A. Haworth - Academia.edu (original) (raw)

Papers by A. Haworth

Radiotherapy and Oncology, 2011

Medical physics, 2015

To describe a new infrastructure and process that will enable end-users to commission model-based... more To describe a new infrastructure and process that will enable end-users to commission model-based dose calculation (MBDC) software for brachytherapy planning, and to invite end-users to participate in the beta testing phase of this process. The AAPM working groups on model-based dose calculation algorithms in brachytherapy (WGDCAB) and brachytherapy source registry (WGBSR) collaboratively implemented the basic MBDC software commissioning workflow described in the AAPM+ESTRO TG-186 report. For a small number of initial test cases virtual CT image, anatomical structure set, treatment plan, and associated 3D dose data for a single dwell position occupied by a WGDCAB generic high-dose-rate Ir-192 virtual source, with or without a generic shielded applicator, were generated. Dose distributions were calculated using Monte Carlo (MC) code MCNP6, Elekta's Advanced Collapsed cone Algorithm (ACE™), and Varian's Acuros™ BV module. All data were saved in DICOM RT format and uploaded to ...

ABSTRACT Purpose: We report our initial clinical experience with a novel position-sensitive sourc... more ABSTRACT Purpose: We report our initial clinical experience with a novel position-sensitive source-tracking system based on a flat panel imager. The system has been trialled with 4 prostate HDR brachytherapy patients (8 treatment fractions) in this initial study.

$Research paper thumbnail of Obtaining information on intra-fraction prostate displacement in radiotherapy determined from pre- and post-treatment kV imaging$

IFMBE Proceedings, 2009

Since 2007 all patients treated with radical intent for prostate cancer at Peter MacCallum Cancer... more Since 2007 all patients treated with radical intent for prostate cancer at Peter MacCallum Cancer Centre have three implanted fiducial markers to facilitate reproducible daily set-up using kV on-board imaging on a linear accelerator. We collected all set-up information prospectively through a record and verify system. In order to assess the appropriateness of patient movements and determine prostate displacement during

$Research paper thumbnail of Seminal vesicle interfraction displacement and margins in image guided radiotherapy for prostate cancer$

Radiation oncology (London, England), 2012

To analyze interfraction motion of seminal vesicles (SV), and its motion relative to rectal and b... more To analyze interfraction motion of seminal vesicles (SV), and its motion relative to rectal and bladder filling. SV and prostate were contoured on 771 daily computed tomography "on rails" scans from 24 prostate cancer patients undergoing radiotherapy. Random and systematic errors for SV centroid displacement were measured relative to the prostate centroid. Margins required for complete geometric coverage of SV were determined using isotropic expansion of reference contours. SV motion relative to rectum and bladder was determined. Systematic error for the SV was 1.9 mm left-right (LR), 2.9 mm anterior-posterior (AP) and 3.6 mm superior-inferior (SI). Random error was 1.4 mm (LR), 2.7 mm (AP) and 2.1 mm (SI). 10 mm margins covered the entire left SV and right SV on at least 90% of fractions in 50% and 33% of patients and 15 mm margins covered 88% and 79% respectively. SV AP movement correlated with movement of the most posterior point of the bladder (mean R2 = 0.46, SD = 0.2...

The Breast, 2005

The aim of this work was to evaluate the role of axillary dissection technique (standard "en-bloc... more The aim of this work was to evaluate the role of axillary dissection technique (standard "en-block" axillary dissection technique versus technicue of preserving nerves and vessels of axilla) in results of combined treatment and quality of life (relapse rates, overall survival, postoperative lymphoedema) of breast cancer patients.

Clinical Oncology, 2014

To evaluate the effect of incorporating daily ultrasound scanning to reduce variation in bladder ... more To evaluate the effect of incorporating daily ultrasound scanning to reduce variation in bladder filling before prostate bed radiotherapy. The primary aim was to confirm that coverage of the planning target volume (PTV) with the 95% isodose was within tolerance when the ultrasound-determined bladder volume was within individualised patient limits. Cone beam computed tomography (CBCT) images were acquired on 10 occasions during the course of treatment to assess systematic changes in rectal or bladder volume as part of a standard offline image-guided radiotherapy (IGRT) protocol. In addition, through a two-part study an ultrasound scan of the bladder was added to the IGRT protocol. In the Part 1 study, the ultrasound-determined bladder volume at the time of treatment simulation in 26 patients was compared with the simulation computed tomography cranio-caudal bladder length. The relationship between the two was used to establish bladder volume tolerance limits for the interventional component of the Part 2 study. In the Part 2 study, 24 patients underwent ultrasound scanning before treatment. When bladder volumes were outside the specified limits, they were asked to drink more water or void as appropriate until the volume was within tolerance. Based on the results of the Part 1 study, a 100 ml tolerance was applied in the Part 2 study. Seventy-six per cent of patients found to have bladder volumes outside tolerance were able to satisfactorily adjust their bladder volumes on demand. Comparing the bladder volumes with the CBCT data revealed that the bladder scanner correctly predicted that the target volume would be accurately targeted (using surrogate end points) in 83% of treatment fractions. A simple hand-held ultrasound bladder scanner provides a practical, inexpensive, online solution to confirming that the bladder volume is within acceptable, patient-specific limits before treatment delivery, with the potential to improve overall treatment accuracy.

Radiation Oncology, 2012

Background: To compare 3 Dimensional Conformal radiotherapy (3D-CRT) with Intensity Modulated Rad... more Background: To compare 3 Dimensional Conformal radiotherapy (3D-CRT) with Intensity Modulated Radiotherapy (IMRT) with Volumetric-Modulated Arc Therapy (VMAT) for bladder cancer. Methods: Radiotherapy plans for 15 patients with T2-T4N0M0 bladder cancer were prospectively developed for 3-DCRT, IMRT and VMAT using Varian Eclipse planning system. The same radiation therapist carried out all planning and the same clinical dosimetric constraints were used. 10 of the patients with well localised tumours had a simultaneous infield boost (SIB) of the primary tumour planned for both IMRT and VMAT. Tumour control probabilities and normal tissue complication probabilities were calculated.

Journal of medical imaging and radiation oncology, 2015

Multicentre radiotherapy clinical trials can incorporate quality assurance (QA) procedures for en... more Multicentre radiotherapy clinical trials can incorporate quality assurance (QA) procedures for ensuring consistent application of the trial protocol in the planning, delivery and reporting of participant treatments. Subsequently detected variations from trial protocol have previously been shown to reduce treatment efficacy, although little has been shown for toxicity rates. The purpose of this study was to investigate the association of QA measures and protocol variations on toxicity incidence in the context of a prostate radiotherapy trial. Using QA records from the TROG 03.04 RADAR trial, the impact of variations on gastrointestinal (GI) and genito-urinary (GU) toxicities was investigated. Protocol variation rates were lower than reported in previous studies, and showed little correlation with GI toxicity outcomes. Variations classified as 'major' showed a non-significant trend for increased toxicity relative to those classified as 'minor'. Results from a Level III...

Radiotherapy and Oncology, 2014

Intensity modulated radiation therapy (IMRT) is a radiation therapy technology that facilitates t... more Intensity modulated radiation therapy (IMRT) is a radiation therapy technology that facilitates the delivery of an improved dose distribution with less dose to surrounding critical structures. This study estimates the longer term effectiveness and cost-effectiveness of IMRT in patients post radical prostatectomy. A Markov decision model was developed to calculate the incremental quality adjusted life years (QALYs) and costs of IMRT compared with three dimensional conformal radiation therapy (3DCRT). Costs were estimated from the perspective of the Australian health care system. IMRT was both more effective and less costly than 3DCRT over 20 years, with an additional 20 QALYs gained and over $1.1 million saved per 1000 patients treated. This result was robust to plausible levels of uncertainty. IMRT was estimated to have a modest long term advantage over 3DCRT in terms of both improved effectiveness and reduced cost. This result was reliant on clinical judgement and interpretation of the existing literature, but provides quantitative guidance on the cost effectiveness of IMRT whilst long term trial evidence is awaited.

Radiotherapy and Oncology, 2009