Role of image guided radiation therapy in obese patients with gynecologic malignancies

The development and implementation of a radiation therapy bariatric protocol

The rate of obesity is increasing in the Australian population, and this also includes patients with cancer. The safety and dignity of this cohort of patients is paramount as well as the timely acquisition of equipment required to assist patients with obesity to complete a course of radiation therapy (RT). The design and manufacture of equipment used in most RT departments is not suitable for the weight or BMI of all patients presenting for treatment. RT also operates under a unique set of circumstances that differs from the routine hospital environment which prompted the design of an RT bariatric protocol for use in our department. The protocol is based on the mapping of a patient's pathway from simulation and treatment. Treatment technique and equipment limitations as well as information relating to a patient with high BMI are used as trigger points that direct a patient pathway. The bariatric protocol provides the RT team with decision-making support for appropriate resource utilisation ensuring safe and efficient treatment delivery for both the patient and staff. This paper will outline how the RT bariatric protocol was developed and implemented in our department, highlighting areas that required more attention due to the RT-specific environment.

The relationship of body mass index to setup errors, dosimetric parameters and incidence of radiation pneumonitis in non-small cell lung cancer patients undergoing intensity-modulated radiation therapy: a single-center observational study

BACKGROUND

The relationship among body mass index (BMI), setup error and radiation pneumonitis is not clearly illustrated.

OBJECTIVE

The present study aimed to investigate the role of BMI in non-small cell lung cancer (NSCLC) patients' radiation treatment, focusing on its relationship with setup error of patient positioning, the dosimetric parameters of intensity-modulated radiation therapy (IMRT) and the incidence of radiation pneumonitis.

METHODS

This prospective observational study included 523 cases of NSCLC patients during 2020-2022. Patients were divided into different groups by different BMI. The setup error was obtained by cone beam CT (CBCT) at three positions, lateral (LAT), longitudinal (LNG) and vertical (VRT). IMRT dosimetric parameters of V5, V20, and mean dose were collected.

RESULTS

Patients with BMI ≥28 kg/m2 showed significantly higher absolute values of LAT, LNG and VRT, higher V5, V20, mean dose, as well as higher total incidence of radiation pneumonitis and grade III radiation pneumonitis compared with patients with BMI <24 kg/m2 or 24-28 kg/m2. Spearman's analysis demonstrated that the absolute values of LAT, LNG and VRT were positively correlated with BMI, and positive correlation existed among BMI, dosimetric parameters and setup errors. ROC curves showed that LAT in setup errors and V5 in dosimetric parameters had the best diagnostic value for prediction of radiation pneumonitis. Only BMI, LAT, V5 and V20 were the independent risk factors for radiation pneumonitis.

CONCLUSIONS

Setup error caused by higher BMI might be associated with the dosimetric parameters, as well as the incidence of radiation pneumonitis in NSCLC patients.

Letter in response to Laing et al., "An evaluation of radiation therapy patient body mass index trends and potential impact on departmental resource planning"

"An evaluation of radiation therapy patient body mass index trends and potential impact on departmental resource planning" by Laing et al. The authors' comment that research into the experiences of larger bodied patients should focus on compassionately improving care for this patient population rather than framing large-bodied patients as a burden or problem, and should include commentary on the effects of weight-bias in the healthcare system.

An evaluation of radiation therapy patient body mass index trends and potential impact on departmental resource planning

INTRODUCTION

Radiation therapy (RT) offers a less invasive management option for bariatric cancer patients. As the proportion of Australians categorised overweight or obese approaches 70%, it is not well understood how this growth will impact RT departments. The aim of this study was to evaluate the current and potential future body mass index (BMI) of RT patients at one centre, with the purpose of identifying variables that may impact resource planning decisions.

METHODS

De-identified demographic data including gender, age, diagnosis code, activity code and BMI were obtained from MOSAIQ® oncology information system for 5548 courses of RT commenced between 2017 and 2020, and retrospectively analysed. Descriptive statistics were used to summarise the data. Simple and multiple linear regression was used to analyse for statistically significant relationships between variables.

RESULTS

Of all patient courses, 64% were overweight or obese. Average BMI increased over time by 0.3 kg/m² per year. Courses related to the young and elderly had a lower average BMI. Breast, brain/skull, and pelvis/prostate treatment sites had a significant association with a higher average BMI. Thorax treatment sites had a lower average BMI, but this average is increasing at the fastest rate of all treatment sites. Prone breast courses had an average BMI 5.58 kg/m² higher than IMRT/VMAT courses.

CONCLUSION

Results demonstrate that patient BMI is increasing. Resources related to breast courses (breast board, prone board) and thorax courses (lung board) may experience increased strain in the future. Modifications to department workflow and scheduling are likely required. Further research into staffing implications is recommended.

DEVIATION BETWEEN THE PLANNED DOSE AND THE IN VIVO DOSIMETRY RESULTS DURING POSTOPERATIVE IRRADIATION IN PATIENTS WITH UTERINE CANCER DEPENDING ON ANTHROPOMETRIC DATA

Topometry is an integral part of irradiation whose task is to repeat the position of the patient set by the simulator to repeat the PTV and the spatial relationship between the radiation field and the risk organs that were identified during planning. The dose distribution formulated in the plan is only an ideal model. There is some gap between the actual and planned dose distribution, especially in overweight patients.

OBJECTIVE

evaluate the effect of anthropometric data on the deviation between the planned dose and the results of dosimetry in vivo in patients with uterine cancer during postoperative irradiation.

MATERIALS AND METHODS

The authors analyzed the results of treatment of 110 patients with stage IB-II uterine can- cer who were treated at the Department of Radiation Therapy of the Institute of Medical Radiology and Oncology of the National Academy of Medical Sciences of Ukraine from 2016 to 2019. The technique of classical fractionation was used with a single focal dose of 2.0 Gy 5 times a week, the total focal dose was 42.0-50.0 Gy. To assess the effect of the patient's anthropometric data on the difference between the actual and calculated dose, the authors per- formed in vivo dosimetry after the first session and in the middle of the postoperative course of external beam radi- ation therapy.

RESULTS

Рatients with BSA < 1.92 m2, had the median relative deviation at the first session -4.12 %, after 20.0 Gy - 3.61 %, patients with BSA > 1.92 m2: -2.06 % and -1.55 % respectively. After 20 Gy 34.8 % of patients with BSA < 1.92 m2 there was an increase in deviation from the planned dose, 65.2 % a decrease, while in 56.1 % of patients with BSA > 1.92 m2 there was an increase, and in 43.9 % - its reduction. With increasing BMI, the actual dose received on the rectal mucosa in the tenth session of irradiation is approaching the calculated one.

CONCLUSIONS

When irradiated on the ROKUS-AM device, we did not find a probable dependence of the influence of the constitutional features of patients between the received and planned radiation dose. When treated with a Clinac 600 C, only body weight and body mass index at the tenth irradiation session have a likely effect on the dose differ- ence. Therefore, issues related to the individual approach to the treatment of uterine cancer, depending on anthro- pometric data is an urgent problem of modern radiotherapy.

Challenges and impact of patient obesity in radiation therapy practice

INTRODUCTION

The prevalence of obesity is rapidly increasing globally and has tripled between 1975 and 2016. Obesity is reported within the literature as having a significant impact on medical practice, professionals, imaging departments and healthcare systems. It is not known how this epidemic will impact radiation therapists' working environment and practice. The aim of this study is to explore the perceived challenges and impacts of patient obesity on radiation therapy practice from the perception of radiation therapists.

METHODS

All radiation therapists working in the Republic of Ireland were invited to participate. Two focus groups were conducted with 6 and 7 participants respectively. A seven staged method of analysis, using a computerised long table approach was developed and used to analyse the data and create themes related to radiation therapists' perception of managing obese patients.

RESULTS

Perceived challenges from the radiation therapists were difficulties; (1) Setting up the patient (2) Imaging (3) communication and emotional impact.

CONCLUSION

An array of concerns were raised during this research about the increase and impact of obese patients on radiation therapists working environment. This study suggests that obese patients can present additional challenges to radiation therapists' current work practices. It is imperative that we recognise the additional challenges this patient cohort add to daily workflow. Further research is needed to identify the common key issues and how to manage this specific patient group.

IMPLICATIONS FOR PRACTICE

At the moment there are no specific management strategies/policies in place for managing obese patients; this study suggests that it is something we need to consider implementing as standard in radiation therapy departments.

Impact of body-mass factors on setup displacement during pelvic irradiation in patients with lower abdominal cancer

Background The aim of the study was investigate the impact of body-mass factors (BMF) on setup displacement during pelvic radiotherapy in patients with lower abdominal cancers. Patients and methods The clinical data of a training cohort composed of 60 patients with gynecological, rectal, or prostate cancer were analyzed. The daily alignment data from image-guided radiotherapy (IGRT) were retrieved. Setup errors for were assessed by systematic error (SE) and random error (RE) through the superior-inferior (SI), anterior-posterior (AP), and medial-lateral (ML) directions. Several BMFs and patient-related parameters were analyzed with binary logistic regression and receiver-operating characteristic curves. A scoring system was proposed to identify those with greater setup displacement during daily treatment. The results were validated by another cohort. Results A large hip lateral diameter correlated with a greater SI-SE and AP-SE, whereas a large umbilical AP diameter correlated with a greater ML-SE and ML-RE. A higher SI-RE was associated with a large hip circumference. The positive predictors for setup uncertainty were chosen to dichotomize patients into groups at high risk and low risk for setup displacement. Based on the scoring system, the adequate treatment margins for the SI direction in the high-and low-risk groups were 5.4 mm and 3.8 mm, whereas those for the ML direction were 8.2 mm and 4.2 mm, respectively. The validated cohort showed a similar trend. Conclusions Large BMFs including hip lateral diameter, hip circumference, and umbilical AP diameter are associated with greater setup uncertainty. Based on the scores, IGRT or required treatment margins can be adapted for patients with high risk features.

Radiation-related toxicities and outcomes in endometrial cancer: are obese women at a disadvantage?

OBJECTIVE

To assess the impact of body mass index (BMI) on radiotherapy toxicities in endometrial cancer patients.

METHODS

This was a retrospective cohort study of women diagnosed with endometrial cancer between January 2006 and December 2014 at the Royal Cornwall Hospital Trust. Women who received radiotherapy as part of their treatment, including external beam radiotherapy (EBRT) and/or vaginal brachytherapy were included. Radiation-related toxicities were graded according to the Radiation Therapy Oncology Group (RTOG) guidelines. Toxicity outcomes were compared across BMI groups-non-obese (BMI <30 kg/m²) and obese (BMI ≥30 kg/m²)-according to radiotherapy treatment received (EBRT, brachytherapy or a combination).

RESULTS

Of a total of 159 women who received radiotherapy, 110 were eligible for inclusion in the study. Sixty-three women had a BMI <30 kg/m² and 47 women were obese. Obese women had poorer Eastern Cooperative Oncology Group performance status (P = 0.021) and more comorbidities (P < 0.001) compared to the non-obese group. Total (any) toxicity rates were 60.3, 72.7 and 52.0% for EBRT and brachytherapy (N = 63), single-mode EBRT (N = 22) and brachytherapy (N = 25), respectively. BMI was not associated with the incidence of acute and late radiation toxicities in the different radiotherapy groups, and there were no differences in individual complications between the BMI groups.

CONCLUSION

When comparing obese to non-obese women, obesity does not negatively impact the incidence of radiation toxicities in endometrial cancer. However, toxicities remain an important challenge as they are common and negatively influence the quality of life (QoL) of survivors. Future studies need to further explore the role of BMI and possible interventions to improve toxicities and QoL.

Should we customize PTV expansions for BMI? Daily cone beam computerized tomography to assess organ motion in postoperative endometrial and cervical cancer patients

AIM

A single-institution review assessing patient characteristics contributing to daily organ motion in postoperative endometrial and cervical cancer patients treated with intensity-modulated radiotherapy (IMRT).

BACKGROUND

The Radiation Therapy Oncology Group has established consensus guidelines for postoperative pelvic IMRT, recommending a 7 mm margin on all three axes of the target volume.

MATERIALS AND METHODS

Daily shifts on 457 radiation setups for 18 patients were recorded in the x axis (lateral), y axis (superior-inferior) and z axis (anterior-posterior); daily positions of the planning tumor volume were referenced with the initial planning scan to quantify variations.

RESULTS

Of the 457 sessions, 85 (18.6%) had plan shifts of at least 7 mm in one of the three dimensions. For obese patients (body mass index [BMI] ≥ 30), 75/306 (24.5%) sessions had plan shifts ≥7 mm. Odds of having a shift ≥7 mm in any direction was greater for obese patients under both univariate (OR 4.227, 95% CI 1.235-14.466, p = 0.021) and multivariate (OR 5.000, 95% CI 1.341-18.646, p = 0.016) analyses (MVA). Under MVA, having a BMI ≥ 30 was associated with increased odds of shifts in the anterior-posterior (1.173 mm, 95% CI 0.281-2.065, p = 0.001) and lateral (2.074 mm, 95% CI 1.284-2.864, p < 0.000) directions but not in the superior-inferior axis (0.298 mm, 95% CI -0.880 to 1.475, p = 0.619) exceeding 7 mm.

CONCLUSIONS

Based on these findings, the standard planned tumor volume expansion of 7 mm is less likely to account for daily treatment changes in obese patients.

Metal Artifact Reduction in Cone-Beam Computed Tomography for Head and Neck Radiotherapy

PURPOSE

To evaluate a method for reducing metal artifacts, arising from dental fillings, on cone-beam computed tomography images.

MATERIALS AND METHODS

A projection interpolation algorithm is applied to cone-beam computed tomography images containing metal artifacts from dental fillings. This technique involves identifying metal regions in individual cone-beam computed tomography projections and interpolating the surrounding values to remove the metal from the projection data. Axial cone-beam computed tomography images are then reconstructed, resulting in a reduction in the streak artifacts produced by the metal. Both phantom and patient imaging data are used to evaluate this technique.

RESULTS

The interpolation substitution technique successfully reduced metal artifacts in all cases. Corrected images had fewer or no streak artifacts compared to their noncorrected counterparts. Quantitatively, regions of interest containing the artifacts showed reduced variance in the corrected images versus the uncorrected images. Average pixel values in regions of interest around the metal object were also closer in value to nonmetal regions after artifact reduction. Artifact correction tended to perform better on patient images with less complex metal objects versus those with multiple large dental fillings.

CONCLUSION

The interpolation substitution is potentially an efficient and effective technique for reducing metal artifacts caused by dental fillings on cone-beam computed tomography image. This technique may be effective in reducing such artifacts in patients with head and neck cancer receiving daily image-guided radiotherapy.