Feasibility of determining external beam radiotherapy dose using LuSy dosimeter.

Introduction: Radiation dose measurement is an essential part of radiotherapy to verify the correct delivery of doses to patients and ensure patient safety. Recent advancements in radiotherapy technology have highlighted the need for fast and precise dosimeters. Technologies like FLASH radiotherapy and magnetic-resonance linear accelerators (MR-LINAC) demand dosimeters that can meet their unique requirements.

Comparison of commercial atlas-based automatic segmentation software for prostate radiotherapy treatment planning.

This study aims to assess the accuracy of automatic atlas-based contours for various key anatomical structures in prostate radiotherapy treatment planning. The evaluated structures include the bladder, rectum, prostate, seminal vesicles, femoral heads and penile bulb. CT images from 20 patients who underwent intensity-modulated radiotherapy were randomly chosen to create an atlas library.

Ex-vivo analysis of demineralisation on irradiated teeth using optical coherence tomography.

Head and neck cancer patients are prone to dental caries after radiotherapy. An ex-vivo study was conducted to assess the feasibility of optical coherence tomography (OCT) to detect tooth demineralization due to caries in irradiated teeth. Thirty-nine human molar teeth were subjected to caries lesion induction through irradiation (Group 1), pH cycling (Group 2-1), and both (Group 2-2).

A multi-center survey on adaptive radiation therapy for head and neck cancer in Malaysia.

The survey is to assess the current state of adaptive radiation therapy (ART) for head and neck (H&N) cases among radiotherapy centers in Malaysia and to identify any implementation limitations. An online questionnaire was sent to all radiotherapy centers in Malaysia. The 24-question questionnaire consists of general information about the center, ART practices, and limitations faced in implementing ART.

Remodeling in Aortic Stenosis With Reduced and Preserved Ejection Fraction: Insight on Motion Abnormality Via 3D + Time Personalized LV Modeling in Cardiac MRI.

Background: Increased afterload in aortic stenosis (AS) induces left ventricle (LV) remodeling to preserve a normal ejection fraction. This compensatory response can become maladaptive and manifest with motion abnormality. It is a clinical challenge to identify contractile and relaxation dysfunction during early subclinical stage to prevent irreversible deterioration.

Evaluation of intrafractional prostate displacement during prostate radiotherapy using real-time ultrasound system.

Transperineal ultrasound (TPUS) is an image-guided radiotherapy system used for tracking intrafraction prostate displacements in real time. The objectives of this study are to evaluate intrafraction prostate displacements and derive planning target volume (PTV) margins for prostate radiotherapy at our institution. The ultrasound (US) data of nine prostate cancer patients referred for VMAT radiotherapy was retrieved.

Assessment of demineralized tooth lesions using optical coherence tomography and other state-of-the-art technologies: a review.

Tooth demineralization is one of the most common intraoral diseases, encompassing (1) caries caused by acid-producing bacteria and (2) erosion induced by acid of non-bacterial origin from intrinsic sources (e.g. stomach acid reflux) and extrinsic sources (e.

Dosimetry audit for megavoltage photon beams applied in non-reference conditions.

Purpose: We have conducted for the first time a Malaysian postal dosimetry audit of external beam under non-reference conditions by evaluating the output performance while screening for systematic errors within the dosimetry chain. The potential use from the choice of detector were investigated along with the search for other sources of discrepancies.

Methods: Ten radiotherapy centres were audited, encompassing 16 megavoltage photon beam arrangements, adopting the IAEA postal dosimetry protocol for non-reference conditions, with a holder modified to accommodate three TLD types: Ge-doped cylindrical silica fibres (CF), Ge-doped flat silica fibres (FF), and TLD-100 powder.

Evaluation of skin dose and skin toxicity in patients undergoing intraoperative radiotherapy for early breast cancer.

Purpose: This study aims to evaluate in vivo skin dose delivered by intraoperative radiotherapy (IORT) and determine the factors associated with an increased risk of radiation-induced skin toxicity.

Methodology: A total of 21 breast cancer patients who underwent breast-conserving surgery and IORT, either as IORT alone or IORT boost plus external beam radiotherapy (EBRT), were recruited in this prospective study. EBT3 film was calibrated in water and used to measure skin dose during IORT at concentric circles of 5 mm and 40 mm away from the applicator.

Evaluation of treatment plan quality for head and neck IMRT: a multicenter study.

Intensity-modulated radiotherapy (IMRT) treatment planning for head and neck cancer is challenging and complex due to many organs at risk (OAR) in this region. The experience and skills of planners may result in substantial variability of treatment plan quality. This study assessed the performance of IMRT planning in Malaysia and observed plan quality variation among participating centers.

Medical physics aspects of Intensity-Modulated Radiotherapy practice in Malaysia.

Purpose: Intensity Modulated Radiotherapy (IMRT) has changed the practice of radiotherapy since its implementation in the 1990s. The purpose of this study is to review current practice of IMRT in Malaysia.

Methods: A survey on medical physics aspects of IMRT is conducted on radiotherapy departments across Malaysia to assess the usage, experience and QA in IMRT, which is done for the first time in this country.

Characterization of MOSkin detector for in vivo dose verification during Cobalt-60 high dose-rate intracavitary brachytherapy.

In vivo dosimetry in high dose-rate (HDR) intracavitary brachytherapy (ICBT) is important for assessing the true dose received by surrounding organs at risk during treatment. It also serves as part of the treatment delivery quality assurance and verification program with the use of a suitable dosimeter. Such a dosimeter should be characterized under brachytherapy conditions before clinical application to ensure the accuracy of in vivo measurement.

Assessing surface characteristics of eroded dentine with optical coherence tomography: a preliminary in vitro validation study.

We conducted the first pilot study to investigate the use of the attenuation coefficient from an optical coherence tomography (OCT) backscattered signal as a measure of surface roughness changes in eroded dentine at an early stage of the erosion process. Ten human premolar root samples were subjected to citric acid treatment before scanning by OCT. The extracted relative attenuation coefficient (μ) from backscattered OCT signals was shown to increase with the duration of acid challenge.

"Edge-on" MOSkin detector for stereotactic beam measurement and verification.

Dosimetry in small radiation field is challenging and complicated because of dose volume averaging and beam perturbations in a detector. We evaluated the suitability of the "Edge-on" MOSkin (MOSFET) detector in small radiation field measurement. We also tested the feasibility for dosimetric verification in stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT).

Evaluation of Imaging Dose From Different Image Guided Systems During Head and Neck Radiotherapy: A Phantom Study.

This work evaluated and compared the absorbed doses to selected organs in the head and neck region from the three image guided radiotherapy systems: cone-beam computed tomography (CBCT) and kilovoltage (kV) planar imaging using the On-board Imager® (OBI) as well as the ExacTrac® X-ray system, all available on the Varian Novalis TX linear accelerator. The head and neck region of an anthropomorphic phantom was used to simulate patients' head within the imaging field. Nanodots optically stimulated luminescent dosemeters were positioned at selected sites to measure the absorbed doses.

The Thermoluminescence Response of Ge-Doped Flat Fibers to Gamma Radiation.

Study has been undertaken of the thermoluminescence (TL) yield of various tailor-made flat cross-section 6 mol% Ge-doped silica fibers, differing only in respect of external dimensions. Key TL dosimetric characteristics have been investigated, including glow curves, dose response, sensitivity, fading and reproducibility. Using a (60)Co source, the samples were irradiated to doses within the range 1 to 10 Gy.

On the Use of Optically Stimulated Luminescent Dosimeter for Surface Dose Measurement during Radiotherapy.

This study was carried out to investigate the suitability of using the optically stimulated luminescence dosimeter (OSLD) in measuring surface dose during radiotherapy. The water equivalent depth (WED) of the OSLD was first determined by comparing the surface dose measured using the OSLD with the percentage depth dose at the buildup region measured using a Markus ionization chamber. Surface doses were measured on a solid water phantom using the OSLD and compared against the Markus ionization chamber and Gafchromic EBT3 film measurements.

Regional assessment of LV wall in infarcted heart using tagged MRI and cardiac modelling.

A segmental two-parameter empirical deformable model is proposed for evaluating regional motion abnormality of the left ventricle. Short-axis tagged MRI scans were acquired from 10 healthy subjects and 10 postinfarct patients. Two motion parameters, contraction and rotation, were quantified for each cardiac segment by fitting the proposed model using a non-rigid registration algorithm.

Characterization of MOSkin detector for in vivo skin dose measurement during megavoltage radiotherapy.

In vivo dosimetry is important during radiotherapy to ensure the accuracy of the dose delivered to the treatment volume. A dosimeter should be characterized based on its application before it is used for in vivo dosimetry. In this study, we characterize a new MOSFET-based detector, the MOSkin detector, on surface for in vivo skin dosimetry.

CT based 3-dimensional treatment planning of intracavitary brachytherapy for cancer of the cervix: comparison between dose-volume histograms and ICRU point doses to the rectum and bladder.

Background: CT based brachytherapy allows 3-dimensional (3D) assessment of organs at risk (OAR) doses with dose volume histograms (DVHs). The purpose of this study was to compare computed tomography (CT) based volumetric calculations and International Commission on Radiation Units and Measurements (ICRU) reference-point estimates of radiation doses to the bladder and rectum in patients with carcinoma of the cervix treated with high-dose-rate (HDR) intracavitary brachytherapy (ICBT).

Materials And Methods: Between March 2011 and May 2012, 20 patients were treated with 55 fractions of brachytherapy using tandem and ovoids and underwent post-implant CT scans.

Treatment outcome for nasopharyngeal carcinoma in University Malaya Medical Centre from 2004-2008.

Background: Nasopharyngeal carcinoma (NPC) is the commonest radiocurable cancer in Malaysia. This study aimed to determine the treatment outcomes and late effects of radiotherapy for NPC patients treated in University Malaya Medical Centre (UMMC).

Materials And Methods: All newly diagnosed patients with NPC referred for treatment to the Oncology unit at UMMC from 2004-2008 were retrospectively analyzed.

Comparison of low-dose, half-rotation, cone-beam CT with electronic portal imaging device for registration of fiducial markers during prostate radiotherapy.

This study evaluated the agreement of fiducial marker localization between two modalities--an electronic portal imaging device (EPID) and cone-beam computed tomography (CBCT)--using a low-dose, half-rotation scanning protocol. Twenty-five prostate cancer patients with implanted fiducial markers were enrolled. Before each daily treatment, EPID and half-rotation CBCT images were acquired.

Dose planning study of target volume coverage with intensity- modulated radiotherapy for nasopharyngeal carcinoma: Penang General Hospital experience.

Background: To compare the dosimetric coverage of target volumes and organs at risk in the radical treatment of nasopharyngeal carcinoma (NPC) between intensity-modulated radiotherapy (IMRT) and three- dimensional conformal radiotherapy (3DCRT).

Materials And Methods: Data from 10 consecutive patients treated with IMRT from June-October 2011 in Penang General Hospital were collected retrospectively for analysis. For each patient, dose volume histograms were generated for both the IMRT and 3DCRT plans using a total dose of 70Gy.