First application of a pixel-wise analysis on bladder dose-surface maps in prostate cancer radiotherapy

Federica Palorini, Cesare Cozzarini, Stefano Gianolini, Andrea Botti, Viviana Carillo, Cinzia Iotti, Tiziana Rancati, Riccardo Valdagni, Claudio Fiorino

Research output: Contribution to journalArticlepeer-review


PURPOSE: To develop a method for investigating local dose effects on the bladder after prostate cancer radiotherapy based on dose-surface maps (DSMs).

BACKGROUND AND PURPOSE: DSMs of patients included in a prospective study (DUE01) were generated by virtually cutting bladder contours at the points intersecting the sagittal plane passing through its center-of-mass: maps were laterally normalized and aligned at the posterior inferior point. The average DSMs of patients with/without toxicity, the DSMs of differences and t statistic were used to select regions better discriminating patients with toxicity. A total of 72 patients with no/mild urinary symptoms before radiotherapy and who were treated with moderate hypo-fractionation (2.5-2.65Gy/fr, 70-74Gy) were considered, and the endpoint was an International Prostate Symptoms Score (IPSS)⩾15 at the end of therapy (IPSSend⩾15, n=25/72).

RESULTS: The DSMs of patients with/without toxicity were significantly different (p<0.05). The percentage of bladder circumference receiving >50-70Gy at 5-7mm from the base was associated with an IPSSend⩾15 (odds ratios: 1.03-1.07). Different patterns were recognized for specific symptoms. With frequency/urgency, a quasi-threshold effect on the absolute posterior dose at 5-12mm from the base (2Gy equivalent doses=80-82Gy, α/β=3-5Gy) was observed.

CONCLUSIONS: Local-dose effects for acute symptoms were detected in a group of patients treated within a moderately hypo-fractionated protocol. The results for frequency/urgency were consistent with a threshold effect on the trigone.

Original languageEnglish
Pages (from-to)123-8
Number of pages6
JournalRadiotherapy and Oncology
Issue number1
Publication statusPublished - Apr 2016


  • Aged
  • Humans
  • Male
  • Middle Aged
  • Prospective Studies
  • Prostatic Neoplasms
  • Radiotherapy Dosage
  • Urinary Bladder
  • Journal Article
  • Research Support, Non-U.S. Gov't

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