Rectal Volume Research Articles

Dosimetric impact of variable air cavity within PTV for rectum cancer.

The aim of this study is to determine the impact of rectal air volume changes on treatment plan quality, and subsequently inform daily cone-beam computed tomography (CBCT) evaluation constraints, in terms of acceptable rectal air volume during treatment. Twelve rectal cancer patients who exhibited rectal air within the PTV on their planning CT were selected. A study was conducted to evaluate the deterioration in plan quality due to expanding air volume. For each case, the air cavity volume was isotropically expanded in three dimensions using predefined margins of 3, 5, 7, and 10mm, while deforming bladder and rectum contours. A constraint was applied to the bony anatomy to restrict the deformation. Treatment plans were then generated for all twelve patients by recalculating the reference plan with the expanded air cavity volume. As the air cavity expanded, the maximum relative change in D98% coverage, compared to the reference plan, decreased by 10.8%±3.5%, while the D2% increased by 3.5%±0.9%. The positioning of the air cavity notably influenced the D98% variability with the 3mm expansion. D98% coverage falls below 95% when the air cavity volume exceeds 17 cm3. On average, D2% coverage increased by 0.5% with each expansion. At the largest expansion, extensive coverage of 102% and 105% isodoses was observed compared to the reference plan. Air cavity volumes above 17 cm3 can potentially degrade the high-dose PTV coverage while increasing the regions covered by the 102% and 105% isodoses. Clinical CBCT guidelines were deduced, recommending a maximum threshold of 3.2cm in diameter in any direction.

Androgen Deprivation Benefits in Low-Dose-Rate Brachytherapy With Hydrogel Spacer.

We aim to investigate the impact of rectal dose reduction of both androgen deprivation therapy (ADT) and concurrent hydrogel spacer placement (HSP) in patients treated with low-dose-rate (LDR) brachytherapy for prostate cancerand to determine whether there are variations in the degree of efficacy of dose reduction across different segments of the rectum. This study involved 130 consecutive patients treated with I-125 LDR brachytherapy, with (ADT: n = 66) or without (nADT: n = 64) prior ADT, from June 2017 to April 2021. Among these, 13 ADT and 17 nADT patients underwent HSP following induction in May 2020, whereas the remaining patients (nHSP) included 53 ADT and 47 nADT individuals. In the post plan, a rectal dose assessment was made using the rectal volume (RV), divided by horizontal sections into three equal-length subparts (sRVs), such as high-, mid-, and low-RV. The mean sRV100 values were compared between the nADT and ADT patient groups, both with and without HSP. Similarly, mean sRV100 was compared between the nHSP and HSP patient groups, both with and without ADT. In nADT patients, HSP significantly reduced the mean RV100 of the high-RV (0.002 cc versus 0.086 cc, p < 0.05) and mid-RV (0.127 cc versus 0.377 cc, p < 0.05), but not of the low-RV (0.060 cc versus 0.150 cc, p = 0.06). In contrast, in ADT patients, HSP significantly reduced the RV100 at all three sites (0.002 cc versus 0.031 cc, p < 0.05; 0.034 cc versus 0.269 cc, p < 0.05; and 0.015 cc versus 0.151 cc, p < 0.05, respectively). No significant difference was observed when comparing mean sRV100 with or without ADT in both HSP and nHSP patients. The combination of ADT and HSP for LDR prostate brachytherapy showed the potential to significantly reduce RV100, especially in the lower rectum.

Long-term evaluation of the safety of a rectal-prostate spacer, the ProSpace® balloon, in patients treated with radiotherapy for prostate cancer

BackgroundDue to the close proximity of the prostate and rectum, rectal toxicity remains a major problem in patient treated by radiotherapy for prostate adenocarcinoma. One method of increasing the distance between the prostate and the rectum is to use a spacer implanted into the rectoprostatic space. This report describes the long-term outcomes obtained with a new ballon spacer.MethodsPatients treated with curative radiotherapy for low- or intermediate-risk prostate adenocarcinoma, who underwent insertion of the ProSpace® (BioProtect Ltd, Tzur Yigal, Israel) rectal-prostate balloon spacer, were included. The main objective was to evaluate the dosimetric benefit of the spacer for OARs. The secondary objectives were to evaluate the feasibility and tolerability of ProSpace® balloon placement and to evaluate its long-term therapeutic efficacy and tolerance.ResultsBetween October 2013 and March 2015, 16 patients were enrolled in the Pasteur Clinic, Toulouse, France. The median follow-up was 85.5 months. From top to bottom, the space created was a mean of 16.3 mm (range: 11–20.5 mm) at the base of the prostate, 12.1 mm (range: 4–16 mm) at the middle and 8.9 mm at the apex (range: 5–15 mm). On average, rectal volumes receiving a dose of 70 Gy, 60 Gy and 50 Gy were significantly lower after balloon implantation: -4.81 cc (1.5 vs. 6.3; p < 0.0005), -8.08 cc (6.4 vs. 14.5; p = 0.002) and -9.06 cc (16.7 vs. 25.7; p = 0.003), respectively. There were significant differences in coverage after balloon implantation: Median V95% (p < 0.0005), median Dmin (p = 0.01) and median V98% (p < 0.001) were higher after balloon implantation. At 5 years, cumulative gastrointestinal toxicity was grade 1 in 6% (1/16 patients). No toxicity of grade 2 or higher was found. At 5 years, no urinary toxicity grade 3 or 4 toxicity was found. The QoL was not deteriorated.ConclusionsThe use of the ProSpace® balloon seems to be well accepted by patients, allowing a double dosimetric gain: a decrease in doses received by the rectum and an improvement in the coverage of the high-risk PTV. The long-term gastrointestinal toxicity remains low and QoL is preserved in all treated patients.

Correlation between dose-volume parameters and rectal bleeding after 12 fractions of carbon ion radiotherapy for prostate cancer.

Carbon ion radiotherapy (CIRT) is currently used to treat prostate cancer. Rectal bleeding is a major cause of toxicity even with CIRT. However, to date, a correlation between the dose and volume parameters of the 12 fractions of CIRT for prostate cancer and rectal bleeding has not been shown. Similarly, the clinical risk factors for rectal bleeding were absent after 12 fractions of CIRT. To identify the risk factors for rectal bleeding in 12 fractions of CIRT for prostate cancer. Among 259 patients who received 51.6 Gy [relative biological effectiveness (RBE)], in 12 fractions of CIRT, 15 had grade 1 (5.8%) and nine had grade 2 rectal bleeding (3.5%). The dose-volume parameters included the volume (cc) of the rectum irradiated with at least x Gy (RBE) (Vx) and the minimum dose in the most irradiated x cc normal rectal volume (Dx). The mean values of D6cc, D2cc, V10 Gy (RBE), V20 Gy (RBE), V30 Gy (RBE), and V40 Gy (RBE) were significantly higher in the patients with rectal bleeding than in those without. The cutoff values were D6cc = 34.34 Gy (RBE), D2cc = 46.46 Gy (RBE), V10 Gy (RBE) = 9.85 cc, V20 Gy (RBE) = 7.00 cc, V30 Gy (RBE) = 6.91 cc, and V40 Gy (RBE) = 4.26 cc. The D2cc, V10 Gy (RBE), and V20 Gy (RBE) cutoff values were significant predictors of grade 2 rectal bleeding. The above dose-volume parameters may serve as guidelines for preventing rectal bleeding after 12 fractions of CIRT for prostate cancer.

Relation between the internal anal sphincter and defecation disorders in patients with anorectal malformations.

To investigate associations between the rectoanal inhibitory reflex (RAIR), type of congenital anorectal malformations (ARMs), type of operation that patients with ARM had undergone, and objectively measured fecal incontinence and defecation problems. We retrospectively included 69 pediatric patients with ARM. All underwent anorectal function tests at the University Medical Center of Groningen during the last 10 years. We assessed anorectal physiology using the Rome IV criteria and anorectal function tests. We found the reflex in 67% of patients and all types of ARMs. All patients who had not been operated on, and those who had undergone less extensive surgery possessed the reflex. In contrast, patients who underwent posterior sagittal anorectoplasty, 44% possessed it. We found no difference between mean rectal volumes in patients with and without the reflex (251 vs. 325 mL, respectively, p = 0.266). We found that over time, patients without the reflex seemed to develop significantly higher rectal volumes than patients who had it. We did not find a significant difference between the reflex and fecal incontinence; however, it seems that the absence of the reflex, resting anal sphincter pressure, and fecal incontinence are related. The RAIR seems present in patients with ARM irrespective of their malformation type. Corrective surgery, however, may impair this reflex. Seemingly, its absence results in constipation with enlarged rectal volumes and fecal incontinence. Every effort should be made to preserve this reflex during surgery and to use extensive surgical procedures as sparingly as possible.

Deformable anthropomorphic pelvis phantom for dose accumulation verification

Objective. The validation of deformable image registration (DIR) for contour propagation is often done using contour-based metrics. Meanwhile, dose accumulation requires evaluation of voxel mapping accuracy, which might not be accurately represented by contour-based metrics. By fabricating a deformable anthropomorphic pelvis phantom, we aim to (1) quantify the voxel mapping accuracy for various deformation scenarios, in high- and low-contrast regions, and (2) identify any correlation between dice similarity coefficient (DSC), a commonly used contour-based metric, and the voxel mapping accuracy for each organ. Approach. Four organs, i.e. pelvic bone, prostate, bladder and rectum (PBR), were 3D printed using PLA and a Polyjet digital material, and assembled. The latter three were implanted with glass bead and CT markers within or on their surfaces. Four deformation scenarios were simulated by varying the bladder and rectum volumes. For each scenario, nine DIRs with different parameters were performed on RayStation v10B. The voxel mapping accuracy was quantified by finding the discrepancy between true and mapped marker positions, termed the target registration error (TRE). Pearson correlation test was done between the DSC and mean TRE for each organ. Main results. For the first time, we fabricated a deformable phantom purely from 3D printing, which successfully reproduced realistic anatomical deformations. Overall, the voxel mapping accuracy dropped with increasing deformation magnitude, but improved when more organs were used to guide the DIR or limit the registration region. DSC was found to be a good indicator of voxel mapping accuracy for prostate and rectum, but a comparatively poorer one for bladder. DSC > 0.85/0.90 was established as the threshold of mean TRE ⩽ 0.3 cm for rectum/prostate. For bladder, extra metrics in addition to DSC should be considered. Significance. This work presented a 3D printed phantom, which enabled quantification of voxel mapping accuracy and evaluation of correlation between DSC and voxel mapping accuracy.

Effect of synthetic CT on dose-derived toxicity predictors for MR-only prostate radiotherapy.

Toxicity-driven adaptive radiotherapy (RT) is enhanced by the superior soft tissue contrast of magnetic resonance (MR) imaging compared with conventional computed tomography (CT). However, in an MR-only RT pathway synthetic CTs (sCT) are required for dose calculation. This study evaluates 3 sCT approaches for accurate rectal toxicity prediction in prostate RT. Thirty-six patients had MR (T2-weighted acquisition optimized for anatomical delineation, and T1-Dixon) with same day standard-of-care planning CT for prostate RT. Multiple sCT were created per patient using bulk density (BD), tissue stratification (TS, from T1-Dixon) and deep-learning (DL) artificial intelligence (AI) (from T2-weighted) approaches for dose distribution calculation and creation of rectal dose volume histograms (DVH) and dose surface maps (DSM) to assess grade-2 (G2) rectal bleeding risk. Maximum absolute errors using sCT for DVH-based G2 rectal bleeding risk (risk range 1.6% to 6.1%) were 0.6% (BD), 0.3% (TS) and 0.1% (DL). DSM-derived risk prediction errors followed a similar pattern. DL sCT has voxel-wise density generated from T2-weighted MR and improved accuracy for both risk-prediction methods. DL improves dosimetric and predicted risk calculation accuracy. Both TS and DL methods are clinically suitable for sCT generation in toxicity-guided RT, however, DL offers increased accuracy and offers efficiencies by removing the need for T1-Dixon MR. This study demonstrates novel insights regarding the effect of sCT on predictive toxicity metrics, demonstrating clear accuracy improvement with increased sCT resolution. Accuracy of toxicity calculation in MR-only RT should be assessed for all treatment sites where dose to critical structures will guide adaptive-RT strategies. Patient data were taken from an ethically approved (UK Health Research Authority) clinical trial run at Guy's and St Thomas' NHS Foundation Trust. Study Name: MR-simulation in Radiotherapy for Prostate Cancer. ClinicalTrials.gov Identifier: NCT03238170.

Robot-Assisted Radical Prostatectomy in PIRADS 5 Lesions Without Prior Biopsy: Is Biopsy Really Necessary in This Cohort?

Introduction: Conventionally, confirmation of clinically significant prostate cancer (csPCa) (Gleason grade group ≥ 2) involves an initial multiparametric magnetic resonance imaging (mpMRI) followed by biopsy. Prostate biopsy incurs inherent risks of infection, bleeding, patient discomfort, and a 6-week delay before robot-assisted laparoscopic radical prostatectomy (RALP). We explored the feasibility of immediate RALP in men with PIRADS 5 lesions without preceding biopsy. Methodology: After obtaining institutional review board approval, a prospective analysis was conducted on 235 patients with PIRADS 5 lesions on mpMRI from December 2018 to February 2023. Patients were divided into 2 groups as follows: Group NoBiopsy (biopsy not done before RALP, cases, n = 118) and Group YesBiopsy (biopsy done before RALP, controls, n = 117). Baseline preoperative, intraoperative, and postoperative parameters were analyzed. Functional outcomes were monitored at 1, 3-, 6-, 9-, and 12-months follow-up post-RALP. Statistical analysis was performed using SPSS and STATA. Results: Ninety-five percent of cases and 87.17% controls had csPCa on final pathology post-RALP. Multivariable analysis did not find significant association between biopsy status and csPCa. Abnormal digital rectal examination (DRE), family history, preoperative PSA, and MRI lesion volume predicted csPCa. Significant differences were observed in console time (NoBiopsy vs. YesBiopsy, 60 ± 10 vs. 70 ± 9 minutes, p < 0.001) and estimated blood loss (80 ± 20 vs. 100 ± 30 mL, p < 0.01) between groups. At 6 months post-RALP, 96% of men in Group NoBiopsy were continent, compared with 88% of men in Group YesBiopsy (p < 0.04). All men in the study cohort were continent (0 pads) at 12 months post-RALP. Ninety-eight percent of cases and 92% of controls at 9 months and 12 months, respectively, were able to have penetrative sex with or without PDE-5 inhibitors post-RALP. Conclusion: RALP without antecedent prostate biopsy in men with PIRADS 5 lesions demonstrated substantial csPCa detection rates and superior functional outcomes, warranting further validation.

Rectal volume is correlated with interfractional positional shifts of the prostate gland in dogs receiving radiation therapy.

Variability in prostate gland positioning during RT for prostate tumors is a recognized challenge in both human and veterinary oncology. This retrospective study investigates the interfractional variability in prostate gland positioning in relation to rectal and bladder volumes in dogs undergoing radiation therapy (RT) for prostate tumors. The study tracked 10 dogs undergoing five RT sessions from February 2016 to November 2021, delivering a total of 25Gy each. Each dog underwent CT scans for treatment simulation, and cone-beam CT (CBCT) images were acquired before each RT. The focus was to analyze the positional shifts of the prostate gland concerning the volumes of the rectum and urinary bladder. The pelvic bones were used as the point of reference. The rectal and bladder volumes were measured before each RT, and shifts in the prostate gland position were calculated by comparing coordinates from planning CT and treatment session images. Findings revealed significant correlations between prostate positional shifts in the dorsal-ventral (repeated measures correlation coefficient of -0.58 [range 00.75-00.33]; P<.001) and cranial-caudal directions (repeated measures correlation coefficient [95%CI] 0.56 [range 0.31-0.74]; P<.001) and rectal volume, while no significant relationship was observed with bladder volume. Shifts in the lateral direction were not correlated with either organ's volume. This study highlights the importance of considering rectal volume in canine prostate tumor RT to minimize positional uncertainties. Maintaining consistent rectal volume may enhance the precision of prostate targeting, potentially influencing the safety of RT.

Assessment of Changes of Bladder Volume and Rectal Volume Using 4DCT Scan During External Beam Radiotherapy for Cervical Cancer- Observation Study

Assessment of Changes of Bladder Volume and Rectal Volume Using 4DCT Scan During External Beam Radiotherapy for Cervical Cancer- Observation Study

Daily Online Adaptive Radiation Therapy of Postoperative Endometrial and Cervical Cancer With PTV Margin Reduction to 5 mm: Dosimetric Outcomes, Acute Toxicity, and First Clinical Experience

PurposeThis study evaluated the first clinical implementation of daily iterative cone-beam computed tomography (iCBCT)-guided online adaptive radiotherapy (oART) in the postoperative treatment of endometrial and cervical cancer. Methods and MaterialsSeventeen consecutive patients treated with daily iCBCT-guided oART were enrolled in this prospective study, with a reduced uniform three-dimensional PTV margin of 5 mm. Treatment plans were designed to deliver 45 or 50.4 Gy in 1.8 Gy daily fractions to PTV. Pre- and posttreatment ultrasound and iCBCT scans were performed to record intrafractional bladder and rectal volume changes. The accuracy of contouring, oART procedure time, dosimetric outcomes and acute toxicity were evaluated. ResultsThe average time from first iCBCT acquisition to completion of treatment was 22 min and 26 s. During this period, bladder volume increased by 44 cm3 using iCBCT contouring, while rectal volume remained stable (62.9 cm3 pretreatment vs. 61.9 cm3 posttreatment). A total of 91.6% of influencers and 88.1% of CTVs required no or minor edits. The adapted plan was selected in all (434) fractions and significantly improved the dosimetry coverage for CTV and PTV, especially the vaginal PTV coverage by nearly 7% (p<0.05). The adapted bladder Dmean was 104.61 cGy, and the rectum Dmean was 123.67 cGy, significantly lower than the scheduled plan of 108.24 and 128.19 cGy, respectively. The bone marrow, femur head left and right dosimetry were also improved with adaptation. Grade 2 acute gastrointestinal and genitourinary toxicities were 24% and 0, respectively. There was a Grade 3 acute toxicity of decreased white blood cell count in one patient. ConclusionsDaily oART was associated with favourable dosimetry improvement and low acute toxicity, supporting its safety and efficacy for postoperative treatment of endometrial and cervical cancer. These results need to be validated in a larger prospective randomized controlled cohort.

Radiation Proctitis in Patients With Locally Advanced Cervical Cancer Treated by Chemoradiation: Analysis and Predictive Factors From a Retrospective Cohort.

Radiation proctitis is a misunderstanding complication of chemoradiation in locally advanced cervical cancer. The objective of our study is to provide a detailed description and analysis of predictive factors associated with radiation proctitis in a retrospective cohort of patients treated by chemoradiation for locally advanced cervical cancer. All patients treated by exclusive chemoradiation or chemoradiation followed by brachytherapy for locally advanced cervical cancer from 2011 to 2017 were included in the study. A bivariate analysis was conducted to establish correlations between the occurrence of radiation proctitis and various clinical and technical variables. A total of 128 patients were included in the study. The mean dose (SD) to the planning target volume was 47.1Gy (6.2). Fifty-nine (46.1%) patients underwent brachytherapy. Sixteen patients (12.5%) developed radiation proctitis, grade 2 or higher in 12 patients (9.3%). In univariate analysis, anticoagulant or antiplatelet treatments ( P =0.039), older age ( P =0.049), rectal volume irradiated at 40Gy ( P =0.01) and 30Gy ( P =0.037) were significantly associated with the occurrence of a grade ≥2 radiation proctitis. The delivered dose to 2cm 3 of rectum (D2cm 3 ) showed a potential association with the occurrence of radiation proctitis of all grades ( P =0.064). This study highlights clinical and technical factors that should be considered in assessing the risk of radiation proctitis. These results contribute to a better understanding of this complication.

Preventing Rectal Toxicity in Prostate Cancer: Diet and Supplement Alternative to Enemas or Rectal Spacer

Background: Rectal toxicity is an important side effect of prostate cancer irradiation affecting 25% of patients. The role of dosimetric variables has a set of dose-volume constraints and curves to estimate the risk of rectal damage. The rectum position at the time of CT planning is different from the position during radiotherapy. Three methods are available to achieve optimal rectum position: enema; prostate cancer spacer; fiber-/fat-free diet. Methods: A 70.2 Gray radiation divided into 26 hypo-fractions was administered to 115 patients with prostate cancer by VMAT referred to a single center in Italy. To empty the rectum, all patients were administered a fiber-/fat-free diet and those with Eating Disorders (ED) were also added with activated charcoal (2 tablets/day) and a macrogol-based medical device (2 sachets/day). During treatment, the volumetric amount of rectum in the target was measured by comparing control-CT with simulation-CT, and acute toxicity was also checked. Results: The rectum position during control-CT in diet-only patients (29) predicted toxicity recorded during treatment, while in the ED group rectum position was adherent to position during simulations. Rectal volume target &gt; 0.25 cc receiving a dose &gt; V70 caused acute G3 toxicity that attenuated or worsened with rectal displacement. Acute rectal toxicity occurred in 6/29 (20.68%) patients (1 G3, 5 G1) in the diet-only group, while only in 1/86 (1.16%) patients (G1) in the ED group. No chronic toxicity was recorded in either group. Conclusion: Prostate cancer patients treated with VMAT, diet, charcoal, and macrogol emptied the rectum optimally and reduced incidence and severity of acute rectal toxicity, also with benefit on late toxicity.

A Review of the Efficacy of the Low Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols (FODMAP) Diet in Managing Gastrointestinal Symptoms Related to Cancer Treatment.

The low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) diet, designed to alleviate symptoms in individuals with irritable bowel syndrome (IBS), focuses on limiting the consumption of poorly absorbed fermentable carbohydrates known as FODMAP. These FODMAP are believed to be the primary triggers for food-related gastrointestinal symptoms in functional gastrointestinal disorders. However, there is currently insufficient direct evidence investigating the role of low FODMAP diets in cancer patients undergoing treatment. This review aims to summarize the current evidence on the low FODMAP diet and its potential implications for cancer patients in terms of treatment outcomes, alleviating gastrointestinal symptoms, and overall health. A systematic literature search was conducted using databases, including PubMed, Scopus, Google Scholar, Web of Science, and Cochrane. Five studies met the criteria for inclusion in the review, and these studies covered rectal toxicity during radiotherapy, gastrointestinal symptoms in colorectal cancer patients, acute gastrointestinal toxicity during pelvic external beam radiotherapy, symptoms in patients with radiation-induced enteropathy, and chronic gastrointestinal sequelae resulting from pelvic organ cancer treatment. The available evidence suggests that a low FODMAP diet may offer advantages in reducing rectal gas and volume during radiotherapy, alleviating diarrhea symptoms, reducing symptom deterioration, and improving quality of life. However, these studies highlight the need for large-scale randomized trials, long-term follow-up, and guidelines to establish the efficacy, safety, and implementation strategies of the low FODMAP diet in different cancer contexts and patient populations. While preliminary findings reported some possible benefits of a low FODMAP diet for certain cancer patients, rigorous studies with large sample sizes are needed to provide more robust evidence. Further research is warranted to optimize the utilization of this diet as an adjunctive intervention for managing gastrointestinal symptoms in this population.

The use of dose surface maps as a tool to investigate spatial dose delivery accuracy for the rectum during prostate radiotherapy.

This study aims to address the lack of spatial dose comparisons of planned and delivered rectal doses during prostate radiotherapy by using dose-surface maps (DSMs) to analyze dose delivery accuracy and comparing these results to those derived using DVHs. Two independent cohorts were used in this study: twenty patients treated with 36.25Gy in five fractions (SBRT) and 20 treated with 60Gy in 20 fractions (IMRT). Daily delivered rectum doses for each patient were retrospectively calculated using daily CBCT images. For each cohort, planned and average-delivered DVHs were generated and compared, as were planned and accumulated DSMs. Permutation testing was used to identify DVH metrics and DSM regions where significant dose differences occurred. Changes in rectal volume and position between planning and delivery were also evaluated to determine possible correlation to dosimetric changes. For both cohorts, DVHs and DSMs reported conflicting findings on how planned and delivered rectum doses differed from each other. DVH analysis determined average-delivered DVHs were on average 7.1%±7.6% (p ≤ 0.002) and 5.0±7.4% (p ≤ 0.021) higher than planned for the IMRT and SBRT cohorts, respectively. Meanwhile, DSM analysis found average delivered posterior rectal wall dose was 3.8±0.6Gy (p=0.014) lower than planned in the IMRT cohort and no significant dose differences in the SBRT cohort. Observed dose differences were moderately correlated with anterior-posterior rectal wall motion, as well as PTV superior-inferior motion in the IMRT cohort. Evidence of both these relationships were discernable in DSMs. DSMs enabled spatial investigations of planned and delivered doses can uncover associations with interfraction motion that are otherwise masked in DVHs. Investigations of dose delivery accuracy in radiotherapy may benefit from using DSMs over DVHs for certain organs such as the rectum.

Surgical effect and gastrointestinal functional recovery of laparoscopic-guided total mesorectal excision in patients with rectal cancer.

To explore the surgical effect and gastrointestinal functional recovery of laparoscopic-guided total mesorectal excision (LGTME) in patients with rectal cancer. A total of 150 rectal cancer patients who underwent surgical treatment in our hospital from July 2022 to July 2023 were selected and randomly divided into two groups using a random number table. There were 75 cases in the control group (CG) who underwent traditional open rectal total mesorectal excision surgery and 75 cases in the experimental group (EG) who underwent LGTME. The surgical effects of the two groups were compared, and the gastrointestinal and anal functional recovery of the two groups were compared before and after treatment. Intraoperative bleeding, incision length, time to initial feeding and time to anal exhaust in the EG were significantly lower than those in the CG ( P < 0.05). Before treatment, there was no significant difference in gastrointestinal function and anal function between the two groups ( P > 0.05). After treatment, the levels of motilin, gastrin, neuropeptide Y and basic fibroblast growth factor in the EG were significantly higher than those in the CG, with statistical significance ( P < 0.05); the maximum anal systolic pressure and resting anal sphincter pressure in the EG were significantly lower than those in the CG ( P < 0.05); the rectal sensitivity threshold volume (RSTV) and rectal maximum volume threshold in the EG were significantly higher than those in the CG ( P < 0.05). There was no significant difference in most postoperative complications between the two groups ( P > 0.05). LGTME improves the surgical effects of rectal cancer patients, promotes the recovery of gastrointestinal function and has a small effect on anal function indicators, thereby reducing hospital stay.

Dosimetric Comparison Study of Proton Therapy Using Line Scanning versus Passive Scattering and Volumetric Modulated Arc Therapy for Localized Prostate Cancer.

The proton irradiation modality has transitioned from passive scattering (PS) to pencil beam scanning. Nevertheless, the documented outcomes predominantly rely on PS. Thirty patients diagnosed with prostate cancer were selected to assess treatment planning across line scanning (LS), PS, and volumetric modulated arc therapy (VMAT). Dose constraints encompassed clinical target volume (CTV) D98 ≥ 73.0 Gy (RBE), rectal wall V65 < 17% and V40 < 35%, and bladder wall V65 < 25% and V40 < 50%. The CTV, rectal wall, and bladder wall dose volumes were calculated and evaluated using the Freidman test. The LS technique adhered to all dose limitations. For the rectal and bladder walls, 10 (33.3%) and 21 (70.0%) patients in the PS method and 5 (16.7%) and 1 (3.3%) patients in VMAT, respectively, failed to meet the stipulated requirements. The wide ranges of the rectal and bladder wall volumes (V10-70) were lower with LS than with PS and VMAT. LS outperformed VMAT across all dose-volume rectal and bladder wall indices. The LS method demonstrated a reduction in rectal and bladder doses relative to PS and VMAT, thereby suggesting the potential for mitigating toxicities.

Predicting cervical cancer target motion using a multivariate regression model to enable patient selection for adaptive external beam radiotherapy

Background and purposeInterfraction motion during cervical cancer radiotherapy is substantial in some patients, minimal in others. Non-adaptive plans may miss the target and/or unnecessarily irradiate normal tissue. Adaptive radiotherapy leads to superior dose-volume metrics but is resource-intensive. The aim of this study was to predict target motion, enabling patient selection and efficient resource allocation. Materials and methodsForty cervical cancer patients had CT with full-bladder (CT-FB) and empty-bladder (CT-EB) at planning, and daily cone-beam CTs (CBCTs). The low-risk clinical target volume (CTVLR) was contoured. Mean coverage of the daily CTVLR by the CT-FB CTVLR was calculated for each patient. Eighty-three investigated variables included measures of organ geometry, patient, tumour and treatment characteristics. Models were trained on 29 patients (171 fractions). The Two-CT multivariate model could use all available data. The Single-CT multivariate model excluded data from the CT-EB. A univariate model was trained using the distance moved by the uterine fundus tip between CTs, the only method of patient selection found in published cervix plan-of-the-day studies. Models were tested on 11 patients (68 fractions). Accuracy in predicting mean coverage was reported as mean absolute error (MAE), mean squared error (MSE) and R2. ResultsThe Two-CT model was based upon rectal volume, dice similarity coefficient between CT-FB and CT-EB CTVLR, and uterine thickness. The Single-CT model was based upon rectal volume, uterine thickness and tumour size. Both performed better than the univariate model in predicting mean coverage (MAE 7 %, 7 % and 8 %; MSE 82 %2, 65 %2, 110 %2; R2 0.2, 0.4, −0.1). ConclusionUterocervix motion is complex and multifactorial. We present two multivariate models which predicted motion with reasonable accuracy using pre-treatment information, and outperformed the only published method.

The Role of Digital Rectal Examination Prostate Volume Category in the Early Detection of Prostate Cancer: Its Correlation with the Magnetic Resonance Imaging Prostate Volume.

To relate the prostate volume category (PVC) assessed with digital rectal examination (DRE)-small, median, and large-and the prostate volumes (PVs) assessed with magnetic resonance imaging (MRI) and transrectal ultrasound (TRUS). To compare the clinically significant prostate cancer (csPCa) discrimination ability of two predictive models based on DRE-PVC and MRI-PV. A prospective trial of 2,090 men with prostate-specific antigen >3 ng/mL and/or PCa suspicious DRE were prospectively recruited in 10 centers from Catalonia (Spain), between 2021 and 2022, in whom DRE-PVC was assessed. Pre-biopsy MRI, and 12-core TRUS-random biopsy was always performed after 2- to 6-core TRUS-fusion targeted biopsy of prostate imaging-report and data system >3 lesions. In 370 men (17.7%) the DRE-PVC was unconclusive. Among the 1,720 men finally analyzed the csPCa (grade group >2) detection was 42.4%. The median (interquartile range) of TRUS and MRI-PVs of small prostates were 33 mL (19-37 mL) and 35 mL (23-30 mL), p=0.410; in median prostates they were 51 mL (38-58 mL) and 55 mL (48-63 mL) respectively, p<0.001; in large prostates 80 mL (60-100 mL) and 95 mL (75-118 mL) respectively, p<0.001. The predictive models sharing the MRI-PV and DRE-PVC showed areas under the curves of 0.832 (95% confidence interval [CI], 0.813-0.851) and 0.828 (95% CI, 0.809-0.848) respectively, p=0.632, as well as similar net benefit and clinical utility. PVC was unconclusive in 17% of DREs. MRI-PV overestimated the TRUS-PV in median and large prostates. The predictive models based on MRI-PV and DRE-PVC showed similar efficacy to predict csPCa. PVC assessed with DRE is helpful to predict the csPCa risk before MRI.

Prognostic Value of Tumor Volume, Tumor Volume Reduction Rate and Magnetic Resonance Tumor Regression Grade in Rectal Cancer.

Background and Objectives: Rectal cancer poses significant treatment challenges, especially in advanced stages. Radiologic assessment, particularly with MRI, is critical for surgeons and oncologists to understand tumor dynamics and tailor treatment strategies to improve patient outcomes. The purpose of this study was to correlate MRI-based tumor volumetric and tumor regression grade analysis in patients with advanced rectal cancer, assessing the impact of preoperative chemotherapy (CT) alone or chemoradiotherapy (CRT) on surgical technique choices. Materials and Methods: Between 2015 and 2022, a prospective study was enrolled, including a cohort of 89 patients diagnosed with rectal cancer at stage II or III. The participants were divided into two distinct therapy groups, ensuring an equal distribution with a ratio of 1:1. The initial group was treated with the contemporary preoperative chemotherapy protocol FOLFOX4. In contrast, the alternative group received conventional preoperative chemoradiotherapy. Before surgery, each patient underwent a rectal MRI scan at 1.5 T, including T2-weighted and diffusion-weighted imaging (DWI) sequences. Results: The CT group showed a 36.52% tumor volume reduction rate (TVRR), and the CRT group showed 54.87%, with varying magnetic resonance and pathological tumor regression grades (mrTRG and pTRG). Analysis revealed a significant interaction between mrTRG and tumor volumetrics (volume and VRR) in both groups, especially CRT, underscoring the complexity of tumor response. Both treatment groups had similar initial tumor volumes, with CRT displaying a higher TVRR, particularly in higher pathological TRG (3/4) cases. This interaction and the strong correlation between mrTRG and pTRG suggest mrTRG's role as a non-invasive predictor for treatment response, highlighting the need for personalized treatment plans. Conclusions: Rectal tumor volume, volume reduction rate, and mrTRG are not just abstract measures; they are concrete indicators that have a direct and practical impact on surgical decision-making, planning, and prognosis, ultimately influencing the quality of care and life expectancy of patients with rectal cancer.