Stereotactic radiosurgery/radiotherapy pre-treatment plan verification using calibration-free Gafchromic EBT2 films

Object. The purpose of this work was to investigate the targeting and dosimetric characteristics of a linear accelerator (LINAC) system dedicated for stereotactic radiosurgery compared with those of a commercial gamma knife (GK) unit. Methods. A phantom was rigidly affixed within a Leksell stereotactic frame and axial computerized tomography scans were obtained using an appropriate stereotactic localization device. Treatment plans were performed, film was inserted into a recessed area, and the phantom was positioned and treated according to each treatment plan. In the case of the LINAC system, four 140° arcs, spanning ± 60° of couch rotation, were used. In the case of the GK unit, all 201 sources were left unplugged. Radiation was delivered using 3- and 8-mm LINAC collimators and 4- and 8-mm collimators of the GK unit. Targeting ability was investigated independently on the dedicated LINAC by using a primate model. Measured 50% spot widths for multisource, single-shot radiation exceeded nominal values in all cases by 38 to 70% for the GK unit and 11 to 33% for the LINAC system. Measured offsets were indicative of submillimeter targeting precision on both devices. In primate studies, the appearance of an magnetic resonance imaging—enhancing lesion coincided with the intended target. Conclusions. Radiosurgery performed using the 3-mm collimator of the dedicated LINAC exhibited characteristics that compared favorably with those of a dedicated GK unit. Overall targeting accuracy in the submillimeter range can be achieved, and dose distributions with sharp falloff can be expected for both devices.

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The “black box” of treatment: Patients’ perspective on what works in opioid maintenance treatment for opioid dependence

Substance Abuse Treatment Prevention and Policy ◽

10.1186/s13011-021-00378-7 ◽

2021 ◽

Vol 16 (1) ◽

Author(s):

Teresa C. Silva ◽

Fredrik B. Andersson

Keyword(s):

Opioid Dependence ◽

Maintenance Treatment ◽

Treatment Plan ◽

Black Box ◽

Opioid Maintenance Treatment ◽

Convenience Sample ◽

Problematic Use ◽

Treatment Stage ◽

Pre Treatment ◽

Patients Perspective

Abstract Background A lack of conceptual modeling of how the components of opioid maintenance treatment (OMT) for opioid dependence (OD) work causes it to occasionally be labeled the “black-box” of treatment. This study had a two-fold objective: First, to analyze which factors related to OMT for OD contribute to the abstinence of problematic use of non-prescribed opioids and sustain recovery, from the patients’ perspective; second, to understand which changes OMT produced in the individuals’ lives might significantly contribute to relapse prevention. Methods We used qualitative methods of design, inquiry, and analysis from a convenience sample of 19 individuals in a Swedish treatment setting. Results All the participants reported previous cycles of problematic use of non-prescribed opioids and other non-prescribed psychoactive substances, treatment, abstinence, recovery, and relapse before starting the current OMT program. During the pre-treatment stage, specific events, internal processes, and social environments enhanced motivation toward abstinence and seeking treatment. During the treatment stage, participants perceived the quality of the human relationships established with primary social groups as important as medication and the individual plan of care in sustaining recovery. From the participants’ perspective, OMT was a turning point in their life course, allowing them a sense of self-fulfillment and the reconstruction of personal and social identity. However, they still struggled with the stigmatization produced by a society that values abstinence-oriented over medication-assisted treatments. Conclusion OMT is not an isolated event in individuals’ lives but rather a process occurring within a specific social context. Structural factors and the sense of acceptance and belonging are essential in supporting the transformation. Treatment achievements and the risk for relapse vary over time, so the objectives of the treatment plan must account for characteristics of the pre-treatment stage and the availability and capacity of individuals to restructure their social network, besides the opioid maintenance treatment and institutional social care.

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A novel index for assessing treatment plan quality in stereotactic radiosurgery

Journal of Neurosurgery ◽

10.3171/2018.7.gks18694 ◽

2018 ◽

Vol 129 (Suppl1) ◽

pp. 118-124 ◽

Cited By ~ 4

Author(s):

Alexis Dimitriadis ◽

Ian Paddick

Keyword(s):

Stereotactic Radiosurgery ◽

Treatment Plan ◽

Efficiency Index ◽

Target Volume ◽

Surrounding Tissue ◽

Plan Quality ◽

Multiple Target ◽

Integral Dose ◽

Plan Optimization ◽

Dose Volume

OBJECTIVEStereotactic radiosurgery (SRS) is characterized by high levels of conformity and steep dose gradients from the periphery of the target to surrounding tissue. Clinical studies have backed up the importance of these factors through evidence of symptomatic complications. Available data suggest that there are threshold doses above which the risk of symptomatic radionecrosis increases with the volume irradiated. Therefore, radiosurgical treatment plans should be optimized by minimizing dose to the surrounding tissue while maximizing dose to the target volume. Several metrics have been proposed to quantify radiosurgical plan quality, but all present certain weaknesses. To overcome limitations of the currently used metrics, a novel metric is proposed, the efficiency index (η50%), which is based on the principle of calculating integral doses: η50% = integral doseTV/integral dosePIV50%.METHODSThe value of η50% can be easily calculated by dividing the integral dose (mean dose × volume) to the target volume (TV) by the integral dose to the volume of 50% of the prescription isodose (PIV50%). Alternatively, differential dose-volume histograms (DVHs) of the TV and PIV50% can be used. The resulting η50% value is effectively the proportion of energy within the PIV50% that falls into the target. This value has theoretical limits of 0 and 1, with 1 being perfect. The index combines conformity, gradient, and mean dose to the target into a single value. The value of η50% was retrospectively calculated for 100 clinical SRS plans.RESULTSThe value of η50% for the 100 clinical SRS plans ranged from 37.7% to 58.0% with a mean value of 49.0%. This study also showed that the same principles used for the calculation of η50% can be adapted to produce an index suitable for multiple-target plans (Gη12Gy). Furthermore, the authors present another adaptation of the index that may play a role in plan optimization by calculating and minimizing the proportion of energy delivered to surrounding organs at risk (OARη50%).CONCLUSIONSThe proposed efficiency index is a novel approach in quantifying plan quality by combining conformity, gradient, and mean dose into a single value. It quantifies the ratio of the dose “doing good” versus the dose “doing harm,” and its adaptations can be used for multiple-target plan optimization and OAR sparing.

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Verification of Treatment Plan Delivery for New Self-Shielded Stereotactic Radiosurgery (SRS) System

International Journal of Radiation Oncology*Biology*Physics ◽

10.1016/j.ijrobp.2019.06.921 ◽

2019 ◽

Vol 105 (1) ◽

pp. E688

Author(s):

S.P. Sorensen ◽

S.P. Srivastava ◽

D. Pinnaduwage ◽

S. Jani ◽

X. Yan ◽

...

Keyword(s):

Stereotactic Radiosurgery ◽

Treatment Plan

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FDG-PET Improves Management of Patients with Colorectal Liver Metastases Allocated for Local Treatment: A Consecutive Prospective Study

Scandinavian Journal of Surgery ◽

10.1177/145749690709600305 ◽

2007 ◽

Vol 96 (3) ◽

pp. 209-213 ◽

Cited By ~ 14

Author(s):

M. Sørensen ◽

F. V. Mortensen ◽

M. Høyer ◽

H. Vilstrup ◽

S. Keiding ◽

...

Keyword(s):

Liver Metastases ◽

Fdg Pet ◽

Colorectal Liver Metastases ◽

Imaging Modality ◽

Treatment Plan ◽

Local Treatment ◽

Liver Lesions ◽

Term Survival ◽

Pre Treatment

Background and Aim: Colorectal cancer is a common cancer in the Nordic countries and 50% of the patients develop liver metastases. Liver resection may result in long term survival. Proper staging is therefore essential and CT is the standard imaging modality. We examined whether additional FDG-PET improves therapeutic management of patients with colorectal liver metastases. Patients and Methods: Fifty-four consecutive patients were enrolled. Each patient had a treatment plan made based on our standard evaluation. The patients then had a PET scan and the treatment plan was re-evaluated, taking these results into account. Results: In 76% of the cases, PET did not change the treatment plan due to complete concordance with CT. In another 19% of the cases, the plan was altered due to finding of more liver lesions by PET than by CT (four patients), fewer or no liver lesions (three patients), and extrahepatic lesions not visible on CT (three patients). In 5% of the cases, non-concordance between PET and CT did not change the therapeutic plan. Conclusion: Pre-treatment FDG-PET, used supplementary to CT, improved the treatment plan in one fifth of the patients with colorectal liver metastases.

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Stereotactic Radiosurgery Associated Neurotoxicity

Technology in Cancer Research & Treatment ◽

10.1177/153303460300200211 ◽

2003 ◽

Vol 2 (2) ◽

pp. 147-151 ◽

Cited By ~ 4

Author(s):

William H. St. Clair ◽

Curtis A. Given

Keyword(s):

Stereotactic Radiosurgery ◽

Therapeutic Option ◽

Treatment Plan ◽

Three Dimensional ◽

Reference Points ◽

Therapeutic Modality ◽

High Dose ◽

Lesion Volume ◽

Three Dimensional Mapping ◽

Effective Therapeutic Option

Stereotactic radiosurgery (SRS) is an evolving therapeutic modality for well demarcated intracranial lesions. Since the inception of stereotactic radiosurgery the types of parenchymal CNS lesions addressed by this mode of treatment has increased. All modern stereotactic radiosurgical procedures employ several common features. Patients are fitted with a stereotactic head frame or fiducial markers followed by radiographic imaging which allows for external reference points and three-dimensional mapping of the intracranial lesion. Armed with this information a highly conformal treatment plan is developed to deliver a high dose of radiation to a sharply defined target, with rapid dose fall-off outside the lesion volume. While an extremely effective therapeutic option, SRS is not without risk of neurotoxicity, with radiation necrosis being the most commonly recognized complication. The neurotoxic effects of SRS are reviewed and discussed.

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Predictive role of Vulnerable Elders Survey-13 screen tool for elder cancer patients in final oncology treatment plan.

Journal of Clinical Oncology ◽

10.1200/jco.2020.38.15_suppl.e24020 ◽

2020 ◽

Vol 38 (15_suppl) ◽

pp. e24020-e24020

Author(s):

Fahad Almugbel ◽

Narhari Timilshina ◽

Naser AlQurini ◽

Rana Jin ◽

Arielle Berger ◽

...

Keyword(s):

Treatment Plan ◽

Local Treatment ◽

Geriatric Oncology ◽

Area Under The Curve ◽

Local Therapy ◽

P Value ◽

Treatment Change ◽

Final Treatment ◽

Pre Treatment ◽

Oncologic Treatment

e24020 Background: The Vulnerable Elders Survey (VES-13) is one of several tools that can identify older patients who are vulnerable (if the score is ≥ 3 out of 10) and more likely to benefit from Comprehensive Geriatric Assessment (CGA) prior to cancer treatment. The optimal cutpoint of the VES-13 to identify those whose final oncologic treatment plan would change after CGA is unclear. We hypothesized that patients with high positive scores (7-10) will have a higher likelihood of a change in the final oncologic treatment plan compared to low positive patients (score 3-6). Methods: Retrospective review of a customized database of all patients seen for pre-treatment assessment (solid tumor and lymphoma) in the geriatric oncology clinic at the Princess Margaret Cancer Centre from June 2015 to June 2019. Various VES-13 score cutpoints were compared with the final treatment plan to identify those individuals whose treatment was modified after CGA. Area under the curve was calculated and subgroups of patients treated locally or systemically were also examined to determine if performance varied by type of patient. Results: 386 patients with mean age 81, 58% males were included. Gastrointestinal cancer was the most common site 31% and 60% were planned to receive curative treatment. The final treatment plan was modified in 50% with VES-13 scores 7-10, 46.7% with scores 3-6 and 26.8 % for scores < 3 (P = 0.002; Table). The optimal VES-13 cutoff was between 3-6 (C-statistics 0.57-0.59).The VES-13 performed similarly in those considering local treatment (surgery with/without radiation) vs. chemotherapy. Modified final treatment for local therapy with VES-13 scores < 3 was 11.4 % compared to 42.9% with scores ≥ 3 was 42.9% (p-value < 0.001), whereas for systemic therapy it was 32.4% and 62.5%, respectively (p-value = 0.002). Conclusions: Although high positive VES-13 scores (7-10) had slightly higher likelihood of having the final oncologic treatment plan modified, there was no strong advantage compared to the conventional cutpoint of 3 or higher. The VES-13 performed similarly in predicting treatment change after CGA for local and systemic treatment plans. Further studies are required to identify the optimal frailty screening tool and cutpoint. [Table: see text]

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Time-of-flight magnetic resonance angiography imaging of a residual arteriovenous malformation nidus after Onyx embolization for stereotactic radiosurgery planning

Neurosurgical FOCUS ◽

10.3171/2009.1.focus08246 ◽

2009 ◽

Vol 26 (5) ◽

pp. E13 ◽

Cited By ~ 11

Author(s):

David N. Loy ◽

Keith M. Rich ◽

Joseph Simpson ◽

Ian Dorward ◽

Lakshmi Santanam ◽

...

Keyword(s):

Stereotactic Radiosurgery ◽

Mr Angiography ◽

Spin Echo ◽

Treatment Plan ◽

Time Of Flight ◽

Brain Structures ◽

Fast Spin Echo ◽

Embolic Agent ◽

Slice Thickness ◽

Arteriovenous Shunting

This report demonstrates that time-of-flight (TOF) MR angiography is a useful adjunct for planning stereotactic radiosurgery (SRS) of large arteriovenous malformations (AVMs) after staged embolization with Onyx. Onyx (ethylene vinyl copolymer), a recently approved liquid embolic agent, has been increasingly used to exclude portions of large AVMs from the parent circulation prior to SRS. Limiting SRS to regions of persistent arteriovenous shunting and excluding regions eliminated by embolization may reduce unnecessary radiation doses to eloquent brain structures. However, SRS dosimetry planning presents unique challenges after Onyx embolization because it creates extensive artifacts on CT scans, and it cannot be delineated from untreated nidus on standard MR sequences. During the radiosurgery procedure, MR images were obtained using a GE Signa 1.5-T unit. Standard axial T2 fast spin echo high-resolution images (TR 3000 msec, TE 108 msec, slice thickness 2.5 mm) were generated for optimal visualization of brain tissue and AVM flow voids. The 3D TOF MR angiography images of the circle of Willis and vertebral arteries were subsequently obtained to visualize AVM regions embolized with Onyx (TR 37 msec, TE 6.9 msec, flip angle 20°). Adjunct TOF MR angiography images demonstrated excellent contrast between nidus embolized with Onyx and regions of persistent arteriovenous shunting within a large AVM prior to SRS. Additional information derived from these sequences resulted in substantial adjustments to the treatment plan and an overall reduction in the treated tissue volume.

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Treatment plan complexity metrics for predicting IMRT pre-treatment quality assurance results

Australasian Physical & Engineering Sciences in Medicine ◽

10.1007/s13246-014-0274-9 ◽

2014 ◽

Vol 37 (3) ◽

pp. 475-482 ◽

Cited By ~ 33

Author(s):

S. B. Crowe ◽

T. Kairn ◽

J. Kenny ◽

R. T. Knight ◽

B. Hill ◽

...

Keyword(s):

Quality Assurance ◽

Treatment Plan ◽

Treatment Quality ◽

Complexity Metrics ◽

Pre Treatment

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Long-Term Survival after Linac-Based Stereotactic Radiosurgery and Radiotherapy with A Micro-Multileaf Collimator for Brain Metastasis

10.21203/rs.3.rs-1185945/v1 ◽

2021 ◽

Author(s):

Ryosuke Matsuda ◽

Masatoshi Hasegawa ◽

Tetsuro Tamamoto ◽

Nobuyoshi Inooka ◽

Mei Nikimoto ◽

...

Keyword(s):

Brain Metastasis ◽

Stereotactic Radiosurgery ◽

Karnofsky Performance Scale ◽

Multileaf Collimator ◽

Extracranial Metastasis ◽

Term Survival ◽

Long Term Survival ◽

Female Sex ◽

Pre Treatment

Abstract Purpose: To evaluate the prognostic factors associated with long-term survival after linear accelerator (linac)-based stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (fSRT) with a micro-multileaf collimator for brain metastasis (BM). Methods: This single-center retrospective study included 226 consecutive patients with BM who were treated with linac-based SRS or fSRT with a micro-multileaf collimator between January 2011 and December 2018. Long-term survival (LTS) was defined as survival for more than 2 years after SRS/fSRT. The tumors originated from the lung (n =189, 83.6%), breast (n = 11, 4.9%), colon (n = 9, 4.0%), stomach (n = 4, 1.8%), kidney (n = 3, 1.3%), esophagus (n = 3, 1.3%), and other regions (n = 7, 3.1%). Results: The median pretreatment Karnofsky performance scale (KPS) score was 90 (range: 40–100). The median follow-up time was 13 (range: 0–120) months. Out of the 226 patients, 72 (31.8%) were categorized in the LTS group. The median survival time was 43 months and 13 months in the LTS group and in the entire cohort, respectively. The 3-year, 4-year, and 5-year survival rate in the LTS group was 59.1%, 49.6%, and 40.7%, respectively. Multivariate regression logistic analysis showed that female sex, a pre-treatment KPS score ≥80, and the absence of extracranial metastasis were associated with long-term survival. Conclusions: Female sex, a favorable pre-treatment KPS score, and the absence of extracranial metastasis were associated with long-term survival in the current cohort of patients with BM.

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