Papers by Sabeena Beveridge
Optimized scoring of end-to-end dosimetry audits for passive motion management – A simulation study using the IROC thorax phantom
Physica medica, May 1, 2024
Adoption of respiratory motion management in radiation therapy
Physics and Imaging in Radiation Oncology
Radiotherapy and Oncology, 2013
European Urology Supplements, 2014
351 Prostate Histoscanning™ for assessment of tumour volume and pathological stage prior to radical prostatectomy: What is its role in routine clinical practice?
European Urology Supplements, 2013
Does Prostate HistoScanningTM accurately identify prostate cancer, measure tumour volume and assess pathological stage prior to radical prostatectomy?
Journal of Clinical Urology, 2013
ABSTRACT
Medical Dosimetry, 2013
Fluorine-18-fluorodeoxyglucose-positron emission tomography ( 18 F-FDG-PET)-guided focal dose esc... more Fluorine-18-fluorodeoxyglucose-positron emission tomography ( 18 F-FDG-PET)-guided focal dose escalation in oropharyngeal cancer may potentially improve local control. We evaluated the feasibility of this approach using volumetric-modulated arc therapy (RapidArc) and compared these plans with fixed-field intensitymodulated radiotherapy (IMRT) focal dose escalation plans. Materials and methods: An initial study of 20 patients compared RapidArc with fixed-field IMRT using standard dose prescriptions. From this cohort, 10 were included in a dose escalation planning study. Dose escalation was applied to 18 F-FDG-PET-positive regions in the primary tumor at dose levels of 5% (DL1), 10% (DL2), and 15% (DL3) above standard radical dose (65 Gy in 30 fractions). Fixed-field IMRT and double-arc RapidArc plans were generated for each dataset. Dose-volume histograms were used for plan evaluation and comparison. The Paddick conformity index (CI Paddick ) and monitor units (MU) for each plan were recorded and compared. Both IMRT and RapidArc produced clinically acceptable plans and achieved planning objectives for target volumes. Dose conformity was significantly better in the RapidArc plans, with lower CI Paddick scores in both primary (PTV1) and elective (PTV2) planning target volumes (largest difference in PTV1 at DL3; 0.81 Ϯ 0.03 [RapidArc] vs. 0.77 Ϯ 0.07 [IMRT], p ϭ 0.04). Maximum dose constraints for spinal cord and brainstem were not exceeded in both RapidArc and IMRT plans, but mean doses were higher with RapidArc (by 2.7 Ϯ 1 Gy for spinal cord and 1.9 Ϯ 1 Gy for brainstem). Contralateral parotid mean dose was lower with RapidArc, which was statistically significant at DL1 (29.0 vs. 29.9 Gy, p ϭ 0.01) and DL2 (29.3 vs. 30.3 Gy, p ϭ 0.03). MU were reduced by 39.8 -49.2% with RapidArc (largest difference at DL3, 641 Ϯ 94 vs. 1261 Ϯ 118, p Ͻ 0.01). 18 F-FDG-PET-guided focal dose escalation in oropharyngeal cancer is feasible with RapidArc. Compared with conventional fixed-field IMRT, RapidArc can achieve better dose conformity, improve contralateral parotid sparing, and uses fewer MU.
Research Square (Research Square), Aug 21, 2023
The accurate assessment of film results is highly dependent on the methodology and techniques use... more The accurate assessment of film results is highly dependent on the methodology and techniques used to process film. This study aims to compare the performance of EBT3 and EBT-XD film for SRS dosimetry using two different film processing methods. Experiments were performed in a solid water slab and an anthropomorphic head phantom. For each experiment, the net optical density of the film was calculated using two different methods; taking the background (initial) optical density from 1) unirradiated film from the same film lot as the irradiated film (stock to stock (S-S) method), and 2) a scan of the same piece of film taken prior to irradiation (film to film (F-F) method). EBT3 and EBT-XD performed similarly across the suite of experiments when using the green channel only or with triple channel RGB dosimetry. The dosimetric performance of EBT-XD was improved across all colour channels by using an F-F method, particularly for the blue channel. In contrast, EBT3 performed similarly well regardless of the net optical density method used. Across 21 SRS treatment plans, the average per-pixel agreement between EBT3 and EBT-XD films, normalised to the 20 Gy prescription dose, was within 2% and 4% for the nontarget (2 -10 Gy) and target (>10 Gy) regions, respectively, when using the F-F method. At doses relevant to SRS, EBT3 provides comparable dosimetric performance to EBT-XD. In addition, an S-S dosimetry method is suitable for EBT3 while an F-F method should be adopted if using EBT-XD.
Does prostate HistoScanning™ play a role in detecting prostate cancer in routine clinical practice? Results from three independent studies
BJU International, 2014
To evaluate the ability of prostate HistoScanning™ (PHS; Advanced Medical Diagnostics, Waterloo, ... more To evaluate the ability of prostate HistoScanning™ (PHS; Advanced Medical Diagnostics, Waterloo, Belgium) to detect, characterize and locally stage prostate cancer, by comparing it with transrectal ultrasonography (TRUS)-guided prostate biopsies, transperineal template prostate biopsies (TTBs) and whole-mount radical prostatectomy specimens. Study 1. We recruited 24 patients awaiting standard 12-core TRUS-guided biopsies of the prostate to undergo PHS immediately beforehand. We compared PHS with the TRUS-guided biopsy results in terms of their ability to detect cancer within the whole prostate and to localize it to the correct side and to the correct region of the prostate. Lesions that were suspicious on PHS were biopsied separately. Study 2. We recruited 57 patients awaiting TTB to have PHS beforehand. We compared PHS with the TTB pathology results in terms of their ability to detect prostate cancer within the whole gland and to localize it to the correct side and to the correct sextant of the prostate. Study 3. We recruited 24 patients awaiting radical prostatectomy for localized prostate cancer to undergo preoperative PHS. We compared PHS with standardized pathological analysis of the whole-mount prostatectomy specimens in terms of their measurement of total tumour volume within the prostate, tumour volume within prostate sextants and volume of index lesions identified by PHS. The PHS-targeted biopsies had an overall cancer detection rate of 38.1%, compared with 62.5% with standard TRUS-guided biopsies. The sensitivity and specificity of PHS for localizing tumour to the correct prostate sextant, compared with standard TRUS-guided biopsies, were 100 and 5.9%, respectively. The PHS-targeted biopsies had an overall cancer detection rate of 13.4% compared with 54.4% for standard TTB. PHS had a sensitivity and specificity for cancer detection in the posterior gland of 100 and 13%, respectively, and for the anterior gland, 6 and 82%, respectively. We found no correlation between total tumour volume estimates from PHS and radical prostatectomy pathology (Pearson correlation coefficient -0.096). Sensitivity and specificity of PHS for detecting tumour foci ≥0.2 mL in volume were 63 and 53%. These three independent studies in 105 patients suggest that PHS does not reliably identify and characterize prostate cancer in the routine clinical setting.
Volumetric-modulated arc therapy (RapidArc) vs. conventional fixed-field intensity-modulated radiotherapy for 18F-FDG-PET-guided dose escalation in oropharyngeal cancer: A planning study
Medical Dosimetry, 2013
Fluorine-18-fluorodeoxyglucose-positron emission tomography (¹⁸F-FDG-PET)-guided focal dose escal... more Fluorine-18-fluorodeoxyglucose-positron emission tomography (¹⁸F-FDG-PET)-guided focal dose escalation in oropharyngeal cancer may potentially improve local control. We evaluated the feasibility of this approach using volumetric-modulated arc therapy (RapidArc) and compared these plans with fixed-field intensity-modulated radiotherapy (IMRT) focal dose escalation plans. An initial study of 20 patients compared RapidArc with fixed-field IMRT using standard dose prescriptions. From this cohort, 10 were included in a dose escalation planning study. Dose escalation was applied to ¹⁸F-FDG-PET-positive regions in the primary tumor at dose levels of 5% (DL1), 10% (DL2), and 15% (DL3) above standard radical dose (65 Gy in 30 fractions). Fixed-field IMRT and double-arc RapidArc plans were generated for each dataset. Dose-volume histograms were used for plan evaluation and comparison. The Paddick conformity index (CI(Paddick)) and monitor units (MU) for each plan were recorded and compared. Both IMRT and RapidArc produced clinically acceptable plans and achieved planning objectives for target volumes. Dose conformity was significantly better in the RapidArc plans, with lower CI(Paddick) scores in both primary (PTV1) and elective (PTV2) planning target volumes (largest difference in PTV1 at DL3; 0.81 ± 0.03 [RapidArc] vs. 0.77 ± 0.07 [IMRT], p = 0.04). Maximum dose constraints for spinal cord and brainstem were not exceeded in both RapidArc and IMRT plans, but mean doses were higher with RapidArc (by 2.7 ± 1 Gy for spinal cord and 1.9 ± 1 Gy for brainstem). Contralateral parotid mean dose was lower with RapidArc, which was statistically significant at DL1 (29.0 vs. 29.9 Gy, p = 0.01) and DL2 (29.3 vs. 30.3 Gy, p = 0.03). MU were reduced by 39.8-49.2% with RapidArc (largest difference at DL3, 641 ± 94 vs. 1261 ± 118, p < 0.01). ¹⁸F-FDG-PET-guided focal dose escalation in oropharyngeal cancer is feasible with RapidArc. Compared with conventional fixed-field IMRT, RapidArc can achieve better dose conformity, improve contralateral parotid sparing, and uses fewer MU.
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Papers by Sabeena Beveridge