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Effect of constipation on dosimetry after permanent seed brachytherapy for prostate cancer.

Otón LF, Dolado MC, Núñez EJ, Otón CA - J Contemp Brachytherapy (2015)

Bottom Line: Target volumes and organs at risk were delineated, and dosimetric parameters were calculated and then compared for each patient between both CT.For rectum, D2cc increased 15.8% (p < 0.001) and D0.1cc 24.05% (p = 0.002) when the rectum was full.A significant difference was also found in dose distribution to prostate, when rectum is distended, a 1% decrease in V100 (p = 0.031) and a 3.25% in D90 (p = 0.033) was registered.

View Article: PubMed Central - PubMed

Affiliation: Radiation Oncology Department, Hospital Universitario de Canarias ; Department of Physical Medicine and Pharmacology, La Laguna University.

ABSTRACT

Purpose: A major concern in prostate brachytherapy is rectal toxicity, which mainly depends on the dose and volume of rectum involved by radiation. We hypothesize that the rectal distension, as produced by constipation, influences the dosimetric parameters of the rectum and other pelvic organs.

Material and methods: An open, controlled, prospective, paired trial (pre-post test) was designed and conducted. Twenty-three patients treated with prostate brachytherapy were recruited, of which 21 were evaluated. All of them underwent two CT scans, the first one with empty rectum and the second with rectum distended by a catheter balloon. Target volumes and organs at risk were delineated, and dosimetric parameters were calculated and then compared for each patient between both CT.

Results: For rectum, D2cc increased 15.8% (p < 0.001) and D0.1cc 24.05% (p = 0.002) when the rectum was full. A significant difference was also found in dose distribution to prostate, when rectum is distended, a 1% decrease in V100 (p = 0.031) and a 3.25% in D90 (p = 0.033) was registered.

Conclusions: The status of rectal distension, as occurs in constipation, has a deleterious influence on prostate brachytherapy dosimetry. This situation increases the radiation to rectum and modifies dose distribution to prostate. We recommend prevention of constipation for at least two half lives of the radioactive seeds.

No MeSH data available.


Related in: MedlinePlus

A) Computed tomography image with “empty rectum” status. B) Same patient, same slice with “full rectum” status: balloon filled with air. Note differences not only in rectum but also in prostate shape
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Figure 0001: A) Computed tomography image with “empty rectum” status. B) Same patient, same slice with “full rectum” status: balloon filled with air. Note differences not only in rectum but also in prostate shape

Mentions: In this position, the first set of images was collected using standardized helical computed tomography at 120 kV and 100 mA. Images included from the upper edge of the sacroiliac joint to the penile bulb. Reconstructions were performed 3 mm thick and 3 mm of spacing between slices. In this first set of images, the investigator ensured that the rectum was completely empty, and that there was no abnormality, which could invalidate the data. These CT images correspond to the empty rectum status (Figure 1A). Then, preventing any movement of the patient, the rectum was dilated by inflating the balloon of the catheter with 30 cc of air. Gently pulling the catheter, the balloon was displaced to lodge in the lowest part of the rectum. One second CT scan was then performed in the same conditions as the first. This second set of images corresponds to the full rectum status (Figure 1B).


Effect of constipation on dosimetry after permanent seed brachytherapy for prostate cancer.

Otón LF, Dolado MC, Núñez EJ, Otón CA - J Contemp Brachytherapy (2015)

A) Computed tomography image with “empty rectum” status. B) Same patient, same slice with “full rectum” status: balloon filled with air. Note differences not only in rectum but also in prostate shape
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4643726&req=5

Figure 0001: A) Computed tomography image with “empty rectum” status. B) Same patient, same slice with “full rectum” status: balloon filled with air. Note differences not only in rectum but also in prostate shape
Mentions: In this position, the first set of images was collected using standardized helical computed tomography at 120 kV and 100 mA. Images included from the upper edge of the sacroiliac joint to the penile bulb. Reconstructions were performed 3 mm thick and 3 mm of spacing between slices. In this first set of images, the investigator ensured that the rectum was completely empty, and that there was no abnormality, which could invalidate the data. These CT images correspond to the empty rectum status (Figure 1A). Then, preventing any movement of the patient, the rectum was dilated by inflating the balloon of the catheter with 30 cc of air. Gently pulling the catheter, the balloon was displaced to lodge in the lowest part of the rectum. One second CT scan was then performed in the same conditions as the first. This second set of images corresponds to the full rectum status (Figure 1B).

Bottom Line: Target volumes and organs at risk were delineated, and dosimetric parameters were calculated and then compared for each patient between both CT.For rectum, D2cc increased 15.8% (p < 0.001) and D0.1cc 24.05% (p = 0.002) when the rectum was full.A significant difference was also found in dose distribution to prostate, when rectum is distended, a 1% decrease in V100 (p = 0.031) and a 3.25% in D90 (p = 0.033) was registered.

View Article: PubMed Central - PubMed

Affiliation: Radiation Oncology Department, Hospital Universitario de Canarias ; Department of Physical Medicine and Pharmacology, La Laguna University.

ABSTRACT

Purpose: A major concern in prostate brachytherapy is rectal toxicity, which mainly depends on the dose and volume of rectum involved by radiation. We hypothesize that the rectal distension, as produced by constipation, influences the dosimetric parameters of the rectum and other pelvic organs.

Material and methods: An open, controlled, prospective, paired trial (pre-post test) was designed and conducted. Twenty-three patients treated with prostate brachytherapy were recruited, of which 21 were evaluated. All of them underwent two CT scans, the first one with empty rectum and the second with rectum distended by a catheter balloon. Target volumes and organs at risk were delineated, and dosimetric parameters were calculated and then compared for each patient between both CT.

Results: For rectum, D2cc increased 15.8% (p < 0.001) and D0.1cc 24.05% (p = 0.002) when the rectum was full. A significant difference was also found in dose distribution to prostate, when rectum is distended, a 1% decrease in V100 (p = 0.031) and a 3.25% in D90 (p = 0.033) was registered.

Conclusions: The status of rectal distension, as occurs in constipation, has a deleterious influence on prostate brachytherapy dosimetry. This situation increases the radiation to rectum and modifies dose distribution to prostate. We recommend prevention of constipation for at least two half lives of the radioactive seeds.

No MeSH data available.


Related in: MedlinePlus