Limits...
Single versus multichannel applicator in high-dose-rate vaginal brachytherapy optimized by inverse treatment planning.

Bahadur YA, Constantinescu C, Hassouna AH, Eltaher MM, Ghassal NM, Awad NA - J Contemp Brachytherapy (2014)

Bottom Line: For the organs-at-risk rectum and bladder, the use of multichannel applicator demonstrated a noticeable dose reduction, when compared to single channel, but statistically significant for rectum only (p = 0.0001).For D2cc of rectum, an average fractional dose of 6.1 ± 0.7 Gy resulted for single channel vs. 5.1 ± 0.6 Gy for multichannel.The dosimetric benefit of fractional re-planning was demonstrated: DVH analysis showed large, but not statistically significant differences between first fraction plan and fractional re-planning, due to large inter-fraction variations for rectum and bladder positioning and filling.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, King Abdulaziz University Hospital, Jeddah, Saudi Arabia.

ABSTRACT

Purpose: To retrospectively compare the potential dosimetric advantages of a multichannel vaginal applicator vs. a single channel one in intracavitary vaginal high-dose-rate (HDR) brachytherapy after hysterectomy, and evaluate the dosimetric advantage of fractional re-planning.

Material and methods: We randomly selected 12 patients with endometrial carcinoma, who received adjuvant vaginal cuff HDR brachytherapy using a multichannel applicator. For each brachytherapy fraction, two inverse treatment plans (for central channel and multichannel loadings) were performed and compared. The advantage of fractional re-planning was also investigated.

Results: Dose-volume-histogram (DVH) analysis showed limited, but statistically significant difference (p = 0.007) regarding clinical-target-volume dose coverage between single and multichannel approaches. For the organs-at-risk rectum and bladder, the use of multichannel applicator demonstrated a noticeable dose reduction, when compared to single channel, but statistically significant for rectum only (p = 0.0001). For D2cc of rectum, an average fractional dose of 6.1 ± 0.7 Gy resulted for single channel vs. 5.1 ± 0.6 Gy for multichannel. For D2cc of bladder, an average fractional dose of 5 ± 0.9 Gy occurred for single channel vs. 4.9 ± 0.8 Gy for multichannel. The dosimetric benefit of fractional re-planning was demonstrated: DVH analysis showed large, but not statistically significant differences between first fraction plan and fractional re-planning, due to large inter-fraction variations for rectum and bladder positioning and filling.

Conclusions: Vaginal HDR brachytherapy using a multichannel vaginal applicator and inverse planning provides dosimetric advantages over single channel cylinder, by reducing the dose to organs at risk without compromising the target volume coverage, but at the expense of an increased vaginal mucosa dose. Due to large inter-fraction dose variations, we recommend individual fraction treatment plan optimization.

No MeSH data available.


Related in: MedlinePlus

The inter-fraction variation in rectum and bladder positioning (A) and filling (B), in sagittal view, for two representative patients. Figure 4A presents the patient with fraction 4; outstanding inter-fraction variations in OARs positioning is observed
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4300361&req=5

Figure 0004: The inter-fraction variation in rectum and bladder positioning (A) and filling (B), in sagittal view, for two representative patients. Figure 4A presents the patient with fraction 4; outstanding inter-fraction variations in OARs positioning is observed

Mentions: Table 2 summarizes the dosimetric comparison between single and multichannel inverse plans. The dosimetric benefit of fractional re-planning was also investigated, using inverse planning optimization and multichannel applicator, for 7 patients (who had more than one multichannel insertion) and 10 paired brachytherapy plans. The DVH analysis showed large, but not statistically significant differences between first fraction plan and fractional re-planning, for all dosimetric parameters analysed, and are revealed in Table 3 and Figure 3. Patient with fraction 4 presented outstanding inter-fraction variation and was excluded from statistical analysis, because the large dose differences and small sample size would have been affected the statistical results. While the D2cc of rectum varied with up to 23.4%, the bladder appeared to be more stable to inter-fraction variations, with differences of D2cc up to 11.3%. The differences were due to large inter-fraction variations for rectum and bladder positioning, as well as marked inconsistencies in OARs filling, as shown in Figure 4.


Single versus multichannel applicator in high-dose-rate vaginal brachytherapy optimized by inverse treatment planning.

Bahadur YA, Constantinescu C, Hassouna AH, Eltaher MM, Ghassal NM, Awad NA - J Contemp Brachytherapy (2014)

The inter-fraction variation in rectum and bladder positioning (A) and filling (B), in sagittal view, for two representative patients. Figure 4A presents the patient with fraction 4; outstanding inter-fraction variations in OARs positioning is observed
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4300361&req=5

Figure 0004: The inter-fraction variation in rectum and bladder positioning (A) and filling (B), in sagittal view, for two representative patients. Figure 4A presents the patient with fraction 4; outstanding inter-fraction variations in OARs positioning is observed
Mentions: Table 2 summarizes the dosimetric comparison between single and multichannel inverse plans. The dosimetric benefit of fractional re-planning was also investigated, using inverse planning optimization and multichannel applicator, for 7 patients (who had more than one multichannel insertion) and 10 paired brachytherapy plans. The DVH analysis showed large, but not statistically significant differences between first fraction plan and fractional re-planning, for all dosimetric parameters analysed, and are revealed in Table 3 and Figure 3. Patient with fraction 4 presented outstanding inter-fraction variation and was excluded from statistical analysis, because the large dose differences and small sample size would have been affected the statistical results. While the D2cc of rectum varied with up to 23.4%, the bladder appeared to be more stable to inter-fraction variations, with differences of D2cc up to 11.3%. The differences were due to large inter-fraction variations for rectum and bladder positioning, as well as marked inconsistencies in OARs filling, as shown in Figure 4.

Bottom Line: For the organs-at-risk rectum and bladder, the use of multichannel applicator demonstrated a noticeable dose reduction, when compared to single channel, but statistically significant for rectum only (p = 0.0001).For D2cc of rectum, an average fractional dose of 6.1 ± 0.7 Gy resulted for single channel vs. 5.1 ± 0.6 Gy for multichannel.The dosimetric benefit of fractional re-planning was demonstrated: DVH analysis showed large, but not statistically significant differences between first fraction plan and fractional re-planning, due to large inter-fraction variations for rectum and bladder positioning and filling.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, King Abdulaziz University Hospital, Jeddah, Saudi Arabia.

ABSTRACT

Purpose: To retrospectively compare the potential dosimetric advantages of a multichannel vaginal applicator vs. a single channel one in intracavitary vaginal high-dose-rate (HDR) brachytherapy after hysterectomy, and evaluate the dosimetric advantage of fractional re-planning.

Material and methods: We randomly selected 12 patients with endometrial carcinoma, who received adjuvant vaginal cuff HDR brachytherapy using a multichannel applicator. For each brachytherapy fraction, two inverse treatment plans (for central channel and multichannel loadings) were performed and compared. The advantage of fractional re-planning was also investigated.

Results: Dose-volume-histogram (DVH) analysis showed limited, but statistically significant difference (p = 0.007) regarding clinical-target-volume dose coverage between single and multichannel approaches. For the organs-at-risk rectum and bladder, the use of multichannel applicator demonstrated a noticeable dose reduction, when compared to single channel, but statistically significant for rectum only (p = 0.0001). For D2cc of rectum, an average fractional dose of 6.1 ± 0.7 Gy resulted for single channel vs. 5.1 ± 0.6 Gy for multichannel. For D2cc of bladder, an average fractional dose of 5 ± 0.9 Gy occurred for single channel vs. 4.9 ± 0.8 Gy for multichannel. The dosimetric benefit of fractional re-planning was demonstrated: DVH analysis showed large, but not statistically significant differences between first fraction plan and fractional re-planning, due to large inter-fraction variations for rectum and bladder positioning and filling.

Conclusions: Vaginal HDR brachytherapy using a multichannel vaginal applicator and inverse planning provides dosimetric advantages over single channel cylinder, by reducing the dose to organs at risk without compromising the target volume coverage, but at the expense of an increased vaginal mucosa dose. Due to large inter-fraction dose variations, we recommend individual fraction treatment plan optimization.

No MeSH data available.


Related in: MedlinePlus