Report of AAPM Task Group 235 Radiochromic Film Dosimetry: An Update to TG-55.

The use of radiochromic film (RCF) dosimetry in radiation therapy is extensive due to its high level of achievable accuracy for a wide range of dose values and its suitability under a variety of measurement conditions. However, since the publication of the 1998 AAPM Task Group 55, Report No. 63 on RCF dosimetry, the chemistry, composition, and readout systems for RCFs have evolved steadily.

Education and training of medical physics in Iran: The past, the present and the future.

Purpose: The aim of this study was to investigate the current status of education and training programs in medical physics in Iran.

Methods: A questionnaire was designed and sent to 274 IAMP (Iranian Association of Medical Physicists) members focusing on these two topics: the educational situation (course syllabus, number of faculty members, number of PhD and MSc students and sub-fields offered in the department) and the professional situation (work experience, workplaces of medical physicists, postgraduate degrees that were granted and the amount of therapy and imaging equipment).

Results: Medical physics education in Iran is provided at 14 universities at master and doctorate levels.

Does short-term exposure to elevated levels of natural gamma radiation in Ramsar cause oxidative stress?

Background: Ramsar, a city in northern Iran, has areas with some of the highest recorded levels of natural radiation among inhabited areas measured on the earth.

Aims: To determine whether short-term exposure to extremely high levels of natural radiation induce oxidative stress.

Materials And Methods: In this study, 53 Wistar rats were randomly divided into five groups of 10-12 animals.

Comparison of uniformity of dose response of double layer radiochromic films (MD-55-2) measured at 5 institutions.

In recent years, double-layer radiochromic films (MD-55-2) also known as new improved Gafchromic Films (NMD-55), have been used for measuring dose distributions of radiation fields. It is reported that the response of radiochromic film is affected by the scanning densitometry systems used to read the film. To quantify the response of MD-55-2 films, two sheets (12.

Combined external beam radiotherapy and Pd-103 brachytherapy boost improves biochemical failure free survival in patients with clinically localized prostate cancer: results of a matched pair analysis.

Background: Dose escalation has resulted in improved biochemical control in patients with clinically localized prostate cancer treated with conformal external beam radiation (EBRT). Conformal dose distributions may also be achieved with brachytherapy. Therefore, biochemical control was evaluated for patients treated with combined external radiation therapy and low dose rate brachytherapy (EBRT + LDR).

Adaptive response studies may help choose astronauts for long-term space travel.

Long-term manned exploratory missions are planned for the future. Exposure to high-energy neutrons, protons and high charge and energy particles during a deep space mission, needs protection against the detrimental effects of space radiation. It has been suggested that exposure to unpredictable extremely large solar particle events would kill the astronauts without massive shielding.

Very high background radiation areas of Ramsar, Iran: preliminary biological studies.

People in some areas of Ramsar, a city in northern Iran, receive an annual radiation absorbed dose from background radiation that is up to 260 mSv y(-1), substantially higher than the 20 mSv y(-1) that is permitted for radiation workers. Inhabitants of Ramsar have lived for many generations in these high background areas. Cytogenetic studies show no significant differences between people in the high background compared to people in normal background areas.

Effects of beam spoiler on radiation dose for head and neck irradiation with 10-MV photon beam.

Purpose: To determine the effects of a lucite beam spoiler on the dose distribution to points inside and outside the primary beam for head and neck irradiation with a 10-MV photon beam.

Methods And Materials: Build-up and depth-dose measurements were performed with a parallel-plate ionization chamber for 5 x 5, 10 x 10, and 15 x 15-cm field sizes using lucite spoilers with two different thicknesses at two different lucite-to-skin distances (LSD) for a 10-MV x-ray beam. Corrections were applied to account for finite chamber size.

Radiation dose perturbation at tissue-titanium dental interfaces in head and neck cancer patients.

Purpose: To determine the dose perturbation effects at the tissue-metal implant interfaces in head and neck cancer patients treated with 6 MV and 10 MV photon beams.

Methods And Materials: Phantom measurements were performed to investigate the magnitude of dose perturbation to the tissue adjacent to the titanium alloy implants with (100 mu and 500 mu thick) and without hydroxylapatite (HA) coating. Radiographic and radiochromic films were placed at the upper (and lower) surface of circular metal discs (diameter x thickness: 15 x 3.

Use of dental implants for rehabilitation of mandibulectomy patients prior to radiation therapy.

The use of dental implants can aid in prosthetic rehabilitation of patients after ablative cancer surgery of the oral cavity. Biological effects of radiation therapy and the enhancement of radiation by metal implants have limited the use of dental implants. This article presents a case of dental implants used prior to radiation therapy for rehabilitation of a mandibulectomy patient and discusses the current understanding of radiation effects on bone and metal implants.

Dosimetric parameters of a modified set of wedges for use with asymmetric fields of a 6 MV linear accelerator.

A set of standard wedge filters has been modified for use with half-collimated beams of a 6 MV linear accelerator. The position of the standard size wedge filter has been shifted as far to one side of the wedge plate to ensure optimum half-collimated field coverage (up to 20 x 30 cm) required in certain clinical situations. Dosimetric parameters were normalized at 1.

Air cavity effects on the radiation dose to the larynx using Co-60, 6 MV, and 10 MV photon beams.

Purpose: To determine the perturbation effect in the surface layers of lesions located in the air-tumor tissue interface of larynx using 60Co, 6 MV, and 10 MV photon beams.

Methods And Materials: Thermoluminescent dosimeters (TLDs), were embedded at 16 measurement locations in slab no. 8 of a humanoid phantom and exposed to two lateral-opposed beams using standard small 7 x 7 cm fields.

Measured dose to ovaries and testes from Hodgkin's fields and determination of genetically significant dose.

Purpose: To determine the genetically significant dose from therapeutic radiation exposure with Hodgkin's fields by estimating the doses to ovaries and testes.

Materials And Methods: Phantom measurements were performed to verify estimated doses to ovaries and testes from Hodgkin's fields. Thermoluminescent LiF dosimeters (TLD-100) of 1 x 3 x 3 mm3 dimensions were embedded in phantoms and exposed to standard mantle and paraaortic fields using Co-60, 4 MV, 6 MV, and 10 MV photon beams.

A stereotactic brain implant technique with high activity I-125 seeds using a conventional brachytherapy treatment planning system.

A stereotactic brain implant program with removable high-activity I-125 seeds has recently been implemented for the treatment of malignant brain tumors. A Brown-Roberts-Wells (BRW) stereotactic frame with an NIH arc system and a guide template is used to introduce parallel catheters precisely into the tumor volume (Fig. 1).

Wedge factor dependence on depth and field size for various beam energies using symmetric and half-collimated asymmetric jaw settings.

The depth- and field-size dependence of the in-phantom wedge factor have been determined for a Cobalt-60 (Co-60) teletherapy unit and four medical linear accelerators with 4-, 6-, 10-, and 18-MV x-ray beams containing 15 degrees-60 degrees (nominal) lead, brass, and steel wedge filters. Measurements were made with ionization chambers in solid water or water with a source-skin distance of 80 or 100 cm. Field sizes varied from 4 x 4 cm up to a maximum allowable size for each wedge filter.

Physical aspects of total body irradiation of bone marrow transplant patients using 18 MV x rays.

The physical aspects of a total body irradiation (TBI) treatment are described. Patients seated in a special chair with their legs bent backwards are irradiated anteriorly and posteriorly (AP/PA). The chair reduces patient movement and facilitates positioning patients during 9 fractions of TBI over a 3-day period.

Routine calibration of brachytherapy sources with a well-type dose calibrator using standard calibrated sources.

Brachytherapy, which refers to short-distance treatment via implanted sources, requires an accurate knowledge of the dose distribution in the implant volume. A critical step in the determination of the dose distribution involves an accurate calibration of brachytherapy source strength. Following the guidelines recommended by AAPM Task Group No.

Evaluation of the reconstruction of seed positions from stereo and orthogonal radiographs for routine radiotherapy planning.

Brachytherapy, which refers to short-distance treatment via implanted sources, requires an accurate knowledge of the dose distribution in the implant volume. A critical step in the determination of the dose distribution involves an accurate reconstruction of seed positions. Stereo and orthogonal radiographs offer two distinct imaging techniques for determining the seed positions in the implant volume.

Film dosimetry of small elongated electron beams for treatment planning.

The characteristics of 5, 7, 10, 12, 15, and 18 Mev electron beams for small elongated fields of dimensions L X W (where L = 1, 2, 3, 4, 5, and 10 cm; and W = 1, 2, 3, 4, 5, and 10 cm) have been studied. Film dosimetry and parallel-plate ion chamber measurements have been used to obtain various dose parameters. Selective results of a series of systematic measurements for central axis depth dose data, uniformity index, field flatness, and relative output factors of small elongated electron beams are reported.

Comparison of measured and calculated dose distributions around an iridium-192 wire.

The relative dose distribution around a 5.0-cm-long piece of 192Ir wire has been measured using LiF chips. Measurements were made at distances of 0.

Performance characteristics of an orthovoltage x-ray therapy machine.

Performance characteristics sufficient to provide physical data base specific to the Siemen's Stabilipan 2 orthovoltage x-ray therapy machine are presented. Operating conditions covering the working range of the unit from 100 to 300 kVp are selected. Beam quality, output, the central axis depth dose, relative output factors, field flatness, uniformity index, and filtration characteristics of the beams are studied.