Mastering Patient Preparation for Precise Balancing of Bladder and Rectal Radiation during Prostate Radiotherapy

Prostate cancer is the second most deadly disease among males. Radiotherapy treats low- and intermediate-risk prostate cancer. Image-guided radiation treatment (IGRT) can assess target and Organs at Risk (OAR) doses. IGRT dose-volume histograms may estimate the prostate, rectum, and bladder radiation dosage. This research examined prostate cancer patients' dose-volume histograms (DVHs) after bladder and rectum preparation. This research also examined the dosimetric changes caused by bladder and rectum volume variations during bladder preparation and clearance. This retrospective analysis examined 396 CBCT scans from 15 individuals. Patients have to meticulously follow a bladder and rectum preparation procedure. DVH was built after irradiation. The maximum, lowest, and average dosage to Urinary Bladder and Rectum were compared to the DVH at the original plan estimated on CT simulation pictures for each patient. The predicted bladder volume and average bladder volume differed significantly. This study's bladder filling methodology produced a 314 mL mean bladder volume. At the end of radiation, the mean bladder volume was 207 mL. The bladder and rectum dosages differed significantly between planning and daily treatment sessions. Rectum volume differed significantly in intended and average volume. Real values (P-value=0.024) and proportions to projected values (P-value=0.007) vary. While bladder capacity decreases, mean dosage increases (P-value=0.00). This research found that rectum and bladder volume significantly affect dosimetry parameters. Bladder volume is key to attaining the best strategy. Bigger bladder capacity in planning leads to larger volume and dosage variations during treatment.


INTRODUCTION
There are several management strategies that may be used in the treatment of prostate cancer.Prostatectomy, external beam radiation, and brachytherapy are some of the treatments that are utilized across the world to control prostate cancer.Brachytherapy is another treatment option.The most detrimental effect on sexual functioning is produced by the prostatectomy, as compared to the other treatment options.In addition, it was shown that individuals having prostatectomy also complain of incontinence of their urinary system.According to Gay and Michalski (2018), people with a low or intermediate risk of cancer are the ones who should get radiation treatment [1].
Radiation treatment has seen significant advancements in the last ten years, allowing it to more effectively reduce the volume of tumors without inflicting any damage to the normal tissues that are nearby.The most current modification to the radiotherapy treatment, known as "Intensity Modulated Radiotherapy" (IMRT), is an innovative approach that offers greater conformity of radiation dosage.This method utilizes 3D imaging methods in order to direct the beam of radiation towards the direction of the tumor [2].
The most significant benefit of IMRT is the ability to treat prostate cancer.This is accomplished by first precisely localizing the tumor and then administering the correct dose.However, the amount of radiation that reaches the prostate is affected by the size and structure of the organs that surround it, such as the rectum and the bladder.Therefore, the relative location and form of the organ at risk (OAR) in conjunction with the target organ is an essential element that determines the precision of the dosage administration [3].
Tomography found its applications in diverse fields including medical applications, digital rock physics, image processing, and others, for instance [4][5][6][7][8][9][10][11].As a result of this continuous developments in technology; the cone-beam computed tomography (CBCT) approach is now being used in conjunction with radiation.Imageguided radiation treatment (IGRT), can perform an accurate assessment of the radiation dosage delivered to both the target and the OARs.Furthermore, investigations have shown that the change in the volume of the rectum and bladder can also be efficiently tracked using this modality [12].
IGRT dose-volume histograms may estimate the prostate, rectum, and bladder radiation dosage.Bladder volume affects anticipated dose distribution, whereas rectal volume affects radiation consequences.Thus, a consistent planning procedure was advised to keep the bladder and rectum dosage constant to reduce toxicity [13].
Dosimetric effects from bladder and rectum preparation protocols are unknown.Thus, this research examined prostate cancer patients' dose-volume histograms (DVHs) after bladder and rectum preparation [12].This research also examined the dosimetric changes caused by bladder and rectum volume variations during bladder preparation and clearance.Numerous studies demonstrated that prostate dosage escalation improves therapy efficacy [14][15][16][17].Protecting the OAR to prevent therapeutic adverse effects is difficult.Successful therapy requires patient preparedness."Geographical miss" is the most prevalent radiation occurrence nowadays.Target delineation mistake, day-to-day target variance, and location fluctuation are examples.Imaging during radiation treatment solved this.This method corrects radiation delivery and location [18,19].
It is widely established that daily dose administration accuracy relies on confirming the relative location and shape of the target and OARs during fractionated therapy.While the primary goal of IGRT technologies in the treatment of prostate cancer is to localize the tumor for precise targeting, these technologies can also track the actual dose delivered to the bladder and rectum and monitor changes in their filling and shape.The target's location (the prostate and the seminal vesicles) shifts as the volume of the bladder and the rectal organs changes.Considerable rectal volume fluctuations might impact delayed side effects, and substantial bladder volume differences can confuse intended dosage distributions.Therefore, it is important to maintain a constant bladder and rectal volume throughout the treatment planning and administration process to lessen target-related positional uncertainty in the bladder and the risk of increased toxicity in the rectal area.The bladder preparation regimen is studied for its applicability to normal organ volume stability and also examines the daily volumes and dosage fluctuations for the bladder and rectum.The purpose of this research is to assess the stability of bladder and rectum volume using our rectum clearing and bladder preparation methodologies, as well as to examine dosimetric changes arising from volume validation linked with the treatment of prostate cancer.
The issue is optimizing prostate cancer treatment, with a focus on radiation therapy, and minimizing side effects like sexual dysfunction and urinary incontinence.New technologies like IMRT administer radiation doses more precisely.However, bladder and rectum volume variations during therapy may greatly impact dosage accuracy and patient outcomes.This study evaluates bladder and rectum volume stability using standard preparation and clearance methods and assesses dosimetric changes from volume variations in prostate cancer therapy.The research seeks to improve prostate cancer treatment accuracy and reduce side effects.

MATERIALS AND METHODS
This retrospective analysis comprised 15 prostate cancer patients who had radiation at Assuta Medical Center from 2017 to 2019.All patients' CBCT data were retrospectively reviewed.Patients were chosen randomly.10 individuals had prostate-only therapy and 5 received prostate-and-lymph node treatment.The two groups vary only in dosage and session number.
Patients were encouraged to maintain a bladder and rectum volume before simulation and daily therapy.Patients were instructed to follow the regimen before treatment.Patients were instructed to empty their rectum and bladder.After drinking 3-4 cups of water, they were sent for treatment after 30 minutes of feeling full.This technique gave patients a full bladder and empty rectum.Patients were retrained if they weren't ready for the planning process.Before therapy, a daily CBCT scan checked the bladder and rectum and corrected any isocenter shifts.
Each CBCT was analyzed retrospectively, and the bladder and rectum were drawn on each slide to match the original design.After that, a DVH was added to each brand-new building, as in figures 1 and figure 2. For each patient, the DVH computed from the CT simulation pictures was compared to the highest, lowest, and average dosage to the urinary bladder and rectum.As illustrated in figures 3 and figure 4, this allowed to track the patient's actual intake and compare it to the intended intake.The goal is to compare the average (relative and absolute) dosage to the volume of the bladder and the volume of the rectum.Maximum likelihood was used to fit the linear mixed effects model.

RESULT AND DISCUSSION
Volumes of the patient's bladder and rectum were measured using CBCT, and the descriptive data are shown in Table 1.Variations in bladder capacity are more common than those in rectum size throughout the whole patient population.
Our findings revealed that there was a difference of 207.59 mL (or 18.9%) between the mean bladder volume in the treatment phase and the mean bladder volume in the planning phase.Similarly, Table 2 and (4) reveal 14.8% difference in rectum volume between the pre-treatment and post-treatment phases.
Bladder volume varied significantly between the pre-treatment and post-treatment stages.P value = 0.009 and P-value = 0.043 indicate that these discrepancies exist between the actual and anticipated values.Table 2 further reveals that the mean treatment volume is 11.06 times larger than the intended volume, and the percentage difference between the two is 19%.This means that the treatment volume accounts for 81.1% of the planned volume.
On the other hand, the findings demonstrated that there are no statistically significant variations in the Bladder dosage throughout the planning phase (relative and absolute) and the treatment period (relative and absolute) with corresponding P values of 0.151, 0.077, 0.145, and 0.076.Even if the proportional differences were rather considerable, the Table 3 demonstrates that these variations do not constitute a statistically significant difference.
In terms of the rectum, the findings indicated that there were statistically significant variations between the volume of the rectum in the planning phase and the average volume during the treatment period.These differences exist in both actual values and proportions to planned values, with P values of 0.024 and 0.007, respectively.In addition, the planning volume was bigger in mean than the average volume during the treatment phase by 12.076 and also greater in percentage by about 14.8%.As indicated in Table 4, the average  In addition, the findings indicate that there were statistically significant differences between the rectum doses during the treatment phase (both relative and absolute) and the rectum doses at the planning phase (both relative and absolute).These changes may be seen in actual values as well as proportions to the values that were anticipated, and their corresponding P values are 0.032 and 0.018.In addition, the planned dosage is lower in mean than the average dose administered throughout the treatment period by 3.162, and it is also lower in percentage by about 11.4%, as shown in table 5.The  In the current study, the results showed that there are statistically significant differences between the bladder and rectum volumes during the planning and the daily treatment sessions.Despite the fact this, among the 15 patients studied, there were no statistically significant differences regarding the bladder dose between the planning and the daily treatment sessions, there was an opposite relationship between the bladder volume and the dose, with the increase in the bladder volume being accompanied by an increase in the dose.This is due to the fact that the larger the volume that  we have, the smaller the volume that has to be irradiated, which results in a lower mean dosage to the bladder.
The aim of the current study was to assess the rectum cleaning and bladder preparation techniques will be used to evaluate the consistency of bladder and rectum volumes, and the resulting dosimetry alterations in relation to prostate cancer therapy will be analyzed.
In a similar study, Hatton et al (2011) have found that the dosage of rectal DVH varies based on the volume fluctuation [20].The same sort of conclusion was revealed in Pawlowski's previous research as well, which likewise examined the topic.Pawlowski et al. (2010) put out the hypothesis that fluctuations in the capacity of both the bladder and the rectal cavity end up being reflected in the dosimetric variations [21].Our findings show that a reduction in volume during treatment sessions compared to the initial amount during the CT simulation leads in a higher dosage to the bladder and rectum.Although it was not statistically significant across all patients, it was obvious that the dosage limit was surpassed in certain individuals.It was also shown that during the late sessions, patients were unable to achieve a full bladder state, which might be attributed to radiation side effects.
According to Collery and Forde (2017), developing a DVH can greatly quantify the variance in the dosage that is given to the rectum and the bladder.The results of this investigation indicated a substantial discrepancy between the planned and on-treatment dose-volume histograms, which is comparable to the findings of our own study.The modification in the dose-volume limits, on the other hand, did not have a statistically significant impact [22].It was also discovered that the changes in volume and dosages that occur throughout the daily treatment sessions are proportional to the size of the bladder volume that has been obtained during the planning phase.This was another finding.This is regarded to be one of the negative effects of radiation treatment since, after a few sessions, patients won't be able to keep their bladders as full as they were previously.

CONCLUSION
Image-guided radiation treatment (IGRT) may assess target and OAR doses.The dose-volume histograms may assist determine the prostate, rectum, and bladder radiation dosage.Bladder volume affects anticipated dose distribution, whereas rectal volume affects radiation consequences.Thus, a consistent planning procedure was advised to maintain bladder and rectum doses.Thus, this research employed optimum planning to examine the dosage received by rectum and bladder and the correlation of bladder and rectum volume with the supplied dose.This research found that rectum and bladder volume significantly affect dosimetric parameters.Bladder volume is key to attaining the best strategy.Bigger bladder capacity in planning leads to larger volume and dosage variations during treatment.Later after therapy, bladder volume varied considerably.Radiation treatment may cause this bladder volume change.

Figure 1 :
Figure 1: All the new bladder structure for one patient which was delineated on CBCTs shown on the original plan.

Figure 2 :
Figure 2: All the new rectum structure for one patient which was delineated on CBCTs shown on the original plan.

Figure 3 :
Figure 3: All the new bladder structure DVH for one patient demonstrate the day to day variations.

Figure 4 :
Figure 4: All the new rectum structure DVH for one patient demonstrate the day to day variations.

Table 1 :
Descriptive Statistics of Bladder and Rectum Volumes.

Table 3 :
Paired Samples T Test for Bladder Differences.

Table 5 :
Paired Samples T TEST for Rectum Differences.