Unforeseen Computed Tomography Resimulation for Initial Radiation Planning: Associated Factors and Clinical Impact

A Simulation-Free Replacement Solution for Radiation Therapy Immobilization Devices Using Computer Numerical Control (CNC) -Milled Polystyrene Molds

Purpose

In radiation therapy (RT), if an immobilization device is lost or damaged, the patient may need to be brought back for resimulation, device fabrication, and treatment planning, causing additional imaging radiation exposure, inconvenience, cost, and delay. We describe a simulation-free method for replacing lost or damaged RT immobilization devices.

Methods and Materials

Replacement immobilization devices were fabricated using existing simulation scans as design templates by computer numerical control (CNC) milling of molds made from extruded polystyrene (XPS). XPS material attenuation and bolusing properties were evaluated, a standard workflow was established, and 12 patients were treated. Setup reproducibility was analyzed postfacto using Dice similarity coefficient (DSC) and mean distance to agreement (MDA) calculations comparing onboard treatment imaging with computed tomography (CT) simulations.

Results

Results showed that XPS foam material had less dosimetric impact (attenuation and bolusing) than materials used for our standard immobilization devices. The average direct cost to produce each replacement mold was $242.17, compared with over $2000 for standard resimulation. Hands-on time to manufacture was 86.3 minutes, whereas molds were delivered in as little as 4 hours and mostly within 24 hours, compared with a week or more required for standard resimulation. Each mold was optically scanned after production and was measured to be within 2-mm tolerance (pointwise displacement) of design input. All patients were successfully treated using the CNC-milled foam mold replacements, and pretreatment imaging verified satisfactory clinical setup reproduction for each case. The external body contours from the setup cone beam CT and the original CT simulation with matching superior-inferior extent were compared by calculating the DSC and MDA. DSC average was 0.966 (SD, 0.011), and MDA average was 2.694 mm (SD, 0.986).

Conclusions

CNC milling of XPS foam is a quicker and more convenient solution than traditional resimulation for replacing lost or damaged RT immobilization devices. Satisfactory patient immobilization, low dosimetric impact compared with standard immobilization devices, and strong correlation of onboard contours with CT simulations are shown. We share our clinical experience, workflow, and manufacturing guide to help other clinicians who may want to adopt this solution.

A retrospective study on the delay in three different timescales of CT simulation among patients with pediatric cancer in a tertiary hospital

Patients with pediatric cancer receive radiotherapy to cure several types of cancer, requiring computed tomography simulation (CT sim) for precise treatment. However, there is currently no suitable framework to reduce the inherent delays in CT sim. The present study aimed to identify the underlying causes of the delays in CT sim regarding three different time periods (duration of patient admission to CT sim, diagnosis to treatment and CT sim to treatment) among patients with pediatric cancer. A total of 58 patients with pediatric cancer who received radiation therapy under anesthesia at King Abdulaziz University Hospital (Jeddah, Saudi Arabia) between 2016 and 2021 (60 months) were included in the current study. The underlying cause of delays regarding three separate time periods was determined according to patient type, diagnosis, therapy type and year of diagnosis. The CT sim processing time averaged 73 days and was received by patients after 28.96±28.5 days. The major delays in terms of frequency and length of duration between different time points such as patient admission and CT sim, interval between diagnosis and treatment, and duration between CT sim and therapy were (mean±SD) 37.13±29.9, 58.08±24.9 and 28.15±7.9 days, respectively. Machine availability, instability of the patients' medical condition and intensity-modulated radiation therapy (IMRT) caused 66.6% of the delays. In conclusion, outpatients may experience CT sim delays. Machine availability, conditions of patients and IMRT treatment were the major reasons to cause the delay in CT sim. Strategies should be employed to prevent CT sim delays and improve patient experience.

Treatment Options for Early Stage Inoperable Breast Cancer: Cryoablation or Radiotherapy?

Background

Surgical removal of the tumour is the gold standard treatment for early stage invasive breast cancer. However, with a global ageing population, a larger number of diagnoses are occurring in women with comorbidities that render them unsuitable for surgery. Hence, it is of interest to explore alternative treatment strategies for this group of women.

Summary

Our narrative review aims to explore two such techniques, cryoablation and external beam radiotherapy, providing a brief summary of the evidence behind each technique. Following this, we discuss which groups of patients would gain the most benefit from each technique. Factors favouring the use of radiotherapy include patients with larger tumours, more superficial tumours, and those with less well-demarcated tumours where there is uncertainty regarding tumour extent. Meanwhile, patients who may benefit more from cryoablation include those who desire a smaller number of treatment sessions, have concerns regarding cosmesis and skin pigmentation, or who have relative contraindications to radiotherapy such as scleroderma, systemic lupus erythematosus, reduced lung function, or cardiac comorbidities.

Key Messages

Continued advancements in both cryoablation and radiotherapy technologies are taking place, in tandem with imaging technologies enabling greater certainty in tumour detection and delineation. These factors will help increase local control rates in this group of non-operable early stage breast cancer patients. Through this review, we hope to aid in the clinical decision-making process regarding the selection and referral of patients for each treatment.

Evaluation of a prospective radiation oncology departmental team review process using standardized simulation directives

INTRODUCTION

The primary objective of this study is to evaluate the utility and value of an institutional, multi-disciplinary radiation oncology team review process prior to radiotherapy (RT) simulation.

METHODS

Over a period of 3 months and through an iterative team-based process, a standardized simulation requisition directive (SSRD) was developed, piloted, modified, and subsequently implemented for all patients treated with external beam RT at a single tertiary care institution from January to December 2020. The SSRDs were reviewed at a daily multi-disciplinary radiation oncology team review conference; modifications consequential to the review were prospectively recorded in a quality database.

RESULTS

1,500 consecutive SSRDs were prospectively reviewed for this study. 397 modifications on 290 (19.3%) SSRDs were recorded and parsed into 5 main categories and 18 subcategories. The most common modifications resulted from changes in immobilization device (n=88, 22.2%), RT care path (n=56, 14.1%), and arm positioning (n=43, 10.8%). On univariate analysis, modifications were associated with RT intent, scan parameters, tumor site, and consultation type. An increased rate modifications was observed for patients had telemedicine consults (n=101, 22.7%) compared to in-person consultations (n=189, 17.9%) (p=0.032). Using logistic regression analysis, there was also a statistically significant relationship between postoperative RT delivery and modification rates (OR: 2.913, 95% CI: 1.014-8.372) (p=0.0126). Overall, only 14 patients (0.9%) needed re-simulation during the entire study period.

CONCLUSIONS

Prospective multi-disciplinary radiation oncology team review prior to simulation identifies actionable change in approximately 19% of procedures, and results in an extremely low rate (<1%) of re-simulation. As departmental processes transition to virtual platforms, thorough attention is needed to identify patients at higher risk of simulation modifications.

A Comprehensive Analysis of a Prospective Multidisciplinary Peer Review Process Before Radiation Therapy Simulation

PURPOSE

Although peer review in radiation oncology (RO) has been recommended to improve quality of care, an analysis of modifications resulting from an RO multidisciplinary presimulation standardized review process has yet to be empirically demonstrated.

METHODS AND MATERIALS

A standardized simulation directive was used for patients undergoing simulation for external beam radiation therapy at a single tertiary care institution. The simulation directives were presented, and all aspects were reviewed by representatives from key RO disciplines. Modifications to the original directives were prospectively captured in a quality improvement registry. Association between key variables and the incidence of modifications were performed using Fisher exact test and t test.

RESULTS

A registry of 500 consecutive simulations for patients undergoing radiation therapy was reviewed. A median of 105 simulations occurred per month. All simulation directives were entered by a physician a median of 3 days before simulation (range, 1-76 days). The treatment intent was curative for 269 patients (53.8%), palliative for 203 patients (40.6%), and benign for 3 patients (0.6%). Twenty-five (5%) patients did not have a treatment intent selected. Based on RO multidisciplinary review, 105 directives (21%) were modified from the original intent, with 29 (5.8%) requiring more than 1 modification. A total of 149 modifications were made and categorized as changes to patient positioning and immobilization (n = 100, 20%), treatment site and care path (n = 34, 6.8%), simulation coordination activities (n = 6, 1.2%), and treatment technique and planning instructions (n = 9, 1.8%). A higher proportion of modifications occurred at the time of multidisciplinary review in patients receiving more complex treatments (intensity modulated radiation therapy/stereotactic radiosurgery/stereotactic body radiation therapy [IMRT/SRS/SBRT] vs 3-dimensional radiation therapy [3DCRT] radiation therapy, 25% vs 16%, P < .025).

CONCLUSIONS

Given the complexity of radiation therapy simulation, standardization of directives with prospective RO multidisciplinary presimulation peer review is critical to optimizing department processes and reducing errors. Approximately 1 in 5 patients benefits from this peer review process, especially patients treated with IMRT/SRS/SBRT.