Homogenous dose prescription in Gamma Knife Radiotherapy: Combining the best of both worlds.

Purpose: Stereotactic radiosurgery with linear accelerators (LINACs) or Leksell Gamma Knife® (LGK, Elekta AB) is an established treatment option for intracranial tumors. When those are involving/abutting organs at risk (OAR), homogenous and normofractionated treatments outmatch single fraction deliveries. In such situations, it would be desirable to balance LINAC's homogeneity benefits with LGK's dose gradient attributes.

Surface guidance compared with ultrasound-based monitoring and diaphragm position in cone-beam computed tomography during abdominal stereotactic radiotherapy in breath-hold.

Background And Purpose: Spirometry induced deep-inspiration-breath-hold (DIBH) reduces intrafractional motion during upper abdominal stereotactic body radiotherapy (SBRT). The aim of this prospective study was to evaluate whether surface scanning (SGRT) is an adequate surrogate for monitoring residual internal motion during DIBH. Residual motion detected by SGRT was compared with experimental 4D-ultrasound (US) and an internal motion detection benchmark (diaphragm-dome-position in kV cone-beam computed tomography (CBCT) projections).

Inverse planning in Gamma Knife radiosurgery: A comparative planning study.

Purpose: To determine the advantages of inverse planning using a prerelease version of Leksell Gamma Knife® (LGK) Lightning (Elekta AB, Sweden) compared to manual forward planning.

Methods: Thirty-eight patients with metastases (MET, n = 15), vestibular schwannomas (VS, n = 11) and meningiomas (MEN, n = 12), treated with LGK Icon™ at our institution, were analyzed retrospectively. For each case, an inverse (inv) and inverse full coverage (fc) treatment plan was generated using LGK Lightning and compared to the clinical plans.

Prospective assessment of mask versus frame fixation during Gamma Knife treatment for brain metastases.

Purpose: The newest generation of the Leksell Gamma Knife (GK) allows frame based as well as frameless treatment. We here report outcomes of a prospective non-randomized study on mask fixation (MF) versus frame fixation (FF) for GK treatment of brain metastases.

Methods: The decision for FF or MF was made on a case-by-case basis.

Postoperative stereotactic radiosurgery and hypofractionated radiotherapy for brain metastases using Gamma Knife and CyberKnife: a dual-center analysis.

Background: Postoperative stereotactic radiosurgery (SRS) and hypofractionated stereotactic radiotherapy (hFSRT) to tumor cavities is emerging as a new standard of care after resection of brain metastases. Both Gamma Knife (GK) and CyberKnife (CK) are modalities commonly used for stereotactic radiotherapy, but fractional schemes are not consistent. The objective of this study was to evaluate outcomes in patients receiving postoperative stereotactic radiotherapy of resected brain metastases (BM) using different fractionation schedules and modalities in two large centers.

Ultrasound-based repositioning and real-time monitoring for abdominal SBRT in DIBH.

Aim: Ultrasound-based repositioning and real-time-monitoring aim at the improvement of the precision of SBRT in deep inspiration breath-hold (DIBH). Accuracy of ultrasound-based daily repositioning was estimated by comparison with DIBH-cone-beam-CT. Intrafraction motion during beam-delivery was assessed by ultrasound-real-time-monitoring.

Radiation-induced optic neuropathy after stereotactic and image guided intensity-modulated radiation therapy (IMRT).

Background/purpose: To quantify the risk of radiation-induced optic neuropathy (RION) after stereotactic/image-guided positioning and intensity-modulated radiotherapy (IMRT) with ≥50 Gy to the anterior visual pathway (AVP).

Methods: Patients irradiated with ≥50 Gy to the AVP using stereotactic/image-guided positioning between 2002 and 2011 in Mannheim were identified. Detailed dosimetric data were collected and patients or family members were retrospectively asked to rate visual acuity and visual disorders.

Validation of frame-based positioning accuracy with cone-beam computed tomography in Gamma Knife Icon radiosurgery.

Background: Frame based positioning accuracy in Gamma Knife (GK) stereotactic radiosurgery (SRS) is extremely high but removal of a post may be necessary to enable the treatment in selected patients.

Objective: To verify the positioning accuracy in clinical scenarios with 4 and 3 posts in patients and phantoms using cone-beam CT (CBCT) of Gamma Knife Icon™.

Methods: We analyzed positioning accuracy for 12 patients with standard 4 post setup using pretreatment CBCT (pre-CBCT) on GK Icon™ and report 4 patients with different clinical scenarios (removal of a post).

Treatment of Adrenal Metastases with Conventional or Hypofractionated Image-guided Radiation Therapy - Patterns and Outcomes.

Background/aim: Metastases involving the adrenal glands can be treated surgically or with radiation therapy. Retrospective studies indicate that radiotherapy for this indication is safe, well-tolerated and associated with symptom palliation and good local control. We conducted this analysis to report on patterns and outcomes of patients with adrenal metastases treated with hypo- or conventionally fractionated image-guided radiotherapy.

Intra-breath-hold residual motion of image-guided DIBH liver-SBRT: An estimation by ultrasound-based monitoring correlated with diaphragm position in CBCT.

Background And Purpose: Craniocaudal motion during image-guided abdominal SBRT can be reduced by computer-controlled deep-inspiratory-breath-hold (DIBH). However, a residual motion can occur in the DIBH-phases which can only be detected with intrafractional real-time-monitoring. We assessed the intra-breath-hold residual motion of DIBH and compared residual motion of target structures during DIBH detected by ultrasound (US).

Fully automated, multi-criterial planning for Volumetric Modulated Arc Therapy - An international multi-center validation for prostate cancer.

Background And Purpose: Reported plan quality improvements with autoplanning of radiotherapy of the prostate and seminal vesicles are poor. A system for automated multi-criterial planning has been validated for this treatment in a large international multi-center study. The system is configured with training plans using a mechanism that strives for quality improvements relative to those plans.

An offline technique to evaluate residual motion of the diaphragm during deep inspiratory breath-hold from cone-beam CT datasets.

Purpose: In radiation therapy, the computer-assisted deep inspiration breath-hold (DIBH) technique is one approach to deal with respiratory motion of tumors in the lung, liver, or upper abdomen. However, inter- and intra-breath-hold deviations from an optimal static tumor position might occur. A novel method is presented to noninvasively measure the diaphragm position and thus estimate its residual deviation (as surrogate for the tumor position) based on cone-beam computed tomography (CBCT) projection data using active breathing control during acquisition.

Study Protocol: Early Stereotactic Gamma Knife Radiosurgery to Residual Tumor After Surgery of Newly Diagnosed Glioblastoma (Gamma-GBM).

Background: Glioblastoma (GBM) is the most common malignant brain tumor in adult patients. Tumor recurrence commonly occurs around the resection cavity, especially after subtotal resection (STR). Consequently, the extent of resection correlates with overall survival (OS), suggesting that depletion of postoperative tumor remnants will improve outcome.

Automated VMAT planning for postoperative adjuvant treatment of advanced gastric cancer.

Background: Postoperative/adjuvant radiotherapy of advanced gastric cancer involves a large planning target volume (PTV) with multi-concave shapes which presents a challenge for volumetric modulated arc therapy (VMAT) planning. This study investigates the advantages of automated VMAT planning for this site compared to manual VMAT planning by expert planners.

Methods: For 20 gastric cancer patients in the postoperative/adjuvant setting, dual-arc VMAT plans were generated using fully automated multi-criterial treatment planning (autoVMAT), and compared to manually generated VMAT plans (manVMAT).

Fully automated treatment planning of spinal metastases - A comparison to manual planning of Volumetric Modulated Arc Therapy for conventionally fractionated irradiation.

Background: Planning for Volumetric Modulated Arc Therapy (VMAT) may be time consuming and its use is limited by available staff resources. Automated multicriterial treatment planning can eliminate this bottleneck. We compared automatically created (auto) VMAT plans generated by Erasmus-iCycle to manually created VMAT plans for treatment of spinal metastases.

Deep Inspiration Breath Hold-Based Radiation Therapy: A Clinical Review.

Several recent developments in linear accelerator-based radiation therapy (RT) such as fast multileaf collimators, accelerated intensity modulation paradigms like volumeric modulated arc therapy and flattening filter-free (FFF) high-dose-rate therapy have dramatically shortened the duration of treatment fractions. Deliverable photon dose distributions have approached physical complexity limits as a consequence of precise dose calculation algorithms and online 3-dimensional image guided patient positioning (image guided RT). Simultaneously, beam quality and treatment speed have continuously been improved in particle beam therapy, especially for scanned particle beams.

Automatically gated image-guided breath-hold IMRT is a fast, precise, and dosimetrically robust treatment for lung cancer patients.

Background: High-dose radiotherapy of lung cancer is challenging. Tumors may move by up to 2 cm in craniocaudal and anteroposterior directions as a function of breathing cycle. Tumor displacement increases with treatment time, which consequentially increases the treatment uncertainty.

Intensity modulated radiosurgery of brain metastases with flattening filter-free beams.

Purpose: Flattening filter free (FFF) irradiation potentially reduces treatment delivery time in radiosurgery thus eliminating intrafraction motion and increasing patient comfort. We compared plan quality and efficiency of VMAT and IMRT plans for FFF- and standard delivery for brain metastases with single fraction doses of 20 Gy and validated the dosimetric accuracy of the FFF delivery.

Material And Methods: CT data of 15 patients with brain metastases were included in this study.

Flattening-filter-free intensity modulated breath-hold image-guided SABR (Stereotactic ABlative Radiotherapy) can be applied in a 15-min treatment slot.

Hypofractionated image-guided stereotactic ablative radiotherapy (igSABR) is effective in small lung/liver lesions. Computer-assisted breath-hold reduces intrafraction motion but, as every gating/triggering strategy, reduces the duty cycle, resulting in long fraction times if combined with intensity-modulated radiotherapy (IMRT). 10 MV flattening-filter-free IMRT reduces daily fraction duration to <10 min for single doses of 5-20 Gy.

Radiotherapy for early mediastinal Hodgkin lymphoma according to the German Hodgkin Study Group (GHSG): the roles of intensity-modulated radiotherapy and involved-node radiotherapy.

Purpose: Cure rates of early Hodgkin lymphoma (HL) are high, and avoidance of late complications and second malignancies have become increasingly important. This comparative treatment planning study analyzes to what extent target volume reduction to involved-node (IN) and intensity-modulated (IM) radiotherapy (RT), compared with involved-field (IF) and three-dimensional (3D) RT, can reduce doses to organs at risk (OAR).

Methods And Materials: Based on 20 computed tomography (CT) datasets of patients with early unfavorable mediastinal HL, we created treatment plans for 3D-RT and IMRT for both the IF and IN according to the guidelines of the German Hodgkin Study Group (GHSG).

Performance of an atlas-based autosegmentation software for delineation of target volumes for radiotherapy of breast and anorectal cancer.

Background And Purpose: To validate atlas-based autosegmentation for contouring breast/anorectal targets.

Methods And Materials: ABAS uses atlases with defined CTVs as template cases to automatically delineate target volumes in other patient CT-datasets. Results are compared with manually contoured CTVs of breast/anorectal cancer according to RTOG-guidelines.

A comparison of several modulated radiotherapy techniques for head and neck cancer and dosimetric validation of VMAT.

Purpose: Volumetric modulated arc therapy (VMAT) has the potential to shorten treatment times for fluence modulated radiotherapy. We compared dose distributions of VMAT, step-and-shoot IMRT and serial tomotherapy for typical head and neck (H&N) planning target volumes (PTV) with sparing of one parotid, a complex paradigm and a situation often encountered in H&N radiotherapy. Finally, we validated the dosimetric accuracy of VMAT delivery.

Reirradiation of spinal column metastases: comparison of several treatment techniques and dosimetric validation for the use of VMAT.

Background: For reirradiation of spinal column metastases, intensity-modulated radiation therapy (IMRT) reduces the dose to the spinal cord, while allowing longer treatment times. We analyzed the potential of volumetric modulated arc therapy (VMAT) to reduce treatment time and number of monitor units (MU).

Patients And Methods: In CT datasets of 9 patients with spinal column metastases, the planned target volume (PTV) encompassed the macroscopic tumor including the spinal cord or medullary cone, respectively.