Letters in Oncology Science

Comparison of the isocenter verification methods and calculating imaging offset of medical linear accelerators.

2022-11-30T10:26:34+01:00

The aim of the presented work was to compare two methods of verification of the medical accelerator’s isocenter and determine the imaging offset. Two methods were used for verification - Machine Performence Check (MPC) application with the IsoCal phantom and the Artiscan software with the PTW Isoball Phantom. Each of the analyzed methods provides an alternative way to the time-consuming and costly verification of the isocenter on radiochromic or gafchromic dosimetry films.

Measurements were performed for ten days and the obtained data were compared for both methods. Using statistical tests, concordance was determined for the results obtained by the two methods. The data were presented in trend function graphs.

Analysis of the results shows that it is not possible to unequivocally state that the methods are not equivalent. In addition, the AAPM TG 142 report assumes that MPC is not a sufficient test for checking medical linear accelerator’s isocentre.

Comparison of radiotherapy planning techniques for breast cancer

2022-12-06T12:54:31+01:00

Radiotherapy is an integral part of the comprehensive treatment of breast cancer, which accounts for over 20% of all cancer cases among women in Poland. Along with technological progress, methods are developed that improve the effectiveness of treatment, patient comfort and reduce the toxicity of therapy. The most popular irradiation technique for breast cancer is Three-Dimensional Conformal Radiotherapy (3DCRT), as it provides the lowest doses of radiation absorbed by the contralateral organs. Compared to static techniques, dynamic techniques provide a more uniform dose distribution in the target volume (PTV, Planning Target Volume), but higher doses in the critical organs (OAR, Organ at Risk). The hybrid method combining the advantages of static and dynamic plans is becoming more and more popular.

The aim of the study was to compare four breast irradiation techniques: 3DCRT, rotary volumetric modulated arc therapy (VMAT), B-VMAT so-called butterfly, in which the emission of the therapeutic beam is blocked in a certain angular range of the arc, and a hybrid technique combining 3D and VMAT fields in one treatment plan.

For a group of 11 patients, plans were prepared in the Eclipse Treatment Planning System (TPS) (Varian Medical Systems, Palo Alto, USA) and compared for each of the discussed techniques. Dose distributions, Dose Volume Histograms (DVH) and mean doses in critical organs: lungs, contralateral lung, heart and healthy breast were evaluated.

Based on the DVH analysis, all treatment plans were found to be clinically acceptable. The 3DCRT treatment plans can be considered the most favorable in terms of doses in OAR. At the same time, it should be noted that in the hybrid technique these doses are only slightly higher. For the VMAT plans, an increase in the percentage of critical organ volumes covered by low dose isodoses was observed, especially for contralateral organs. Blocking the beam emission in the part of the arc in the B-VMAT technique partially offset this effect, but as in the case of VMAT, the OAR volumes in which low doses are deposited are noticeably higher than for the 3DCRT and hybrid plans.

The hybrid technique of breast irradiation is a good alternative to 3DCRT plans and can be implemented for clinical use, shortening the time of implementation of treatment plans on a medical accelerator and improving the comfort of treated patients.

Imaging methods in Image-Guided Radiation Therapy (IGRT)

2022-12-04T12:25:56+01:00

Image-Guided Radiation Therapy (IGRT) is a technique that uses two- and three-dimensional imaging. It is applied to accurately locate the treatment area prior to patient exposure to the therapeutic beam, generated to implement treatment plans with high dose distribution conformality, based on beam intensity modulation techniques

The aim of this study was to discuss the currently used imaging methods in IGRT - volumetric and planar, based on the use of ionizing radiation, and other, based on non-ionization phenomena.

Intraoperative Electron Radiation Therapy (IOERT)

2022-11-29T12:13:22+01:00

Treatment tactics that combine sparing surgery with radiation therapy have become the standard in the treatment of early cancers. One example of combined treatment is intraoperative radiotherapy, which is performed during surgery while the patient is still under anesthesia in a sterile operating room.

The aim of this work is to discuss the technique of intraoperative electron beam radiotherapy (IOERT) generated by mobile accelerators.

The IOERT method is used in the treatment of neoplasms such as: breast, prostate, pancreas, colon and rectum. Based on the literature reports, the following were discussed: the course of the procedure, the most frequently used physical parameters and the challenges related to the quality control and radiological protection of personnel.

Imaging doses in image-guided radiation therapy

2022-12-04T12:28:43+01:00

The modern gold standard of cancer treatment using radiotherapy is the use of ionizing radiation beam imaging with kilovolt or megavoltage effective accelerating potential for positioning the patient on the therapeutic table - therefore the patient is exposed to an additional dose. In line with the ALARA principle, it is important to achieve the desired clinical effect with the lowest possible radiation dose, and this also applies to imaging.

The aim of this article was to analyze the problem of estimating the dose level from imaging using various techniques in Image-Guided Radiation Therapy (IGRT).