Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology
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To evaluate the influence of uterus and bladder size on large and small bowel sparing with intensity modulated whole pelvic radiotherapy (IM-WPRT) in gynecologic patients. ⋯ IMRT significantly reduced the absolute volume of rectal wall, bladder and bowel irradiated at the prescribed dose level in gynaecologic patients. Main differences between POST and DEF patients receiving IM-WPRT were absolute volumes of LB irradiated to doses between 35 and 50Gy, suggesting an impact of intact uterus on LB volume in the pelvis. POST patients seem to benefit most from elective nodal IMRT. Bladder filling is an important co-factor influencing the benefit of IMRT with respect to OAR sparing.
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To evaluate the early side effects of a short course hypofractionated radiotherapy regimen in prostate cancer. ⋯ Though no grade 3-4 side effects were observed, the investigated schedule results in a marked increase of grade 1-2 early side effects as compared to a conventional regimen. Side effects resolved within two months post-treatment.
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Multicenter Study
Clinical experience with the MammoSite radiation therapy system for brachytherapy of breast cancer: results from an international phase II trial.
In a prospective multi-center phase II trial, we investigated the MammoSite Radiation Therapy System, a new device for delivering intracavitary brachytherapy following breast conserving surgery. The MammoSite is a dual lumen, closed ended catheter with a small, spherical inflatable balloon and a port for connecting a remote afterloader to the central lumen. We analyzed the surgical procedure and placement of the MammoSite, treatment planning and radiation delivery complications and cosmesis, as well the comfort for the patients. ⋯ The MammoSite Radiation Therapy System is a feasible treatment modality for intracavitary brachytherapy of breast cancer after breast conserving surgery. The advantage of the system is only one applicator is necessary for the delivery of a fractionated radiotherapy. In addition, patient tolerance of the procedure is high. Critical issues concern possible overdosages at the skin reflected by a high rate of late skin damage after only 20 months of follow-up time. The method could serve as an alternative to conventional multi-catheter brachytherapy for a selected group of patients.
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Comparative Study
Dosimetric comparisons between high dose rate interstitial and MammoSite balloon brachytherapy for breast cancer.
To make a quantitative dosimetric comparison between treatment plans of multicatheter-based interstitial brachytherapy (IB) and MammoSite brachytherapy (MSB) for breast cancer. ⋯ Target volume coverage was better for MSB than conventional IB, and it was comparable to conformal IB. The suboptimal coverage for IB patients is due to radiography based planning, which is unable to provide 3D information of the target. Dose homogeneity was somewhat better for MSB than IB(CONV), but the dose to skin and lung was higher for MSB. The MSB provides dosimetrically acceptable dose plans. The quality of interstitial implants can be improved with image-guided catheter insertions regarding both homogeneity and conformality.
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In 1998 Stock and Stone demonstrated a dose response relationship correlating D90 with probability of biochemical control and showed that a D90 of 140 Gy is a highly significant factor in predicting PSA relapse free survival (PSA-RFS). Although, a mean D90 of over 140 Gy was achieved in our series, there is nevertheless a normal distribution with 20% of patients achieving a D90 of less than 120 Gy. We have analysed the possible causes for the low D90 and the impact on outcome. ⋯ D90 was found to be a good discriminator for those with low risk where failure to achieve local control is likely to be the dominant cause of PSA failure. No significant dose response relationship between D90 and PSA was found in the intermediate and high-risk population of patients. This could be due to (1) the presence of oedema or discrepancy between pre- and post-implant volumes causing a low D90, (2) the possibility that the underdosed area could be situated where there is unlikely to be tumour, (3) the fact that biochemical control does not equate to local control because some patients fail outside the prostate, particularly in the high and intermediate risk patients, (4) if D90 is a good discriminator only for low risk patients, the absence of a dose response correlation in this series which contained 53.8% intermediate and high risk patients could be related to case mix.