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

Abstract

PurposeRepeat computed tomography (CT) simulation is problematic because of additional expense of clinic resources, patient inconvenience, additional radiation exposure, and treatment delay. We investigated the factors and clinical impact of unplanned CT resimulations in our network.Methods and MaterialsWe used the billing records of 18,170 patients treated at 5 clinics. A total of 213 patients were resimulated before their first treatment. The disease site, location, use of 4-dimensional CT (4DCT), contrast, image fusion, and cause for resimulation were recorded. Odds ratios determined statistical significance.ResultsOur total rate of resimulation was 1.2%. Anal/colorectal (P < .001) and head and neck (P < .001) disease sites had higher rates of resimulation. Brain (P = .001) and lung/thorax (P = .008) had lower rates of resimulation. The most common causes for resimulation were setup change (11.7%), change in patient anatomy (9.8%), and rectal filling (8.5%). The resimulation rate for 4DCTs was 3.03% compared with 1.0% for non-4DCTs (P < .001). Median time between simulations was 7 days.ConclusionsThe most common sites for resimulation were anal/colorectal and head and neck, largely because of change in setup or changes in anatomy. The 4DCT technique correlated with higher resimulation rates. The resimulation rate was 1.2%, and median treatment delay was 7 days. Further studies are warranted to limit the rate of resimulation.

Repeat Computed Tomography Simulation among Patients with Head and Neck Cancer Experiencing Delayed Radiation Therapy During the COVID-19 Pandemic

“…Head and neck sites are commonplace for repeat CT simulations, largely due to changes in anatomy from the aggressive nature of such tumors. 7 The necessity for repeat planning is paramount with more conformal therapies such as intensitymodulated radiotherapy (IMRT) becoming available, where it is deemed essential in ensuring adequate target doses and safe normal tissue exposure. 9,13 In this study that included non-metastatic, locally advanced head and neck cancers, as well as primary cancers metastatic to this location, the median time to radiotherapy initiation was 37 days, with a range from zero to as much as 278 days.…”

“…A study by Metzger evaluating frequencies for all cancer histologies found that the repeat simulation rate in 683 patients with head and neck cancer was relatively high at 3.07%, attributed primarily to changes in anatomy from the delay of treatment initiation. 7 The possible causes for repeat simulation include set up changes, immobilization devices, and changes in RT plan. Changes in the set up that typically lead to repeat simulation include radiotherapy field adjustments and the need for patient repositioning.…”

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

“…After the simulation scan is performed, radiotherapy planning is done over several days, following which quality checks are done. In some cases, changes that occur in between simulation and the start of treatment, or during the course of radiotherapy treatment, may necessitate a repeat simulation and replanning process, such issues include weight loss, development of seromas, or difficulty reproducing the treatment position due to injury [61]. Thus, for patients who prefer to complete their treatment over a shorter period of time and avoid the more lengthy process of radiotherapy simulation, planning, and multiple visits for treatment, cryoablation may be the preferred option.…”

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

“…Globally, computed tomography simulation (CT sim) operations are susceptible to inevitable delays due to limited resources and the simulator's typical 9-h shift without a break (3)(4)(5). In addition, multiple doctors are competing for patients' sim time slots.…”