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Kogarah, Australia

Hau E.K.C.,St George Cancer Care Center | Oborn B.M.,Wollongong Hospital | Oborn B.M.,University of Wollongong | Bucci J.,St George Cancer Care Center
Brachytherapy | Year: 2011

Purpose: We report a case of prostate brachytherapy seed migration to the vertebral venous plexus and subsequently to the renal artery with corresponding dosimetry analysis describing nerve doses. Methods and Materials: A 52-year-old male with low-risk prostate carcinoma (clinical stage T1c; Gleason score. =6; prostate-specific antigen level of 5.5) underwent transperineal permanent prostate seed implant. Postimplantation routine imaging had failed to locate the missing seed, but he subsequently presented with back pain and parathesia with radiation down the leg. Results: CT with bony windows and MRI had located the seed in the left L5 vertebral venous plexus. Neurosurgical intervention failed to locate and remove the migrated seed. Postsurgery, the left lower limb parathesia persisted but had normal nerve conduction studies. Dose to the spinal nerve roots and nearby structures were estimated using a GEANT4 Monte Carlo simulation. Serial X-ray imaging and CT had found that the seed had further migrated to left renal hilum. Conclusions: Seed migration to vertebral venous plexus is uncommon and to our knowledge this is the third reported case. Its subsequent migration to the renal hilum is most unusual. CT with bony windows or MRI are required if this is suspected. There is risk of spinal or nerve root damage and dose to these structures has to be estimated using GEANT4, although the tissue tolerance in the setting of low-dose rates are unknown and long-term followup of this patient is required. © 2011.

Chen F.Q.,Westmead Cancer Care Center | Gupta R.,St George Cancer Care Center | Metcalfe P.,University of Wollongong
Australasian Physical and Engineering Sciences in Medicine | Year: 2010

A new PTW advanced Markus ionization chamber has been implemented in IMRT fields, to measure surface dose at ICRU and ICRP reference depth of 0.07 mm [ICRU Report 39, Determination of dose equivalents resulting from external radiation sources, 1985; ICRP Publication 60, 1990 recommendations of the International Commission on Radiological Protection, 1991]. This chamber has a small radius with a revised guard ring design, therefore less prone to surface over-response effects. The over response correction for advanced Markus chamber is 3.3%, which is significantly smaller than 10.1% which was the original Markus chamber over response. After over response correction, the surface dose can be accurately measured by either data extrapolation or by adding one layer of plastic sheet protector to the top of Markus chamber. The surface dose measurements for small fields, e.g 3 × 3 cm, the polarity effect of advanced Markus chamber is 12%, which is significantly higher than the 5% polarity effect of the original Markus. For a 12 × 12 cm field size, surface dose (at 0.07 mm) measured by advanced Markus chamber is 19.8% for open field and 19.2% for an unmodulated step-and-shoot IMRT field. The variation in surface dose due to intensity modulated IMRT fields has also been investigated. For an intensity modulated, step-wedge IMRT field, surface dose varies from 15.7 ±1% for the highest intensity segment to 26.9 ±1% for the lowest intensity segment. The results of chamber measurements have been compared against EBT type GAFCHROMIC® film results. © Australasian College of Physical Scientists and Engineers in Medicine 2010.

Pramana A.,St George Cancer Care Center | Browne L.,St George Cancer Care Center | Graham P.H.,St George Cancer Care Center | Graham P.H.,University of New South Wales
Journal of Medical Imaging and Radiation Oncology | Year: 2012

Introduction: Information regarding the addition of tissue equivalent bolus to adjuvant radiotherapy (RT) for intra-parotid metastatic head and neck cutaneous squamous cell carcinoma is lacking. This study aimed to evaluate the effect of bolus versus no bolus on the patterns of regional and distant recurrence, regional control (RC), cancer-specific survival (CSS), overall survival, RT toxicity and RT interruption. Methods: A retrospective study was performed on consecutive patients diagnosed between 1994 and 2008 with metastatic head and neck cutaneous squamous cell carcinoma who were treated with parotidectomy ± selective neck dissection and adjuvant RT ± parotid bolus. Results: Seventy-five patients were identified: 64 males and 11 females, with median age of 79 years (range 40-96) of which 39 had bolus during RT. Median follow up was 48 months (range 4-177). There were 23 regional recurrences - 14 dermal, six dermal + nodal and three isolated nodal - and only two systemic recurrences. Nine patients had RT interruption >6 days due to acute skin toxicity. Bolus was associated with increased grade ≥3 radiation dermatitis (P = 0.02). RT interruption >6 days was significantly associated with inferior RC and hazard ratio, 2.83 (95% confidence interval: 1.04-7.71, P = 0.042). Lympho-vascular space invasion, positive margins and nodes >2 cm were adversely significant on CSS multivariate analysis. RC, CSS and overall survival at 5 years were 67, 66 and 52%, respectively. Conclusions: Dermal involvement dominated the pattern of regional recurrence. Bolus was associated with significantly worse skin reaction. Bolus use was not associated with a significant overall benefit on RC. This analysis does not support the use of bolus as applied in this cohort. © 2012 The Authors. Journal of Medical Imaging and Radiation Oncology © 2012 The Royal Australian and New Zealand College of Radiologists.

Tenconi C.,Medical Physics Unit | Tenconi C.,University of Milan | Carrara M.,Medical Physics Unit | Borroni M.,Medical Physics Unit | And 8 more authors.
Radiation Measurements | Year: 2014

The increasing complexity and high amount of dose per fraction delivered in prostate high dose rate (HDR) brachytherapy treatments call for the implementation of accurate and effective methods for the systematic and independent quality control of the overall treatment procedure. In this study, MOSkin detectors were placed on a trans-rectal ultrasound (TRUS) probe with the aim of performing both imaging and real time rectal wall in vivo dosimetry with the use of just one single instrument. After an adequate calibration of the detectors, which was carried out in a solid water phantom, the use of MOSkins integrated to the TRUS probe was studied in a gel phantom with a typical (simplified) prostate implant. Measured and calculated doses from the treatment planning system were compared, with a resulting very low average discrepancy of -0.6 ± 2.6%. The results are very promising and of particular clinical importance, however, further in vivo investigation is planned to validate the proposed method. © 2014 Elsevier Ltd. All rights reserved.

Loo K.J.,University of Wollongong | Loo K.J.,Czech Technical University | Jakubek J.,Czech Technical University | Zemlicka J.,Czech Technical University | And 5 more authors.
Radiation Measurements | Year: 2014

BrachyView is a novel in-body imaging system for real-time intraoperative prostate brachytherapy treatment planning, which monitors the position of low dose rate brachytherapy seeds using an array of high-resolution pixelated silicon detectors (Timepix). The detector array is also capable of performing in-body imaging of the prostate when used in conjunction with an external X-ray source. This study presents a quantitative analysis of the Timepix detector for use as a soft-tissue imaging plane by evaluating varying thicknesses of tissue-equivalent plastic incorporated into a medical prostate phantom. The feasibility of using BrachyView as a diagnostic tool is established by demonstrating the resolving power and high contrast obtainable with this configuration. © 2014 Elsevier Ltd. All rights reserved.

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