Electromagnetic tracking system (EMTS)

Image-guided therapy relies on the localization of the equipment with respect to the patient. This localization in three-dimensional space is referred to as tracking and is a key enabling technology for computer-assisted interventions. Electromagnetic (EM) tracking has emerged as the method of choice that enables localization of small EM sensors in a given EM field without the requirement for line-of-sight [3]. The introduction of continuous EM tracking has allowed the intrafraction motion to be measured and corrected in real-time during treatment [2]. When a receiving sensor moving in space, an EMTS can accurately calculate its position and orientation, it can provide dynamic, real-time measuring position and orientation angle [1].
«The term “electromagnetic” to describe the tracking phenomenon arises from the fact that electromagnets are responsible for producing changing or quasi-static magnetic fields, which induce currents in solenoids or fluxgate sensors embedded in the detectors. The phenomenon responsible for the operation of these tracking systems relies solely on magnetic induction rather than any strict electromagnetic effect. Nevertheless, while this technology is referred to by both the terms “magnetic tracking” (MT) and “electromagnetic tracking” (EMT), the latter has become the more common, having been adopted by the manufacturers of these devices, (...) [3].»

Bibliographic references:

[1] Zhang Z, Liu G. The Design and Analysis of Electromagnetic Tracking System. Journal of Electromagnetic Analysis and Applications. 2013;5:85-9. Available at: http://dx.doi.org/10.4236/jemaa.2013.52014.

[2] Litzenberg DW, Gallagher I, Masi KJ, et al. A measurement technique to determine the calibration accuracy of an electromagnetic tracking system to radiation isocenter. Med Phys. 2013 Aug;40(8):081711. Available at: https://doi.org/10.1118/1.4813910.

[3] Franz AM, Haidegger T, Birkfellner W, et al. Electromagnetic tracking in medicine - a review of technology, validation, and applications. IEEE Trans Med Imaging. 2014 Aug;33(8):1702-25. Available at: https://doi.org/10.1109/TMI.2014.2321777.

SPECT (single photon emission computed tomography)

SPECT, or less commonly, SPET [3], is a medical imaging technique that is based on conventional nuclear medicine imaging, using gamma rays, and tomographic reconstruction methods. It is «performed by using a gamma camera to acquire multiple two-dimensional (2D) images from multiple angles» [4]. «The images reflect functional information about patients similar to that obtained with positron emission tomography (PET). Both SPECT and PET (...) give information based on the spatial concentration of injected radiopharmaceuticals» [1]. It «is a type of nuclear imaging test that shows how blood flows to tissues and organs» [2]. It is very similar to conventional nuclear medicine planar imaging using a gamma camera (that is, scintigraphy), but, it is able to provide true three-dimensional (3D) information [3]. A computer is used to apply a tomographic reconstruction algorithm to the multiple 2D projections, yielding a 3D dataset. «This dataset may then be manipulated to show thin slices along any chosen axis of the body» [4]. SPECT can be used to complement any gamma imaging study, where a true 3D representation can be helpful, (e.g., tumor imaging, infection (leukocyte) imaging, thyroid imaging or bone scintigraphy). Because SPECT permits accurate localization in 3D space, it can be used to provide information about the localized function in internal organs, such as functional cardiac or brain imaging [3].

Bibliographic references:

[1] National Research Council (US) and Institute of Medicine (US) Committee on the Mathematics and Physics of Emerging Dynamic Biomedical Imaging. Mathematics and Physics of Emerging Biomedical Imaging. Washington (DC): National Academies Press (US); 1996. Chapter 5, Single Photon Emission Computed Tomography. Available at: https://www.ncbi.nlm.nih.gov/books/NBK232492/. Accessed October 15, 2017.

[2] SPECT (single photon emission computed tomography) scan. Mayfield Brain & Spine. 2016. Available at: https://www.mayfieldclinic.com/PE-SPECT.htm. Accessed October 15, 2017.

[3] Single-photon emission computed tomography. Enwikipediaorg. 2017. Available at: https://en.wikipedia.org/wiki/Single-photon_emission_computed_tomography. Accessed October 15, 2017.
[4] Hricak H, Akin O, Vargas HA. (2013). C. In: L. Brady and T. Yaeger, ed., Encyclopedia of Radiation Oncology, 1st ed. Springer-Verlag Berlin Heidelberg, pp.790.

Dia do Interno Radioncologia (Portuguese) (Radiation Oncology Resident's Day)

• Venue: October 20, 2017 - Hospital de Santa Maria, Centro Hospitalar Lisboa Norte, EPE, Lisbon, Portugal:

• Free registration, deadline: October 2, 2017 - diadointernospro@gmail.com
• Program:

New IMRT technique used for first time on head and neck cancer patient

I wanted to share this interesting News Item from ecancer: 'New IMRT technique used for first time on head and neck cancer patient' http://ecancer.org/news/12406-new-imrt-technique-used-for-first-time-on-head-and-neck-cancer-patient.php

Endorectal Brachytherapy Boost After External Beam Radiation Therapy in Elderly or Medically Inoperable Patients With Rectal Cancer: Primary Outcomes of the Phase 1 HERBERT Study

Endorectal Brachytherapy Boost After External Beam Radiation Therapy in Elderly or Medically Inoperable Patients With Rectal Cancer: Primary Outcomes of the Phase 1 HERBERT Study: To evaluate the toxicity and efficacy of the combination of external beam radiation therapy (EBRT) followed by high-dose-rate endorectal brachytherapy (HDREBT) boost in elderly and medically inoperable patients with rectal cancer.

Preoperative chemotherapy versus chemoradiotherapy in locally advanced adenocarcinomas of the oesophagogastric junction (POET): Long-term results of a controlled randomised trial

Preoperative chemotherapy versus chemoradiotherapy in locally advanced adenocarcinomas of the oesophagogastric junction (POET): Long-term results of a controlled randomised trial: Results of the PreOperative therapy in Esophagogastric adenocarcinoma Trial (POET)
showed some benefits when including radiotherapy into the preoperative treatment.
This article is reporting long-term results of this phase III study.

ITV (internal target volume)

It consists of an internal margin added to the CTV to compensate for internal physiologic movement and variations in size, shape, and position of the CTV [1]. It's an expansion of CTV for internal (e.g. breathing) movement [2].

Bibliographic references:

[1] Reiff J. E. (2013). C. In: L. Brady and T. Yaeger, ed., Encyclopedia of Radiation Oncology, 1st ed. Springer-Verlag Berlin Heidelberg, pp.343-399.

[2] Balter J. Target definition (margin selection) for radiotherapy (IMRT). aapmorg. 2017. Available at: https://www.aapm.org/meetings/03SS/Presentations/Balter.pdf. Accessed September 11, 2017.

Moulding a radiotherapy mask

Conformity index (CI)

It is defined as the ratio of the treated volume to the PTV (planning target volume) [1]. It is a tool for treatment plan analysis in conformal radiotherapy [2].

Bibliographic references:

[1] International Commission on Radiation Units and Measurements. ICRU Report 62. Prescribing, Recording and Reporting Photon Beam Therapy. Supplement to ICRU Report 50. Bethesda, MD: ICRU; 1999.

[2] Kataria T, Sharma K, Subramani V, et al. Homogeneity Index: An objective tool for assessment of conformal radiation treatments. J Med Phys. 2012 Oct;37(4):207-13. Available at https://doi.org/10.4103/0971-6203.103606.

PARP (poly-[adenosine diphosphate-ribose] polymerase)

Poly-(ADP)-ribose polymerase is «a family of proteins involved in a number of cellular processes involving mainly DNA [deoxyribonucleic acid] repair and programmed cell death. The PARP family comprises 17 members (10 putative). They have all very different structures and functions in the cell. One important function of PARP is assisting in the repair of single-strand DNA breaks [1]». It is «a SSB [single-strand break] detector protein» [2].
«Drugs which inhibit (...) PARP (...) are particularly effective in tumors with HR [homologous recombination] deficiencies, such as breast tumors with BCRA1 or BCRA2 [breast cancer 1 or 2] deficiencies. (...) probably (...) PARP inhibitors suppress SSB repair, resulting in greater numbers of unrepaired SSBs, which therefore have a greater chance of hitting a replication fork. Under normal circumstances, the resulting DSB [double-strand break] would be repaired by HR, so the absence or reduction of this backup pathway leads to a substantial increase in DSBs and thus cellular lethality [2].»

Bibliographic references:
[1] Tortora, G., Bergmann, L., Lindh, M., Cervantes-Ruiperez, A., Dziadziuszko, R., Eckhardt, S., Lenz, H., Normanno, N., Perez, D., Scarpa, A., Syrigos, K., Tabernero, J. and Troiani, T. (2014). ESMO glossary in molecular biology of cancer. Viganello-Lugano, Switzerland: European Society for Medical Oncology, p.127.

[2] Joiner, M. and Kogel, A. (2009). Basic clinical radiobiology. 1st ed. Boca Raton, Florida: CRC Press, p.24.

Cytoreduction

It is the debulking, or reduction «(...) of the size of, a cancerous tumor. Surgery and radiation therapy are two common cytoreductive treatments used to debulk tumors. Debulking means to remove as much of the cancer as possible [1].» «(...) "cytoreduction" refers to reducing the number of tumor cells [2].» «Tumor debulking may increase the chance that chemotherapy or radiation therapy will kill all the tumor cells. It may also be done to relieve symptoms or help the patient live longer [3].» 

Bibliographic references:

[1] CancerCenter.com. (2017). Cytoreductive Therapy : Cancer Glossary | CTCA. [online] Available at: http://www.cancercenter.com/terms/cytoreductive-therapy/ [Accessed 15 May 2017].

[2] En.wikipedia.org. (2017). Debulking. [online] Available at: https://en.wikipedia.org/wiki/Debulking [Accessed 15 May 2017].

[3] National Cancer Institute. (n.d.). NCI Dictionary of Cancer Terms. [online] Available at: https://www.cancer.gov/publications/dictionaries/cancer-terms?cdrid=46635 [Accessed 15 May 2017].

Adjuvant therapy

It is an «additional cancer treatment given after the primary treatment to lower the risk that (...) cancer will come back. Adjuvant therapy may include chemotherapy, radiation therapy, hormone therapy, targeted therapy, or biological therapy.»

Bibliographic reference: National Cancer Institute. (n.d.). NCI Dictionary of Cancer Terms. [online] Available at: https://www.cancer.gov/publications/dictionaries/cancer-terms?CdrID=45587 [Accessed 10 May 2017].

p53

It «(...) is one of the most commonly mutated tumor suppressors whose function is to regulate genes that control both cell cycle checkpoints and (...) apoptosis. Consequently, activation of p53 after irradiation can lead either to a block in proliferation or directly to cell death. (...) in unstressed normal cells, p53 is made continuously but is degraded and thus non-functional. Following DNA [deoxyribonucleic acid] damage, ATM [ataxia telangiectasia mutated] phosphorylates both p53 and MDM2 [murine double minute 2]. These events destabilize the p53-MDM2 interaction, and (...) p53 protein is no longer degraded. In addition to this stabilization, direct phosphorylation of p53 by ATM leads to its activation as a transcription factor and thus the upregulation of its many target genes [1].»

«Cells irradiated in the G1 phase are influenced by the action of p53. ATM protein is activated by double-strand DNA breaks and phosphorylates both MDM2 and p53. This leads to stabilization and activation of p53, which induces genes that can promote apoptosis (Bax [Bcl-2-associated X], Puma [p53 upregulated modulator of apoptosis]) and induces checkpoints. (...) cells are blocked at the G1/S border [1].»

Is has «(...) a mass of 53 kDa (hence its name); p53 protein is normally induced in cells having undergone DNA damage, (...); its principal effects are to stop the cell cycle and prevent the cell from undergoing mitosis; thus, DNA mutations/damage can either be repaired or a damaged cell can be eliminated from the organism, for example via apoptosis. p53 is also known as the guardian of the genome [2].»

Bibliographic references:

[1] Joiner, M. and Kogel, A. (2009). Basic clinical radiobiology. 1st ed. Boca Raton, Florida: CRC Press, p.17.

[2] Tortora, G., Bergmann, L., Lindh, M., Cervantes-Ruiperez, A., Dziadziuszko, R., Eckhardt, S., Lenz, H., Normanno, N., Perez, D., Scarpa, A., Syrigos, K., Tabernero, J. and Troiani, T. (2014). ESMO glossary in molecular biology of cancer. Viganello-Lugano, Switzerland: European Society for Medical Oncology, p.117.

Ratio

It's the relationship between two sets with different characteristics. The numerator is not included in the denominator. It is different from proportion.

Proportion

It's the relationship between the number of individuals who have a characteristic and the total population. The numerator is included in the denominator. It is different from ratio.

Symbols with short codes

In: Awesome Daily Staff. StumbleUpon. Stumbleuponcom. 2014. Available at: http://www.stumbleupon.com/su/2XigqH. Accessed February 25, 2017.

Lower urothelium (or lower transitional cell epithelium)

It coats the interior walls of the «urinary bladder, the ureters, the superior urethra, and the prostatic and ejaculatory ducts of the prostate.»

Bibliographic reference: Transitional epithelium. Enwikipediaorg. 2017. Available at: https://en.wikipedia.org/wiki/Transitional_epithelium. Accessed February 20, 2017.

Upper urothelium (or upper transitional cell epithelium)

It coats the interior walls of the pyelocaliceal cavities and ureter.

Bibliographic references: Rouprêt M, Babjuk M, Böhle A, et al. Upper Urinary Tract Urothelial Cell Carcinoma. EAU - European Association of Urology. 2017. Available at: https://uroweb.org/guideline/upper-urinary-tract-urothelial-cell-carcinoma/#3. Accessed February 20, 2017.

Urological organs

«The organs under the domain of urology include the kidneys, adrenal glands, ureters, urinary bladder, urethra, and the male reproductive organs (testes, epididymis, vas deferens, seminal vesicles, prostate, and penis).»

Bibliographic reference: Urology. Enwikipediaorg. 2016. Available at: https://en.wikipedia.org/wiki/Urology. Accessed February 20, 2017.

Redistribution

«Reassortment. The radiosensitivities of cells vary according to phases of the cell cycle.» «The duration of the cell cycle phases are: G1 = 1.5–14 h, S = 6–9 h, G2 = 1–5 h, and M = 0.5–1 h. The most sensitive are M and G2. The most resistant is S.» «Cells in the resistant phases of the cell cycle may progress into the sensitive phases in the next fraction, when radiation is given in fractions. Therefore, the probability of tumor cells to be exposed to radiation at sensitive phases increases. This probability will continue for the whole treatment, and the benefit from radiation will increase.»

Bibliographic reference: Beyzadeoglu M, Ozyigit G, Selek U. Radiation Oncology. 1st ed. Berlin: Springer; 2012:112-114.