

BACKGROUND

Registration of computed tomography (CT) and magnetic resonance (MR) images are commonly performed to define the different target regions used in radiotherapy treatment planning (RTTP). The accuracy of target definition will then depend on the spatial accuracy of the CT and MR data, and on the technique used to register the images. CT images are usually regarded as geometrically correct, while MR images are known to suffer from geometric distortion. The aim of this paper is to discuss the possible impact of MR image distortions in the radiotherapy treatment planning process.

METHODS

The origin, magnitude, and relative impact of the different sources of geometric distortions that affect the MR image data at different magnetic fields and for different acquisition settings are described. Techniques for distortion correction are reviewed, and their limitations are outlined. The sensitivity of image registration techniques to the presence of geometric distortions in the MR data is discussed. Finally, an overview of image registration techniques used and results obtained in clinical radiotherapy treatment planning applications is given.

RESULTS

Spatial distortions in MR images vary with field strength and with the image acquisition protocol. The spatial accuracy generally decreases with distance from the magnet isocenter. Distortion correction techniques based on phantom evaluations cannot adequately model patient-induced distortions.

CONCLUSION

Image protocols with high gradient bandwidths should be used to reduce the spatial distortions in MR images. Correction techniques based only on phantom measurements could be sufficient at low magnetic fields, while at higher fields additional corrections of patient-related distortions might be needed. Registration techniques based on matching of Landmark points located far from the magnet isocenter are especially prone to MR distortions.

Effect of pelvic irradiation on gastrointestinal function: a prospective longitudinal study

PURPOSE

Although radiation enteritis is a well-recognized sequel of therapeutic irradiation, the effects of abdominal and/or pelvic irradiation on gastrointestinal function are poorly defined and treatment is often unsuccessful. To determine both the short- and long-term effects of therapeutic irradiation on gastrointestinal function, we performed a prospective study.

PATIENTS AND METHODS

Various aspects of gastrointestinal function were evaluated in 27 patients with potentially curable malignant disease (23 female, 4 male) before the commencement of, during, and 6 to 8 weeks, 12 to 16 weeks, and 1 to 2 years following completion of radiation therapy. Seventeen patients received pelvic irradiation alone and 10 patients received both abdominal and pelvic irradiation. Gastrointestinal symptoms, absorption of bile acid, vitamin B12, lactose, and fat, gastric emptying, small-intestinal and whole-gut transit, stool weight, and intestinal permeability were measured. Results were compared with those obtained in 18 normal volunteers.

RESULTS

All 27 patients completed at least 2 series of measurements and 18 patients completed all 5 series of experiments. During radiation treatment, increased stool frequency (p < 0.001) was associated with decreased bile acid and vitamin B12 absorption (p < 0.001 for both), increased fecal fat excretion (p < 0.05), an increased prevalence of lactose malabsorption (p < 0.01), and more rapid small-intestinal (p < 0.01) and whole-gut (p < 0.05) transit. Although there was improvement in most of these changes with time, at 1 to 2 years after the completion of irradiation, the frequency of bowel actions was greater (p < 0.001), bile acid absorption was less (p < 0.05), and small-intestinal transit was more rapid (p < 0.01) when compared with that of baseline and the normal subjects. At this time, at least 1 parameter of gastrointestinal function was abnormal in 16 of the 18 patients. Stool weight was greater (p < 0.05) and whole-gut transit faster (p < 0.01) in patients who received both pelvic and abdominal irradiation, when compared with those who received pelvic irradiation alone. Stool frequency (p < 0.001) and fecal fat excretion (p < 0.05) were greater in those patients who had surgery before radiation therapy.

CONCLUSION

Pelvic irradiation is usually associated with widespread, persistent effects on gastrointestinal function.

Algorithm-based management of patients with gastrointestinal symptoms in patients after pelvic radiation treatment (ORBIT): a randomised controlled trial

BACKGROUND

Chronic gastrointestinal symptoms after pelvic radiotherapy are common, multifactorial in cause, and affect patients' quality of life. We assessed whether such patients could be helped if a practitioner followed an investigative and management algorithm, and whether outcomes differed by whether a nurse or a gastroenterologist led this algorithm-based care.

METHODS

For this three-arm randomised controlled trial we recruited patients (aged ≥18 years) from clinics in London, UK, with new-onset gastrointestinal symptoms persisting 6 months after pelvic radiotherapy. Using a computer-generated randomisation sequence, we randomly allocated patients to one of three groups (1:1:1; stratified by tumour site [urological, gynaecological, or gastrointestinal], and degree of bowel dysfunction [IBDQ-B score <60 vs 60-70]): usual care (a detailed self-help booklet), gastroenterologist-led algorithm-based treatment, or nurse-led algorithm-based treatment. The primary endpoint was change in Inflammatory Bowel Disease Questionnaire-Bowel subset score (IBDQ-B) at 6 months, analysed by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00737230.

FINDINGS

Between Nov 26, 2007, and Dec 12, 2011, we enrolled and randomly allocated 218 patients to treatment: 80 to the nurse group, 70 to the gastroenterologist group, and 68 to the booklet group (figure). Most had a baseline IBDQ-B score indicating moderate-to-severe symptoms. We recorded the following pair-wise mean difference in change in IBDQ-B score between groups: nurse versus booklet 4·12 (95% CI 0·04-8·19; p=0·04), gastroenterologist versus booklet 5·47 (1·14-9·81; p=0·01). Outcomes in the nurse group were not inferior to outcomes in the gastroenterologist group (mean difference 1·36, one sided 95% CI -1·48).

INTERPRETATION

Patients given targeted intervention following a detailed clinical algorithm had better improvements in radiotherapy-induced gastrointestinal symptoms than did patients given usual care. Our findings suggest that, for most patients, this algorithm-based care can be given by a trained nurse.

FUNDING

The National Institute for Health Research.

Peripheral nerve and ureteral tolerance to intraoperative radiation therapy: clinical and dose-response analysis

Between April 1981 and July 1984, 51 patients received intraoperative radiation therapy (IORT) as a component of therapy for the management of primary or recurrent pelvic malignancies which were initially unresectable for cure. For these patients, curative surgical alternatives did not exist, or would have involved extensive procedures such as pelvic exenteration, distal sacrectomy, hemipelvectomy, or hemicorporectomy. The primary disease was colorectal in 38 patients. Treatment consisted of external beam radiation (range 3000 to 6890 cGy, median 5040 cGy), surgical debulking when feasible, and an intraoperative electron beam boost to the gross or microscopic residual disease (dose range 1000 to 2500 cGy, median 1750 cGy) utilizing 9-18 MeV electrons. The most common IORT associated toxicities were peripheral neuropathy and ureteral obstruction. None were life-threatening or fatal in severity. Of the 50 patients evaluable for neurotoxicity analysis, 16 (32%) developed peripheral neuropathy consisting of pain in 16 patients, numbness and tingling in 11, and weakness in 8. The pain, numbness and tingling resolved in about 40% of patients, while weakness resolved in only 1 of 8. Sixteen ureters were initially unobstructed by tumor at the time of IORT. Of these, 10 (63%) subsequently showed evidence of obstruction and hydronephrosis. The development of neurotoxicity was more common at IORT doses of 1500 cGy or more versus 1000 cGy. Ureteral obstruction with hydronephrosis occurred more frequently at IORT doses of 1250 cGy or more compared to 1000 cGy. There was no relationship between the likelihood of developing complications and the total external beam dose. The observed dependence of human nerve toxicity primarily on the IORT dose is consistent with data generated from animal experiments.

Gastrointestinal symptoms after pelvic radiotherapy: role for the gastroenterologist?

PURPOSE

To analyze the cause of GI symptoms after pelvic radiotherapy (RT) in a consecutive series of patients with symptoms beginning after RT. A striking lack of evidence is available concerning the optimal treatment for the 50% of patients who develop permanent changes in bowel habits affecting their quality of life after pelvic RT. As a result, in the UK, most such patients are never referred to a gastroenterologist.

METHODS AND MATERIALS

All diagnoses were prospectively recorded from a consecutive series of patients with symptoms that started after RT and who were referred during a 32-month period to a gastroenterology clinic. Patients either underwent direct access flexible sigmoidoscopy or were investigated in a standard manner by one gastroenterologist after first being seen in the clinic.

RESULTS

A total of 265 patients referred from 15 institutions were investigated. They included 90 women (median age, 61.5 years; range, 22-84 years) and 175 men (median age, 70 years; range, 31-85 years). RT had been completed a median of 3 years (range, 0.1-34 years) before the study in the women and 2 years (range, 0-21 years) before in the men. Of the 265 patients, 171 had primary urologic, 78 gynecologic, and 16 GI tumors. The GI symptoms included rectal bleeding in 171, urgency in 82, frequency in 80, tenesmus, discomfort, or pain in 79, fecal incontinence in 79, change in bowel habit in 42, weight loss in 19, vomiting without other obstructive symptoms in 18, steatorrhea in 7, nocturnal defecation in 8, obstructive symptoms in 4, and other in 24. After investigation, significant neoplasia was found in 12%. One-third of all diagnoses were unrelated to the previous RT. More than one-half of the patients had at least two diagnoses. Many of the abnormalities diagnosed were readily treatable. The symptoms were generally unhelpful in predicting the diagnosis, with the exception of pain, which was associated with neoplasia (p < 0.001).

CONCLUSION

The results of our study have shown that radiation enteritis is not a single disease entity. More than one-half of the patients had more than one GI diagnosis contributing to their symptoms. After pelvic RT, specific GI symptoms were not a reliable measure of the underlying diagnoses, and the evaluation of new GI symptoms is worthwhile. An algorithm for this purpose is proposed.

Age is not a limiting factor for radical radiotherapy in pelvic malignancies

BACKGROUND AND PURPOSE

Pelvic radiotherapy (RT) toxicity in the elderly is poorly documented. We developed a study aiming to evaluate whether or not a limit of age could be identified beyond which toxicities in patients receiving pelvic RT were more frequent or more severe.

MATERIAL AND METHODS

1619 patients with pelvic cancers enrolled in nine EORTC trials, RT arms, were retrospectively studied. Patients were split into six age ranges from 50 years to 70 years and over. Survivals and late toxicity occurrence were calculated with the Kaplan-Meier method and comparison between age groups with the logrank test. A trend test was done to examine if chronological age had an impact on acute toxicity occurrence.

RESULTS

Survival was comparable in each age group for prostate (P = 0.18), uterus (0.41), anal canal cancer (P = 0.6) and slightly better for the younger group of rectum cancer (P = 0.04). A total of 1722 acute and 514 late grade > or = 1 were recorded. Acute nausea/ vomiting, skin complications and performance status deterioration were significantly more frequent in younger patients. There was no trend toward more aged patients to experience diarrhea (P = 0.149) and after adjustment on RT dose, acute urinary complications were observed equally in each age range (P = 0.32). Eighty percent of patients were free of late complication at 5 years in each age range (P = 0.79). For the grade > 2 late side-effects, a plateau was observed after 1 year at near 9% without any difference (P = 0.06) nor trend (P = 0.13) between age-groups.

CONCLUSION

Age per se is not a limiting factor for radical radiotherapy in pelvic malignancies.