Assessing the Efficiency and Consistency of Daily Image-guided Radiation Therapy in a Modern Radiotherapy Centre

An evaluation of isocentre shift magnitude and treatment site on image-guided radiation therapy online decision analysis times

INTRODUCTION

The ability to capture more anatomical detail in cone-beam computed tomography (CBCT) imaging compared to kilovoltage (kV) and megavoltage (MV) imaging, has seen a documented shift towards CBCT image verification and staff adopting more extensive image analysis processes. The timeframe associated with assessing online CBCT images, termed the online decision analysis time, if drawn out, can affect treatment efficiency and accuracy. This study aimed to determine the current CBCT online decision analysis time at Radiation Oncology Princess Alexandra Ipswich Road (ROPAIR) and investigate the influence of isocentre shift magnitude and treatment site considerations on this timeframe.

METHODS

This retrospective clinical audit collected treatment parameters from 202 CBCT images over 2 treatment days. The online decision analysis time was calculated by subtracting the image acquisition timestamp from the image verification shift application timestamp. The quantitative data were analysed using mean, standard deviation, and range in the following categories: all CBCTs, CBCTs grouped by isocentre shift magnitude and CBCTs grouped by treatment site. Content analysis was performed on staff comments made during image analysis.

RESULTS

The average online decision analysis time was 2:37 ± 1:28 min. On average approximately, head and neck, spine and extremity treatment sites measured 1 min, pelvis, breast, and chest measured 2-3 min with abdomen measuring 4 min. Common categories reported in staff comments included anatomical changes, repositioning, and organs at risk size.

CONCLUSION

The results provide baseline online decision analysis times. Further refinement is required to determine if the image match method, treatment site considerations, and rotational discrepancies influence this timeframe.

Image-guided radiotherapy (IGRT) in Lombardy, Italy: a survey by the Lombardy section of the Italian Association of Radiotherapy and Clinical Oncology (AIRO-Lombardy)

BACKGROUND

Image-guided radiation therapy (IGRT) has changed clinical practice. We proposed a survey to radiotherapy centers in Lombardy to picture the current clinical practice of its use.

RESEARCH DESIGN AND METHODS

The survey consisted of 32 multiple-choice questions, divided into five topics: type of hospital, patients treated in 2019, number of LINACs; presence of protocols and staff involved in IGRT; IGRT in stereotaxis; IGRT in non-stereotactic treatments; availability of medical and technical staff.

RESULTS

Twenty-seven directors answered (77%). Most centers (74%) have produced protocols to ensure uniformity in the IGRT process. The most widely used IGRT modality (92%) is cone-beam CT. Daily IGRT control is favored for prostate (100%), head and neck (87%), and lung (78%) neoplasms. The resident doctors can always perform supervised IGRT matching in only six centers. Radiation therapists perform IGRT controls only for some sites in 12 cases (44%) and always in 9 cases (33%). Radiation oncologists are present in real time, in most cases.

CONCLUSIONS

Today, IGRT can be considered standard practice but at the price of more time-consuming procedures. A balance between a fully physician-controlled process and an increased role for specifically trained RTTs is actively being sought.

Impact of abdominal compression on setup error and image matching during radical abdominal radiotherapy

PURPOSE

To determine the impact of abdominal compression (AC) on setup error and image matching time.

MATERIALS AND METHODS

This study included 72 liver, pancreas and abdominal node patients treated radically from 2016 to 2019 in a single centre. Patients received either SBRT or conventional radical fractionation (CRF). Compressed patients were supine, arms up with kneefix and AC equipment. Uncompressed patients were supine, arms up with kneefix. All patients received daily online-matched CBCTs before treatment. Initial setup error was determined for all patients. Registration error was assessed for 10 liver and 10 pancreas patients. Image matching times were determined using beam on times. Statistical tests conducted were an F-test to compare variances in setup error, Student's t-tests for setup error and average image analysis, and a Wilcoxon Mann Whitney test for imaging matching time analysis.

RESULTS

Initial setup displacement was similar between compressed and uncompressed patients. Displacements > 1 cm occurred more frequently in the longitudinal direction for most patients. SBRT patients required more additional manual positioning following imaging. Mean absolute registration error in the SI direction was 5.4 mm and 3.3 mm for uncompressed and compressed pancreas patients respectively and 1.7 mm and 0.8 mm for uncompressed and compressed liver patients respectively. Compressed patients required less time for image matching and fewer images per fraction on average. Repeat imaging occurred more frequently in SBRT and uncompressed patients.

CONCLUSIONS

Although abdominal compression has no significant impact on setup error, it can reduce imaging matching times resulting in improved treatment accuracy.

Evidence-based region of interest matching guidelines for sarcoma volumetric image-guided radiation therapy

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Region-of-interest (ROI) guidelines for soft tissue sarcoma CBCT-guidance were developed.

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ROI guidelines were developed for four anatomic sites using the PDSA cycle.

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ROI guidelines are intended to increase image registration reproducibility.

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Results include improved image guidance decision making and workflow efficiencies.

Purpose

Region-of-interest (ROI) guidelines for online cone-beam computed tomography (CBCT) radiotherapy may improve matching reproducibility and reduce inter-user variability of soft tissue sarcoma (STS) image guidance. The purpose of this work is to standardize ROI STS CBCT image registration guidelines using the plan-do-study-act (PDSA) cycle for the lower extremity, retroperitoneal, pelvis, and thorax.

Methods

Based on anatomic bony surrogates, initial ROI matching guidelines for STS were developed by a team of radiation therapists, physicists and oncologists (Plan). Retrospective, qualitative evaluation of the guidelines was completed by the designated sarcoma lead therapist to determine clinical feasibility (Do). Validation of the ROI guidelines was performed through independent evaluation by radiation therapy CBCT imaging experts on a cohort of 10 patients per anatomic region (Study).

Results

Draft ROI guidelines were evaluated by 2 independent observers who registered weekly CBCT images to test their validity. Each observer assessed 5 patients per anatomic site, testing ROI options for accuracy of image registration and feasibility, while some ROI borders were adjusted based on algorithm matching performance. Validated ROI guidelines were presented to the sarcoma multidisciplinary site group, and an inter-professional committee of imaging experts for approval prior to clinical implementation (Act).

Conclusion

ROI matching guidelines for STS IGRT were standardized for 4 anatomic sites using the PDSA cycle for change testing and implementation. IGRT guidelines are intended to improve STS image registration reproducibility, and in turn, are expected to improve the confidence of IGRT decision making and workflow efficiencies for a rare disease with diverse presentation.

Analysis of Online and Offline Head and Neck Image-guided Radiation Therapy

PURPOSE

The introduction of a daily image-guided radiation therapy (IGRT) program is an important step. It has implications for the radiation therapy team in terms of accuracy, workflow, and decision making. This study assesses how successful a radiation therapy department has been in using this technology and the accuracy of individual decision making when comparing online and offline image match data.

METHODS

Twenty intensity-modulated radiation therapy head and neck patients had their IGRT data assessed retrospectively. Online analysis was completed based on a 0-mm action threshold. Offline analysis was then conducted on the same data. Any discrepancies in decision making were then assessed.

RESULTS

Results indicated that the treating radiation therapy team was able to image match consistently when benchmarked against their colleagues in the offline environment. Analysis of online versus offline corrections in each of the three orthogonal directions showed strong agreement. Further analysis revealed no statistically significant differences for systematic errors, whereas a statistically significant but small difference was present for random error.

CONCLUSION

In this age of sophisticated equipment, daily IGRT is a valuable modality. However, the introduction of daily online IGRT inclusive of a 0-mm action threshold for head and neck IGRT requires careful consideration and evidence that such accuracy can be achieved. Ultimately, it is still the radiation therapist who must make the decision, which places great importance on the competency of the treating radiation therapy team.