Related Experiment Video
Updated: Feb 2, 2026

Voluntary Breath-hold Technique for Reducing Heart Dose in Left Breast Radiotherapy
Published on: July 3, 2014
Ano-rectal wall dose-surface maps localize the dosimetric benefit of hydrogel rectum spacers in prostate cancer
Ben G L Vanneste1, Florian Buettner2, Michael Pinkawa3
1MAASTRO Clinic, Maastricht, The Netherlands.
Background And Purpose:
To evaluate spatial differences in dose distributions of the ano-rectal wall (ARW) using dose-surface maps (DSMs) between prostate cancer patients receiving intensity-modulated radiation therapy with and without implantable rectum spacer (IMRT+IRS; IMRT-IRS, respectively), and to correlate this with late gastro-intestinal (GI) toxicities using validated spatial and non-spatial normal-tissue complication probability (NTCP) models.
Materials And Methods:
For 26 patients DSMs of the ARW were generated. From the DSMs various shape-based dose measures were calculated at different dose levels: lateral extent, longitudinal extent, and eccentricity. The contiguity of the ARW dose distribution was assessed by the contiguous-DSH (cDSH). Predicted complication rates between IMRT+IRS and IMRT-IRS plans were assessed using a spatial NTCP model and compared against a non-spatial NTCP model.
Results:
Dose surface maps are generated for prostate radiotherapy using an IRS. Lateral extent, longitudinal extent and cDSH were significantly lower in IMRT+IRS than for IMRT-IRS at high-dose levels. Largest significant differences were observed for cDSH at dose levels >50 Gy, followed by lateral extent at doses >57 Gy, and longitudinal extent in anterior and superior-inferior directions. Significant decreases (p = 0.01) in median rectal and anal NTCPs (respectively, Gr 2 late rectal bleeding and subjective sphincter control) were predicted when using an IRS.
Conclusions:
Local-dose effects are predicted to be significantly reduced by an IRS. The spatial NTCP model predicts a significant decrease in Gr 2 late rectal bleeding and subjective sphincter control. Dose constraints can be improved for current clinical treatment planning.
Related Concept Videos
Assessment of the Rectum and Anus
Rectal Inspection
Begin by inspecting the perianal and anal areas for color, texture, rashes,...
Benefits of Self-Esteem
Assessing Body Temperature - Rectal
Follow these steps for rectal temperature assessment:
Step 1: Perform hand hygiene and don clean gloves to prevent cross-infection.
Step 2: Position the patient in a side-lying position to better visualize the rectal...
Plant Cell Wall
Dose Size and Dosing Frequency: Determination Methods
Local Anesthetics: Clinical Application as Surface, Infiltration, and Conduction Block Anesthesia

