890 Acute small bowel and colon toxicity after pelvic IMRT for prostate cancer

IMRT to Escalate the Dose to the Prostate while Treating the Pelvic Nodes

“…However, even taking into consideration this fact, it should be noted that pelvic IMRT is superior to 4FB across the entire rectal DVH, as shown in Figure 5. We believe that clinical testing of this approach within a prospective phase I-II study is warranted and such a study has been open at UTMB for patients with prostate cancer at significant risk of pelvic node involvement referred to us for definitive radiotherapy [39]. Based on the findings of the present study, pelvic IMRT followed by a conformal boost is our initial approach.…”

“…For the IMRT pelvis plans, dose objectives for bladder and rectum were set slightly lower than those achieved by the IMRT boost plan in hopes to yield the "most optimal" plan. In addition, for the IMRT pelvis plan, in-house dose objectives were used for the intestinal cavity [39].…”

Feasibility of IMRT to Cover Pelvic Nodes While Escalating the Dose to the Prostate Gland: Dosimetric Data on 35 Consecutive Patients

“…Figure 7 provides DVH data for the intestinal cavity, although one should note the dose objectives used for this organ-at-risk were based on a dose-response relationship that was found to be statistically significant when compared to the absolute volume of the cavity, not with the fractional volume. 30 Radiation-absorbed dose was also recorded to each pertinent region of interest as per the recommendations of the Intensity Modulated Radiation Therapy Collaborative Working Group. 23 The maximum, mean, minimum dose, and D 95 to each planning target volume is provided: prostate (82.2, 78.2, 72.6, 75.2 Gy); SV (79.0, 72.5, 56.9, 61.1 Gy); and PN (80.4, 59.7, 46.5, 53.3 Gy), respectively.…”

Dosimetric predictors of diarrhea during radiotherapy for prostate cancer

“…The IC volume was initially included in the "unspecified tissue" volume or the "anti-PTV" with a maximum dose constraint of 35 Gy for the portion not overlapping with the PTV. After a preliminary analysis on the first 24 patients that showed a dose-response correlation between the dose to the IC and the duration of diarrhea [17], the IC volume was separated from unspecified tissue. A secondary dose-volume objective was placed on the portion of the IC overlapping with the PTV; this was set at a uniform dose objective of 55 Gy.…”