Conformal stereotactic radiosurgery treatment: plan evaluation methods and results

The purpose of our study was the objective evaluation of micro-multileaf collimator (mMLC)-based stereotactic radiosurgery treatment plans. Forty-seven patients, 71 lesions received static beam conformal stereotactic radiosurgery treatment in our institute between November 2005 and June 2008. Target volume and organs at risk were outlined on a MRI-CT image fusion basis. BrainSCAN 5.31 system (BrainLAB AG, Heimstetten, Germany) was used for treatment planning, Elekta Presice TS linear accelerator (Elekta Oncology Systems Ltd, Crawley, UK) and BrainLAB m3 mMLC were used for treatment delivery. An invasive head frame, mounted to the treatment table, was used with four screws for patient head fixation. Treatment plans were analysed with objective parameters, such as conformal index (COIN), homogeneity index (HI), coverage index (CI) and healthy tissue relative overdose factor (HTOF) tools. x2 tests were performed between COIN, HI and the geometrical parameters of the target volume (lesion volume - LV, lesion-organ distance - LOD, lesion deformity index - LDI). Mean value of COIN, HI, HTOF and CI was 0.52 (SD 0.13), 1.16 (SD 0.1), 0.88 (SD 0.53), and 0.94 (SD 0.11), respectively. COIN significantly correlated with (p<0.001 in all three cases), while HI was independent of LV, LOD, LDI (p=0.94; 0.14 and 0.72). COIN is similar, HTOF is less than data from the literature. According to our results geometrical parameters of the target volume (size, location, deformation) significantly influence the COIN, but they have no effect on HI

Modern három dimenziós konformális craniospinalis besugárzási technika.

The main problem of craniospinal irradiation (CSI) is the matching of the fields. The use of a suitable technique is very important because matching of the fields is necessary to use for the optimal cancer irradiation of the long planning target volume (PTV). Since 2007, 8 patients have received CT-based, 3D-planned conformal CSI in our Institute. Patient immobilization was made in prone position in a vacuum bed, using skull and pelvis masks. Organ-at-risk (OAR) contours were made by radiographers. PTV was contoured by radiation oncologists. The prescribed dose to the PTV was 36 Gy with 1.8 Gy dose per fraction. In the planning process the following aspects were taken under consideration: all points of the PTV had to receive at least 95% of the prescribed dose (according to ICRU 50, 62); at junction field edges the overlapping parts were eliminated using a multisegmental technique, where the adjacent segment ends of the neighbouring fields were shifted two times 2 cm, so that the three equally weighted segments used in one field had 2-2 cm distance from each other. In the CSI planning the shape of the patient and so the length of the PTV has made a big emphasis on determining the number of field matching. Thus in some cases instead of two, only one field matching was sufficient - this could be achieved by increasing the source-to-skin distance (SSD) of the fields. The verification made with a solid-water phantom justified the precision of the field matching. The offset used at junction field edges in between one treatment facilitates the verification of field matching - and so the patient positioning. Thus the possibility of having overdosed regions could be reduced, which was very important from a radiation biological point of view

Quality assurance for the EORTC 22071¿26071 study: dummy run prospective analysis.

PurposeThe phase III 22071¿26071 trial was designed to evaluate the addition of panitumumab to adjuvant chemotherapy plus intensity modulated radiotherapy (IMRT) in locally advanced resected squamous cell head and neck cancer. We report the results of the dummy run (DR) performed to detect deviations from protocol guidelines.Methods and MaterialsDR datasets consisting of target volumes, organs at risk (OAR) and treatment plans were digitally uploaded, then compared with reference contours and protocol guidelines by six central reviewers. Summary statistics and analyses of potential correlations between delineations and plan characteristics were performed.ResultsOf 23 datasets, 20 (87.0\%) GTVs were evaluated as acceptable/borderline, along with 13 (56.5\%) CTVs and 10 (43.5\%) PTVs. All PTV dose requirements were met by 73.9 of cases. Dose constraints were met for 65.2-100 of mandatory OARs. Statistically significant correlations were observed between the subjective acceptability of contours and the ability to meet dose constraints for all OARs (p¿¿¿0.01) except for the parotids and spinal cord. Ipsilateral parotid doses correlated significantly with CTV and PTV volumes (p¿¿¿0.05).ConclusionsThe observed wide variations in treatment planning, despite strict guidelines, confirms the complexity of development and quality assurance of IMRT-based multicentre studies for head and neck cancer

Induced acute erythema and late pigmentation may not be correlated: In regards to Perera et al. (Int J Radiat Oncol Biol Phys 2005;62:1283-1290)

peer reviewed[No abstract available

Quality assurance of the EORTC 22043-30041 trial in post-operative radiotherapy in prostate cancer: Results of the Dummy Run procedure

Background and purpose: The EORTC 22043-30041 trial investigates the role of the addition of androgen suppression to post-operative radiotherapy in patients who have undergone radical prostatectomy. As part of the quality assurance of radiotherapy (QART) a Dummy Run (DR) procedure was performed. Materials and method: The protocol included detailed and published delineation guidelines. Participating institutions digitally submitted radiotherapy treatment volumes and a treatment plan for a standard clinical case. Submissions were centrally reviewed using the VODCA software platform. Results: Thirty-eight submissions from thirty-one institutions were reviewed. Six were accepted without comments. Twenty-three were accepted with comments on one or more items: target volume delineation (22), OAR delineation (23), planning and dosimetry (3) or treatment verification (1). Nine submissions were rejected requiring resubmission, seven for target volume delineation reasons alone. Intervention to highlight the importance of delineation guidelines was made prior to the entry of the first patient in the trial. After this, a lower percentage of resubmissions was required. Conclusions: The EORTC 22043-30041 Dummy Run highlights the need for timely and effective QART in clinical trials. The variation in target volume and OAR definition demonstrates that clinical guidelines and radiotherapy protocols are not a substitute for QART procedures. Early intervention in response to the Dummy Run improved protocol understanding. © 2013 Elsevier Ireland Ltd. All rights reserved