BackgroundAlthough primary treatment of localized prostate cancer provides excellent oncologic control, some men who chose radiotherapy experience a recurrence of disease. There is no consensus on the most appropriate management of these patients after radiotherapy failure. In this single-institution review, we compare our oncologic outcome and toxicity between salvage prostatectomy and cryotherapy treatments.MethodsFrom January 2004 to June 2013, a total of 23 salvage procedures were performed. Six of those patients underwent salvage prostatectomy while 17 underwent salvage cryotherapy by two high-volume fellowship-trained urologists.Patients being considered for salvage therapy had localized disease at presentation, a prostate-specific antigen (PSA) < 10 ng/mL at recurrence, life expectancy > 10 years at recurrence, and a negative metastatic workup. Patients were followed to observe cancer progression and toxicity of treatment.ResultsPatients who underwent salvage cryotherapy were statistically older with a higher incidence of hypertension than our salvage prostatectomy cohort. With a mean follow up of 14.1 months and 7.2 months, the incidence of disease progression was 23.5% and 16.7% after salvage cryotherapy and prostatectomy, respectively. The overall complication rate was also 23.5% versus 16.7%, with the most frequent complication after salvage cryotherapy being urethral stricture and after salvage prostatectomy being severe urinary incontinence. There were no rectal injuries with salvage prostatectomy and one rectourethral fistula in the cohort after salvage cryotherapy.ConclusionWhile recurrences from primary radiotherapy for prostate cancer do occur, there is no consensus on its management. In our experience, salvage procedures were generally safe and effective. Both salvage cryotherapy and salvage prostatectomy allow for adequate cancer control with minimal toxicity.
Purpose: Due to film processing variation and the optical density not being linear with the dose, a full calibration has to be obtained for every IMRT‐QA with film. We are proposing the application of a linearization method and the use of a single dose calibration EDR film for relative and absolute dose measurement in IMRT‐QA. Method and Materials: The linearization method was studied for the EDR films using 6, 10 and 15 MV photon beams. The films were developed in a Konica film processor, then scanned with a Vidar VXR‐16 scanner and analyzed using RIT‐114 version 4.1. A standard 30‐point calibration curve was obtained with the 6 MV beam. Using the method developed in a previous paper, a curve fitting was obtained for a sigmoid expression modulated by a 3rd degree polynomial: ; where x is the net optical density, m is the net saturation density, b, a1, a2 and a3 are parameters of the model. Results: A value of 1870.1945 was obtained for b that is a parameter related to the dose unit. The net saturation density was 3.5587 for our system. The parameters a1, a2 and a3 are, respectively, −0.4551, 0.1167, −0.0134. For every IMRT‐QA a spreadsheet is used to obtain a 70 point calibration curve for RIT, using only one exposed film developed together with the composed and enface films, obtaining <5% uncertainty. Conclusion: Some softwares are available to make film dosimetry in IMRT QA less cumbersome, however daily calibration still remains a time consuming procedure. Absolute dosimetry requires a full calibration every time film is used. The linearization method presented here is being used in our department for isodose comparison and for absolute measurement at calculation point. The overall time is reduced while obtaining uncertainty comparable to the existing methods.
Purpose: Cone‐beam artifacts can be a significant contributor in the degradation of brain image quality. The purpose of this study is to evaluate the frequency split cone‐beam reduction reconstruction algorithm as a means of improving IQ in brain imaging. The design of the frequency split filters and their effect on image quality and noise are evaluated. Also the potential of increasing the x‐ray beam collimation and reducing total scan time for head imaging is investigated. Method and Materials:Head scans from Philips iCT 256 slice and Brilliance 64 scanners, and simulations based on the Philips iCT 256 slice scanner were used in this study. The scans were reconstructed using conventional reconstruction techniques and frequency split reconstruction. The level of cone‐beam artifacts introduced when using larger beam collimations and the effectiveness of frequency split reconstruction for reducing cone‐beam artifacts were investigated. Also, the effect of the filters parameters in frequency split reconstruction on image quality and on noise texture were evaluated. The pediatric head IQ from the clinical data sets, and especially the delineation of the bone‐brain boundary and contrast detail in the posterior fossa, were evaluated. Results: Review of images reconstructed with frequency split reconstruction show significant reduction in the level of cone‐beam artifacts. Clinical images show significant improvements in uniformity and contrast in the posterior fossa. Improvement in image uniformity of up to1 5 HU has been realized by frequency split reconstruction. With proper design of frequency split filters, the change in image noise and NPS and can be minimized while achieving significant reduction of cone‐beam artifacts. Conclusions: Cone‐beam artifacts can be a significant contributor to image artifacts. The optimized frequency split reconstruction algorithm realizes significant IQ improvements in heads imaging. The frequency split cone‐beam reduction algorithm could also result in shorter scan times by allowing wider collimations during scan. Authors are employed by Philips Healthcare
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