Proton versus photon therapy for high-risk prostate cancer with dose escalation of dominant intraprostatic lesions: a preliminary planning study.

Background and purpose: This study aimed to investigate the feasibility of safe-dose escalation to dominant intraprostatic lesions (DILs) and assess the clinical impact using dose-volume (DV) and biological metrics in photon and proton therapy. Biological parameters defined as late grade ≥ 2 gastrointestinal (GI) and genitourinary (GU) derived from planned (D P) and accumulated dose (D A) were utilized. Materials and methods: In total, 10 patients with high-risk prostate cancer with multiparametric MRI-defined DILs were investigated. Each patient had two plans with a focal boost to the DILs using intensity-modulated proton therapy (IMPT) and volumetric-modulated arc therapy (VMAT). Plans were optimized to obtain DIL coverage while respecting the mandatory organ-at-risk constraints. For the planning evaluation, DV metrics, tumor control probability (TCP) for the DILs and whole prostate excluding the DILs (prostate-DILs), and normal tissue complication probability (NTCP) for the rectum and bladder were calculated. Wilcoxon signed-rank test was used for analyzing TCP and NTCP data. Results: IMPT achieved a higher Dmean for the DILs compared to VMAT (IMPT: 68.1 GyRBE vs. VMAT: 66.6 Gy, p < 0.05). Intermediate-high rectal and bladder doses were lower for IMPT (p < 0.05), while the high-dose region (V60 Gy) remained comparable. IMPT-TCP for prostate-DIL were higher compared to VMAT (IMPT: 86%; α/ß = 3, 94.3%; α/ß = 1.5 vs. VMAT: 84.7%; α/ß = 3, 93.9%; α/ß = 1.5, p < 0.05). Likewise, IMPT obtained a moderately higher DIL TCP (IMPT: 97%; α/ß = 3, 99.3%; α/ß = 1.5 vs. VMAT: 95.9%; α/ß = 3, 98.9%; α/ß = 1.5, p < 0.05). Rectal D A-NTCP displayed the highest GI toxicity risk at 5.6%, and IMPT has a lower GI toxicity risk compared to VMAT-predicted Quantec-NTCP (p < 0.05). Bladder D P-NTCP projected a higher GU toxicity than D A-NTCP, with VMAT having the highest risk (p < 0.05). Conclusion: Dose escalation using IMPT is able to achieve a high TCP for the DILs, with the lowest rectal and bladder DV doses at the intermediate-high-dose range. The reduction in physical dose was translated into a lower NTCP (p < 0.05) for the bladder, although rectal toxicity remained equivalent.

A planning-based feasibility study of MR-Linac treatment for anal cancer radiation therapy.

The hybrid magnetic resonance image (MRI) scanner and radiation therapy linear accelerator (MR-Linac) has the potential to enhance clinical outcomes for anal cancer (AC) patients with improved soft tissue visualization and daily plan adaption but has planning and delivery limitations due to the incorporation of MRI. We aimed to identify if Elekta Unity MR-Linac-based radiation therapy is feasible for anal cancer. Ten prospectively enrolled AC patients treated with radical chemoradiotherapy were replanned for MR-Linac treatment using departmental planning criteria. For comparison, and to reduce interobserver variability, volumetric modulated arc radiation therapy (VMAT) plans were also created for each patient by the same single senior radiation therapist. Plans were compared using departmental dosimetric plan criteria, as well as conformity and homogeneity indices, monitor units (MUs) and measured plan delivery (beam-on) time. Results were deemed clinically acceptable. Target and organ at risk (OAR) doses were comparable between MR-Linac plans and VMAT plans, although PTV45Gy D98% coverage was compromised in 3 of 10 MR-Linac plans due to caudocranial length exceeding the limits of the MR-Linac. MR-Linac plans had lower MUs, median of 689.1 vs 849.65 (p = 0.002), but took over twice as long to deliver, 529.5s vs 224s (p = <0.0001) as VMAT plans. MR-Linac planning and treatment of AC is feasible for a subset of patients. The current physical limitations of the Elekta Unity system mean patients with large caudocranial elective PTV45Gy target volumes may not be covered dosimetrically to the required clinical standard. Longer image verification and treatment delivery times of the MR-Linac also mean patient selection and intrafractional IGRT are likely to be integral to ensuring high quality clinical outcomes in this rare cancer.

Predictors for late genitourinary toxicity in men receiving radiotherapy for high-risk prostate cancer using planned and accumulated dose.

Background and purpose: Significant deviations between bladder dose planned (DP) and dose accumulated (DA) have been reported in patients receiving radiotherapy for prostate cancer. This study aimed to construct multivariate analysis (MVA) models to predict the risk of late genitourinary (GU) toxicity with clinical and DP or DA as dose-volume (DV) variables. Materials and methods: Bladder DA obtained from 150 patients were compared with DP. MVA models were built from significant clinical and DV variables (p < 0.05) at univariate analysis. Previously developed dose-based-region-of-interest (DB-ROI) metrics using expanded ring structures from the prostate were included. Goodness-of-fit test and calibration plots were generated to determine model performance. Internal validation was accomplished using Bootstrapping. Results: Intermediate-high DA (V30-65 Gy and DB-ROI-20-50 mm) for bladder increased compared to DP. However, at the very high dose region, DA (D0.003 cc, V75 Gy, and DB-ROI-5-10 mm) were significantly lower. In MVA, single variable models were generated with odds ratio (OR) < 1. DB-ROI-50 mm was predictive of Grade ≥ 1 GU toxicity for DA and DP (DA and DP; OR: 0.96, p: 0.04) and achieved an area under the receiver operating curve (AUC) of > 0.6. Prostate volume (OR: 0.87, p: 0.01) was significant in predicting Grade 2 GU toxicity with a high AUC of 0.81. Conclusions: Higher DA (V30-65 Gy) received by the bladder were not translated to higher late GU toxicity. DB-ROIs demonstrated higher predictive power than standard DV metrics in associating Grade ≥ 1 toxicity. Smaller prostate volumes have a minor protective effect on late Grade 2 GU toxicity.

A phenomenological study investigating experiences of student learning using an online radiation therapy planning curriculum.

Introduction: Traditionally radiation therapy planning was taught on campus in planning labs, or in the case of fully online programs, during clinical placements. In 2017, an innovative online planning curriculum was developed using a structured, self-directed approach of online learning and assessment, supported by a cloud-based planning system. This study aimed to explore student experiences of learning and practising planning online, and the application of acquired knowledge and skills to clinical practice. Methods: Student experiences were investigated using an interpretive phenomenological method. A purposive sample of under-graduate and graduate entry students was recruited through email and snowballing. A combination of online individual and group interviews were conducted. Two researchers analysed the data, and used reflection, discussion and note taking processes to immerse themselves in the data. Following data collection, the process of organising data for analysis, applying a coding and condensing process to reduce the data into themes and sub-themes was conducted. Results: Seventeen students from three cohorts participated in the interviews. Five key themes were identified: Flexibility, Connectedness, Personal relevance, Professional Experts and Safe environment. Sub-component themes were also identified. Discussion: Student engagement was based on a range of factors that influence the student experience. The planning curriculum allowed students to develop confidence and competence in pre-clinical planning skills prior to placement. Conclusion: Although initial experiences were overwhelming, over time students experienced a sense of engagement with their learning when supported by clinical and academic experts. Students felt more prepared for clinical placement as a result of their experiences.

Dose-volume analysis of planned versus accumulated dose as a predictor for late gastrointestinal toxicity in men receiving radiotherapy for high-risk prostate cancer.

Background and purpose: Significant dose deviations have been reported between planned (DP) and accumulated (DA) dose in prostate radiotherapy. This study aimed to develop multivariate analysis (MVA) models associating Grade 1 and 2 gastrointestinal (GI) toxicity with clinical and DP or DA dosimetric variables separately. Materials and methods: Dose volume (DV) metrics were compared between DA and DP for 150 high-risk prostate cancer patients. MV models were generated from significant clinical and dosimetric variables (p < 0.05) at univariate level. Dose-based-region of interest (DB-ROI) metrics were included. Model performance was measured, and additional subgroup analysis were performed. Results: Rectal DA demonstrated a higher intermediate-high dose (V30-65 Gy and DB-ROI at 15-50 mm) compared to DP. Conversely, at the very high dose region, rectal DA (V75 Gy and DB-ROI at 5-10 mm) were significantly lower. In MVA, rectal DB-ROI at 10 mm was predictive for Grade ≥ 1 GI toxicity for DA and DP. Age, rectal DA for D0.03 cc, and rectal DP for DB-ROI 10 mm were predictors for Grade 2 GI toxicity. Subgroup analysis revealed that patients ≥ 72 years old and a rectal DA of ≥ 78.2 Gy were highly predictive of Grade 2 GI toxicity. Conclusions: The dosimetric impact of a higher dose rectal dose in DA due to volumetric changes was minimal and was not predictive of detrimental clinical toxicity apart from rectal D0.03 cc ≥ 78.2 Gy for Grade 2 GI toxicity. The use of the DB-ROI method can provide equivalent predictive power as the DV method in toxicity prediction.

A pilot study investigating the role of 18 F-FDG-PET in the early identification of chemoradiotherapy response in anal cancer.

INTRODUCTION: Anal cancer (AC) is 18 F-FDG-PET avid and has been used to evaluate treatment response several months after chemoradiotherapy. This pilot study aimed to assess the utility of semi-automated contouring methods and quantitative measures of treatment response using 18 F-FDG-PET imaging at the early time point of 1-month post-chemoradiotherapy. METHODS: Eleven patients with AC referred for chemoradiotherapy were prospectively enrolled into this study, with 10 meeting eligibility requirements. 18 F-FDG-PET imaging was obtained pre-chemoradiotherapy (TP1), and then 1-month (TP2), 3-6 months (TP3) and 9-12 months (TP4) post-chemoradiotherapy. Manual and semi-automated (Threshold) contouring methods were used to define the primary tumour on all 18 F-FDG-PET images. Resultant contours from each method were interrogated using quantitative measures, including volume, response index (RI), total lesion glycolysis (TLG), SUVmax , SUVmedian and SUVmean . Response was assessed quantitatively as reductions in these measures and also qualitatively against established criteria. RESULTS: Nine patients were qualitatively classified as complete metabolic responders at TP2 and all 10 at TP3. All quantitative measures demonstrated significant (P < 0.05) reductions at TP2 for both Manual and Threshold methods. All reduced further at TP3 and again at TP4 for Threshold methods. TLG showed the highest reduction at all post-chemoradiotherapy time points and classified the most responders for each method at each time point. All patients are recurrence-free at minimum 4-year follow-up. CONCLUSION: Based on our small sample size, semi-automated methods of disease definition using 18 F-FDG-PET imaging are feasible and appear to facilitate quantitative response classification of AC as early as 1-month post-chemoradiotherapy. Early identification of treatment response may potentially improve disease management.

Application of an automated dose accumulation workflow in high-risk prostate cancer - validation and dose-volume analysis between planned and delivered dose.

Inter-fraction organ variations cause deviations between planned and delivered doses in patients receiving radiotherapy for prostate cancer. This study compared planned (DP) vs accumulated doses (DA) obtained from daily cone-beam computed tomography (CBCT) scans in high-risk- prostate cancer with pelvic lymph nodes irradiation. An intensity-based deformable image registration algorithm used to estimate contours for DA was validated using geometrical agreement between radiation oncologist's and deformable image registration algorithm propagated contours. Spearman rank correlations (rs) between geometric measures and changes in organ volumes were evaluated for 20 cases. Dose-volume (DV) differences between DA and DP were compared (Wilcoxon rank test, p < 0.05). A novel region-of-interest (ROI) method was developed and mean doses were analyzed. Geometrical measures for the prostate and organ-at-risk contours were within clinically acceptable criteria. Inter-group mean (± SD) CBCT volumes for the rectum were larger compared to planning CT (pCT) (51.1 ± 11.3 cm3vs 46.6 ± 16.1 cm3), and were moderately correlated with variations in pCT volumes, rs = 0.663, p < 0.01. Mean rectum DV for DA was higher at V30-40 Gy and lower at V70-75 Gy, p < 0.05. Mean bladder CBCT volumes were smaller compared to pCT (198.8 ± 55 cm3vs 211.5 ± 89.1 cm3), and was moderately correlated with pCT volumes, rs = 0.789, p < 0.01. Bladder DA was higher at V30-65 Gy and lower at V70-75 Gy (p < 0.05). For the ROI method, rectum and bladder DA were lower at 5 to 10 mm (p < 0.01) as compared to DP, whilst bladder DA was higher than DP at 20 to 50 mm (p < 0.01). Generated DA demonstrated significant differences in organ-at-risk doses as compared to DP. A well-constructed workflow incorporating a ROI DV-extraction method has been validated in terms of efficiency and accuracy designed for seamless integration in the clinic to guide future plan adaptation.

Predictive modelling for late rectal and urinary toxicities after prostate radiotherapy using planned and delivered dose.

Background and purpose: Normal tissue complication probability (NTCP) parameters derived from traditional 3D plans may not be ideal in defining toxicity outcomes for modern radiotherapy techniques. This study aimed to derive parameters of the Lyman-Kutcher-Burman (LKB) NTCP model using prospectively scored clinical data for late gastrointestinal (GI) and genitourinary (GU) toxicities for high-risk prostate cancer patients treated using volumetric-modulated-arc-therapy (VMAT). Dose-volume-histograms (DVH) extracted from planned (DP) and accumulated dose (DA) were used. Material and methods: DP and DA obtained from the DVH of 150 prostate cancer patients with pelvic-lymph-nodes irradiation treated using VMAT were used to generate LKB-NTCP parameters using maximum likelihood estimations. Defined GI and GU toxicities were recorded up to 3-years post RT follow-up. Model performance was measured using Hosmer-Lemeshow goodness of fit test and the mean area under the receiver operating characteristics curve (AUC). Bootstrapping method was used for internal validation. Results: For mild-severe (Grade ≥1) GI toxicity, the model generated similar parameters based on DA and DP DVH data (DA-D50:71.6 Gy vs DP-D50:73.4; DA-m:0.17 vs DP-m:0.19 and DA/P-n 0.04). The 95% CI for DA-D50 was narrower and achieved an AUC of >0.6. For moderate-severe (Grade ≥2) GI toxicity, DA-D50 parameter was higher and had a narrower 95% CI (DA-D50:77.9 Gy, 95% CI:76.4-79.6 Gy vs DP-D50:74.6, 95% CI:69.1-85.4 Gy) with good model performance (AUC>0.7). For Grade ≥1 late GU toxicity, D50 and n parameters for DA and DP were similar (DA-D50: 58.8 Gy vs DP-D50: 59.5 Gy; DA-n: 0.21 vs DP-n: 0.19) with a low AUC of<0.6. For Grade ≥2 late GU toxicity, similar NTCP parameters were attained from DA and DP DVH data (DA-D50:81.7 Gy vs DP-D50:81.9 Gy; DA-n:0.12 vs DP-n:0.14) with an acceptable AUCs of >0.6. Conclusions: The achieved NTCP parameters using modern RT techniques and accounting for organ motion differs from QUANTEC reported parameters. DA-D50 of 77.9 Gy for GI and DA/DP-D50 of 81.7-81.9 Gy for GU demonstrated good predictability in determining the risk of Grade ≥2 toxicities especially for GI derived D50 and are recommended to incorporate as part of the DV planning constraints to guide dose escalation strategies while minimising the risk of toxicity.

A Prospective Trial Demonstrating the Benefit of Personalized Selection Of Breath-Hold Technique for Upper-Abdominal Radiation Therapy Using the Active Breathing Coordinator.

PURPOSE: For upper abdominal tumors, our institutional-standard motion reduction method is the expiration breath-hold (EBH) technique, using Active Breathing Coordinator (ABC). However, an individual patient's breath-hold (BH) reproducibility (RBH) may be improved in deep inspiration or inspiration breath-hold (DIBH or IBH). This trial compared the tumor position RBH, stability (SBH), and breath-hold time (TBH) of 3 BH methods, using ABC, to personalize the selection of technique, by using a preplanning screening assessment. METHODS AND MATERIALS: We invited patients planned for upper abdominal radiation therapy (kidney, pancreas, liver, or adrenal gland) to participate in this prospective trial. We conducted ABC education with the study participants, who then attempted EBH, DIBH, and IBH in randomized order. During 5 consecutive BH's for each method, we acquire kV fluoroscopy images of the diaphragm. We personalized the BH technique selection according to a decision matrix. We analyzed the EBH and the personalized technique cohort mean RBH and SBH. RESULTS: Between May 2019 and March 2020, we recruited 19 participants. Median age of participants was 68 years (range 32-81). Tumor sites included kidney (n = 1), adrenal gland (n = 5) and liver (n = 14). We excluded 1 participant due to poor BH compliance, leaving 270 images from 18 participants for analysis. Mean TBH was 22.1, 23.9, and 24.2 seconds for EBH, DIBH, and IBH respectively. Screening selected EBH for 44% (n = 8), IBH for 39% (n = 7), and DIBH for 17% (n = 3) of participants. The mean RBH was superior at 0.92 mm (0.79 mm SD) for the personalized technique, compared with EBH of 1.79 mm (1.49 mm SD) (P = .016). Preplanned subset analysis of participants whose personalized technique was not EBH showed improved mean RBH of 0.63 mm (0.29 mm SD) compared with their EBH RBH of 2.2 mm (1.7 mm SD) (P = .011). CONCLUSIONS: In 56% of participants, DIBH or IBH demonstrated superior RBH compared with EBH. Personalised BH screening can inform selection of an ABC BH method which provides optimal RBH with improved TBH for an individual's planning and treatment course.

Development of an automated radiotherapy dose accumulation workflow for locally advanced high-risk prostate cancer - A technical report.

An automated dose accumulation and contour propagation workflow using daily cone beam computed tomography (CBCTs) images for prostate cases that require pelvic lymph nodes irradiation (PLNs) was developed. This workflow was constructed using MIM® software with the intention to provide accurate dose transformations for plans with two different isocentres, whereby two sequential treatment phases were prescribed. The pre-processing steps for data extractions from treatment plans, CBCTs, determination of couch shift information and management of missing CBCTs are described. To ensure that the imported translational couch shifts were in the correct orientation and readable in MIM, phantom commissioning was performed. For dose transformation, rigid registration with corrected setup shifts and scaled fractional dose was performed for pCT to daily CBCTs, which were then deformed onto CBCT1 . Fractional dose summation resulted in the final accumulated dose for the patient allowing differences in dosimetry between the planned and accumulated dose to be analysed. Contour propagations of the prostate, bladder and rectum were performed within the same workflow. Transformed contours were then deformed onto daily CBCTs to generate trending reports for analysis, including Dice Similarity Coefficient (DSC) and Mean Distance to Agreement (MDA). Results obtained from phantom commissioning (DSC = 0.96, MDA = 0.89 mm) and geometrical analysis of the propagated contours for twenty patients; prostate (DSC: 0.9 ± 0.0, MDA: 1.0 ± 0.3 mm), rectum (DSC: 0.8 ± 0.1, mm, MDA: 1.7 ± 0.6 mm) and bladder (DSC: 0.8 ± 0.1, MDA: 2.8 ± 1.0 mm) were within clinically accepted tolerances for both DSC (>0.8) and MDA (< 0.3 mm). The developed workflow is being performed on a larger patient cohort for predictive model building, with the goal of correlating observed toxicity with the actual accumulated dose received by the patient.

Technical considerations for positioning and placement of a transperineal ultrasound probe during prostate radiotherapy.

This technical evaluation aims to provide practice 'how to' guidelines for radiation therapists (RTs) when positioning a transperineal ultrasound (TPUS) probe during prostate radiotherapy. Recommendations and practical tips will be provided for the best practice in TPUS-guided workflow to obtain optimal ultrasound images for accurate interpretation and registration of the prostate gland. This will assist the RTs in making consistent and accurate clinical decision in an ultrasound-guided radiotherapy workflow for prostate treatment. The implementation process and the associated successes and challenges will also be described to assist institutions who may be investigating the potential of implementing this system.

Protocol of a study investigating breath-hold techniques for upper-abdominal radiation therapy (BURDIE): addressing the challenge of a moving target.

BACKGROUND: Radiation therapy to upper abdominal sites is technically challenging due to motion of tumors and surrounding organs resulting from normal respiration. Breath-hold, using an Active Breathing Coordinator is one strategy used to reduce motion in these tumor sites. Though widely used, no studies have prospectively compared the different breath-hold techniques (inspiration, deep-inspiration and expiration) using ABC in the same patient cohort. METHODS: Patients planned for radiation therapy to upper abdominal tumors are invited to participate in this prospective study. Participants attempt three breath hold techniques: inspiration, deep-inspiration and expiration breath-hold, in random order. kV fluoroscopy images of the dome of diaphragm are taken of five consecutive breath-holds in each technique. Reproducibility and stability of tumour position are measured, and used to select the technique with which to proceed to planning and treatment. Reproducibility at planning and each treatment fraction is measured, along with breath hold time, treatment efficiency and patient experience. DISCUSSION: The screening method was validated after the first three participants. This screening process may be able to select the best breath-hold technique for an individual, which may lead to improved reproducibility. The screening process is being piloted as a prospective clinical trial. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry (ANZCTR): 12618001691235. Registered 12th October 2018. https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=376109&isReview=true .

Duration-dependent margins for prostate radiotherapy-a practical motion mitigation strategy.

BACKGROUND AND OBJECTIVE: The magnitude of intra-fractional prostate displacement (change from initial position over time) is associated with the duration of the patient lying on the radiotherapy treatment couch. This study reports a minute-by-minute association and calculates the impact of this displacement on duration-dependent margins using real-time intra-fractional position data monitored by four-dimensional transperineal ultrasound (4D TPUS). MATERIALS AND METHODS: A total of 55 patients were recruited prospectively. Intra-fractional position of the prostate was monitored in real-time using a 4D TPUS Clarity® system. A total of 1745 monitoring sessions were analysed. Van Herk's margin recipe (2.5∑ + 1.64((σ2 + σp2)1/2 - σp)) was used to estimate the duration-dependant margins for every minute, up to the 15th minute. Linear regression analysis was then performed on the overall margins against time and direction. RESULTS: The mean intra-fractional position was 0.76 mm Inferior (Inf), 0 mm Lateral (Lat) and 0.94 mm Posterior (Post) at the 15th minute. A minimum margin expansion of 2.42 mm (Superior/Inf), 1.02 mm (Left/Right) and 2.65 mm (Anterior/Post) was required for an 8­minute treatment compared to 4.29 mm (Sup/Inf), 1.84 mm (Lt/Rt) and 4.63 mm (Ant/Post) for a 15-minute treatment. The required margin expansion increased linearly (R2 = 0.99) in all directions (p < 0.01). However, while there was no statistically significant difference (p = 0.10) in the required margin expansion in the Sup/Inf and Ant/Post directions respective of the time duration, the margins were much bigger compared to those in the Lt/Rt direction (p < 0.01). CONCLUSION: We report our experience in deriving the minimum duration-dependant margin to generate the required planning target volume for prostate radiotherapy. The required margin increases linearly in all directions within the 15-min duration; thus, the margin will depend on the duration of the technique chosen (IMRT/VMAT/3DCRT/proton).

Analysis of a Standardized Perioperative Pain Management Order Set in Highly Opioid-Tolerant Patients.

OBJECTIVE: The aim was to assess a standardized order set for perioperative pain management in highly opioid-tolerant patients undergoing elective orthopedic surgery. METHODS: This retrospective chart review evaluated a pain order set in highly opioid-tolerant patients undergoing elective total knee or total hip arthroplasty from January 2010 through August 2012. Based on the date of the surgery, patients were allocated into preimplementation or postimplementation order set groups. The primary outcome assessed whether an adjustment in daily opioid dosage was required within the first 48 hours postoperatively. Secondary outcomes included pain scores, length of hospitalization, and safety outcomes. RESULTS: Sixty patients were included in the analysis. An adjustment to postoperative opioid therapy occurred in 62% of the patients in the preimplementation group and in 56% of postimplementation group patients (P = 0.786). There were no differences in median pain scores 48 hours postoperatively (P = 0.348). Cumulative toxicity was increased after order set implementation compared with previous patients (44% versus 5%, P < 0.005); however, opioid doses held for sedation was the only individual toxicity to reach statistical significance (P = 0.011). CONCLUSIONS: This study is the first to evaluate a standardized order set for pain management in highly opioid-tolerant patients undergoing elective orthopedic surgery. The order set demonstrated similar efficacy to previous treatment modalities, but opioid-induced sedation was of concern with the order set. After the initial analysis, the order set was modified to minimize opioid-induced sedation. Continual safety analysis is warranted for quality improvement to enhance perioperative pain management in highly opioid-tolerant patients.

Analysis of intra-fraction prostate motion and derivation of duration-dependent margins for radiotherapy using real-time 4D ultrasound.

BACKGROUND AND PURPOSE: During radiotherapy, prostate motion changes over time. Quantifying and accounting for this motion is essential. This study aimed to assess intra-fraction prostate motion and derive duration-dependent planning margins for two treatment techniques. MATERIAL AND METHODS: A four-dimension (4D) transperineal ultrasound Clarity® system was used to track prostate motion. We analysed 1913 fractions from 60 patients undergoing volumetric-modulated arc therapy (VMAT) to the prostate. The mean VMAT treatment duration was 3.4 min. Extended monitoring was conducted weekly to simulate motion during intensity-modulated radiation therapy (IMRT) treatment (an additional seven minutes). A motion-time trend analysis was conducted and the mean intra-fraction motion between VMAT and IMRT treatments compared. Duration-dependent margins were calculated and anisotropic margins for VMAT and IMRT treatments were derived. RESULTS: There were statistically significant differences in the mean intra-fraction motion between VMAT and the simulated IMRT duration in the inferior (0.1 mm versus 0.3 mm) and posterior (-0.2 versus -0.4 mm) directions respectively (p ≪ 0.01). An intra-fraction motion trend inferiorly and posteriorly was observed. The recommended minimum anisotropic margins are 1.7 mm/2.7 mm (superior/inferior); 0.8 mm (left/right), 1.7 mm/2.9 mm (anterior/posterior) for VMAT treatments and 2.9 mm/4.3 mm (superior/inferior), 1.5 mm (left/right), 2.8 mm/4.8 mm (anterior/posterior) for IMRT treatments. Smaller anisotropic margins were required for VMAT compared to IMRT (differences ranging from 1.2 to 1.6 mm superiorly/inferiorly, 0.7 mm laterally and 1.1-1.9 mm anteriorly/posteriorly). CONCLUSIONS: VMAT treatment is preferred over IMRT as prostate motion increases with time. Larger margins should be employed in the inferior and posterior directions for both treatment durations. Duration-dependent margins should be applied in the presence of prolonged imaging and verification time.

Reduction of intra-fraction prostate motion - Determining optimal bladder volume and filling for prostate radiotherapy using daily 4D TPUS and CBCT.

BACKGROUND AND PURPOSE: Inconsistent bladder and rectal volumes have been associated with motion uncertainties during prostate radiotherapy. This study investigates the impact of these volumes to determine the optimal bladder volume. MATERIALS AND METHODS: 60 patients from two Asian hospitals were recruited prospectively. 1887 daily cone-beam computed tomography (CBCT) images were analysed. Intra-fraction motion of the prostate was monitored real-time using a four-dimension transperineal ultrasound (4D TPUS) Clarity® system. The impact of planned bladder volume, adequacy of daily bladder filling, and rectum volume on mean intra-fraction motion of the prostate was analysed. Patients' ability to comply with the full bladder hydration protocol and level of frustration was assessed using a questionaire. Acute side effects were assessed using the Common Terminology Criteria for Adverse Events (CTCAE) version 3.0 and quality of life (QoL) assessed using the International Prostate Symptom Score (IPSS). RESULTS: The mean (SD) bladder and rectum volumes achieved during daily treatment were 139.7 cm3 (82.4 cm3) and 53.3 cm3 (18 cm3) respectively. Mean (SD) percentage change from planned CT volumes in bladder volume was reduced by 8.2% (48.7%) and rectum volume was increased by 12.4% (42.2%). Linear Mixed effect model analysis revealed a reduction in intra-fraction motion in both the Sup/Inf (p = 0.008) and Ant/Post (p = 0.0001) directions when the daily bladder was filled between 82 and 113% (3rd Quartiles) of the planned CT volumes. A reduction in intra-fraction motion of the prostate in the Ant/Post direction (z-plane) (p = 0.03) was observed when the planned bladder volume was greater than 200 ml. Patients complied well with the hydration protocol with minimal frustration (mean (SD) scores of 2.1 (1.4) and 1.8 (1.2) respectively). There was a moderate positive correlation (0.496) between mean bladder volume and IPSS reported post-treatment urinary straining (p = 0.001). CONCLUSIONS: A planned bladder volume >200 cm3 and daily filling between 82 and 113%, reduced intra-fraction motion of the prostate. The hydration protocol was well tolerated.

A comparison of interfraction setup error, patient comfort, and therapist acceptance for 2 different prostate radiation therapy immobilization devices.

PURPOSE: Our purpose was to investigate interfraction setup error of the immobilization device required to implement transperineal ultrasound compared with the current, standard immobilization device. Patient comfort and radiation therapist (RT) satisfaction were also assessed. METHODS AND MATERIALS: Cone beam computed tomography images were acquired before 4069 fractions from 111 patients (control group, n = 56; intervention group, n = 55) were analyzed. The intervention group was immobilized using the Clarity Immobilization System (CIS), comprising a knee rest with autoscan probe kit and transperineal ultrasound probe (n = 55), and control group using a leg immobilizer (LI) (n = 56). Interfraction setup errors were compared for both groups. Weekly questionnaires using a 10-point visual analog scale were administered to both patient groups to measure and compare patient comfort. RT acceptance for both devices was also compared using a survey. RESULTS: There was no significant difference in the magnitude of interfraction cone beam computed tomography-derived setup shifts in the lateral and anteroposterior direction between the LI and CIS (P = .878 and .690, respectively). However, a significant difference (P = .003) was observed in the superoinferior direction between the 2 groups of patients. Patient-reported level of comfort and stability demonstrated no significant difference between groups (P = .994 and .132). RT user acceptance measures for the LI and CIS were ease of handling (100% vs 53.7%), storage (100% vs 61.1%), and cleaning of the devices (100% vs 64.8%), respectively. CONCLUSIONS: The CIS demonstrated stability and reproducibility in prostate treatment setup comparable to LI. The CIS device had no impact on patient comfort; however, RTs indicated a preference for LI over the CIS mainly because of its weight and bulkiness.

Occupational burnout among radiographers, sonographers and radiologists in Australia and New Zealand: Findings from a national survey.

INTRODUCTION: Evidence demonstrates that health care professionals are more prone to burnout than other professionals due to the emotionally taxing interactions they have with their patients on a daily basis. The aims of this study were to measure occupational burnout levels among sonographers, radiographers and radiologists and to examine predictors of burnout according to demographic characteristics. METHODS: A cross-sectional online survey was administered in 2010 to radiographers, sonographers and radiologists who were members of the following professional bodies: Australian Institute of Radiography, Australian Sonographers Association and The Royal Australian and New Zealand College of Radiologists. The Maslach Burnout Inventory was used to measure burnout levels for each profession. Data were analysed using SPSS Ver 20 (IBM, Chicago, IL, USA) statistical software. RESULTS: A total of 613 radiographers, 121 sonographers and 35 radiologists participated in the survey. Radiographers, sonographers and radiologists had a high mean (±SD) burnout score for emotional exhaustion (39.9 ± 8.5, 42.2 ± 8.5 and 44.9 ± 7.1 respectively) and depersonalization (18.9 ± 5.5, 20.3 ± 5.8 and 20.6 ± 5.6) compared to MBI norms. Radiographers also had low personal achievement (30.8 ± 5.5) compared to MBI norms. Radiographers and sonographers who were male, worked >10 hours overtime and spent <10% of their time training students per week had significantly higher depersonalization scores (p < 0.05). CONCLUSION: Burnout levels among radiographers, sonographers and radiologists are high and likely to vary according to some demographic and work-related factors. Further research is needed to examine ways to alleviate burnout in these professions so that loss of experienced staff due to burnout can be minimized and quality of patient care can be maintained.

Impact of tumour bed boost integration on acute and late toxicity in patients with breast cancer: A systematic review.

The purpose of this systematic review was to summarise the evidence from studies investigating the integration of tumour bed boosts into whole breast irradiation for patients with Stage 0-III breast cancer, with a focus on its impact on acute and late toxicities. A comprehensive systematic electronic search through the Ovid MEDLINE, EMBASE and PubMed databases from January 2000 to January 2015 was conducted. Studies were considered eligible if they investigated the efficacy of hypo- or normofractionated whole breast irradiation with the inclusion of a daily concurrent boost. The primary outcomes of interest were the degree of observed acute and late toxicity following radiotherapy treatment. Methodological quality assessment was performed on all included studies using either the Newcastle-Ottawa Scale or a previously published investigator-derived quality instrument. The search identified 35 articles, of which 17 satisfied our eligibility criteria. Thirteen and eleven studies reported on acute and late toxicities respectively. Grade 3 acute skin toxicity ranged from 1 to 7% whilst moderate to severe fibrosis and telangiectasia were both limited to 9%. Reported toxicity profiles were comparable to historical data at similar time-points. Studies investigating the delivery of concurrent boosts with whole breast radiotherapy courses report safe short to medium-term toxicity profiles and cosmesis rates. Whilst the quality of evidence and length of follow-up supporting these findings is low, sufficient evidence has been generated to consider concurrent boost techniques as an alternative to conventional sequential techniques.