Interfraction Prostate Movement in Bone Alignment After Rectal Enema for Radiotherapy

Abstract

PurposeTo assess the effect of a rectal enema on interfraction prostate movement in bone alignment (BA) for prostate radiotherapy (RT), we analyzed the spatial difference in prostates in a bone-matched setup.Materials and MethodsWe performed BA retrospectively with data from prostate cancer patients who underwent image-guided RT (IGRT). The prostate was identified with implanted fiducial markers. The setup for the IGRT was conducted with the matching of three fiducial markers on RT planning computed tomography images and those on two oblique kV x-ray images. Offline BA was performed at the same position. The coordinates of a virtual prostate in BA and a real prostate were obtained by use of the ExaxTrac/NovalisBody system, and the distance between them was calculated as the spatial difference. Interfraction prostate displacement was drawn from the comparison of the spatial differences.ResultsA total of 15 patients with localized prostate cancer treated with curative hypofractionated IGRT were enrolled. A total of 420 fractions were analyzed. The mean of the interfraction prostate displacements after BA was 3.12±2.00 mm (range, 0.20-10.53 mm). The directional difference was profound in the anterior-posterior and supero-inferior directions (2.14±1.73 mm and 1.97±1.44 mm, respectively) compared with the right-left direction (0.26±0.22 mm, p<0.05). The required margin around the clinical target volume was 4.97 mm with the formula of van Herk et al.ConclusionsThe interfraction prostate displacement was less frequent when a rectal enema was performed before the procedure. A rectal enema can be used to reduce interfraction prostate displacement and resulting clinical target volume-to-planning target volume margin.

A systematic review: Effectiveness of rectal emptying preparation in prostate cancer patients

“…There was no prospective randomized study comparing enemas to any other intervention, with most studies making comparisons with either retrospective cohorts 17 or previous published results. [22][23][24] The 1 small prospective study resulted in some improvement with reduced rectal volume and accompanying anterior-posterior prostate motion. 13 However, the rectal volume was only measured along the length of the prostate, which excludes the superior section of the rectum where the maximum changes occur, thus making comparison with other studies (where measurements of average rectal volume have been determined using the whole length of the rectum) difficult.…”

“…It is interesting that 1 of the studies suggested that care professionals administering the enemas may be a more effective strategy than self-administration. 24 There is also known variability between subjects in the ease of administering bowel preparation regimens and a difficulty in achieving rapid, reproducible, and effective cleansing with minimal discomfort. 25,26 Despite these drawbacks the use of enemas coupled with clear guidance on timing, use, and recording of rectal dimensions warrants further investigation with accompanying data regarding patient compliance, which is currently lacking.…”

“…Three studies investigated the use of enemas as a single intervention and found some reduction of rectal volume or prostate motion 13,17,24 (Table 3). The remaining 2 studies used enemas in combination with rectal emptying 22 and rectal emptying and diet 23 and reported reduced prostate motion compared with earlier published results (Table 3).…”

Effect of rectal enema on intrafraction prostate movement during image‐guided radiotherapy

“…Rectal enemas have been effective in reducing intrafraction prostate motion in this study and in another 17 and have also been reported to be efficient in decreasing interfraction prostate movement. 16,18 On this basis, we think that the use of rectal enemas is a feasible method for reducing prostate movement during RT.…”

Stereotactic Body Radiation Therapy Treatment for Prostate Cancer: From Setup to Delivery Strategies

“…Intermodality shifts between the different technologies seem comparable, as reported by Mayyas et al 20 Among the methods, localization using markers results in the least interuser disagreement compared with using anatomy or soft tissues. 14,21 Different authors have reported that the choice of imaging frequency and timing are key components in delivering the desired dose while reducing the associated overhead, such as imaging dose, preparation, and processing time.…”