AimsThe aim of the study was to assess the effect on rectal consistency, of introducing a micro-enema in the preparation of patients receiving radiotherapy treatment of urinary bladder cancer.Materials and methodsThe treatment cone beam computed tomography (CBCT) images from patients receiving radiotherapy for bladder cancer were retrospectively assessed. CBCT datasets from nine patients treated without rectal preparation (97 CBCT), and 13 patients (134 CBCT) treated following micro-enema use before planning and treatment were evaluated. CBCT were compared with the planning computed tomography for rectal status, rectal diameter and presence of gas.ResultsReproducibility of an empty rectum was achieved in 70% of treatment fractions delivered using an enema protocol compared with 33% of fractions delivered without preparation. In total, 10% of fractions were delivered with the presence of faeces or faeces and gas, compared with 46% of fractions for the non-intervention group. Enemas did not affect the proportion of fractions delivered with gas, however, where gas was present, 65% of CBCT fractions had <5% gas for patients using enemas compared with 32% without.FindingsThe use of a micro-enema before planning scan and each fraction was well tolerated and proved effective in managing and reducing inter-fraction variations in rectal volume and contents.
PurposeTo evaluate and develop an image-guided radiotherapy (IGRT) protocol for the effective treatment of prostate and pelvic lymph nodes.Methods and materialsThis study comprised of nine patients receiving radiotherapy for node negative prostate cancer, who had a pair of planar kV images taken for 37 treatment fractions. The positioning accuracy for both implanted fiducial markers and pelvic bony anatomy (surrogate for pelvic node position) was calculated using random and systematic errors. Appropriate margins were also determined. All patients followed a strict bladder and bowel protocol before computed tomography planning and treatment.ResultsIn total, 292 sets of images were used for fiducial marker and pelvic bone registration. A discrepancy of >5 mm between the fiducial markers and the anatomical pelvic bone was seen in 4% of treatment sessions. The maximum displacement observed between the fiducial match and the bone match was 7, 10 and 4 mm in the A/P (anterior/posterior), S/I (superior/inferior) and R/L (right/left) directions, respectively.ConclusionThe margins used in combination with an online IGRT strategy ensure both the fiducial match and the bone match correlate within 5 mm thus allows good coverage of both prostate and nodal target volumes. It is essential that this is combined with a strict bladder and rectal preparation protocol to ensure accuracy and reproducibility.
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