Obesity does not influence prostate intrafractional motion

Abstract

IntroductionMotion of the prostate is problematic in the accurate delivery of external beam radiation therapy (EBRT) for prostate cancer. This study investigated the relationship between body mass index (BMI), an easily measured indicator of obesity, and prostate motion.MethodsProstate motion during EBRT was assessed by measuring the displacement of fiducial markers implanted within the prostate in 130 prostate cancer patients. Interfractional motion was corrected on daily imaging through pre‐treatment cone‐beam‐computed tomography (CBCT) and intrafractional motion measured using movie sequences captured using an electronic portal imaging device (EPID) during treatment delivery.ResultsThere was no statistically significant relationship between the mean intrafractional motion and BMI, except in the left‐right (LR) translation (P = 0.049) over the study population. For each BMI category, there was no statistical significance (P > 0.05) between any of the translations/rotations except LR (P = 0.003).ConclusionWhile intrafractional motion is an important consideration, prostate motion cannot be reliably predicted through measurement of patient's BMI.

Injection of hydrogel spacer increased intrafractional prostate motion during volumetric modulated arc therapy-stereotactic body radiation therapy for prostate cancer

“…Knowledge about parameters related to intrafractional prostate motion is absolutely limited. Brown et al (16) showed that there was no statistically signi cant relationship between intrafractional prostate motion and BMI by using linear regression analysis. Oates et al (17) investigated a relationship between maximum rectal diameter (MRD) and intrafractional prostate motion.…”

“…Less is known about risk factors related to intrafractional prostate motion. While the variability in location of external skin markers relative to internal anatomy in obese patients caused a signi cant difference in terms of interfractional prostate shift (15), there was no relationship between body mass index (BMI) and intrafractional prostate motion (16). It was reported that the shorter the maximum rectal diameter is, the less the intrafractional prostate motion is (17).…”

Injection of hydrogel spacer increased maximal intrafractional prostate motion in anterior and superior directions during volumetric modulated arc therapy-stereotactic body radiation therapy for prostate cancer

“…Less is known about risk factors related to intrafractional prostate motion. While the variability in location of external skin markers relative to internal anatomy in obese patients caused a significant difference in terms of interfractional prostate shift [21], there was no relationship between body mass index (BMI) and intrafractional prostate motion [22]. It was reported that the shorter the maximum rectal diameter is, the less the intrafractional prostate motion is [23].…”

Effect of patient thickness on acute gastrointestinal toxicities following radiotherapy for prostate cancer

“…In addition, several studies focused on the impact of patient size on other aspects of radiotherapy, namely patient setup accuracy [16,20,21] and radiation dosimetry [22][23][24], which may have an effect on radiation toxicities. Thereby, the relationship between patient size and toxicities is multifaceted.…”