Search

AIMS: Image-guided radiotherapy (IGRT) and intensity-modulated radiotherapy (IMRT) represent two important technical developments that will probably improve patient outcome. Helical tomotherapy, provided by the TomoTherapy HiArt system, provides an elegant integrated solution providing both technologies, although others are available. Here we report our experience of clinical implementation of daily online IGRT and IMRT using helical tomotherapy. MATERIALS AND METHODS: Methods were needed to select patients who would probably benefit. Machine-specific commissioning, a quality assurance programme and patient-specific delivery quality assurance were also needed. The planning target volume dose was prescribed as the median dose, with the added criterion that the 95% isodose should cover 99% of the target volume. Although back-up plans, for delivery on conventional linear accelerators, were initially prepared, this practice was abandoned because they were used very rarely. RESULTS: In the first 12 months, 114 patients were accepted for treatment, and 3343 fractions delivered. New starts averaged 2.6 per week, with an average of 17.5 fractions treated per day, and the total number capped at 22. This has subsequently been raised to 24. Of the first 100 patients, 96 were treated with radical intent. Five were considered to have been untreatable on our standard equipment. IGRT is radiographer led and all patients were imaged daily, with positional correction made before treatment, using an action level of 1mm. A formal training programme was developed and implemented before installation. The in-room time fell significantly during the year, reflecting increasing experience and a software upgrade. More recently, after a couch upgrade in April 2009, the mean in-room time fell to 18.6 min. CONCLUSIONS: Successful implementation of tomotherapy was the result of careful planning and effective teamwork. Treatment, including daily image guidance, positional correction and intensity-modulated delivery, is fast and efficient, and can be integrated into routine service. This should encourage the adoption of these technologies. [ABSTRACT FROM AUTHOR]

Background: Brain metastases from prostate cancer are rare and usually only occur in the context of widespread systemic disease. This is the first case report of a solitary brain oligometastasis, in a neurologically intact prostate cancer patient with no other systemic disease, detected using [ 68 Ga]Ga-THP-PSMA PET/CT and only the second one using a PSMA-based radiopharmaceutical., Case Presentation: We report the case of a prostate cancer patient presenting 5 years after robot-assisted laparoscopic prostatectomy with biochemical recurrence, no neurological symptoms, and in the absence of metastatic lesions in the body on conventional imaging. A solitary cerebral metastasis was detected using [ 68 Ga]Ga-THP-PSMA PET/CT, surgically resected, leading to a drop in serum PSA and a good recovery., Conclusion: In this case, [ 68 Ga]Ga-THP-PSMA PET/CT resulted in a major change in clinical management and avoided additional morbidity associated with delayed diagnosis and treatment. This report demonstrates the importance of considering the presence of metastatic disease outside the conventional locations of prostate cancer spread, as well as the importance of ensuring comprehensive [ 68 Ga]Ga-PSMA PET/CT coverage from vertex to upper thighs.

Purpose: To establish the toxicity profile of high-dose pelvic lymph node intensity-modulated radiation therapy (IMRT) and to assess whether it is safely deliverable at multiple centers., Methods and Materials: In this phase 2 noncomparative multicenter trial, 124 patients with locally advanced, high-risk prostate cancer were randomized between prostate-only IMRT (PO) (74 Gy/37 fractions) and prostate and pelvic lymph node IMRT (P&P; 74 Gy/37 fractions to prostate, 60 Gy/37 fractions to pelvis). The primary endpoint was acute lower gastrointestinal (GI) Radiation Therapy Oncology Group (RTOG) toxicity at week 18, aiming to exclude a grade 2 or greater (G2+) toxicity-free rate of 80% in the P&P group. Key secondary endpoints included patient-reported outcomes and late toxicity., Results: One hundred twenty-four participants were randomized (62 PO, 62 P&P) from May 2011 to March 2013. Median follow-up was 37.6 months (interquartile range [IQR], 35.4-38.9 months). Participants had a median age of 69 years (IQR, 64-74 years) and median diagnostic prostate-specific androgen level of 21.6 ng/mL (IQR, 11.8-35.1 ng/mL). At week 18, G2+ lower GI toxicity-free rates were 59 of 61 (96.7%; 90% confidence interval [CI], 90.0-99.4) for the PO group and 59 of 62 (95.2%; 90% CI, 88.0-98.7) for the P&P group. Patients in both groups reported similarly low Inflammatory Bowel Disease Questionnaire symptoms and Vaizey incontinence scores. The largest difference occurred at week 6 with 4 of 61 (7%) and 16 of 61 (26%) PO and P&P patients, respectively, experiencing G2+ toxicity. At 2 years, the cumulative proportion of RTOG G2+ GI toxicity was 16.9% (95% CI, 8.9%-30.9%) for the PO group and 24.0% (95% CI, 8.4%-57.9%) for the P&P group; in addition, RTOG G2+ bladder toxicity was 5.1% (95% CI, 1.7%-14.9%) for the PO group and 5.6% (95% CI, 1.8%-16.7%) for the P&P group., Conclusions: PIVOTAL demonstrated that high-dose pelvic lymph node IMRT can be delivered at multiple centers with a modest side effect profile. Although safety data from the present study are encouraging, the impact of P&P IMRT on disease control remains to be established., (Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.)

The VoxTox research programme has applied expertise from the physical sciences to the problem of radiotherapy toxicity, bringing together expertise from engineering, mathematics, high energy physics (including the Large Hadron Collider), medical physics and radiation oncology. In our initial cohort of 109 men treated with curative radiotherapy for prostate cancer, daily image guidance computed tomography (CT) scans have been used to calculate delivered dose to the rectum, as distinct from planned dose, using an automated approach. Clinical toxicity data have been collected, allowing us to address the hypothesis that delivered dose provides a better predictor of toxicity than planned dose.

Background and Purpose: To measure the geometric uncertainty resulting from intra-fraction motion and intra-observer image matching, for patients having image-guided prostate radiotherapy on TomoTherapy., Material and Methods: All patients had already been selected for prostate radiotherapy on TomoTherapy, with daily MV-CT imaging. The study involved performing an additional MV-CT image at the end of treatment, on 5 occasions during the course of 37 treatments. 54 patients were recruited to the study. A new formula was derived to calculate the PTV margin for intra-fraction motion., Results: The mean values of the intra-fraction differences were 0.0mm, 0.5mm, 0.5mm and 0.0° for LR, SI, AP and roll, respectively. The corresponding standard deviations were 1.1mm, 0.8mm, 0.8mm and 0.6° for systematic uncertainties (Σ), 1.3mm, 2.0mm, 2.2mm and 0.3° for random uncertainties (σ). This intra-fraction motion requires margins of 2.2mm in LR, 2.1mm in SI and 2.1mm in AP directions. Inclusion of estimates of the effect of rotations and matching errors increases these margins to approximately 4mm in LR and 5mm in SI and AP directions., Conclusions: A new margin recipe has been developed to calculate margins for intra-fraction motion. This recipe is applicable to any measurement technique that is based on the difference between images taken before and after treatment., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Objective: To illustrate the wider potential scope of image-guided intensity-modulated radiotherapy (IG-IMRT), outside of the "standard" indications for IMRT., Methods: Nine challenging clinical cases were selected. All were treated with radical intent, although it was accepted that in several of the cases the probability of cure was low. IMRT alone was not adequate owing to the close proximity of the target to organs at risk, the risk of geographical miss, or the need to tighten planning margins, making image-guided radiotherapy an essential integral part of the treatment. Discrepancies between the initial planning scan and the daily on-treatment megavoltage CT were recorded for each case. The three-dimensional displacement was compared with the margin used to create the planning target volume (PTV)., Results: All but one patient achieved local control. Three patients developed metastatic disease but benefited from good local palliation; two have since died. A further patient died of an unrelated condition. Four patients are alive and well. Toxicity was low in all cases. Without daily image guidance, the PTV margin would have been insufficient to ensure complete coverage in 49% of fractions. It was inadequate by >3 mm in 19% of fractions, and by >5 mm in 9%., Conclusion: IG-IMRT ensures accurate dose delivery to treat the target and avoid critical structures, acting as daily quality assurance for the delivery of complex IMRT plans. These patients could not have been adequately treated without image guidance., Advances in Knowledge: IG-IMRT can offer improved outcomes in less common clinical situations, where conventional techniques would provide suboptimal treatment.

Objective: To estimate the benefit of introduction of image-guided radiotherapy (IGRT) to prostate radiotherapy practice with current clinical target volume-planning target volume (PTV) margins of 5-10 mm., Methods: Systematic error data collected from 50 patients were used together with a random error of σ=3.0 mm to model non-IGRT treatment. IGRT was modelled with residual errors of Σ=σ=1.5 mm. Population tumour control probability (TCP(pop)) was calculated for two three-dimensional conformal radiotherapy techniques: two-phase and concomitant boost. Treatment volumes and dose prescriptions were ostensibly the same. The relative field sizes of the treatment techniques, distribution of systematic errors and correlations between movement axes were examined., Results: The differences in TCP(pop) between the IGRT and non-IGRT regimes were 0.3% for the two-phase and 1.5% for the concomitant boost techniques. A 2-phase plan, in each phase of which the 95% isodose conformed to its respective PTV, required fields that were 3.5 mm larger than those required for the concomitant boost plan. Despite the larger field sizes, the TCP (without IGRT) in the two-phase plan was only 1.7% higher than the TCP in the concomitant boost plan. The deviation of craniocaudal systematic errors (p=0.02) from a normal distribution, and the correlation of translations in the craniocaudal and anteroposterior directions (p<0.0001) were statistically significant., Conclusions: The expected population benefit of IGRT for the modelled situation was too small to be detected by a clinical trial of reasonable size, although there was a significant benefit to individual patients. For IGRT to have an observable population benefit, the trial would need to use smaller margins than those used in this study. Concomitant treatment techniques permit smaller fields and tighter conformality than two phases planned separately.

Aims: To study the feasibility of using implanted gold seeds in combination with a commercial software system for daily localisation of the prostate gland during conformal radiotherapy, and to assess the effect this may have on departmental workload., Materials and Methods: Six patients had three gold radio-opaque seeds implanted into the prostate gland before starting a course of radiotherapy. The seeds were identified on daily portal images and an automated online system provided immediate vector analysis of discrepancies between the planned and actual daily position of the intraprostatic seeds. In total, 138 interfractional displacements were analysed. The workload impact for the department was assessed using the basic treatment equivalence model, by comparing measurements of daily treatment session durations with a control group of patients receiving standard conformal radiotherapy, matched for treatment complexity., Results: No acute complications of seed insertion were observed. A number of developmental issues required solutions to be identified before clinical implementation was possible. The standard deviations of the set-up and organ motion systematic errors in the left-right, superior-inferior and anterior-posterior directions were 2.4, 3.0 and 2.5 mm, respectively. The standard deviations of the set-up and organ motion random errors calculated were 2.5, 2.9 and 3.7 mm. The mean treatment session duration with this daily prostate localisation system was increased by 3 min compared with matched controls using standard imaging practice. If all radical prostate patients in our department were to receive image-guided radiotherapy in this way, this would increase machine workload time by 2.2 h/day., Conclusions: The implementation of this image-guided system is feasible. No additional linear accelerator modification is required and standard imaging devices can be used. It would be a useful addition to any department's image-guided radiotherapy developmental strategy.

The general characteristics of the reaction between sorbic acid and thiols are reviewed. Cysteine adds to the conjugated diene in position 5 to form the substituted 3-hexenoic acid. This is labile in acid solution, yielding a quantitative amount of sorbic acid. When wheat flour doughs are treated with sorbic acid and heated, a significant amount of the sorbic acid is not recovered on extraction with methanol. The use of acidified methanol leads to a quantitative recovery of the preservation and evidence is presented to suggest that sorbic acid-thiol adducts are formed. This is the first report of 'reversibly bound' sorbic acid in a food.