Improving organ at risk sparing in oropharyngeal treatment planning by increasing target dose heterogeneity: A feasibility study.

Target dose homogeneity has historically been a priority in radiotherapy treatment planning. However, in an era of more advanced modulated techniques, there is now greater flexibility in shaping dose distributions suggesting that allowing controlled target dose heterogeneity may consequently improve organ at risk (OAR) sparing. This study sought to determine the feasibility of allowing an increase in target dose heterogeneity in oropharyngeal VMAT plans, and to examine the dosimetric impact this has on target coverage and OARs such as the parotid glands, spinal cord, brainstem and mandible.

Daily Rectal Dose-volume Histogram Variation in Prostate Intensity-modulated Radiation Therapy: Is It Clinically Significant in the Era of Image Guidance?

Aim: Because of the steep dose gradient associated with dose-escalated intensity-modulated radiation therapy, interfraction motion and variation in rectal volume may result in the rectum receiving a larger dose than predicted at treatment planning. This study aims to quantify the variation in daily rectal dose-volume histograms (DVHs) from the treatment plan and to discuss the potential clinical significance of this variation.

Materials And Methods: Daily cone beam computed tomography scans of nine patients treated with definitive prostate intensity-modulated radiation therapy were collected.

Adherence to ICRU-83 reporting recommendations is inadequate in prostate dosimetry studies.

Purpose: This study aimed to investigate if the International Commission on Radiation Units and Measurements (ICRU) 83 recommendations for reporting dosimetric endpoints are followed in published prostate studies using modulated techniques.

Methods And Materials: Prostate dosimetry studies using inverse planning techniques were identified through a search of PubMed and EMBASE databases. These studies were analyzed to determine if the endpoints reported followed the recommendations outlined in ICRU-83.

A Dosimetric Evaluation of Threshold Bladder Volumes for Prostate Cancer Radiotherapy.

Background: An interfraction variation in bladder filling results in uncertainties of dose received and also has workflow implications for busy departments. This study aims to examine the dosimetric impact of a reduced bladder volume while determining a suitable threshold for treatment.

Materials And Methods: A total of 15 definitive prostate patients were included for this retrospective dosimetry study.

The impact of intensity-modulated radiation therapy plan normalization in the postprostatectomy setting-does it matter?

The International Commission on Radiation Units & Measurements -83 recommends prescribing intensity-modulated radiation therapy (IMRT) in a dose-volume manner. Despite this, clinical variation still exists in how prostate IMRT plans are prescribed. This study aims to investigate the impact of different plan normalization methods for postprostatectomy IMRT.

The dilemma of parotid gland and pharyngeal constrictor muscles preservation-Is daily online image guidance required? A dosimetric analysis.

With margin reduction common in head and neck radiotherapy, it is critical that the dosimetric effects of setup deviations are quantified. With past studies focusing on the quantification of positional and volumetric changes of organs at risk (OARs), this study aimed to measure the dose delivered to these the parotid gland (PG) and pharyngeal constrictor muscles (PCMs) using cone beam computed tomography (CBCT). Furthermore, this investigation sought to establish a potential time trend of change in dose delivered to target volumes secondary to ascertaining the need for daily image guidance (IG) to reduce the dose burden to these important OARs.

A review of the use of fiducial markers for image-guided bladder radiotherapy.

Background: Enhancing target visualization and reducing set-up errors in image-guided radiotherapy (IGRT) are issues faced when trying to implement more conformal and partial bladder techniques. This review examines the evidence available pertaining to the clinical use of Lipiodol and gold fiducials for IGRT for bladder cancer.

Material And Methods: Nine published articles relating to the feasibility of using Lipiodol injections or gold fiducial markers in IGRT for bladder patients were recruited from a database search strategy.

Effect of stereotactic dosimetric end points on overall survival for Stage I non-small cell lung cancer: a critical review.

Stereotactic body radiation therapy (SBRT) delivers a high biologically effective dose while minimizing toxicities to surrounding tissues. Within the scope of clinical trials and local practice, there are inconsistencies in dosimetrics used to evaluate plan quality. The purpose of this critical review was to determine if dosimetric parameters used in SBRT plans have an effect on local control (LC), overall survival (OS), and toxicities.

A class solution for volumetric-modulated arc therapy planning in postprostatectomy radiotherapy.

This study is aimed to test a postprostatectomy volumetric-modulated arc therapy (VMAT) planning class solution. The solution applies to both the progressive resolution optimizer algorithm version 2 (PRO 2) and the algorithm version 3 (PRO 3), addressing the effect of an upgraded algorithm. A total of 10 radical postprostatectomy patients received 68 Gy to 95% of the planning target volume (PTV), which was planned using VMAT.

A volumetric approach to path-length measurements is essential when treating radiotherapy with modulated beams.

The established dosimetric benefits of intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy have lead to their increased use in prostate radiotherapy. Complimenting these techniques, volumetric image guidance has supported increased positional accuracy. In addition, 3-dimensional image guidance has also allowed for assessment of potential dosimetric variation that can be attributed to a deformation of either internal or external structures, such as rectal distension or body contour.

Volumetric-modulated arc therapy in postprostatectomy radiotherapy patients: a planning comparison study.

The purpose of this study was to compare postprostatectomy planning for volumetric-modulated arc therapy (VMAT) with both single arc (SA) and double arcs (DA) against dynamic sliding window intensity-modulated radiotherapy (IMRT). Ten cases were planned with IMRT, SA VMAT, and DA VMAT. All cases were planned to achieve a minimum dose of 68Gy to 95% of the planning target volume (PTV) and goals to limit rectal volume >40Gy to 35% and >65Gy to 17%, and bladder volumes >40Gy to 50% and >65Gy to 25%.

Image-guided dose-escalated intensity-modulated radiation therapy for prostate cancer: treating to doses beyond 78 Gy.

Unlabelled: Study Type - Therapy (case series) Level of Evidence 4 What's known on the subject? and What does the study add? High doses of radiotherapy correspond to higher cure rates. Most radiation centers in the UK and Australia limit prescription doses to 74-78 Gy and do not use IGRT and IMRT for all patients. The combination of IGRT and IMRT can limit the rectum and bladder to low doses allowing doses above 78 Gy to be delivered, including pelvic lymph node treatment, with low side effects.